Method and apparatus for supporting multi-path relay in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. More specifically, the present disclosure provides a method performed by a first terminal in a wireless communication system, the method comprising the steps of: receiving, from a second terminal, a signal for measuring a sidelink with the second terminal; and transmitting, to the second terminal or a base station, a measurement report including a result of measurement based on the signal, wherein the measurement report may include information indicating a measurement unit on which the result of the measurement is based.

Description

Method and device for supporting multi-path relay in wireless communication system

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for utilizing a multi-path relay in a wireless communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] The present disclosure provides a method and device for supporting multi-path relay in a wireless communication system, thereby providing a multi-path relay service.

[0009] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0010] The present disclosure relates to a method performed by a first terminal in a wireless communication system, the method comprising: receiving, from a second terminal, a signal for measurement of a sidelink with the second terminal; and transmitting, to the second terminal or a base station, a measurement report including a result of the measurement based on the signal, wherein the measurement report may include information indicating a measurement unit on which the result of the measurement is based.

[0011] In addition, the present disclosure relates to a method performed by a second terminal in a wireless communication system, the method comprising: transmitting, to a first terminal, a signal for measurement of a sidelink with the first terminal; and receiving, from the first terminal, a measurement report including a result of the measurement based on the signal, wherein the measurement report may include information indicating a measurement unit on which the result of the measurement is based.

[0012] In addition, the present disclosure relates to a first terminal in a wireless communication system, wherein the first terminal comprises: a transceiver; and a controller connected to the transceiver, wherein the controller is configured to: receive a signal for measurement of a sidelink with the second terminal from a second terminal, and transmit a measurement report including a result of the measurement based on the signal to the second terminal or a base station, wherein the measurement report may include information indicating a measurement unit on which the result of the measurement is based.

[0013] In addition, the present disclosure provides a second terminal in a wireless communication system, wherein the second terminal includes a transceiver; and a controller connected to the transceiver, wherein the controller is configured to: transmit a signal for measurement of a sidelink with the first terminal to the first terminal, and receive, from the first terminal, a measurement report including a result of the measurement based on the signal, wherein the measurement report may include information indicating a measurement unit on which the result of the measurement is based.

[0014] According to one embodiment of the present disclosure, a device and method for effectively providing a service in a wireless communication system can be provided.

[0015] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0016] FIG. 1 is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0017] FIG. 2 is a diagram illustrating a user plane wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0018] FIG. 3 is a diagram illustrating a control plane wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0019] FIG. 4 is a diagram illustrating the structure of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0020] FIG. 5 is a diagram illustrating the structure of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0021] FIG. 6A is a diagram illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0022] FIG. 6b is a diagram illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0023] FIG. 6c is a diagram illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0024] FIG. 6d is a diagram illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0025] FIG. 6e is a diagram illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0026] FIG. 7a is a diagram illustrating examples of a transmission method of sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0027] FIG. 7b is a diagram illustrating examples of a transmission method of sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0028] FIG. 8 is a diagram illustrating an example of a sidelink resource pool in a wireless communication system according to an embodiment of the present disclosure.

[0029] FIG. 9 is a diagram illustrating an example of a signal flow for allocating transmission resources of a side link in a wireless communication system according to an embodiment of the present disclosure.

[0030] FIG. 10 is a diagram illustrating another example of a signal flow for allocating transmission resources of a side link in a wireless communication system according to an embodiment of the present disclosure.

[0031] FIG. 11 is a diagram illustrating an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0032] FIG. 12a is a diagram illustrating a user plane wireless protocol structure of a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0033] FIG. 12b is a diagram illustrating a control plane wireless protocol structure of a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0034] FIG. 12c is a diagram illustrating a user plane wireless protocol structure of a multi-path terminal-network relay using terminal-to-terminal communication not defined in 3GPP according to an embodiment of the present disclosure.

[0035] FIG. 12d is a diagram illustrating a control plane wireless protocol structure of a multi-path terminal-network relay using terminal-to-terminal communication not defined in 3GPP according to an embodiment of the present disclosure.

[0036] FIG. 13A is a diagram of a signal flow for transmitting a threshold condition of a multi-path terminal-network relay to a relay terminal according to an embodiment of the present disclosure.

[0037] FIG. 13b is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0038] FIG. 13c is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0039] FIG. 14A is a diagram of a signal flow for transmitting a threshold condition of a multi-path terminal-network relay to a remote terminal according to an embodiment of the present disclosure.

[0040] FIG. 14b is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0041] FIG. 15 is a flowchart illustrating a method of using a threshold value for multi-path terminal-network relay operation by a terminal according to an embodiment of the present disclosure.

[0042] FIG. 16 is a flowchart illustrating a process in which a terminal performs measurement and measurement reporting in a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0043] FIG. 17 is a flowchart illustrating a process in which a terminal performs measurement and measurement reporting in a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0044] FIG. 18 is a flowchart illustrating a process by which a terminal selects or reselects a relay terminal during a multi-path terminal-network relay operation according to an embodiment of the present disclosure.

[0045] FIG. 19 is a flowchart illustrating a process in which a terminal reports an indirect path failure to a base station during a multi-path terminal-network relay operation according to an embodiment of the present disclosure.

[0046] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0047] In describing the embodiments, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to convey the gist of the present disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0048] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0049] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals designate like elements throughout the disclosure. In addition, when describing the present disclosure, if a specific description of a related function or configuration is determined to unnecessarily obscure the gist of the present disclosure, a detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions of the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout the present disclosure.

[0050] In explaining the embodiments of the present disclosure, the main target is New Radio (NR), which is a wireless access network, and the core network, packet core 5G System, or 5G Core Network, or NG Core (Next Generation Core) in the 5G mobile communication standard specified by 3GPP (3rd Generation Partnership Project), a mobile communication standard standardization organization. However, the main gist of the present disclosure can be applied to other communication systems with similar technical backgrounds with slight modifications within a range that does not significantly deviate from the scope of the present disclosure, and this will be possible at the discretion of a person skilled in the art of the present disclosure.

[0051] For convenience of explanation, some terms and names defined in the 3GPP standards (standards for 5G, NR, LTE, or similar systems) may be used below. However, the present disclosure is not limited by these terms and names, and can be equally applied to systems conforming to other standards.

[0052] Hereinafter, terms used in the description to identify connection nodes, terms referring to network objects (network entities), terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms used in the present disclosure, and other terms referring to objects with equivalent technical meanings may be used.

[0053] Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

[0054] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0055] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0056] Here, the term '~ unit' used in the present embodiment means software or hardware components such as FPGA (field programmable gate array) or ASIC (application specific integrated circuit), and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Therefore, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, the components and '~parts' may be implemented to play one or more central processing units (CPUs) within the device or secure multimedia card. In addition, in the embodiment, the '~part' may include one or more processors.

[0057] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0058] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0059] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0060] In addition, standardization of radio interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) to provide nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) to simplify random access procedures is also in progress, and standardization of system architecture / services for 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal is also in progress.

[0061] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0062] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0063] The present disclosure relates to a method and device for supporting a multi-path (MP) relay that simultaneously utilizes a direct path and an indirect path in a UE-to-Network (U2N) relay. Specifically, the multi-path relay may be comprised of a terminal capable of operating as a relay terminal in a multi-path relay, a terminal capable of operating as a remote terminal in the multi-path relay, and a base station supporting multi-path relay. The multi-path remote terminal can communicate with the base station via the multi-path relay, and the terminal-to-terminal link and the terminal-to-base station link that support such data flow can be integrated and referred to as an indirect path. In addition, the multi-path remote terminal can communicate directly with the base station, and the terminal-to-base station link for direct communication can be referred to as a direct path. The base station can control the multi-path operation by adding, modifying, or deleting indirect paths and direct paths to the multi-path remote terminal. The base station can control the operation of multi-path remote terminals and multi-path relay terminals by setting different threshold conditions that can be used in U2N and threshold conditions that can be used in MP. The base station can transmit an instruction to set the MP operation to the multi-path remote terminals and multi-path relay terminals in order to control the terminals to which the threshold conditions that can be used in MP are applied. The base station can set the multi-path remote terminals and multi-path relay terminals to report the measurement results for the surrounding base stations or surrounding terminals periodically or when a specific condition is satisfied in order to control the indirect path and direct path. At this time, the base station can set the unit to be measured (e.g., SL-RSRP or SD-RSRP) to the terminal, and the terminal can explicitly notify the base station of the unit set to be measured by including it in the measurement result report.To manage direct or indirect paths of multi-path remote terminals at a base station, relay terminal selection or reselection of multi-path remote terminals may not be performed. Multi-path remote terminals may notify the base station of whether to use a terminal-to-terminal link based on instructions from a higher layer.

[0064] FIG. 1 is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0065] Referring to FIG. 1, a wireless access network of a next-generation mobile communication system (hereinafter referred to as NR or 5G) may be configured to include a next-generation base station (new radio node B, hereinafter referred to as NR gNB, gNB or base station) (120) and an NR CN (110, new radio core network). A user terminal (new radio user equipment, hereinafter referred to as NR UE or terminal) (150) may access an external network through the NR gNB (120) and the NR CN (110).

[0066] In Fig. 1, the NR gNB (120) may correspond to the eNB (140) of the LTE system. The NR gNB (120) is connected to the NR UE (150) via a wireless channel and may provide a service superior to that of the eNB (140). In the next-generation mobile communication system, since all user traffic is serviced through a shared channel, a device that collects status information such as the buffer status of UEs, available transmission power status, and channel status and performs scheduling is required, and the NR gNB (120) may be responsible for this. One NR gNB (120) can typically control multiple cells. In order to implement ultra-high-speed data transmission compared to LTE, a bandwidth greater than the maximum bandwidth of LTE can be used, and beamforming technology can be additionally grafted using the OFDM method as a wireless access technology. In addition, an Adaptive Modulation and Coding (AMC) method that determines a modulation scheme and a channel coding rate according to the channel status of the terminal can be applied. The NR CN (110) can perform functions such as mobility support and QoS settings. The NR CN (110) is a device that handles various control functions as well as mobility management functions for terminals and can be connected to multiple base stations. In addition, the next-generation mobile communication system can be linked with the LTE system, and the NR CN (110) can be connected to the MME (130) through a network interface. The MME (130) can be connected to the eNB (140).

[0067] FIG. 2 is a diagram illustrating a user plane wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0068] Referring to FIG. 2, the user plane wireless protocol of the next generation mobile communication system may be composed of SDAP (211), PDCP (212), RLC (213), MAC (214), and / or PHY (215) in the terminal (210). The base station (220) may be composed of SDAP (221), PDCP (222), RLC (223), MAC (224), and / or PHY (225). In the present disclosure, the term “may be composed of” may be replaced with the term “may include.” For example, the user plane wireless protocol of the next generation mobile communication system may be composed of SDAP (211), PDCP (212), RLC (213), MAC (214), and / or PHY (215) in the terminal (210).

[0069] The functions of SDAP (211, 221) may include at least some of the following functions, but are not limited thereto.

[0070] - Mapping between a QoS flow and a data radio bearer

[0071] - Marking QoS flow ID (QFI) in both DL and UL packets

[0072] The main functions of PDCP (212, 222) may include, but are not limited to, some of the following functions.

[0073] - Transfer of data (user plane or control plane)

[0074] - Maintenance of PDCP sequence numbers (PDCP SNs)

[0075] - Header compression and decompression using the ROHC protocol

[0076] - Header compression and decompression using EHC protocol

[0077] - Compression and decompression of uplink PDCP SDUs (DEFLATE based UDC only)

[0078] - Ciphering and deciphering

[0079] - Integrity protection and integrity verification

[0080] - Timer-based SDU discard

[0081] - Routing for split bearers (For split bearers, routing)

[0082] - Duplication

[0083] - Reordering and in-order delivery

[0084] - Out-of-order delivery

[0085] - Duplicate discarding

[0086] The main functions of RLC (213, 223) may include, but are not limited to, some of the following functions.

[0087] - Transfer of upper layer PDUs

[0088] - Sequence numbering independent of the one in PDCP (UM and AM)

[0089] - Error Correction through ARQ (AM only)

[0090] - Segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs

[0091] - Reassembly of SDU (AM and UM)

[0092] - Duplicate Detection (AM only)

[0093] - RLC SDU discard (AM and UM)

[0094] - RLC re-establishment

[0095] - Protocol error detection (AM only)

[0096] The main functions of MAC (214, 224) may include at least some of the following functions, but are not limited thereto.

[0097] - Mapping between logical channels and transport channels

[0098] - Multiplexing of MAC SDUs from one or more logical channels onto transport blocks (TB) to be delivered to the physical layer on transport channels

[0099] - Demultiplexing of MAC SDUs belonging to one or more logical channels (demultiplexing of MAC SDUs to one or different logical channels from transport blocks (TB) delivered from the physical layer on transport channels)

[0100] - Scheduling information reporting

[0101] - Error correction through HARQ

[0102] - Logical channel prioritization

[0103] - Priority handling between overlapping resources of one UE

[0104] The PHY layer (215, 225) can encode and modulate upper layer data to generate OFDM symbols, convert them into RF band signals, and transmit them via an antenna. In addition, the PHY layer (215, 225) can demodulate and decode received OFDM symbols and transmit them to the upper layer.

[0105] FIG. 3 is a diagram illustrating a control plane wireless protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0106] Referring to FIG. 3, the control plane wireless protocol of the next-generation mobile communication system may be composed of RRC (311), PDCP (312), RLC (313), MAC (314), and / or PHY (315) in a terminal (310). It may be composed of RRC (321), PDCP (322), RLC (323), MAC (324), and / or PHY (325) in a base station (320).

[0107] The functions of RRC (311, 321) may include at least some of the following functions.

[0108] - Broadcast of System Information related to AS and NAS

[0109] - Paging initiated by 5GC or NG-RAN

[0110] - Establishment, maintenance, and release of an RRC connection between the UE and NG-RAN, including: Addition, modification, and release of carrier aggregation; Addition, modification, and release of dual connectivity in NR or between E-UTRA and NR.

[0111] - Security functions including key management

[0112] - Establishment, configuration, maintenance and release of Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs)

[0113] - Terminal mobility support (Mobility functions including: Handover and context transfer; UE cell selection and reselection and control of cell selection and reselection; Inter-RAT mobility.)

[0114] - QoS management functions

[0115] - UE measurement reporting and control of the reporting

[0116] - Detection of and recovery from radio link failure

[0117] - NAS message transfer (NAS message transfer to / from NAS from / to UE)

[0118] The main functions of PDCP (312, 322), RLC (313, 323), MAC (314, 324), and / or PHY (315 / 325) may follow the example of FIG. 2.

[0119] FIG. 4 is a diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0120] Referring to FIG. 4, the base station may include a transceiver (405), a control unit (410), and a storage unit (415). The transceiver (405), the control unit (410), and the storage unit (415) may operate according to the communication method of the base station described above. The network device may also correspond to the structure of the base station. However, the components of the base station are not limited to the examples described above. For example, the base station may include more or fewer components than the components described above. For example, the base station may include a transceiver (405) and a control unit (410). In addition, the transceiver (405), the control unit (410), and the storage unit (415) may be implemented in the form of a single chip.

[0121] The transceiver (405) is a general term for the receiving unit and the transmitting unit of the base station, and can transmit and receive signals with terminals, other base stations, or other network devices. At this time, the transmitted and received signals may include control information and data. The transceiver (405) may, for example, transmit system information to the terminal, and may transmit a synchronization signal or a reference signal. To this end, the transceiver (405) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-down-converts a received signal. However, this is only one embodiment of the transceiver (405), and the components of the transceiver (405) are not limited to the RF transmitter and RF receiver. The transceiver (405) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (405) can receive a signal through a communication channel (e.g., a wireless channel) and output it to the control unit (410), and transmit the signal output from the control unit (410) through the communication channel. In addition, the transceiver (405) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a terminal, another base station, or another entity through a wired or wireless network.

[0122] The storage unit (415) can store programs and data required for the operation of the base station. In addition, the storage unit (415) can store control information or data included in signals acquired from the base station. The storage unit (415) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, the storage unit (415) can store at least one of information transmitted and received through the transceiver unit (405) and information generated through the control unit (410).

[0123] In the present disclosure, the control unit (410) may be defined as a circuit or application-specific integrated circuit, or at least one processor. The processor may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. The control unit (410) may control the overall operation of the base station according to the embodiment proposed in the present disclosure. For example, the control unit (410) may control the signal flow between each block to perform operations according to the flowchart described above.

[0124] FIG. 5 is a diagram illustrating the structure of a terminal according to an embodiment of the present disclosure.

[0125] Referring to FIG. 5, the terminal may include a transceiver (505), a control unit (510), and a storage unit (515). The transceiver (505), the control unit (510), and the storage unit (515) may operate according to the communication method of the terminal described above. However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the components described above. For example, the terminal may include a transceiver (505) and a control unit (510). In addition, the transceiver (505), the control unit (510), and the storage unit (515) may be implemented in the form of a single chip.

[0126] The transceiver (505) is a general term for the receiving unit and the transmitting unit of the terminal, and can transmit and receive signals with a base station, another terminal, or a network entity. The signals transmitted and received with the base station may include control information and data. The transceiver (505) may, for example, receive system information from the base station and may receive a synchronization signal or a reference signal. To this end, the transceiver (505) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-downconverts the received signal. However, this is only one embodiment of the transceiver (505), and the components of the transceiver (505) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (505) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (505) can receive a signal through a wireless channel and output it to the control unit (510), and transmit the signal output from the control unit (510) through the wireless channel. In addition, the transceiver (505) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a network entity through a wired or wireless network.

[0127] The storage unit (515) can store programs and data necessary for the operation of the terminal. In addition, the memory (515) can store control information or data included in signals obtained from the terminal. The storage unit (515) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD.

[0128] In the present disclosure, the control unit (510) may be defined as a circuit or application-specific integrated circuit, or at least one processor. The processor may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs. The control unit (510) may control the overall operation of the terminal according to the embodiment proposed in the present disclosure. For example, the control unit (510) may control the signal flow between each block to perform operations according to the flowchart described above.

[0129] FIGS. 6A to 6E are diagrams illustrating examples of scenarios for sidelink communication in a wireless communication system according to an embodiment of the present disclosure.

[0130] FIG. 6a illustrates an in-coverage (IC) scenario where sidelink terminals (620, 625) are located within the coverage (610) of a base station (600).

[0131] Referring to FIG. 6A, sidelink terminals (620, 625) can receive data and control information from a base station (600) via a downlink (DL), or transmit data and control information to the base station (600) via an uplink (UL). At this time, the data and control information may be data and control information for sidelink communication, or data and control information for general cellular communication rather than sidelink communication. In addition, the sidelink terminals (620, 625) can transmit and receive data and control information for sidelink communication via the sidelink. In addition, the first terminal (620) can receive data and control information from the base station (600) via a direct path via the DL or UL, or can receive data and control information from the base station (600) via an indirect path via a relay of the second terminal (625). The first terminal (620) may be referred to as a remote terminal (remote UE), and the second terminal (625) may be referred to as a relay terminal (relay UE). A scenario in which the first terminal (620) accesses the base station (600) through the second terminal (625) may be referred to as a UE-to-Network relay (U2N relay). In addition, the first terminal (620) may transmit and receive data and control information with the base station (600) by simultaneously using a direct path and an indirect path, and such a scenario may be referred to as a multi-path relay.

[0132] FIG. 6b illustrates a case of partial coverage (PC) in which a first terminal (620) among side link terminals is located within the coverage (610) of the base station (600) and a second terminal (625) is located outside the coverage (610) of the base station (600).

[0133] Referring to FIG. 6B, a first terminal (620) located within the coverage (610) of a base station (600) can receive data and control information from the base station (600) via downlink or transmit data and control information to the base station (600) via uplink. A second terminal (625) located outside the coverage of the base station (600) cannot directly receive data and control information from the base station (600) via downlink and cannot directly transmit data and control information to the base station (600) via uplink. The second terminal (625) can transmit and receive data and control information for sidelink communication with the first terminal (620) via sidelink.

[0134] FIG. 6c is an example of a case where sidelink terminals (e.g., first terminal (620), second terminal (625)) are located out of coverage (OOC) of the base station (600) (610).

[0135] Referring to FIG. 6c, the first terminal (620) and the second terminal (625) cannot receive data and control information from the base station via the downlink, and cannot transmit data and control information to the base station via the uplink. The first terminal (620) and the second terminal (625) can transmit and receive data and control information for sidelink communication via the sidelink.

[0136] FIG. 6d illustrates a case where a first terminal (620) and a second terminal (625) performing sidelink communication are connected to (e.g., in an RRC connected state) or camping on (e.g., in an RRC disconnected state, i.e., in an RRC idle or inactive state) different base stations (e.g., the first base station (600) and the second base station (605)) and perform inter-cell sidelink communication. At this time, referring to FIG. 6d, the first terminal (620) may be a sidelink transmitting terminal and the second terminal (625) may be a sidelink receiving terminal. Alternatively, the first terminal (620) may be a sidelink receiving terminal and the second terminal (625) may be a sidelink transmitting terminal. A first terminal (620) can receive a sidelink-only SIB (system information block) from a base station (600) to which it is connected (or at which it is camping), and a second terminal (625) can receive a sidelink-only SIB from another base station (605) to which it is connected (or at which it is camping). At this time, the information of the sidelink-only SIB received by the first terminal (620) and the information of the sidelink-only SIB received by the second terminal (625) may be different from each other. Therefore, in order to perform sidelink communication between terminals located in different cells, unification of information or additional assumptions and interpretation methods may be required. In addition, the first terminal (620) can receive data and control information from the first base station (600) through a direct path via DL or UL, or can receive data and control information from the second base station (605) through an indirect path via a relay of the second terminal (625). The first terminal (620) may be referred to as a remote terminal, and the second terminal (625) may be referred to as a relay terminal. A scenario in which the first terminal (620) connects to the second base station (605) via the second terminal (625) may be referred to as a terminal-network relay.In addition, the first terminal (620) can transmit and receive data and control information with the first base station (600) and the second base station (605) by simultaneously using a direct path and an indirect path, and this scenario can be called a multi-path relay.

[0137] FIG. 6E illustrates a case where a first terminal (620), a second terminal (625), and a third terminal (630) performing sidelink communication configure a terminal-to-terminal relay and perform sidelink communication. At this time, referring to FIG. 6E, the first terminal (620) may be a source End UE, which is an end terminal of the terminal-to-terminal relay, and the third terminal (630) may be a target End UE, which is an end terminal of the terminal-to-terminal relay. Alternatively, the first terminal (620) may be a target End UE, which is an end terminal of the terminal-to-terminal relay, and the third terminal (630) may be a source End UE, which is an end terminal of the terminal-to-terminal relay. The second terminal (625) may be a relay UE that relays data between end terminals in the terminal-to-terminal relay. The first terminal (620), the second terminal (625), and the third terminal (630) may be connected to the same or different base stations (e.g., RRC connected state), camped (e.g., RRC disconnected state, i.e., RRC idle or inactive state), performed inter-cell sidelink communication, or in OOC, as shown in the examples of FIGS. 6A to 6D.

[0138] In the examples of FIGS. 6A to 6E, for the sake of convenience of explanation, a sidelink system composed of two or three terminals (e.g., a first terminal (620), a second terminal (625), and a third terminal (630)) is described as an example. However, the present disclosure is not limited thereto and may also be applied to a sidelink system in which three or more terminals participate. In addition, the uplink and downlink between the base station (600) and the sidelink terminals may be referred to as a Uu interface, and the sidelink between the sidelink terminals may be referred to as a PC5 interface. In addition, a sidelink terminal located in an OOC where the base station (600) and the Uu interface are not connected may indirectly receive data and control information from the base station through a relay of another sidelink terminal located in an IC where the base station and the Uu interface are connected. In the following description, the uplink or downlink and the Uu interface may be used interchangeably, and the sidelink and the PC5 interface may be used interchangeably.

[0139] Meanwhile, in the present disclosure, a terminal may refer to a vehicle supporting vehicular-to-vehicular (V2V) communication, a vehicle supporting vehicular-to-pedestrian (V2P) communication, or a pedestrian's handset (e.g., a smartphone), a vehicle supporting vehicular-to-network (V2N) communication, or a vehicle supporting vehicular-to-infrastructure (V2I) communication. In addition, in the present disclosure, a terminal may refer to a road side unit (RSU) equipped with a terminal function, an RSU equipped with a base station function, or an RSU equipped with a part of a base station function and a part of a terminal function. In addition, it may refer to a terminal that supports proximity service (hereinafter referred to as ProSe) and terminal-to-terminal relay (e.g., end UE or relay UE of terminal-to-terminal relay) or terminal-to-network relay (e.g., remote UE or relay UE of terminal-to-network relay) using proximity service.

[0140] Additionally, in the present disclosure, a base station may be a base station that supports both sidelink and general cellular communication, or a base station that supports only sidelink. In this case, the base station may be a 5G base station (gNB), a 4G base station (eNB), or an RSU. Therefore, in the present disclosure, the base station may also be referred to as an RSU.

[0141] Figures 7a and 7b illustrate examples of transmission methods for sidelink communication in a wireless communication system according to an embodiment of the present disclosure. Figure 7a illustrates a unicast method, and Figure 7b illustrates a groupcast method.

[0142] Referring to FIG. 7a, a transmitting terminal (700) and a receiving terminal (705) can perform one-to-one communication (710). A transmission method such as FIG. 7a may be referred to as unicast communication.

[0143] Referring to FIG. 7b, transmitting terminals (730, 745) and receiving terminals (735, 740, 750, 755, 760) can perform one-to-many communication. A transmission method such as FIG. 7b may be referred to as groupcast or multicast.

[0144] In Fig. 7b, a first terminal (730), a second terminal (735), and a third terminal (740) form one group and perform groupcast communication, and a fourth terminal (745), a fifth terminal (750), a sixth terminal (755), and a seventh terminal (760) form another group and perform groupcast communication. The terminals perform groupcast communication within the group to which they belong, and can perform unicast, groupcast, or broadcast communication with at least one other terminal belonging to different groups. In Fig. 7b, two groups are exemplified, but the present disclosure is not limited thereto and can be applied even when a larger number of groups are formed.

[0145] Meanwhile, although not illustrated in FIG. 7A or FIG. 7B , sidelink terminals may also perform broadcast communication. Broadcast communication refers to a method in which all sidelink terminals receive data and control information transmitted by a sidelink transmitting terminal via the sidelink. For example, in FIG. 7B , if the first terminal (730) is a transmitting terminal, the remaining terminals (735, 740, 745, 750, 755, and 760) can receive data and control information transmitted by the first terminal (730).

[0146] The aforementioned sidelink unicast communication, groupcast communication, and broadcast communication can be supported in an in-coverage scenario, a partial-coverage scenario, or an out-of-coverage scenario.

[0147] FIG. 8 illustrates an example of a sidelink resource pool in a wireless communication system according to an embodiment of the present disclosure. A resource pool may be defined as a set of resources in the time and frequency domains used for sidelink transmission and reception.

[0148] Within a resource pool, a resource allocation unit on the time axis can be one or more orthogonal frequency division multiplexing (OFDM) symbols. Additionally, a resource allocation unit on the frequency axis can be one or more physical resource blocks (PRBs).

[0149] When a resource pool is allocated in the time domain and frequency domain, an area comprised of resources indicated by hatching represents an area set as a resource pool in time and frequency. While the present disclosure describes a case where a resource pool is allocated non-contiguously in time, the present disclosure is not limited thereto and can also be applied to a case where a resource pool is allocated continuously in time. Furthermore, while the present disclosure describes a case where a resource pool is allocated continuously in frequency, the present disclosure is not limited thereto and can also be applied to a case where a resource pool is allocated non-contiguously in frequency.

[0150] Referring to FIG. 8, the time domain (800) of the configured resource pool exemplifies a case where resources are allocated non-contiguously in the time domain. In the time domain (800) of the resource pool, the unit of resource allocation on the time axis (resource granularity) may be a slot. Specifically, one slot composed of 14 OFDM symbols may be the basic unit of resource allocation on the time axis. Referring to the time domain (800) of the configured resource pool, shaded slots represent slots allocated to the resource pool in time, and the slots allocated to the resource pool in time may be indicated using system information. For example, the slots allocated to the resource pool in time may be indicated using the time-based resource pool configuration information in the SIB. Specifically, at least one slot set to the resource pool in time may be indicated through a bitmap. Referring to FIG. 8, physical slots (800) belonging to a non-contiguous resource pool on the time axis can be mapped to logical slots (825). In general, a set of slots belonging to a resource pool for a physical sidelink shared channel (PSSCH) can be expressed as (t0, t1, …, ti, …, tTmax).

[0151] Referring to FIG. 8, the frequency domain (805) of the configured resource pool exemplifies a case where resources are allocated consecutively in the frequency domain. In the frequency domain (805) of the resource pool, the unit of resource allocation on the frequency axis may be a subchannel (810). Specifically, one subchannel (810) composed of one or more resource blocks (RBs) may be defined as a basic unit of resource allocation on the frequency. That is, the subchannel (810) may be defined as an integer multiple of an RB. Referring to FIG. 8, the subchannel size (sizeSubchannel) may be composed of five consecutive PRBs, but the present disclosure is not limited thereto, and the size of the subchannel may be set differently. In addition, one subchannel is generally composed of consecutive PRBs, but does not necessarily have to be composed of consecutive PRBs. The subchannel (810) may be a basic unit of resource allocation for the PSSCH. Additionally, a subchannel for the physical sidelink feedback channel (PSFCH) can be defined independently of the PSSCH.

[0152] Referring to FIG. 8, the starting position of a subchannel on a frequency in a resource pool can be indicated by startRB-Subchannel (815). When resource allocation on the frequency axis is performed in units of subchannels (810), the resource pool configuration on the frequency can be performed using configuration information for the RB index (startRB-Subchannel) (815) at which the subchannel starts, information for indicating how many RBs the subchannel consists of (sizeSubchannel) (810), and the total number of subchannels (numSubchannel). In addition, the resource pool configuration on the frequency can also be performed using configuration information for the RB index (EndRB-Subchannel) (820) at which the subchannel ends. According to various embodiments, the subchannels allocated to the resource pool on the frequency can be indicated using system information. For example, at least one of startRB-Subchannel, sizeSubchannel, EndRB-SubChannel, and numSubchannel can be indicated as frequency resource pool configuration information in the SIB. If the subchannel for the PSFCH is defined independently from the PSSCH, the subchannel configuration information of the PSFCH and the PSSCH can be indicated to the terminal respectively.

[0153] FIG. 9 illustrates an example of a signal flow for allocating sidelink transmission resources in a wireless communication system according to an embodiment of the present disclosure. FIG. 9 illustrates signal exchange between a transmitting terminal (901), a receiving terminal (902), and a base station (903).

[0154] As described below, the method by which a base station allocates transmission resources for sidelink communication may be referred to as Mode 1. Mode 1 is a method based on scheduled resource allocation by the base station. More specifically, in Mode 1 resource allocation, the base station can allocate resources used for sidelink transmission to RRC-connected terminals according to a dedicated scheduling method. Since the base station can manage the resources used for sidelink transmission, scheduled resource allocation can be advantageous for interference management and resource pool management (e.g., dynamic allocation and / or configured grant (CG)).

[0155] Referring to FIG. 9, in operation 907, a transmitting terminal (901) that is camping on a cell (905) may receive a sidelink SIB from a base station (903). In operation 909, a receiving terminal (902) may monitor sidelink communication based on a sidelink SIB or an RRC message received from a base station (e.g., 903), or an Rx resource pool included in pre-configuration. Here, the receiving terminal (902) refers to a terminal that receives data transmitted by the transmitting terminal (901). The sidelink SIB may be transmitted periodically or on demand. In addition, the sidelink SIB may include at least one of sidelink resource pool information for sidelink communication, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. Although operations 907 and 909 have been described sequentially above, this is for convenience of explanation, and operations 907 and 909 can be performed in parallel.

[0156] In operation 913, when data traffic for sidelink communication is generated in the transmitting terminal (901), the transmitting terminal (901) may initiate an RRC connection procedure with the base station (903) to request transmission resources (915). Here, the RRC connection between the transmitting terminal (901) and the base station (903) may be referred to as Uu-RRC. The Uu-RRC connection may be performed before the data traffic of the transmitting terminal (901) is generated. In addition, in case of mode 1, the transmitting terminal (901) may perform transmission to the receiving terminal (902) via the sidelink when the Uu-RRC connection is established between the base station (903) and the receiving terminal (902). In addition, in case of mode 1, the transmitting terminal (901) may perform transmission to the receiving terminal (902) via the sidelink even when the Uu-RRC connection is not established between the base station (903) and the receiving terminal (902).

[0157] In operation 915, the transmitting terminal (901) may request the base station (903) for transmission resources for transmitting sidelink data to the receiving terminal (902). At this time, the transmitting terminal (901) may request the base station (903) for transmission resources for the sidelink using at least one of a physical uplink control channel (PUCCH), an RRC message, or MAC CE. For example, when MAC CE is used, the MAC CE may be a MAC CE for a buffer status report having a new format that includes at least one of an indicator for indicating that it is a buffer status report (BSR) for sidelink communication and information on the size of data stored in a buffer for device-to-device (D2D) communication (or V2X communication). Such a MAC CE may be referred to as a sidelink BSR MAC CE. In addition, when PUCCH is used, the transmitting terminal (901) can request sidelink resources through bits of a scheduling request (SR) transmitted through an uplink physical control channel. In addition, when RRC is used, the transmitting terminal (901) can transmit information about frequencies for transmission and reception of various types of sidelink communications, including sidelink discovery, sidelink data communication, and sidelink relay communication, and information about the receiving terminal (902) to the base station through Uu-RRC, and at least one of the following information can be included through the same or different RRC messages.

[0158] * Frequency to be used for reception in sidelink communication

[0159] * Frequency to be used for transmission in sidelink communication

[0160] * Types of sidelink data transmitted in sidelink communication

[0161] * Period and size of sidelink data transmitted in sidelink communication

[0162] * Information on the target terminal receiving sidelink data transmitted in sidelink communication (target terminal ID, terminal capability, DRX information, etc.)

[0163] * QoS information of sidelink data transmitted in sidelink communication

[0164] * Cast type of sidelink data transmitted in sidelink communication

[0165] * RLC mode of sidelink data transmitted in sidelink communication

[0166] In operation 915, PUCCH, MAC CE, and RRC messages can be used independently or mixed together depending on the purpose. In addition, operation 915 is described after operation 913, but this is for convenience of explanation, and can also be used to request resources for sidelink data to be transmitted in the unicast layer-2 link establishment procedure (911) for establishing a PC5 unicast link between a transmitting terminal (901) and a receiving terminal (902), and can be performed in parallel or simultaneously with other operations.

[0167] In operation 917, the base station (903) can transmit an RRC message containing information on transmission resources to be used by the transmitting terminal (901) to the transmitting terminal (901).

[0168] In operation 919, the base station (903) can transmit DCI (downlink control information) to the transmitting terminal (901) via PDCCH.

[0169] Through operations 917 to 919, the base station (903) can instruct the transmitting terminal (901) to schedule sidelink communication with the receiving terminal (902). More specifically, the base station (903) can allocate sidelink transmission resources to the transmitting terminal (901) according to at least one of a dynamic grant (DG) method or a configured grant (CG) method.

[0170] In the case of the dynamic grant (DG) scheme, the base station (903) can allocate resources for at least one transport block (TB) transmission by transmitting a DCI (919) to the transmitting terminal (901). Sidelink scheduling information included in the DCI can include resource pool information, parameters related to initial transmission time and / or retransmission transmission time, and parameters related to a frequency allocation location information field. The DCI for the dynamic grant scheme can be CRC (cyclic redundancy check) scrambled based on a sidelink radio network temporary identifier (SL-RNTI) to indicate that the transmission resource allocation scheme is the dynamic grant scheme.

[0171] In the case of the configuration grant (CG) method, the base station (903) can periodically allocate resources for transmitting at least one TB or set the periodicity of the sidelink CG through an RRC message (917). Additionally, the base station (903) can activate and / or deactivate an existing configured CG or instruct retransmission by transmitting a DCI to the transmitting terminal (901). The sidelink scheduling information included in the DCI can include parameters related to the initial transmission time and / or the retransmission time, and parameters related to the frequency allocation location information field. In the case of the configuration grant method, the initial transmission time and / or the retransmission time and the frequency allocation location can be determined according to the transmitted DCI, and the resources can be repeated at the periodic interval of the CG. The DCI for the configuration grant scheme may be CRC scrambled based on the sidelink configured scheduling radio network temporary identifier (SL-CS-RNTI) to indicate that the transmission resource allocation scheme is the configuration grant scheme. Furthermore, the configuration grant scheme may be categorized into Type 1 CG and Type 2 CG.

[0172] When broadcast transmission is performed between transmitting and receiving terminals (901, 902), in operations 921 and 923, the transmitting terminal (901) can broadcast SCI and data to at least one receiving terminal (e.g., 902) via PSCCH and PSSCH without PC5 unicast link connection.

[0173] When unicast or groupcast transmission is performed between transmitting and receiving terminals (901, 902), in operation 911, the transmitting terminal (901) can perform a unicast layer-2 link establishment procedure (911) for direct communication with other terminals (e.g., receiving terminal (902)). At this time, the upper layer (e.g., ProSe or V2X layer) of the transmitting and receiving terminals (901, 902) can provide a PC5 link ID and / or a source Layer-2 ID and a destination Layer-2 ID so that the AS layer of the transmitting and receiving terminals (901, 902) can identify the PC5 unicast link. The RRC connection between the terminals (901, 902) can be used in unicast communication, and is a logical RRC connection corresponding to a pair of source Layer-2 ID and destination Layer-2 ID. The RRC connection between these terminals (901, 902) may be referred to as PC5-RRC to distinguish it from Uu-RRC. In the case of groupcast transmission, a PC5-RRC connection may be individually established between a transmitting terminal and a receiving terminal within a group. Referring to FIG. 9, the Unicast layer-2 link establishment procedure (911) is depicted as an operation after reception (907) of a sidelink SIB, but the Unicast layer-2 link establishment procedure (911) may be performed before reception of the sidelink SIB, or may not be performed in the case of broadcast or groupcast transmission that does not require PC5-RRC. If a PC5-RRC connection is required, the Unicast layer-2 link establishment procedure (911) may be performed. In operation 921, the transmitting terminal (901) may transmit a 1-action SCI to the receiving terminal (902) via the PSCCH. Additionally, in operation 921, the transmitting terminal (901) can transmit 2-action SCI and sidelink data to the receiving terminal (902) via the PSSCH.In mode 1, the transmitting terminal (901) can identify sidelink scheduling information included in the DCI received from the base station (903) and perform scheduling for the sidelink based on the sidelink scheduling information. The SCI can be divided into a 1st-stage SCI transmitted on the PSCCH and a 2nd-stage SCI transmitted on the PSSCH, and the 1st-stage SCI can include at least one of the following information.

[0174] * Priority

[0175] * Frequency resource assignment

[0176] * Time resource assignment

[0177] * Resource reservation period

[0178] * DMRS (de-modulation reference signal) pattern

[0179] * 2nd-stage SCI format

[0180] * Beta_offset indicator

[0181] * Number of DMRS ports

[0182] * Modulation and coding scheme

[0183] * Additional MCS table indicator

[0184] * PSFCH overhead indication

[0185] * Reserved

[0186] * Conflict information receiver flag

[0187] Priority can be transmitted or set in the upper layer, and can be specified as a maximum of 8 values ​​in 3 bits, such as 1 being 000, 2 being 001, etc. This value can have the highest value among the priorities of all logical channels or MAC CEs included in the TB scheduled by the corresponding SCI in the case of sidelink data. If a MAC CE or SCI for inter-UE coordination is transmitted, it can have a value set with an RRC parameter different from the priority of the corresponding MAC CE. If there is no setting of the RRC parameter, the Inter-UE Coordination Request MAC CE can have the highest value among the priorities of all logical channels or MAC CEs included in the TB to be transmitted to the UE receiving the corresponding MAC CE, and the Inter-UE Coordination Information MAC CE transmitted by the terminal receiving it to respond to the request can have the same value as the value corresponding to the Priority field in the Inter-UE Coordination Request MAC CE. Additionally, if the Inter-UE Coordination Information MAC CE is transmitted under a specific condition (e.g., when the RSRP of a resource reserved by a third terminal is higher than a specific value) rather than at the request of another terminal, the priority can be arbitrarily selected by the terminal from among values ​​1 to 8.

[0188] The reservation interval is indicated as a fixed value for the interval between TBs when resources for multiple TBs (i.e., multiple MAC PDUs (protocol data units)) are selected, and when resources for one TB are selected, the value of the interval between TBs may be indicated as '0'.

[0189] The 2nd-stage SCI may be included in the PSSCH resource indicated in the 1st-stage SCI transmitted in operation 921 and transmitted together with data in operation 923. The 2nd-stage SCI may include at least one of the following information:

[0190] * HARQ process number

[0191] * New data indicator

[0192] * Redundancy version

[0193] * Source ID

[0194] * Destination ID

[0195] * HARQ feedback enabled / disabled indicator

[0196] * Cast type indicator

[0197] * CSI request

[0198] * Zone ID

[0199] * Communication range requirement

[0200] * Providing / Requesting indicator

[0201] * Resource combinations

[0202] * First resource location

[0203] * Reference slot location

[0204] * Resource set type

[0205] * Lowest subchannel indices

[0206] * Priority

[0207] * Number of subchannels

[0208] * Resource reservation period

[0209] * Resource selection window location

[0210] * Resource set type

[0211] * Padding bits

[0212] And, in operation 925, the receiving terminal (902) can transmit to the transmitting terminal (901) whether the demodulation / decoding of the data received through operations 921 and 923 was successful through first HARQ feedback information. Here, the first HARQ feedback information includes ACK (success) or NACK (failure) information, and the receiving terminal (902) transmits the first HARQ feedback information to the transmitting terminal (901) through the PSFCH channel. In operation 927, the transmitting terminal (901) transmits the transmission result to the base station (903) as second HARQ feedback information based on the first HARQ feedback information received from the receiving terminal (902). The second HARQ feedback is transmitted to the base station through the PUCCH. At this time, the second HARQ feedback information may or may not be the same as the first HARQ feedback information. In addition, the second HARQ feedback information may include a plurality of first HARQ feedback information. The plurality of first HARQ feedback information may include a plurality of HARQ feedback information received from a single receiving terminal, or may include one or a plurality of HARQ feedback information received from multiple terminals. Through the second HARQ feedback information, the base station may be able to allocate resources for retransmission to the transmitting terminal (901), allocate resources for new transmission, or stop resource allocation when there are no more transmission resources to allocate to the transmitting terminal (901). The PUCCH transmission resource may be determined by DCI information that the base station transmits to the transmitting terminal on the PDCCH. The PSFCH (925) transmission resource may be determined by the SCI of the PSCCH or may be determined by the transmission resource region in which the PSSCH is transmitted and received.

[0213] FIG. 10 illustrates another example of a signal flow for allocating sidelink transmission resources in a wireless communication system according to an embodiment of the present disclosure. FIG. 10 illustrates signal exchange between a transmitting terminal (1001), a receiving terminal (1002), and a base station (1003).

[0214] As described below, the method in which a terminal directly allocates sidelink transmission resources through sensing in the sidelink may be referred to as Mode 2. Mode 2 may also be referred to as UE autonomous resource selection. Specifically, according to Mode 2, the base station (1003) may provide a sidelink transmission / reception resource pool for the sidelink to the terminal through a sidelink SIB or an RRC message (e.g., an RRCReconfiguration message or a PC5 RRC message), and the transmitting terminal (1001) selects the resource pool and resources according to established rules. Unlike Mode 1 in which the base station described in FIG. 9 directly participates in resource allocation, Mode 2 described in FIG. 10 allows the transmitting terminal (1001) to autonomously select resources and transmit data based on a resource pool previously received through a sidelink SIB, an RRC message, or pre-configuration.

[0215] Referring to FIG. 10, in operation 1007, a transmitting terminal (1001) that is camping on (1005) may receive a sidelink SIB from a base station (1003). In operation 1009, a receiving terminal (1002) may monitor sidelink communication based on a sidelink SIB or an RRC message received from a base station (e.g., 1003), or an Rx resource pool included in pre-configuration. Here, the receiving terminal (1002) refers to a terminal that receives data transmitted by the transmitting terminal (1001). The sidelink SIB may be transmitted periodically or on demand. In addition, the sidelink SIB may include at least one of sidelink resource pool information for sidelink communication, parameter setting information for sensing operation, information for setting sidelink synchronization, or carrier information for sidelink communication operating at different frequencies. Although operations 1007 and 1009 have been described sequentially above, this is for convenience of explanation, and operations 1007 and 1009 may be performed in parallel. In the case of FIG. 9 described above, the base station (1003) and the transmitting terminal (1001) operate in a state in which the RRC is connected, whereas in FIG. 10, the base station (1003) and the transmitting terminal (1001) may operate regardless of whether the RRC is connected between the base station (1003) and the transmitting terminal (1001) in operation 1013. That is, when the transmitting terminal (1001) is an IC, mode 2-based sidelink communication may be performed even when the RRC is connected, in an idle or inactive state in which the RRC is not connected, or in an OOC state. Additionally, even when RRC is connected, the base station (1003) can be configured to allow the transmitting terminal (1001) to autonomously select transmission resources without being directly involved in resource allocation.

[0216] In operation 1013, when data traffic for sidelink communication is generated at the transmitting terminal (1001), the transmitting terminal (1001) may initiate an RRC connection procedure with the base station (1003) to request transmission resources (1015). Here, the RRC connection between the transmitting terminal (1001) and the base station (1003) may be referred to as Uu-RRC. The Uu-RRC connection may be performed before the transmitting terminal (1001) generates data traffic.

[0217] In operation 1015, the transmitting terminal (1001) may request a transmission resource for transmitting sidelink data to the receiving terminal (1002) from the base station (1003) using an RRC message. The transmitting terminal (1001) may transmit information on a frequency for transmitting and receiving various types of sidelink communication, including sidelink discovery, sidelink data communication, and sidelink relay communication, and information on the receiving terminal (1002) to the base station through Uu-RRC, and may include at least one of the information as in the example of FIG. 9 described above through the same or different RRC messages.

[0218] In operation 1017, the base station (1003) can set a resource pool for the transmitting terminal (1001) based on the transmission resources requested from the transmitting terminal (1001).

[0219] In operation 1019, the transmitting terminal (1001) can directly select time and frequency domain resources through sensing within the sidelink SIB (1007) of the base station (1003), or the RRC message (1017), or the transmission resource pool set by pre-configuration.

[0220] When broadcast transmission is performed between transmitting and receiving terminals (1001, 1002), in operations 1021 and 1023, the transmitting terminal (1001) can broadcast SCI and data to at least one receiving terminal (e.g., 1002) via PSCCH and PSSCH without PC5 unicast link connection.

[0221] When unicast or groupcast transmission is performed between transmitting and receiving terminals (1001, 1002), in operation 1011, the transmitting terminal (1001) can perform a unicast layer-2 link establishment procedure (1011) for direct communication with other terminals (e.g., receiving terminal (1002)). At this time, the upper layer (e.g., ProSe or V2X layer) of the transmitting and receiving terminals (1001, 1002) can provide a PC5 link ID and / or a source Layer-2 ID and a destination Layer-2 ID so that the AS layer of the transmitting and receiving terminals (1001, 1002) can identify the PC5 unicast link. The RRC connection between the terminals (1001, 1002) can be used in unicast communication, and is a logical RRC connection corresponding to a pair of source Layer-2 ID and destination Layer-2 ID. The RRC connection between these terminals (1001, 1002) may be referred to as PC5-RRC to distinguish it from Uu-RRC. In the case of groupcast transmission, a PC5-RRC connection may be individually established between a transmitting terminal and a receiving terminal within a group. Referring to FIG. 10, the Unicast layer-2 link establishment procedure (1011) is depicted as an operation after reception (1007) of a sidelink SIB, but the Unicast layer-2 link establishment procedure (1011) may be performed before reception of the sidelink SIB, or may not be performed in the case of broadcast or groupcast transmission that does not require PC5-RRC. If a PC5-RRC connection is required, the Unicast layer-2 link establishment procedure (1011) may be performed. In operation 1021, the transmitting terminal (1001) may transmit a 1-action SCI to the receiving terminal (1002) via the PSCCH.Additionally, in operation 921, the transmitting terminal (1001) can transmit 2-stage SCI and sidelink data to the receiving terminal (1002) via the PSSCH. In mode 1, the transmitting terminal (901) can identify sidelink scheduling information included in the DCI received from the base station (903) and perform scheduling for the sidelink based on the sidelink scheduling information. In mode 2, the transmitting terminal (1001) can directly perform scheduling for the sidelink by performing sensing and transmission resource selection operations. The 1st-stage SCI and 2nd-stage SCI used in operations 1021 and 1023 may be as in the example of FIG. 9.

[0222] And, in operation 1025, the receiving terminal (1002) can transmit to the transmitting terminal (1001) whether the demodulation / decoding of the data received in operations 1021 and 1023 was successful through HARQ feedback information. Here, the HARQ feedback information includes ACK (success) or NACK (failure) information, and the receiving terminal (1002) transmits the HARQ feedback information to the transmitting terminal (1001) through the PSFCH channel.

[0223] In addition, although not shown in FIG. 9 or FIG. 10, when any transmitting terminal (e.g., 1001) performs sidelink communication in OOC, mode 2 resource allocation can be used, and information for sidelink communication that can be used for this can use information stored in the terminal through pre-configuration or receive configuration information from the base station through a sidelink relay.

[0224] FIG. 11 illustrates an example of a channel structure of a slot used for sidelink communication in a wireless communication system according to an embodiment of the present disclosure. FIG. 11 illustrates physical channels mapped to slots for sidelink communication.

[0225] Referring to FIG. 11, an automatic control gain symbol (AGC) (1105) that can be used by a receiving terminal is mapped to the first symbol of a slot (1100). Thereafter, a PSCCH (1110), a PSSCH (1115), a GUARD (1120), an AGC for a PSFCH (1125), a PSFCH (1130), and a GUARD (1135) may be sequentially mapped.

[0226] Before transmitting a PSCCH in the corresponding slot (1100), the transmitting terminal may transmit a signal for AGC purposes having the same information as the symbol in which the PSCCH (1110) is transmitted in one or more symbols. The AGC symbol (1105) may be used to enable the receiving terminal to properly perform AGC (automatic gain control) for adjusting the strength of amplification when amplifying the power of a received signal. The signal for AGC may be referred to as a 'synchronization signal', a 'sidelink synchronization signal', a 'sidelink reference signal', a 'midamble', an 'initial signal', a 'wake-up signal' or other terms having an equivalent technical meaning therefor.

[0227] Using symbols transmitted at the beginning of a slot, a PSCCH (1110) containing control information is transmitted, followed by a PSSCH (1115) scheduled by the control information of the PSCCH (1110). At least a portion of the SCI, which is control information, may be mapped to the PSSCH (1115). Thereafter, a GUARD (1120) and an AGC (1125) for the PSFCH exist, and a PSFCH (1130), which is a physical channel transmitting feedback information, may be mapped.

[0228] In the case of Fig. 11, PSFCH (1130) is exemplified as being located in the second symbol from the back of the slot. By securing GUARD (1120), which is an empty period of a certain period of time, between PSSCH (1115) and PSFCH (1130), a terminal that has transmitted or received PSSCH (1115) can prepare (e.g., switch between transmission and reception) to transmit or receive PSFCH (1130). In addition, AGC (1125) for PSFCH (1130) may exist. After PSFCH (1130), GUARD (1135), which is an empty period of a certain period of time, exists.

[0229] A terminal can be preset with the location of the slot in which it can transmit the PSFCH. Pre-setting may refer to a procedure in which the slot is preset during the terminal's creation process, transmitted upon connection to a sidelink-related system, transmitted from a base station upon connection to the base station, or transmitted from another terminal.

[0230] In the embodiment of FIG. 11, it has been described that a preamble signal for performing AGC is transmitted separately in a physical channel structure within a sidelink slot. However, according to another embodiment, instead of transmitting a separate preamble signal, it is also possible for a receiver of a receiving terminal to perform an AGC operation using a physical channel for control information or data transmission while receiving a physical channel for control information or data transmission.

[0231] FIG. 12a is a diagram illustrating a user plane wireless protocol structure of a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0232] Referring to FIG. 12A, a PC5 unicast link is established / formed between a first terminal (1210) and a second terminal (1220) for transmitting and receiving data, and a Uu link is established / formed between a second terminal (1220) and a base station (1230) for transmitting and receiving data. The second terminal (1220) can relay data transmitted by the first terminal (1210) to the base station (1230), and the second terminal (1220) can relay data transmitted by the base station (1230) to the first terminal (1210). Data transmission and reception between the first terminal (1210) and the base station (1230) via the second terminal (1220) can be referred to as a U2N relay, and can be referred to as an indirect path in the present disclosure to clarify that it is not a direct communication link with the base station (1230). In addition, the first terminal (1210) has a Uu link established for transmitting and receiving data with the base station (1230), and the first terminal (1210) can transmit and receive DL or UL data with the base station (1230). In order to clearly indicate that data transmission and reception between the first terminal (1210) and the base station (1230) is not data transmission and reception through an indirect path or relay, it may be referred to as a direct path in the present disclosure. The second terminal (1220) that forms an indirect path from the first terminal (1210) to the base station (1230) through the second terminal (1220) may be referred to as a serving relay, and the base station (1230) that forms a direct path from the first terminal (1210) to the base station (1230) may be referred to as a serving gNB or a cell of the base station, which may be referred to as a serving cell.

[0233] The first terminal (1210) can transmit and receive data through a U2N relay with the base station (1230), and may be referred to as a U2N remote terminal (remote UE). The second terminal (1220) can transmit and receive data between the first terminal (1210) and the base station (1230) through a U2N relay, and may be referred to as a U2N relay terminal (relay UE).

[0234] For transmitting and receiving user data through direct pass and indirect pass, the user plane wireless protocols of the first terminal (1210), the second terminal (1210), and the base station (1230) are Uu-SDAP (1211-1, 1231-1), Uu-PDCP (1212, 1232), PC5-SRAP (1213, 1221) and Uu-SRAP (1225, 1233), PC5-RLC (1214, 1222) and Uu-RLC (1217, 1226, 1234, 1237), PC5-MAC (1215, 1223) and Uu-MAC (1218, 1227, 1235, 1238), PC5-PHY (1216, 1224), and It may include Uu-PHY (1219, 1228, 1236, 1239).

[0235] The functionality of Uu-SDAP (1211-1, 1231-1) may include at least some of the following functions, but is not limited to the functions described below.

[0236] - Mapping between a PC5 QoS flow and a SL-DRB for NR sidelink communication

[0237] - Marking PC5 QoS flow ID in unicast sidelink packets (marking PC5 QoS flow ID in unicast of NR sidelink communication packets)

[0238] The main functions of Uu-PDCP (1212, 1232) may include some of the following functions, but are not limited to the functions described below.

[0239] - Transfer of data (user plane or control plane)

[0240] - Maintenance of PDCP sequence numbers (PDCP SNs)

[0241] - Header compression and decompression using the ROHC protocol

[0242] - Header compression and decompression using EHC protocol

[0243] - Compression and decompression of uplink PDCP SDUs (DEFLATE based UDC only)

[0244] - Ciphering and deciphering

[0245] - Integrity protection and integrity verification

[0246] - Timer-based SDU discard

[0247] - Routing for split bearers (For split bearers, routing)

[0248] - Duplication

[0249] - Reordering and in-order delivery

[0250] - Out-of-order delivery

[0251] - Duplicate discarding

[0252] The main functions of PC5-SRAP (1213, 1221) and Uu-SRAP (1225, 1233) may include some of the following functions, but are not limited to the functions described below.

[0253] - Data transfer

[0254] - Determination of UE ID field and BEARER ID field for data packets

[0255] - Determination of egress link

[0256] - Determination of egress RLC channel

[0257] The main functions of PC5-RLC (1214, 1222) and Uu-RLC (1217, 1226, 1234, 1237) may include, but are not limited to, some of the following functions.

[0258] - Transfer of upper layer PDUs

[0259] - Sequence numbering independent of the one in PDCP (UM and AM)

[0260] - Error Correction through ARQ (AM only)

[0261] - Segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs

[0262] - Reassembly of SDU (AM and UM)

[0263] - Duplicate Detection (AM only)

[0264] - RLC SDU discard (AM and UM)

[0265] - RLC re-establishment

[0266] - Protocol error detection (AM only)

[0267] The main functions of PC5-MAC (1215, 1223) and Uu-MAC (1218, 1227, 1235, 1238) may include at least some of the following functions, but are not limited to the functions described below.

[0268] - Mapping between logical channels and transport channels

[0269] - Multiplexing of MAC SDUs from one or more logical channels onto transport blocks (TB) to be delivered to the physical layer on transport channels

[0270] - Demultiplexing of MAC SDUs belonging to one or more logical channels (demultiplexing of MAC SDUs to one or different logical channels from transport blocks (TB) delivered from the physical layer on transport channels)

[0271] - Scheduling information reporting

[0272] - Error correction through HARQ

[0273] - Logical channel prioritization

[0274] - Priority handling between overlapping resources of one UE

[0275] - Radio resource selection

[0276] PC5-PHY (1216, 1224) and Uu-PHY (1219, 1228, 1236, 1239) can encode and modulate upper layer data to generate OFDM symbols, convert them into RF band signals, and transmit them via antennas. In addition, the PHY layer can demodulate and decode received OFDM symbols and transmit them to upper layers.

[0277] FIG. 12b is a diagram illustrating a control plane wireless protocol structure of a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0278] Referring to FIG. 12B, a PC5 unicast link is established / formed between a first terminal (1210) and a second terminal (1220) for transmitting and receiving sidelink data, and a Uu link is established / formed between a second terminal (1220) and a base station (1230) for transmitting and receiving data. The second terminal (1220) can relay data transmitted by the first terminal (1210) to the base station (1230), and the second terminal (1220) can relay data transmitted by the base station (1230) to the first terminal (1210). Data transmission and reception between the first terminal (1210) and the base station (1230) via the second terminal (1220) can be referred to as a U2N relay, and may be referred to as an indirect path in the present disclosure to clarify that it is not a direct communication link with the base station (1230). In addition, the first terminal (1210) has a Uu link established / formed for transmitting and receiving data with the base station (1230), and the first terminal (1210) can transmit and receive DL or UL data with the base station (1230). In order to clearly indicate that data transmission and reception between the first terminal (1210) and the base station (1230) is not data transmission and reception through an indirect path or relay, it may be referred to as a direct path in the present disclosure. The second terminal (1220) that constitutes an indirect path from the first terminal (1210) to the base station (1230) through the second terminal (1220) may be referred to as a serving relay, and the base station (1230) that constitutes a direct path from the first terminal (1210) to the base station (1230) may be referred to as a serving gNB or a cell of the base station, which may be referred to as a serving cell.

[0279] For transmission and reception of control data through direct path and indirect path, the control plane wireless protocols of the first terminal (1210), the second terminal (1210), and the base station (1230) are Uu-RRC (1211-2, 1231-2), Uu-PDCP (1212, 1232), PC5-SRAP (1213, 1221) and Uu-SRAP (1225, 1233), PC5-RLC (1214, 1222) and Uu-RLC (1217, 1226, 1234, 1237), PC5-MAC (1215, 1223) and Uu-MAC (1218, 1227, 1235, 1238), PC5-PHY (1216, 1224) and It may include Uu-PHY (1219, 1228, 1236, 1239).

[0280] The functionality of Uu-RRC (1311-2, 1331-2) may include at least some of the following functions, but is not limited to the functions described below.

[0281] - Broadcast of System Information related to AS and NAS

[0282] - Paging initiated by 5GC or NG-RAN

[0283] - Establishment, maintenance, and release of an RRC connection between the UE and NG-RAN, including: Addition, modification, and release of carrier aggregation; Addition, modification, and release of dual connectivity in NR or between E-UTRA and NR.

[0284] - Security functions including key management

[0285] - Establishment, configuration, maintenance and release of Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs)

[0286] - Terminal mobility support (Mobility functions including: Handover and context transfer; UE cell selection and reselection and control of cell selection and reselection; Inter-RAT mobility.)

[0287] - QoS management functions

[0288] - UE measurement reporting and control of the reporting

[0289] - Detection of and recovery from radio link failure

[0290] - NAS message transfer (NAS message transfer to / from NAS from / to UE)

[0291] FIG. 12c is a diagram illustrating a user plane wireless protocol structure of a multi-path terminal-network relay that does not use 3GPP connections for terminal-to-terminal communication according to an embodiment of the present disclosure.

[0292] Referring to FIG. 12c, a first terminal (1210) has a non-3GPP link (1240, 1250) established / formed for transmitting and receiving data with a second terminal (1220), and a Uu link has been established / formed for transmitting and receiving data with a base station (1230) with the second terminal (1220). The second terminal (1220) can relay data transmitted by the first terminal (1210) to the base station (1230), and the second terminal (1220) can relay data transmitted by the base station (1230) to the first terminal (1210). Data transmission and reception between the first terminal (1210) and the base station (1230) via the second terminal (1220) may be referred to as a U2N relay, and may be referred to as an indirect path in the present disclosure to clarify that it is not a direct communication link with the base station (1230). In addition, the first terminal (1210) has a Uu link established / formed for transmitting and receiving data with the base station (1230), and the first terminal (1210) can transmit and receive DL or UL data with the base station (1230). Data transmission and reception between the first terminal (1210) and the base station (1230) may be referred to as a direct path in the present disclosure to clarify that it is not data transmission and reception via an indirect path or relay. The second terminal (1220) that constitutes an indirect path from the first terminal (1210) to the base station (1230) via the second terminal (1220) may be referred to as a serving relay, and the base station (1230) that constitutes a direct path from the first terminal (1210) to the base station (1230) may be referred to as a serving gNB or a cell of the base station, which may be referred to as a serving cell.A non-3GPP link (1240, 1250) may be a terminal-to-terminal communication method that may include Wi-Fi or Bluetooth, etc. that does not use technologies defined by 3GPP, such as V2X, ProSe, Sidelink, etc. that utilize RAT such as LTE / NR.

[0293] For transmitting and receiving user data through direct pass and indirect pass, the user plane wireless protocols of the first terminal (1210), the second terminal (1210), and the base station (1230) may include Uu-SDAP (1211-1, 1231-1), Uu-PDCP (1212, 1232), Uu-RLC (1217, 1226, 1234, 1237), Uu-MAC (1218, 1227, 1235, 1238), and Uu-PHY (1219, 1228, 1236, 1239). The Non-3GPP link (1240, 1250) connection between the first terminal (1210) and the second terminal (1220) may be configured in a manner not defined in 3GPP, such as ensuring that the first terminal (1210) and the second terminal (1220) are always connected, or may be connected in a manner not defined in 3GPP.

[0294] FIG. 12d is a diagram illustrating a control plane wireless protocol structure of a multi-path terminal-network relay that does not use a 3GPP connection for terminal-to-terminal communication according to an embodiment of the present disclosure.

[0295] Referring to FIG. 12D, a first terminal (1210) has a non-3GPP link (1240, 1250) established for transmitting and receiving data with a second terminal (1220), and a Uu link has been established for transmitting and receiving data with a base station (1230) with the second terminal (1220). The second terminal (1220) can relay data transmitted by the first terminal (1210) to the base station (1230), and the second terminal (1220) can relay data transmitted by the base station (1230) to the first terminal (1210). Data transmission and reception between the first terminal (1210) and the base station (1230) via the second terminal (1220) can be referred to as a U2N relay, and may be referred to as an indirect path in the present disclosure to clarify that it is not a direct communication link with the base station (1230). In addition, the first terminal (1210) has a Uu link established for transmitting and receiving data with the base station (1230), and the first terminal (1210) can transmit and receive DL or UL data with the base station (1230). In order to clearly indicate that data transmission and reception between the first terminal (1210) and the base station (1230) is not data transmission and reception through an indirect path or relay, it may be referred to as a direct path in the present disclosure. The second terminal (1220) that forms the indirect path in the first terminal (1210) may be referred to as a serving relay, and the base station (1230) that forms the direct path in the first terminal (1210) may be referred to as a serving gNB or a cell of the base station, and may be referred to as a serving cell. Non-3GPP link (1240, 1250) is a terminal-to-terminal communication method that may include Wi-Fi or Bluetooth, etc. that does not use technologies defined by 3GPP, such as V2X, ProSe, Sidelink, etc. that utilize RAT such as LTE / NR.

[0296] For transmission and reception of control data through direct pass and indirect pass, the control plane wireless protocol of the first terminal (1210), the second terminal (1210), and the base station (1230) may include Uu-RRC (1211-2, 1231-2), Uu-PDCP (1212, 1232), Uu-RLC (1217, 1226, 1234, 1237), Uu-MAC (1218, 1227, 1235, 1238), and Uu-PHY (1219, 1228, 1236, 1239). The Non-3GPP link (1240, 1250) connection between the first terminal (1210) and the second terminal (1220) may be configured in a method not defined in 3GPP so that the first terminal (1210) and the second terminal (1220) are always connected, or may be connected in a method not defined in 3GPP.

[0297] FIG. 13A is a diagram of a signal flow for transmitting a threshold condition of a multi-path terminal-network relay to a relay terminal according to an embodiment of the present disclosure.

[0298] Referring to FIG. 13a, the first terminal (1310) is an in-coverage (IC) terminal located within the coverage of the base station (1320) and may be a terminal supporting multi-path relay.

[0299] The base station (1320) can indicate whether Relay is supported in a SIB message (e.g., SIB12), and the first terminal (1310) can confirm that the base station (1320) supports Relay if the SIB message includes an indicator indicating that Relay is supported. At this time, whether the base station (1320) supports Relay can include L2 U2N Relay, non-relay discovery, L3U2N Relay discovery, etc., and whether MP (multi-path) Relay is supported can also be transmitted in the form of true / false. The first terminal (1310) in the RRC_IDLE or RRC_INACTIVE state can perform a procedure (1312) for establishing an RRC connection to the base station (1320) supporting L2 U2N Relay and / or MP Relay when transmission of an MP Relay discovery message is required.

[0300] The base station (1320) may request capability information of the first terminal (1310) through an RRC message (1313) (e.g., UECapabilityEnquiry) to obtain capability information of the first terminal (1310) in the RRC_CONNECTED state. The first terminal (1310) may transmit an indicator including information supporting sidelink relay of 3GPP Release 18 or an indicator including information supporting multipath relay to the base station (1320) through an RRC message (1314) (e.g., UECapabilityInformation). Whether multipath relay is supported or whether sidelink relay of Release 18 is supported may indicate differently whether operation of a relay or remote terminal is supported. For example, the RRC message (1314) may be information (capability information) indicating that the first terminal (1310) supports multipath relay and has the capability to operate as a relay terminal of the multipath relay. Through this message (RRC message (1314)), the base station (1320) can know that the first terminal (1310) is a terminal that supports multi-path relay. In addition, although not shown in this drawing, the AMF (Access and Mobility Management Function) can receive information from the UDM (Unified Data Management) or UDR (Unified Data Repository) about whether the first terminal (1310) allows L2 and / or L3 terminal-network relay operations, and whether relay and / or remote terminal operations for each operation are allowed, and transmit this to the base station (1320) through the NGAP, etc.

[0301] When the first terminal (1310) supports MP Relay UE operation and is in an RRC_CONNECTED state with an RRC connection established with the base station (1320), the first terminal (1310) may transmit an RRC message (1315) (e.g., SidelinkUEInformationNR) to the base station (1320) to request the base station (1320) to share information related to discovery used in multi-path relay and to provide resources for transmitting / receiving discovery messages. This information may be transmitted as shown in Table 1 below.

[0302]

[0303] At this time, the source layer-2 ID used when the first terminal (1310) transmits discovery for MP Relay may be the same as or different from the source layer-2 ID used when the first terminal (1310) transmits discovery for U2N Relay. If the source layer-2 ID used when the first terminal (1310) transmits discovery for MP Relay is different from the source layer-2 ID used when the first terminal (1310) transmits discovery for U2N Relay, the two IDs may be distinguished by sl-DiscoveryType or a similar IE, or may be distinguished in the form of a new IE (e.g., sl-SourceIdentityMPRelayUE). In addition, in order to distinguish the purpose of discovery transmission from U2N relay, information indicating that multi-path relay discovery is transmitted (e.g., mp-Relay) may be included in sl-DiscoveryType or a similar IE.

[0304] The base station (1320) that receives the RRC message transmitted by the first terminal (1310) can set resources and thresholds for transmitting / receiving discovery messages for U2N Relay and / or MP Relay to the first terminal (1310) through an RRC message (1316) (e.g., RRCReconfiguration).

[0305] According to one embodiment of the present disclosure, when a first terminal (1310) supports U2N Relay UE operation and is in an RRC_CONNECTED state in which an RRC connection with a base station (1320) is established, the base station (1320) may set a range of thresholds for transmission and / or reception of a discovery message of the first terminal (1310) through an RRC message (1316) (e.g., RRCReconfiguration). The thresholds may be configured as (or may include) at least one or more of threshHighRelay, threshLowRelay, hystMaxRelay, and hystMinRelay.

[0306] According to one embodiment of the present disclosure, when the first terminal (1310) supports U2N Relay UE operation and is in an RRC_IDLE or RRC_INACTIVE state in which an RRC connection with the base station (1320) is not established, the base station (1320) may set a range of thresholds for transmission and / or reception of a discovery message of the first terminal (1310) through a SIB message (1311) (e.g., SIB12). The threshold may be configured as at least one of (or may include at least one of) threshHighRelay, threshLowRelay, hystMaxRelay, and hystMinRelay. The first terminal (1310) may determine that the first terminal (1310) satisfies a threshold condition for determining whether the first terminal (1310) will operate as a U2N Relay UE if the measured RSRP value of the serving cell, primary cell, or camping cell is lower than (smaller than) the value obtained by subtracting hystMaxRelay from threshHighRelay, or if the measured RSRP value of the serving cell, primary cell, or camping cell is higher than (larger than) the value obtained by adding hystMinRelay to threshLowRelay. If it is determined that the first terminal (1310) satisfies the threshold condition, the first terminal (1310) may operate as a U2N Relay UE.

[0307] In addition, the first terminal (1310) may determine that the first terminal (1310) does not satisfy the threshold condition for determining whether the first terminal (1310) operates as a U2N Relay UE if the measured RSRP value of the serving cell, primary cell, or camping cell is higher than (greater than) threshHighRelay or if the measured RSRP value of the serving cell, primary cell, or camping cell is lower than (smaller than) threshLowRelay. If it is determined that the first terminal (1310) does not satisfy the threshold condition, the first terminal (130) cannot operate as a U2N Relay UE. This operation may be exemplified as shown in Table 2 below.

[0308]

[0309] The threshold conditions for U2N Relay and MP Relay may be different. That is, in the indirect path configured through a multi-path relay terminal with poor Uu link quality, transmission failures and retransmissions may frequently occur, which may adversely affect the MP Relay. Therefore, the lower threshold condition for determining whether to operate as a U2N Relay UE, which can be set to threshLowRelay and hystMinRelay, needs to be set differently depending on the channel conditions in the multi-path relay. In addition, since the U2N Relay service is a service that provides extended coverage and stable DL / UL transmission through the relay service when the Uu link quality between the U2N Remote UE and the base station (1320) is poor, if the U2N Relay UE has good coverage with the base station (1320) or better than threshHighRelay, the PC5 connection between the U2N Remote UE, which is expected to be far from the base station (1320), and the U2N Relay UE may not be good. Therefore, in the case of U2N Relay, if the U2N Relay UE does not satisfy the threshold condition, the U2N Relay cannot send / receive discovery messages.

[0310] Also, if the threshold conditions for the U2N Relay service and the threshold conditions for the MP Relay service are used identically, the MP Remote UE may not be able to discover the MP Relay UE that does not satisfy the threshold conditions. In addition, unlike U2N Relay, in the case of MP Relay, even when the MP Remote UE is in a good coverage area close to the base station (1320), reliability and throughput increase can be provided through an additional indirect path. In addition, in the case of MP Relay, even when both the MP Relay UE and the MP Remote UE are in a good coverage area close to the base station (1320), an improved service can be provided using the MP Relay. Therefore, there is a need to provide an extended service by allowing a terminal to operate as an MP Relay UE even in a good coverage state (i.e., a Uu link quality of threshHighRelay or higher) that does not satisfy the U2N Relay UE threshold conditions. That is, the lower threshold condition for determining whether to operate as a U2N Relay UE, which can be set to threshLowRelay and hystMinRelay, and the upper threshold condition for determining whether to operate as a U2N Relay UE, which can be set to threshHighRelay and hystMaxRelay, are differently set and applied by the base station (1320) for the MP Relay UE, thereby solving problems in existing operations that may occur when the threshold condition for the U2N Relay service and the threshold condition for the MP Relay service are used identically.

[0311] To make it clear that the thresholds applicable to MP Relay UEs are only used in MP Relay, IEs different from the thresholds applicable to existing U2N Relay UEs (e.g., threshHighMPRelay, threshLowMPRelay, hystMaxMPRelay, hystMinMPRelay) can be used / defined / configured / set, and for example, can be used / defined / configured / set as shown in Table 3 below.

[0312]

[0313] In order to set and apply a threshold value applicable to an MP Relay UE, if the first terminal (1310) supports MP Relay UE operation and is in an RRC_CONNECTED state in which an RRC connection with the base station (1320) is established, the base station (1320) may set a range of threshold values ​​for transmission and / or reception of a discovery message of the first terminal (1310) through an RRC message (1316) (e.g., RRCReconfiguration). The threshold value may be configured as at least one of (or may include at least one of) threshHighMPRelay, threshLowMPRelay, hystMaxMPRelay, and hystMinMPRelay. When the first terminal (1310) supports U2N MP Relay UE operation and is in an RRC_IDLE or RRC_INACTIVE state in which an RRC connection with the base station (1320) is not established, the base station (1320) may set a range of thresholds for transmission and / or reception of a discovery message of the first terminal (1310) through a SIB message (1311) (e.g., SIB12). The thresholds included in the SIB may be configured with at least one or more of threshHighMPRelay, threshLowMPRelay, hystMaxMPRelay, and hystMinMPRelay (or may include at least one or more of them).

[0314] FIG. 13b is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0315] Referring to FIG. 13b, a terminal supporting an MP Relay UE may determine that the threshold condition for determining whether to operate as an MP Relay UE is satisfied if the measured RSRP of the serving cell, the primary cell, or the camping cell is lower (smaller) than the value obtained by subtracting hystMaxMPRelay from threshHighMPRelay, and if the measured RSRP of the serving cell, the primary cell, or the camping cell is higher (greater) than the value obtained by adding hystMinMPRelay to threshLowMPRelay. If the threshold condition for determining whether to operate as an MP Relay UE is satisfied, the terminal may operate as an MP Relay UE. If threshHighMPRelay or threshLowMPRelay is not set, the terminal supporting an MP Relay UE may always determine that the threshHighMPRelay or threshLowMPRelay condition for determining whether to operate as an MP Relay UE is satisfied.

[0316] When the threshold condition of MP Relay is satisfied, the terminal supporting MP Relay UE may determine that the threshold condition for determining whether to operate as an MP Relay UE is no longer satisfied if the measured RSRP value of the serving cell, primary cell, or camping cell is higher than (greater than) threshHighMPRelay or the measured RSRP value of the serving cell, primary cell, or camping cell is lower than (less than) threshLowMPRelay. If the threshold condition for determining whether to operate as an MP Relay UE is not satisfied, the terminal may not operate as an MP Relay UE.

[0317] FIG. 13c is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0318] Referring to FIG. 13c, a terminal supporting an MP Relay UE may determine that the threshold condition for determining whether to operate as an MP Relay UE is satisfied if the measured RSRP of the serving cell, the primary cell, or the camping cell is lower than (smaller than) the value obtained by subtracting hystMaxMPRelay from threshHighMPRelay, or if the measured RSRP of the serving cell, the primary cell, or the camping cell is higher than (greater than) the value obtained by adding hystMinMPRelay to threshLowMPRelay. If the threshold condition for determining whether to operate as an MP Relay UE is satisfied, the terminal can operate as an MP Relay UE. If threshHighMPRelay or threshLowMPRelay is not set, the terminal supporting an MP Relay UE may use threshHighRelay or threshLowRelay, which are used to determine whether to operate as a U2N Relay UE, instead of threshHighMPRelay or threshLowMPRelay, to determine the threshold condition for determining whether to operate as an MP Relay UE and whether it is satisfied. At this time, if threshHighMPRelay or threshLowMPRelay is not set and threshHighRelay or threshLowRelay is not set, a terminal supporting MP Relay UE can always be determined to have satisfied threshHighRelay or threshLowRelay.In addition, when the threshold condition of the MP Relay is satisfied, the terminal supporting the MP Relay UE can determine that the threshold condition is no longer satisfied as an MP Relay UE if the measured RSRP value of the serving cell, the primary cell, or the camping cell is higher than (greater than) threshHighMPRelay or the measured RSRP value of the serving cell, the primary cell, or the camping cell is lower than (less than) threshLowMPRelay. In addition, when threshHighMPRelay or threshLowMPRelay is not set, the terminal supporting the MP Relay UE can determine whether the MP Relay UE threshold is not satisfied using threshHighRelay or threshLowRelay.

[0319] When the MP Relay UE threshold condition is not used (or, when the MP Relay UE threshold condition is not set), the base station can instruct the terminal through an RRC message or SIB message whether the terminal uses the U2N Relay UE threshold condition to check whether the threshold is satisfied.

[0320] FIG. 14A is a diagram of a signal flow for transmitting a threshold condition of a multi-path terminal-network relay to a remote terminal according to an embodiment of the present disclosure.

[0321] Referring to FIG. 14a, the first terminal (1410) is an in-coverage (IC) terminal located within the coverage of a base station (1420) and may be a terminal supporting multi-path relay.

[0322] The base station (1420) can indicate whether Relay is supported in the SIB message (1411) (e.g., SIB12), and the first terminal (1410) can confirm that the base station (1420) supports Relay if the SIB message includes an indicator indicating that Relay is supported. At this time, whether the base station (1420) supports Relay may include L2 U2N Relay, non-relay discovery, L3U2N Relay discovery, etc., and whether MP Relay is supported may also be transmitted in the form of true / false. The first terminal (1410) in the RRC_IDLE or RRC_INACTIVE state may perform a procedure (1412) for establishing an RRC connection to the base station (1420) supporting L2 U2N Relay and / or MP Relay when transmission of an MP Relay discovery message is required.

[0323] The base station (1420) may request capability information of the first terminal (1410) through an RRC message (1413) (e.g., UECapabilityEnquiry) to obtain capability information of the first terminal (1410) in the RRC_CONNECTED state. The first terminal (1410) may transmit an indicator including information supporting sidelink relay of 3GPP Release 18 or an indicator including information supporting multipath relay to the base station (1420) through an RRC message (1414) (e.g., UECapabilityInformation). Whether multipath relay is supported or whether sidelink relay of Release 18 is supported may indicate differently whether relay or remote terminal operation is supported. For example, the RRC message (1414) may be capability information indicating that the first terminal (1410) supports multi-path relay and has the ability to operate as a remote terminal of the multi-path relay. Through this message (RRC message (1414)), the base station (1420) can know that the first terminal (1410) is a terminal that supports multi-path relay. In addition, although not shown in the drawing, the AMF (Access and Mobility Management Function) may receive information on whether the L2 and / or L3 terminal-network relay operation of the first terminal (1410) is permitted and whether the relay and / or remote terminal operation for each operation is permitted from the UDM (Unified Data Management) or the UDR (Unified Data Repository), and may transmit it to the base station (1420) through the NGAP, etc.

[0324] When the first terminal (1410) supports MP Remote UE operation and is in the RRC_CONNECTED state in which an RRC connection with the base station (1420) is established, an RRC message (1415) (e.g., SidelinkUEInformationNR) for requesting information for transmitting / receiving a discovery message used in a multi-path relay can be transmitted to the base station (1420). This information can be transmitted as shown in Table 1 above.

[0325] At this time, the first terminal (1410) may include information (e.g., mp-Relay) indicating that the first terminal (1410) transmits multi-path relay discovery in the sl-DiscoveryType or similar IE in order to distinguish the purpose of discovery transmission from U2N relay. In addition, the source L2ID used for discovery transmission of the MP Remote UE may be included.

[0326] The base station (1420) that receives the RRC message transmitted by the first terminal (1410) can set resources and thresholds for transmitting / receiving discovery messages for U2N Relay and / or MP Relay to the first terminal (1410) through an RRC message (1416) (e.g., RRCReconfiguration).

[0327] According to one embodiment of the present disclosure, when a first terminal (1410) supports U2N Remote UE operation and is in an RRC_CONNECTED state in which an RRC connection with a base station (1420) is established, the base station (1420) may set a range of a threshold for transmission and / or reception of a discovery message of the first terminal (1410) through an RRC message (1416) (e.g., RRCReconfiguration). The threshold may be configured as (or may include) at least one or more of threshHighRemote and hystMaxRemote.

[0328] According to one embodiment of the present disclosure, when the first terminal (1410) supports U2N Remote UE operation and is in an RRC_IDLE or RRC_INACTIVE state in which an RRC connection with the base station (1420) is not established, the base station (1420) may set a range of a threshold for transmission and / or reception of a discovery message of the first terminal (1410) through an SIB message (1411) (e.g., SIB12). The threshold may be configured as (or may include) at least one or more of threshHighRemote and hystMaxRemote. The first terminal (1410) may determine that the first terminal (1410) satisfies the threshold condition for determining whether the first terminal (1410) will operate as a U2N Remote UE if the measured RSRP of the serving cell, the primary cell, or the camping cell is lower than (smaller than) the value obtained by subtracting hystMaxRemote from threshHighRemote. If it is determined that the threshold condition is satisfied by the first terminal (1410), the first terminal (1410) can operate as a U2N Remote UE.

[0329] In addition, if the measured RSRP value of the serving cell, primary cell, or camping cell is higher (larger) than threshHighRemote, the first terminal (1410) may determine that the first terminal (1410) does not satisfy the threshold condition for determining whether the first terminal (1410) will operate as a U2N Remote UE. If the threshold condition is determined to be not satisfied by the first terminal (1410), the first terminal (1410) cannot operate as a U2N Remote UE. This operation may be exemplified as shown in Table 4 below.

[0330]

[0331] For smooth provision of MP Relay services, the MP Remote UE's Uu link quality must be good. In direct paths with poor Uu link quality, transmission failures and retransmissions can frequently occur, adversely affecting MP Relay. Therefore, the upper threshold condition for determining whether a UE can operate as a U2N Remote UE, which can be set to threshHighRemote and hystMaxRemote, needs to be set to a different value for multi-path relays.

[0332] In addition, if the U2N Remote UE does not satisfy the threshold condition, that is, if the Uu link quality with the base station (1420) is good, the U2N Remote UE cannot send / receive discovery messages. Therefore, if the threshold condition for the U2N Relay service and the threshold condition for the MP Relay service are used in the same way, the MP Remote UE may receive the MP Relay service only when the Uu link quality is poor, and the MP Remote UE may not discover the MP Relay UE when the Uu link quality is good. In addition, unlike U2N Relay, MP Relay can provide increased reliability and throughput through an additional indirect path even when the MP Remote UE is in a good coverage area close to the base station (1420). In addition, in the case of MP Relay, an improved service can be provided using MP Relay even when both the MP Relay UE and the MP Remote UE are in a good coverage area close to the base station (1420). Therefore, even when the terminal is in a good coverage state (i.e., Uu link quality higher than threshHighRemote) that does not satisfy the U2N Remote UE threshold condition, it is necessary to provide extended services by allowing the terminal to operate as an MP Remote UE. That is, the upper threshold condition for determining whether to operate as a U2N Remote UE, which can be set to threshHighRemote and hystMaxRemote, is set and applied differently for the MP Remote UE, thereby solving problems in the existing operation that may occur when the threshold condition for the U2N Remote UE and the threshold condition for the MP Remote UE are used identically.

[0333] In addition, according to one embodiment of the present disclosure, it is necessary to guarantee the Uu link quality to a minimum through a lower threshold condition. In order to make it clear that the thresholds to be applied to the MP Remote UE with the added upper / lower thresholds and the corresponding hysteresis are used only for the MP Remote UE and not for the U2N Remote UE, IEs (e.g., threshHighMPRemote, threshLowMPRemote, hystMaxMPRemote, hystMinMPRemote) different from the thresholds applied to the existing U2N Remote UE can be used / defined / configured / set, and for example, can be used / defined / configured / set as shown in Table 5 below.

[0334]

[0335] In order to set and apply a threshold value applicable to the MP Remote UE, if the first terminal (1410) supports the MP Remote UE operation and is in the RRC_CONNECTED state in which an RRC connection with the base station (1420) is established, the base station (1420) may set a range of threshold values ​​for the transmission and / or reception operation of the discovery message of the first terminal (1410) through an RRC message (1416) (e.g., RRCReconfiguration). The threshold value may be configured as at least one of (or may include at least one of) threshHighMPRemote, threshLowMPRemote, hystMaxMPRemote, and hystMinMPRemote. When the first terminal (1410) supports MP Remote UE operation and is in an RRC_IDLE or RRC_INACTIVE state in which an RRC connection with the base station (1420) is not established, the base station (1420) can set a range of thresholds for transmission and / or reception of a discovery message of the first terminal (1410) through SIB (1411) (e.g., SIB12). The first terminal (1410) receiving SIB12 applies the threshold, and the threshold may be configured as at least one of threshHighMPRemote, threshLowMPRemote, hystMaxMPRemote, and hystMinMPRemote (or may include at least one of them).

[0336] FIG. 14b is a flowchart for determining whether a terminal according to an embodiment of the present disclosure satisfies a threshold condition of a multi-path terminal-network relay.

[0337] Referring to FIG. 14b, a terminal supporting MP Remote UE can determine that the terminal satisfies the threshold condition for determining whether to operate as an MP Remote UE if the measured RSRP value of the serving cell, primary cell, or camping cell is lower than (smaller than) the value obtained by subtracting hystMaxMPRemote from threshHighMPRemote, or if the measured RSRP value of the serving cell, primary cell, or camping cell is higher than (larger than) the value obtained by adding hystMinMPRemote to threshLowMPRemote. If the threshold condition for determining whether to operate as an MP Remote UE is satisfied, the terminal can operate as an MP Remote UE. In addition, the terminal supporting MP Remote UE may determine that the terminal no longer satisfies the threshold condition for determining whether to operate as an MP Remote UE if the RSRP measured by the terminal supporting MP Remote UE of the serving cell, primary cell, or camping cell is higher than (greater than) threshHighMPRemote, or if the RSRP measured by the terminal supporting MP Remote UE of the serving cell, primary cell, or camping cell is lower than (less than) threshLowMPRemote. If the threshold condition for determining whether to operate as an MP Remote UE is not satisfied, the terminal may not operate as an MP Remote UE. In addition, if threshHighMPRemote or threshLowMPRemote is not set, the terminal supporting MP Remote UE may always determine that the terminal satisfies the threshHighMPRemote or threshLowMPRemote condition for determining whether to operate as an MP Remote UE.

[0338] FIG. 15 is a flowchart illustrating a method of using a threshold value for multi-path terminal-network relay operation by a terminal according to an embodiment of the present disclosure.

[0339] Referring to FIG. 15, the first terminal (1510) may be an in-coverage (IC) terminal located within the coverage of the base station (1520) and may be a terminal supporting multi-path relay. When the first terminal (1510) is in the RRC_CONNECTED state, it may follow the settings included in the RRC message (e.g., RRCReconfiguration) transmitted by the base station (1520). In addition, when the first terminal (1510) is in the RRC_INACTIVE or RRC_IDLE state, the first terminal (1510) may follow the settings included in the SIB message (e.g., SIB12) transmitted by the base station (1520). The threshold applied to the MP Relay for the MP Relay UE or MP Remote UE described in FIGS. 13A and 14A may also be transmitted to and used by the terminal using different methods (e.g., RRCReconfiguration or SIB12) depending on the RRC state of the first terminal (1510). If the threshold for determining whether to operate as an MP Relay UE or MP Remote UE is not set, the MP Relay UE or MP Remote UE may determine that the terminal always satisfies the threshold condition, or may follow the threshold condition for determining whether to operate as a U2N Relay UE or U2N Remote UE to determine whether to operate as an MP Relay UE or MP Remote UE.

[0340] The first terminal (1510) in the RRC_CONNECTED state can confirm / judge / decide / identify whether it operates as an MP Relay UE or an MP Remote UE based on the UE capability information that the base station (1520) has (information received from the first terminal (1510) through UE capability information or information received from the AMF) or the UE capability information that the first terminal (1510) has. If the threshold applied to the MP Relay described in FIGS. 13A and 14A is not set or defined, the base station (1520) can set the threshold applied to the U2N Relay to be used by the first terminal (1510) in the RRC_CONNECTED state as the threshold applied to the MP Relay through an RRC message (1511). That is, when the first terminal (1510) is a U2N Relay UE and when it is an MP Relay UE, by setting at least one value among threshHighRelay, threshLowRelay, hystMaxRelay, and hystMinRelay differently, the threshold that the first terminal (1510) should use in relation to the MP Relay UE operation can be replaced with the U2N Relay UE threshold value without an explicit instruction related to the MP Relay UE threshold value to the first terminal (1510). In addition, when the first terminal (1510) is an MP Remote UE, by setting at least one value among threshHighRemote and hystMaxRemote differently, the threshold that the first terminal (1510) should use in relation to the MP Remote UE operation can be replaced with the U2N Remote UE threshold value without an explicit instruction related to the MP Remote UE threshold value to the first terminal (1510).

[0341] If both the threshold applied to the MP Relay described in FIGS. 13a and 14a and the threshold applied to the U2N Relay are provided to the first terminal (1510) through an RRC message (1511) or an SIB message (1512), it may not be clear to the AS layer of the first terminal (1510) which value should be used between the threshold applied to the MP Relay described in FIGS. 13a and 14a and the threshold applied to the U2N Relay. The first terminal (1510) may determine that the first terminal (1510) should use the threshold applied to the MP Relay through at least one of the following methods and settings.

[0342] - Supports Release 18 SL Relay

[0343] - Supports Release 18 Multi-path Relay

[0344] - Capable of operating as a relay UE in Release 18 Multi-path Relay

[0345] - Able to operate as a remote UE in Release 18 Multi-path Relay

[0346] - Set up operation as a multi-path relay UE at the upper layer (e.g. ProSe layer)

[0347] - Set up operation as a multi-path remote UE at the upper layer (e.g. ProSe layer)

[0348] - Base station (1520) sets the threshold applied to MP Relay in RRC message

[0349] - The base station (1520) instructs MP Relay UE operation through an RRC message.

[0350] - The base station (1520) instructs MP Remote UE operation through an RRC message.

[0351] When the first terminal (1510) is in the RRC_CONNECTED state, the base station (1520) can set a threshold applied to the MP Relay in the RRC message (1513). When the first terminal (1510) confirms that the threshold used in the MP Relay UE and / or MP Remote UE is included in the RRC message (1513), the first terminal (1510) can determine whether the discovery transmission / reception condition is satisfied using the MP Relay threshold. Alternatively, the base station (1520) can directly instruct the first terminal (1510) to perform the operation of the MP Relay UE and / or MP Remote UE through the RRC message (1514), and the first terminal (1510) can operate as the MP Relay UE and / or MP Remote UE until the corresponding setting is released.

[0352] When the first terminal (1510) is in the RRC_IDLE state or the RRC_INACTIVE state, the base station (1520) may include the MP Relay threshold in the SIB (1512) (e.g., SIB12) to indicate the MP Relay threshold to an unspecified number of terminals, including the first terminal (1510) in the RRC_IDLE state or the RRC_INACTIVE state. The SIB may not include UE-specific settings that are applied only to a specific terminal (e.g., the first terminal (1510)) among the unspecified number of terminals in the RRC_IDLE or RRC_IMACTIVE state. Therefore, in order to allow a specific terminal (e.g., the first terminal (1510)) to use the MP Relay threshold in the RRC_IDLE or RRC_INACTIVE state, the base station (1520) can transmit an indicator via an RRC message (1515) (e.g., RRCRelease) to the first terminal (1510) in the RRC_CONNECTED state, which instructs to use the MP Relay threshold even in the RRC_IDLE or RRC_INACITVE state. The indicator instructing to use the MP Relay threshold even in the RRC_IDLE or RRC_INACITVE state can be an explicit operation indicator as an MP Relay UE or MP Remote UE, or an MP Relay or MP Remote threshold to be used in RRC_IDLE or INACTIVE. The first terminal (1510) that receives the indicator can use the MP Relay threshold included in the SIB (1512) in RRC_IDLE or RRC_INACTIVE.The base station (1520) can instruct the first terminal (1510) to set a timer that can be set with the above indicator, and the first terminal (1510) can stop using the MP Relay threshold by at least one combination of the following: when the RRC state changes from RRC_IDLE or RRC_INACTIVE, when it leaves the SI validity area, when cell reselection is performed, or when the timer expires. If the base station (1520) does not instruct the first terminal (1510) to use the MP Relay UE or MP Remote UE through an RRC message, the first terminal (1510) can determine that it can operate as an MP Relay / Remote UE based on capability information (1516) of the terminal or a setting (1517) of an upper layer (e.g., ProSe), and if the base station (1520) includes a threshold value to be used in MP Relay in the SIB (1512), the first terminal (1510) can use the threshold value of the MP Relay / Remote UE in the RRC_IDLE or RRC_INACTIVE state.

[0353] FIG. 16 is a flowchart illustrating a process in which a terminal performs measurement and measurement reporting in a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0354] Referring to FIG. 16, the first terminal (1610) and the second terminal (1620) may be in-coverage within the coverage of the base station (1630), and the first terminal (1610) may operate as an MP Remote UE, and the second terminal (1620) may operate as an MP Relay UE.

[0355] In order for the first terminal (1610) to measure an L2 U2N Relay UE or an L2 MP Relay UE (e.g., the second terminal (1620)), the base station (1630) can set a measurement configuration including an L2 U2N Relay Object to the first terminal (1610) via an RRC message on an indirect path (1611) or a direct path (1612). When the L2 U2N Relay Object is set, the first terminal (1610) performs measurement and measurement result reporting (1613, 1614) on a serving NR Cell and candidate L2 U2N Relay UE. (For L2 U2N Relay object(s), the UE measures and reports on the serving NR cell(s), as well as the discovered L2 U2N Relay UEs.)

[0356] When a first terminal (1610) and a second terminal (1620), and the first terminal (1610) and a base station (1630) are connected via an MP Relay, the base station (1630) can set the first terminal (1610) to measure candidate MP Relay UEs located near the first terminal (1610), and the base station (1630) can perform an indirect path switch based on information of candidate MP Relay UEs included in the measurement results reported by the first terminal (1610). At this time, the first terminal (1610) needs to simultaneously measure and report not only the candidate MP Relay UE but also the serving MP Relay UE (i.e., the second terminal (1620)). Accordingly, the base station (1630) can compare the link quality between the first terminal (1610) and the serving MP Relay UE and the link quality between the first terminal (1610) and the candidate MP Relay UE, which are reported by the first terminal (1610), and perform related operations such as indirect path change. In addition, if the U2N Remote UE can simultaneously measure and transmit the link quality with the serving L2 U2N Relay UE and the link quality with the candidate U2N Relay UE, the base station (1630) can perform path switch operations such as indirect path switch. Accordingly, if the L2 U2N Relay Object is set for the first terminal (1610), the first terminal (1610) needs to perform measurement and measurement result reporting for the serving NR Cell, the serving Relay UE, and the candidate L2 U2N Relay UE.(That is, For L2 U2N Relay object(s), the UE measures and reports on the serving NR cell(s), serving Relay UE, as well as the discovered L2 U2N Relay UEs.).

[0357] The operation of an L2 MP Remote UE performing measurements on an L2 MP Relay UE and reporting the measurement results can be processed in the same manner as the operation of an L2 U2N Remote UE performing measurements on an L2 U2N Relay UE and reporting the measurement results. That is, the L2 MP Relay UE and the L2 MP Remote UE can be UEs capable of MP Relay operations among L2 U2N Relay UEs, and can be UEs capable of MP Remote operations among L2 U2N Remote UEs. In other words, among L2 U2N Relay UEs, a UE capable of MP Relay operations can be an L2 MP Relay UE, and among L2 U2N Remote UEs, a UE capable of MP Remote operations can be an L2 MP Remote UE. In another case, L2 U2N Relay UE and L2 U2N Remote UE and L2 MP Relay UE and L2 MP Remote UE are terminals that perform different operations, and operations that are not performed by L2 U2N Relay UE or L2 U2N Remote UE may be included in the operations of L2 MP Relay UE or L2 MP Remote UE. These operations may include the MP Relay UE threshold value determination and MP Remote UE threshold value use operations described in FIGS. 13a, 14a, and 15.

[0358] Additionally, the operation of measuring and reporting (1613, 1614) for the first terminal (1610) to the second terminal (1620) which is the indirect path and the base station (1630) which is the direct path may be included in the measurement and measurement reporting operations in the multi-path terminal-network relay. That is, the MP Remote UE may include the measurement results for the serving NR cell(s) and the serving L2 MP Relay UE set in the servingCellMO in the measurement report.

[0359] When an MP Remote UE (e.g., a first terminal (1610)) reports a measurement result for an MP Relay UE (e.g., a second terminal (1620)) to a base station (1630), the cell identifier, which is a PCell or a camping cell of the MP Relay UE, an L2ID used for sidelink discovery and / or sidelink communication transmitted by the MP Relay UE, and the result of measuring the corresponding sidelink signal may be included, and may be configured / set / defined as shown in Table 6 below.

[0360]

[0361] According to one embodiment of the present disclosure, the MP Relay may consider a scenario in which both an MP Remote UE (e.g., a first terminal (1610)) and an MP Relay UE (e.g., a second terminal (1620)) are served by the same base station (1630). In this case, when the first terminal (1610) measures and reports the serving relay UE, the first terminal (1610) may not include a cell identifier because the PCell or camping cell of the first terminal (1610) and the second terminal (1620) is the same base station (1630) that is directly linked to the first terminal (1610) and the second terminal (1620), respectively. That is, the cellIdentity of Table 6 above may not be transmitted.

[0362] According to one embodiment of the present disclosure, further, when the first terminal (1610) is in MP Relay operation with both a direct path and an indirect path set, the base station (1630) may instruct the first terminal (1610) to discover and measure a candidate Relay UE for the purpose of an indirect path change, etc. In this case, the PCell or camping cell of the candidate Relay UE may be different from the PCell or camping cell of the first terminal (1610), and in this case, the scenario in which the candidate Relay UE and the first terminal (1610) are served by the same base station (1630) may not be such that the first terminal (1610) may not determine, among the discovered candidate Relay UEs, a candidate Relay UE that is not served by the PCell or camping cell of the first terminal (1610) as a reporting target.

[0363] In order to distinguish between the reporting operation in a scenario where both the MP Remote UE (e.g., the first terminal (1610)) and the MP Relay UE (e.g., the second terminal (1620)) are served by the same base station (1630) and the reporting operation in a scenario where the MP Remote UE (e.g., the first terminal (1610)) and the MP Relay UE (e.g., the second terminal (1620)) are served by different base stations (1630), the base station may, when instructing the reporting operation, instruct the terminal by distinguishing between the L2 U2N Relay measurement object and the L2 MP Relay measurement object.

[0364] Additionally, if the indirect path and direct path are established through different base stations (1630), cellIdentity may need to be included in the measurement report of the candidate relay UE. Therefore, the cellIdentity in Table 6 may be in the OPTIONAL form, which can be reported as needed, considering cases where the path is established through different base stations (1630).

[0365] FIG. 17 is a flowchart illustrating a process in which a terminal performs measurement and measurement reporting in a multi-path terminal-network relay according to an embodiment of the present disclosure.

[0366] Referring to FIG. 17, the first terminal (1710), the second terminal (1720), and the third terminal (1730) may be in-coverage within the coverage of the base station (1740), and the first terminal (1710) may operate as an MP Remote UE, while the second terminal (1720) and the third terminal (1730) may operate as MP Relay UEs. The second terminal (1720) may be a serving Relay UE of the first terminal (1710).

[0367] Referring to FIG. 17, the base station (1740) can set the measurement report triggering event that triggers a measurement report to the first terminal (1710) to simultaneously consider one or more of the serving NR cell(s), the serving Relay UE, and the neighbor NR cell and the candidate Relay UE. That is, when the first terminal (1710) provides a U2N Relay service to the base station (1740) through the second terminal (1720), the base station (1740) can set (1711) a measurement report triggering event to check whether the first terminal (1710) is suitable for providing the MP Relay service by adding a direct path through which the first terminal (1710) can directly communicate with the base station (1740) through the direct path. The measurement report triggering event may be satisfied when the link quality of the PC5 link between the first terminal (1710) and the second terminal (1720) is a PC5 link quality higher than a specific threshold. Alternatively, the measurement report triggering event may be satisfied when the link quality of the PC5 link between the first terminal (1710) and the second terminal (1720) is a PC5 link quality higher than a specific threshold, and the quality of the Uu link between the first terminal (1710) and the base station (1740) is a Uu link quality higher than a specific threshold. In this case, the unit for measuring the signal strength of the second terminal (1720) (i.e., serving U2N Relay) by the first terminal (1710) may be SL-RSRP (sidelink-Reference Signals Received Power) based on the signal strength of the sidelink communication or SD-RSRP (sidelink discovery Reference Signals Received Power) based on the signal strength of the sidelink discovery message.The base station (1740) can designate / set a different unit to be used for measuring the second terminal (1720) for each measurement report triggering event to the first terminal (1710), and can designate / set either SL-RSRP or SD-RSRP, or both SL-RSRP and SD-RSRP as the measurement unit. The measurement unit can also be applied to a measurement report triggering event associated with the first terminal (1710), the second terminal (1720), a third terminal (1730) not connected to the first terminal (1710), or another terminal not shown in the drawing. The conditions of such a measurement report triggering event can be as follows.

[0368] - When the PC5 link quality of the Remote UE and the serving Relay UE is above the threshold.

[0369] - When the PC5 link quality of the Remote UE and serving Relay UE is above the threshold, and the Uu link quality of the Remote UE and NR Cell is above the threshold.

[0370] When the condition of the measurement report triggering event is satisfied (1712), the first terminal (1710) may include the measurement result and additional information, which may include the serving cell, NR cell, serving Relay UE, candidate Relay UE, etc., which the first terminal (1710) is configured to measure, in the measurement report message through the measurement object. At this time, the measurement result may include one of SL-RSRP or SD-RSRP configured by the base station (1740), or both SL-RSRP and SD-RSRP, and in order to match the measurement unit configured by the base station (1740) and the measurement unit reported by the first terminal (1710), a setting for explicitly indicating that it is SL-RSRP or SD-RSRP may be exemplarily set / configured / defined as in Table 7 below.

[0371]

[0372] If the first terminal (1710) is configured to measure and report a candidate Relay UE other than the serving Relay UE, the measurement unit for the candidate Relay UE and the reporting unit for the serving Relay UE may be different. For example, if the first terminal (1710) is configured to measure and report SL-RSRP for the candidate Relay UE, but the serving Relay UE of the first terminal (1710) does not send sidelink data, SL-RSRP measurement for the serving Relay UE of the first terminal (1710) may not be possible, and only SD-RSRP measurement via a sidelink discovery message for the serving Relay UE of the first terminal (1710) may be possible. In this case, it may be difficult to compare the PC5 link quality for the candidate Relay UE and the PC5 link quality for the serving Relay UE, and thus the base station (1740) may have difficulty managing the indirect path of the first terminal (1710) even if it receives the measurement report. Therefore, an explicit instruction and reporting procedure for the measurement units of the serving Relay UE and candidate Relay UE measured by the first terminal (1710) may be required. When the measurement result for the serving Relay UE of the first terminal (1710) is included in the measurement report of the first terminal (1710), the measurement result may include SL-RSRP, and in the case of no sidelink data transmission, the measurement result may include SD-RSRP. According to one embodiment of the present disclosure, the first terminal (1710) may measure candidate relay UEs in units of SL-RSRP or SD-RSRP, and the base station (1740) may set a threshold for SL-RSRP and / or SD-RSRP.At this time, the first terminal (1710) can report (1713) the measurement result of the Serving Relay UE using the same measurement unit as the unit set in the measurement report triggering event for reporting the candidate relay UE (i.e., the measurement unit of ReportConfig associated with the L2U2N Relay measurement object) without explicitly setting the measurement unit for the serving Relay UE. For example, if the measurement report triggering condition of the set candidate Relay UE is SD-RSRP, the measurement report (1713) reported by satisfying the measurement report triggering condition of the set candidate Relay UE may include the result of the first terminal (1710) measuring the SD-RSRP of the serving Relay UE. Alternatively, the measurement result that the first terminal (1710) can currently report for the serving Relay UE, i.e., at least one of SD-RSRP and SL-RSRP, may be included in the measurement report (1713).

[0373] FIG. 18 is a flowchart illustrating a process by which a terminal selects or reselects a relay terminal during a multi-path terminal-network relay operation according to an embodiment of the present disclosure.

[0374] When the first terminal operates as a U2N Remote UE, the U2N Relay service can be used by selecting or reselecting the U2N Relay UE. The conditions for the first terminal to select or reselect the U2N Relay UE may include: when the serving cell of the first terminal does not exist; when the RSRP of the camping cell or PCell satisfies the threshold condition of the U2N Remote UE and the U2N Relay UE is not selected; when the SL-RSRP of the serving Relay UE is worse than sl-RSRP-Thresh; when the SL-RSRP of the serving Relay UE is unavailable; when the SD-RSRP of the serving Relay UE is worse than sl-RSRP-Thresh; when the upper layer instructs not to use the serving Relay UE; when the upper layer instructs to release the PC5-RRC connection with the serving Relay UE; when an RLF is detected in the sidelink with the serving Relay UE; and when at least one or more of the cases included in the conditions for the first terminal to select or reselect the U2N Relay UE is satisfied, a discovery procedure for finding a candidate Relay UE may be performed. Among the discovered candidate relay UEs, those that satisfy the AS layer threshold (e.g., sl-RSRP-Thresh) can be considered for selection. This procedure can be exemplified in Table 8 below.

[0375]

[0376] Unlike U2N Relay, the selection or reselection of an MP Relay UE for the MP Relay service of the first terminal can be performed by the base station. That is, instead of the first terminal performing the selection or reselection of the MP Relay UE, the first terminal performs a procedure for measuring a candidate MP Relay UE and reporting the measurement result to the base station. Through this procedure, the base station, which receives the candidate MP Relay UE from the first terminal, can select an MP Relay UE to use in the indirect path.

[0377] In order to prevent the MP Remote UE from selecting or reselecting the MP Relay UE, the terminal may not select or reselect the Relay UE in at least one of the following cases.

[0378] - A terminal that is set up and operating as an MP Remote UE, i.e. a terminal with a direct path and an indirect path set up, does not select or reselect an MP Relay UE.

[0379] - Among terminals communicating via the direct path, terminals that satisfy the MP Remote UE threshold conditions do not select or reselect the MP Relay UE. In this case, if the U2N Remote UE threshold conditions are also satisfied, the selection or reselection conditions for the U2N Remote UE may be followed.

[0380] FIG. 19 is a flowchart illustrating a process in which a terminal reports an indirect path failure to a base station during a multi-path terminal-network relay operation according to an embodiment of the present disclosure.

[0381] Referring to FIG. 19, the first terminal (1910) and the second terminal (1920) may be in-coverage within the coverage of the base station (1930), and the first terminal (1910) may operate as an MP Remote UE, while the second terminal (1920) may operate as an MP Relay UE. The first terminal (1910) may be in MP relay operation in which both an indirect path through the second terminal (1920) and a direct path through the base station (1930) are established.

[0382] When the first terminal (1910) detects (1911) a PC5 RLF or link failure in the connection with the second terminal, the first terminal (1910) can report an indirect path failure to the base station (1930) using an RRC message (1912) via the direct link. The PC5 RLF can be detected when at least one of the following cases is satisfied: when RLC retransmissions for a specific target occur a specified number of times, when the T400 timer for a specific target expires, when HARQ DRXs for a specific target occur a specified number of times, or when the integrity check of SL-SRB2 or SL-SRB3 for a specific target fails. In addition, when a wireless access technology other than 3GPP is used, link failure can be detected by the detection method of the wireless access technology.

[0383] In addition to the case where the first terminal (1910) detects / detects PC5 RLF and link failure for the second terminal (1920), the first terminal (1910) may be instructed by the upper layer to discontinue the connection with the second terminal (1920). For example, the upper layer of the first terminal (1910) may issue an instruction (1913) to release the PC5-RRC connection with the second terminal (1920). In addition, the upper layer of the first terminal (1910) may issue an instruction (1913) to no longer use the MP Relay with the second terminal (1920). In this case, the first terminal (1910) may not transmit an indirect path failure report to the base station (1930) because a PC5 RLF or link failure has not occurred, and thus the base station (1930) cannot clearly know why the connection between the first terminal (1910) and the second terminal (1920) was terminated. Therefore, when the first terminal (1910) terminates PC5-RRC by a higher layer or no longer uses the second terminal (1920) as an MP Relay UE (1913), a method may be needed for the first terminal (1910) to notify the base station (1930) of this.

[0384] According to one embodiment of the present disclosure, the first terminal (1910) uses an indirect path failure report (1914), and the indirect path failure report (1914) can be transmitted to the base station (1930) using an indirect path or a direct path. This message (1914) can include an indicator for notifying the base station (1930) that a higher layer has requested PC5-RRC release, or has sent an indication that the second terminal (1920) is no longer being used, and can include an identifier (e.g., L2ID) that can identify the second terminal (1920) and an identifier of a serving cell, PCell, or camping cell of the second terminal.

[0385] According to one embodiment of the present disclosure, in another method, the first terminal (1910) can transmit an RRC message (1915) (e.g., sidelinkUEInformationNR) to the base station (1930) using an indirect path or a direct path, indicating that the first terminal (1910) no longer requests resources for communicating with the second terminal (1920). This message (1915) can include an identifier (e.g., L2ID) that can identify the second terminal (1920) and an identifier of the serving cell, PCell, or camping cell of the second terminal. The base station (1930) can know that the first terminal (1910) will not continue to communicate with the second terminal (1920) based on the fact that the first terminal (1910) does not request resources for communicating with the second terminal (1920).

[0386] According to one embodiment of the present disclosure, in another method, the first terminal (1910) may transmit an RRC message (1916) (e.g., sidelinkUEInformationNR) to the base station (1930) via an indirect path or a direct path, indicating that the first terminal (1910) will no longer communicate with the second terminal (1920). This message (1916) may include an identifier (e.g., L2ID) that can identify the second terminal (1920) and an identifier of the second terminal's serving cell, PCell, or camping cell. Including such information allows the base station (1930) to efficiently utilize resources through management such as releasing indirect paths that may no longer be used.

[0387] The methods according to the claims of the present disclosure or the embodiments described in the disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0388] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments of the present disclosure.

[0389] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0390] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

[0391] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0392] Meanwhile, the embodiments of the present disclosure disclosed in the present disclosure and the drawings are only specific examples to easily explain the technical contents of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the above-mentioned embodiments can be combined and operated with each other as needed. For example, parts of one embodiment of the present disclosure and parts of another embodiment can be combined with each other to operate a base station and a terminal. For example, parts of the first embodiment and the second embodiment of the present disclosure can be combined with each other to operate a base station and a terminal. In addition, although the above-mentioned embodiments have been presented based on an FDD LTE system, other modifications based on the technical idea of ​​the above-mentioned embodiments can be implemented with other systems such as a TDD LTE system, 5G, or NR system.

[0393] Meanwhile, the order of description in the drawings explaining the method of the present disclosure does not necessarily correspond to the order of execution, and the order of precedence may be changed or executed in parallel.

[0394] Alternatively, the drawings illustrating the method of the present disclosure may omit some components and include only some components without detracting from the essence of the present disclosure.

[0395] In addition, the method of the present disclosure may be implemented by combining some or all of the contents included in each embodiment within a scope that does not harm the essence of the disclosure.

[0396] Various embodiments of the present disclosure have been described above. The foregoing description of the present disclosure is for illustrative purposes only, and the embodiments of the present disclosure are not limited to the disclosed embodiments. Those skilled in the art will appreciate that the present disclosure can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present disclosure. The scope of the present disclosure is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present disclosure.

Claims

1. A method performed by a first terminal in a wireless communication system, the method comprising: A step of receiving a signal for measuring a sidelink with the second terminal from the second terminal; and Including a step of transmitting a measurement report including the result of the measurement based on the signal to the second terminal or base station, A method wherein the above measurement report includes information indicating the measurement unit on which the result of the above measurement is based.

2. In paragraph 1, A method in which the information indicating the above measurement unit indicates one of sidelink-Reference Signals Received Power (SL-RSRP) or sidelink discovery reference signals received power (SD-RSRP).

3. In paragraph 2, A method wherein the result of the above measurement includes a measurement result based on the SL-RSRP or a measurement result based on the SD-RSRP.

4. In paragraph 2, A method in which no separate setting for the measurement unit is configured for the first terminal.

5. A method performed by a second terminal in a wireless communication system, the method comprising: A step of transmitting a signal for measuring a sidelink with the first terminal to the first terminal; and Including a step of receiving a measurement report including the result of the measurement based on the signal from the first terminal, A method wherein the above measurement report includes information indicating the measurement unit on which the result of the above measurement is based.

6. In paragraph 5, A method in which the information indicating the above measurement unit indicates one of sidelink-Reference Signals Received Power (SL-RSRP) or sidelink discovery reference signals received power (SD-RSRP).

7. In paragraph 6, A method wherein the result of the above measurement includes a measurement result based on the SL-RSRP or a measurement result based on the SD-RSRP.

8. In paragraph 6, A method in which no separate setting for the measurement unit is configured for the first terminal.

9. In a wireless communication system, in a first terminal, the first terminal, transceiver; and Including a controller connected to the above transceiver, The above controller: Receive a signal for measuring a sidelink with the second terminal from the second terminal, configured to transmit a measurement report including the result of the measurement based on the signal to the second terminal or base station, The above measurement report includes information indicating the measurement unit on which the result of the above measurement is based, the first terminal.

10. In paragraph 9, The information indicating the above measurement unit is a first terminal indicating either SL-RSRP (sidelink-Reference Signals Received Power) or SD-RSRP (sidelink discovery reference signals received power).

11. In Article 10, The first terminal, wherein the result of the above measurement includes a measurement result based on the SL-RSRP or a measurement result based on the SD-RSRP.

12. In paragraph 10, A first terminal for which no separate setting for the measurement unit is configured for the first terminal.

13. In a wireless communication system, in a second terminal, the second terminal, transceiver; and Including a controller connected to the above transceiver, The above controller: Transmitting a signal for measuring sidelink with the first terminal to the first terminal, configured to receive, from the first terminal, a measurement report including the result of the measurement based on the signal, The second terminal, wherein the above measurement report includes information indicating the measurement unit on which the result of the above measurement is based.

14. In paragraph 13, The second terminal, wherein the information indicating the above measurement unit indicates either SL-RSRP (sidelink-Reference Signals Received Power) or SD-RSRP (sidelink discovery reference signals received power).

15. In paragraph 14, The second terminal, wherein the result of the above measurement includes a measurement result based on the SL-RSRP or a measurement result based on the SD-RSRP.

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