Method and device for managing end-to-end connection configured through terminal relay in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. This method, performed by a first UE in a wireless communication system, may include the steps of: identifying either the expiration of a timer associated with an end-to-end (E2E) connection for sidelink communication with a second UE through a relay UE, or the failure of an integrity check of an SL SRB for the E2E connection; and deleting an SRAP setting for the E2E connection.

Description

Method and device for managing end-to-end connections established through terminal relays in a wireless communication system

[0001] The present disclosure relates to a wireless communication system. More specifically, the present disclosure relates to a method and device for establishing an end-to-end connection with another terminal based on a sidelink with a relay terminal in a wireless communication system and managing the end-to-end connection.

[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 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.

[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] An embodiment of the present disclosure seeks to provide a device and method capable of effectively providing a service in a wireless communication system.

[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 can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0010] According to one embodiment, a method performed by a first UE in a wireless communication system may include identifying an expiration of a timer associated with an end-to-end (E2E) connection for sidelink communication with a second UE via a relay UE, or a failure of an integrity check of a sidelink (SL) signaling radio bearer (SRB) for the E2E connection, and discarding a sidelink relay adaptation protocol (SRAP) configuration for the E2E connection.

[0011] According to one embodiment of the present disclosure, a device and method can be provided that can effectively provide a service and expand service coverage in a wireless communication system.

[0012] 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.

[0013] FIG. 1A is a diagram illustrating a wireless communication system according to one embodiment of the present disclosure.

[0014] FIG. 1b is a diagram illustrating a wireless communication system according to one embodiment of the present disclosure.

[0015] FIG. 2 is a diagram illustrating a configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0016] FIG. 3 is a diagram illustrating a configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0017] FIG. 4 is a diagram illustrating the configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure.

[0018] FIG. 5 is a diagram illustrating a structure of time-frequency resources of a wireless communication system according to an embodiment of the present disclosure.

[0019] FIG. 6 is a diagram illustrating a signal flow for managing a terminal connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0020] FIG. 7 is a diagram illustrating a signal flow for managing a terminal connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0021] FIG. 8 is a diagram illustrating a signal flow between a remote terminal and a terminal relay that manages an end-to-end connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0022] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the attached drawings. It should be noted that, where possible, identical components are represented by identical reference numerals in the attached drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present disclosure will be omitted.

[0023] In describing the embodiments in this specification, 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 avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0024] 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 may be assigned the same reference number.

[0025] 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 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 solely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure. The present disclosure is defined solely by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0026] At this time, it can 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).

[0027] 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.

[0028] Here, the term '~ unit' used in the present embodiment means a software or hardware component such as an FPGA or ASIC, 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. Accordingly, 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'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0029] In specifically explaining the embodiments of the present disclosure, the main target is the New RAN (NR) radio access network and the packet core (5G system, or 5G core network, or NG Core: next generation core) core network of the 5G mobile communication standard specified by the 3GPP, a mobile communication standard standardization organization. However, the main gist of the present disclosure can be applied to other communication systems having a similar technical background 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.

[0030] In a 5G system, a network data collection and analysis function (NWDAF) may be defined to support network automation, providing the ability to analyze and provide data collected from the 5G network. For example, the NWDAF may collect, store, and / or analyze information from the 5G network and provide the results to an unspecified network function (NF). The analysis results can be independently utilized by each NF.

[0031] For convenience of explanation below, some terms and names defined in the 3rd generation partnership project long-term evolution (3GPP) standards (standards for 5G, NR, LTE, or similar systems) may be used. However, the present disclosure is not limited to the terms and names and can be equally applied to systems conforming to other standards.

[0032] The present disclosure relates to a method and device for managing a PC5 termination connection established between two remote terminals in a wireless communication system when the terminal is connected to another terminal through a sidelink relay.

[0033] One embodiment of the present disclosure can expand service coverage, increase reliability of data transmission and reception, and minimize or reduce battery usage of the terminal by allowing the terminal to transmit and receive data / signaling with other terminals through a sidelink relay.

[0034] The terms used in the following description, including terms referring to signals, channels, control information, network entities, and device components, are provided for convenience of explanation. Therefore, the present disclosure is not limited to these terms, and other terms that refer to objects with equivalent technical meanings may be used.

[0035] Hereinafter, a 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. However, this is merely an example, and the base station and the terminal are not limited to these examples. In the present disclosure, eNB may be used interchangeably with gNB for the convenience of description. That is, a base station described as an eNB may represent a gNB. In the present disclosure, the term terminal may refer to various wireless communication devices as well as mobile phones, NB-IoT (internet of things) devices, and sensors.

[0036] In the following description, the terms "physical channel" and "signal" may be used interchangeably with data or control signals. For example, while PDSCH (physical downlink shared channel) refers to a physical channel through which data is transmitted, PDSCH can also be used to refer to data. That is, in the present disclosure, the expression "transmitting a physical channel" can be interpreted equivalently to the expression "transmitting data or a signal through a physical channel."

[0037] Hereinafter, in the present disclosure, upper signaling refers to a signal transmission method in which a base station transmits a signal to a terminal using a downlink data channel of the physical layer, or a terminal transmits a signal to a base station using an uplink data channel of the physical layer. Upper signaling can be understood as radio resource control (RRC) signaling or a media access control (MAC) control element (CE).

[0038] Additionally, in the present disclosure, expressions such as "more than" and "less than" are used to determine whether a specific condition is satisfied or fulfilled. However, this is merely a description to express an example and does not exclude descriptions of more than or less than. Conditions described as "more than" may be replaced with "more than," conditions described as "less than" may be replaced with "less than," and conditions described as "more than and less than" may be replaced with "more than and less than."

[0039] Additionally, while this disclosure describes embodiments using terminology used in certain communication standards (e.g., 3rd Generation Partnership Project (3GPP)), this is merely an example for illustrative purposes. Embodiments of this disclosure can be easily modified and applied to other communication systems.

[0040] The present disclosure states that in a wireless communication system, when a terminal is connected to another terminal through a sidelink relay, the terminal, the other terminal, and the sidelink relay may be in an RRC_CONNECTED state, an RRC_INACTIVE state, an RRC_IDLE state, or an OUT-OF-COVERAGE state from a network perspective, and the states of each terminal, including the sidelink relay, may operate independently. The terminal, the other terminal, and the sidelink relay may be connected to the same cell, different cells, the same base station, or different base stations, respectively.

[0041] Additionally, sidelink communication using 5G communication systems is being studied, and it is expected that direct communication between terminals will be applied to, for example, vehicle-to-everything (V2X) communication and public safety networks, and will be able to provide various services to users.

[0042] In particular, there is a need for a method that utilizes sidelink relays that can support expansion of service coverage, increased reliability of data transmission, and reduced power consumption of terminals.

[0043] The present disclosure, which aims to solve the above-mentioned problem, relates to a method and apparatus for handling a problem situation of a terminal connection established by two remote terminals in a system that relays and transmits data or signaling between terminals (i.e., two remote terminals) based on a sidelink with a relay terminal in a wireless communication system. The problem situation of a terminal connection established by two remote terminals according to an embodiment of the present disclosure may include at least one of a case in which a transmitting terminal transmits a PC5 RRC message (RRCReconfigurationSidelink message) for configuration and establishment of a terminal connection and does not receive a PC5 RRC response message (RRCReconfigurationCompleteSidelink message) from a receiving terminal for a predetermined time (e.g., T400 timer), and a case in which integrity protection of a PDCP (packet data convergence protocol) PDU (protocol data unit) corresponding to data or signaling transmitted by the transmitting terminal to the receiving terminal is determined to have failed.

[0044] FIG. 1A is a diagram illustrating a wireless communication system according to one embodiment of the present disclosure.

[0045] FIG. 1A illustrates a sidelink relay (120) that can relay data transmission and reception between a base station (110), a terminal (130, 140), and / or a base station and a terminal as part of nodes utilizing a wireless channel in a wireless communication system (or mobile communication system). For example, the sidelink relay may be a U2N (UE to network) relay.

[0046] Although FIG. 1A of the present disclosure illustrates only one base station, the wireless communication system (or mobile communication system) may further include other base stations identical or similar to the base station (110), and may further include more relays (or relay UEs). That is, the configuration of the wireless communication system of FIG. 1A is exemplary, and may further include other components (e.g., base stations, UEs, servers) not illustrated in FIG.

[0047] According to one embodiment, the base station (110) may be a network infrastructure that provides wireless access to terminals (130, 140) and a relay (120). The base station (110) may have coverage defined as a certain geographical area based on the distance at which a signal can be transmitted. For example, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5th generation node', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)' or other terms having an equivalent technical meaning in addition to the base station.

[0048] According to one embodiment, the relay (120) is an apparatus or device used by a user or network infrastructure, and can communicate with the base station (110) via a wireless channel. For example, a link from the base station (110) to the relay (120) may be referred to as a downlink (DL), and a link from the relay (120) to the base station (110) may be referred to as an uplink (UL). The base station (110) and the relay (120) may be connected via a Uu interface. The uplink (UL) may be referred to as a wireless link through which the relay (120) transmits data or control signals to the base station (110), and the downlink (DL) may be referred to as a wireless link through which the base station (110) transmits data or control signals to the relay (120).

[0049] According to one embodiment, the relay (120) may communicate with the terminal (130) and the terminal (140) via a wireless channel. For example, the link between the relay (120) and the terminal (130) and the link between the relay (120) and the terminal (140) may be referred to as a sidelink, and the sidelink may be referred to as a PC5 interface.

[0050] According to one embodiment, each of the terminals (130, 140) is a device or apparatus used by a user, and can communicate with a base station (110) through a wireless channel or communicate with a network through a wireless channel with a relay (120).

[0051] According to one embodiment, each of the terminals (130) and (140) may communicate with the relay (120) via a wireless channel. For example, at least one of the terminals (130) and (140) may be operated without user intervention. That is, at least one of the terminals (130) and (140) may be a device that performs machine type communication (MTC) and may not be carried by the user.

[0052] For example, each of the terminal (130) and the terminal (140) may be referred to or referred to as a 'user equipment (UE)', a 'mobile station', a 'subscriber station', a 'remote terminal', a 'wireless terminal', or a 'user device' or other terms having an equivalent technical meaning.

[0053] FIG. 1b is a diagram illustrating a wireless communication system according to one embodiment of the present disclosure.

[0054] FIG. 1b illustrates a wireless communication system (or mobile communication system) that includes terminals (150, 170) and a sidelink relay (160) capable of relaying data transmission and reception between terminals, as part of nodes utilizing a wireless channel. For example, the sidelink relay (160) may be a U2U (UE to UE) relay. Of course, the wireless communication system is not limited to the examples described above. That is, the configuration of the wireless communication system of FIG. 1b is an example, and may further include other components not illustrated in FIG. 1b.

[0055] According to one embodiment, the relay (160) may communicate with the terminal (150) and the terminal (170) via a wireless channel. For example, the link between the relay (160) and the terminal (150) and the link between the relay (160) and the terminal (170) may be referred to as a sidelink, and the sidelink may be referred to or referred to as a PC5 interface.

[0056] According to one embodiment, each of the terminal (150) and the terminal (170) is a device or apparatus used by a user, and can perform direct communication through a wireless channel or can perform communication with the counterpart terminal through a wireless channel with the relay (160). For example, the link between the terminal (150) and the terminal (170), the link between the terminal (150) and the relay (160), and the link between the terminal (170) and the relay (160) may be referred to as a side link, and the side link may also be referred to as a PC5 interface.

[0057] According to one embodiment, at least one of the terminal (150) or the terminal (170) may be operated without user intervention. For example, at least one of the terminal (150) or the terminal (170) may be a device or apparatus performing machine type communication (MTC), and at least one of the terminal (150) or the terminal (170) may not be carried by the user. For example, each of the terminal (150) and the terminal (170) may be referred to or referred to as a 'user equipment (UE)', a 'mobile station', a 'subscriber station', a 'remote terminal', a 'wireless terminal', a 'user device', or other terms having equivalent technical meanings thereto.

[0058] In the following description, the uplink and downlink can be mixed with the Uu interface, and the sidelink can be mixed with the PC-5.

[0059] In the following description, the description of the uplink may be applied to the downlink, and the description of the downlink may be applied to the uplink. As another example, the terms Uu interface, sidelink, and PC-5 may be used interchangeably. That is, the description of the Uu interface may be referred to as the description of the sidelink and / or PC-5, and the description of the sidelink may be referred to as the description of the Uu interface and / or PC-5.

[0060] For example, the Uu interface may be referred to as an interface between a UE and a base station (e.g., an eNoB or gNB), and PC-5 may be referred to as a communication technology for data transmission between vehicles (V2V) and / or vehicles to everything (V2X) and / or devices to devices (D2D).

[0061] The base station (110), relays (120, 160), and / or terminals (130, 140, 150, 170) illustrated in FIGS. 1A and 1B can transmit and / or receive wireless signals in a millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz). To improve channel gain, the base station (110), relays (120, 160), and / or terminals (130, 140, 150, 170) can perform beamforming. For example, the beamforming can include transmit beamforming and receive beamforming. That is, the base station (110), relays (120, 160), and terminals (130, 140, 150, 170) can impart directionality to a transmit signal or a receive signal. To this end, the base station (110), relays (120, 160), and / or terminals (130, 140, 150, 170) can select serving beams (112, 113, 121, 131, 141, 151, 161, 171) through a beam search or beam management procedure. After the serving beams (112, 113, 121, 131, 141, 151, 161, 171) are selected, communication can be performed through resources that are in a quasi-co-located (QCL) relationship with the resources that transmitted the serving beams (112, 113, 121, 131, 141, 151, 161, 171).

[0062] According to one embodiment, the first antenna port and the second antenna port may be in a QCL relationship or may be evaluated as being in a QCL relationship if, in case that large-scale characteristics of the channel carrying the symbol on the first antenna port can be inferred from the channel carrying the symbol on the second antenna port. For example, the large-scale characteristics (or characteristics associated with the QCL relationship) may include at least one of a delay spread, a Doppler spread, a Doppler shift, an average gain, an average delay, or a spatial receiver parameter.

[0063] According to one embodiment, the terminal (130), the terminal (140), the terminal (150), and / or the terminal (170) illustrated in FIG. 1A and / or FIG. 1B may support vehicle communication. For vehicle communication, in the LTE system, standardization work on vehicle to everything (V2X) technology based on a device-to-device (D2D) architecture was completed in 3GPP Release 14 and Release 15, and standardization work on V2X technology based on 5G NR was completed in 3GPP Release 16. For example, NR V2X may support unicast communication, groupcast (or multicast) communication, and / or broadcast communication between terminals. In addition, unlike LTE V2X, which aims to transmit and receive basic safety information required for vehicle driving on the road, NR V2X aims to provide more advanced services such as platooning, advanced driving, extended sensor, and remote driving.

[0064] V2X services can be divided into basic safety services and advanced services. Basic safety services may include sub-services such as vehicle notification (cooperative awareness messages (CAM) or basic safety message (BSM)) services, left turn alert services, forward collision warning services, emergency vehicle approach alert services, forward obstacle warning services, and / or intersection signal information services. V2X information may be transmitted and received using broadcast, unicast, or groupcast transmission methods. Advanced services not only have stronger quality of service (QoS) requirements than basic safety services, but also require methods to transmit and receive V2X information using unicast and groupcast transmission methods in addition to broadcast, so that V2X information can be transmitted and received within a specific vehicle group or between two vehicles. Advanced services may include sub-services of platooning services, autonomous driving services, remote driving services, and / or extended sensor-based V2X services. Additionally, NR V2X can provide public safety services by supporting direct communication services between terminals in areas without network infrastructure.

[0065] Hereinafter, sidelink (SL) may be referred to as a transmission / reception path for signals between terminals or a transmission / reception path for signals between terminals and relays. Sidelink may be used interchangeably with the PC5 interface.

[0066] The term "base station" hereinafter refers to an entity that performs resource allocation for terminals and relays. It may be a base station that supports both V2X communication and general cellular communication, or a base station that supports only V2X communication. For example, a base station may be referred to as an NR base station (e.g., gNB), an LTE base station (e.g., eNB), or an RSU (road site unit).

[0067] For example, a terminal may include not only a general user equipment, a mobile station, but also a vehicle supporting vehicular-to-vehicular (V2V) communication, a vehicle or pedestrian handset (e.g., a smart phone) supporting vehicular-to-pedestrian (V2P) communication, a vehicle supporting vehicular-to-network (V2N) communication, or a vehicle supporting vehicular-to-infrastructure (V2I) communication, and an RSU equipped with terminal functions, an RSU equipped with base station functions, or an RSU equipped with a part of base station functions and a part of terminal functions.

[0068] In the present disclosure, a terminal may be referred to as a vehicle supporting vehicular-to-vehicular (V2V) communication, a vehicle or a pedestrian's handset (e.g., a smartphone) supporting vehicular-to-pedestrian (V2P) communication, a vehicle supporting vehicular-to-network (V2N) communication, or a vehicle supporting vehicular-to-infrastructure (V2I) communication. A terminal may be referred to as a user device supporting device-to-device communication of a public safety network.

[0069] In the present disclosure, a terminal may be referred to as an RSU (road side unit) 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.

[0070] In the present disclosure, a relay may be referred to as a vehicle supporting V2X communication or a user device supporting communication between devices in a public safety network. Furthermore, in the present disclosure, a relay may be referred to as a device equipped with terminal functions, a device equipped with base station functions, or a device equipped with a portion of terminal functions and a portion of base station functions.

[0071] FIG. 2 is a diagram illustrating a configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0072] Referring to FIG. 2, the configuration illustrated in FIG. 2 can be understood as the configuration of a base station (110). Terms such as "... unit" and "... unit" used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0073] Referring to FIG. 2, a base station (110) according to an embodiment may include a wireless communication unit (210), a backhaul communication unit (220), a storage unit (230), and / or a control unit (240). However, the components of the base station (110) are not limited to the examples described above. For example, the base station (110) may include more or fewer components than the components described above. In addition, the wireless communication unit (210), the backhaul communication unit (220), the storage unit (230), and the control unit (240) may be implemented in the form of a single chip. In addition, the control unit (240) may include one or more processors. For example, the base station (110) may include a transceiver and a controller coupled with the transceiver. As another example, the base station (110) may include at least one transceiver and at least one processor coupled with the at least one transceiver. As another example, the base station (110) may include a memory storing instructions to be executed by the controller, a transceiver, and a controller.

[0074] According to one embodiment, the wireless communication unit (210) may perform functions for transmitting and / or receiving signals via a wireless channel. For example, the wireless communication unit (210) may perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the wireless communication unit (210) may generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the wireless communication unit (210) may restore a reception bit stream by demodulating and decoding a baseband signal. For example, the wireless communication unit (210) may be replaced with a transceiver, a receiver, and / or a transmitter.

[0075] According to one embodiment, the wireless communication unit (210) may up-convert a baseband signal into an RF (radio frequency) band signal and transmit the same through an antenna, and may down-convert an RF band signal received through the antenna into a baseband signal. For example, the wireless communication unit (210) may include an RFIC (radio frequency integrated circuit). For example, the wireless communication unit (210) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), and / or an analog to digital convertor (ADC).

[0076] According to one embodiment, the wireless communication unit (210) may include a plurality of transmission and reception paths. Furthermore, the wireless communication unit (210) may include at least one antenna array composed of a plurality of antenna elements. For example, at least one antenna array may include at least one antenna element.

[0077] According to one embodiment, in terms of hardware, the wireless communication unit (210) may be composed of a digital unit and an analog unit. For example, the analog unit may be implemented or composed of a plurality of sub-units depending on operating power, operating frequency, etc. For example, the digital unit may be implemented or composed of at least one processor (e.g., a digital signal processor (DSP)). In the present disclosure, the expressions “may be composed of” or “may be implemented” may be replaced with the expression “may include.” For example, the analog unit may include a plurality of sub-units depending on operating power, operating frequency, etc. For example, the digital unit may include at least one processor.

[0078] According to one embodiment, the wireless communication unit (210) transmits and / or receives RF (radio frequency) signals. For example, all or part of the wireless communication unit (210) may be referred to as a "transmitter," a "receiver," or a "transceiver." In addition, in the following description, transmission and reception performed through a wireless channel are used to mean that the wireless communication unit (210) performs the processing described above.

[0079] According to one embodiment, the backhaul communication unit (220) may provide an interface for communicating with other nodes within the network. For example, the backhaul communication unit (220) may convert a bit string transmitted from the base station (110) to another node, such as another access node, another base station, an upper node, a core network, etc., into a physical signal. The backhaul communication unit (220) may convert a physical signal received from another node into a bit string.

[0080] According to one embodiment, the storage unit (230) may store data for basic programs, application programs, and / or configuration information for the operation of the base station (110). For example, the storage unit (230) may be configured as volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. For example, the storage unit (230) may provide stored data upon request of the control unit (240).

[0081] According to one embodiment, the controller (240) can control the overall operations of the base station (110). For example, the controller (240) can transmit and / or receive signals through the wireless communication unit (210) or the backhaul communication unit (220). For another example, the controller (240) can write data to and read data from the storage unit (230). For example, the controller (240) can perform functions of a protocol stack required by a communication standard.

[0082] According to one embodiment, the protocol stack may be included in the wireless communication unit (210). For example, the control unit (240) may include at least one processor. According to one embodiment, the control unit (240) may control the base station (110) to perform operations according to the embodiments described below.

[0083] FIG. 3 is a diagram illustrating a configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0084] The configuration illustrated in FIG. 3 can be understood as the configuration of a terminal (120). Terms such as '... unit', '... device', etc. used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0085] Referring to FIG. 3, a terminal (120) according to an embodiment of the present disclosure may include a communication unit (310), a storage unit (320), and / or a control unit (330). However, the components of the terminal (120) are not limited to the examples described above. For example, the terminal (120) may include more or fewer components than the components described above. In addition, the communication unit (310), the storage unit (320), and the control unit (330) may be implemented in the form of a single chip. In addition, the control unit (330) may include one or more processors. For example, the terminal (120) may include a transceiver and a controller coupled with the transceiver. As another example, the terminal (120) may include at least one transceiver and at least one processor coupled with the at least one transceiver. As another example, the terminal (120) may include a memory storing instructions to be executed by the controller, a transceiver, and a controller.

[0086] According to one embodiment, the communication unit (310) performs functions for transmitting and / or receiving signals via a wireless channel. For example, the communication unit (310) may perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication unit (310) may generate complex symbols by encoding and modulating a transmission bit stream. For example, when receiving data, the communication unit (310) may restore a reception bit stream by demodulating and decoding a baseband signal. For example, the communication unit (310) may up-convert a baseband signal to an RF band signal and then transmit it through an antenna, and may down-convert an RF band signal received through the antenna to a baseband signal. For example, the communication unit (310) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, and / or an ADC.

[0087] For example, the communication unit (310) may include at least one RFIC, at least one intermediate frequency integrated circuit (IFIC), and / or at least one communication processor (CP).

[0088] According to one embodiment, the communication unit (310) may include a plurality of transmission and reception paths. For example, the communication unit (310) may include at least one antenna array composed of a plurality of antenna elements.

[0089] According to one embodiment, in terms of hardware, the communication unit (310) may be composed of digital circuits and analog circuits (e.g., a radio frequency integrated circuit (RFIC)). For example, the digital circuits and analog circuits may be implemented in a single package. For example, the communication unit (310) may include a plurality of RF chains. The communication unit (310) may perform beamforming.

[0090] According to one embodiment, the communication unit (310) may transmit and / or receive RF signals. Accordingly, all or part of the communication unit (310) may be referred to or referred to as a "transmitter," a "receiver," or a "transmitter-receiver unit." Furthermore, in the following description, transmission and reception performed via a wireless channel may be used to mean that the communication unit (310) performs the processing described above.

[0091] According to one embodiment, the storage unit (320) can store data such as basic programs, application programs, and setting information for the operation of the terminal (120). The storage unit (320) can be configured as volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. In addition, the storage unit (320) can provide stored data upon request from the control unit (330).

[0092] According to one embodiment, the control unit (330) controls the overall operations of the terminal (120). For example, the operations of the terminal (120) described in FIGS. 1 to 8 below can be substantially understood as operations of the controller (330).

[0093] For example, the control unit (330) can transmit and / or receive signals through the communication unit (310). For example, the control unit (330) can record and read data in the storage unit (320). For example, the control unit (330) can perform functions of the protocol stack required by the communication standard.

[0094] According to one embodiment, the control unit (330) may include at least one processor or microprocessor, or the control unit (330) may be a part of a processor. Additionally, a part of the communication unit (310) and the control unit (330) may be referred to as a CP (communication processor). According to one embodiment, the control unit (330) may control the terminal (120) to perform operations according to one embodiment described below.

[0095] FIG. 4 is a diagram illustrating the configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure.

[0096] Fig. 4 illustrates an exemplary configuration of the wireless communication unit (210) of Fig. 2 or the communication unit (310) of Fig. 3. For example, Fig. 4 illustrates components for performing beamforming as part of the wireless communication unit (210) of Fig. 2 or the communication unit (310) of Fig. 3.

[0097] Referring to FIG. 4, a wireless communication unit (210) or a communication unit (310) according to an embodiment of the present disclosure may include an encoding and modulation unit (402), a digital beamforming unit (404), a plurality of transmission paths (406-1 to 406-N), and / or an analog beamforming unit (408).

[0098] According to one embodiment, the encoding and modulation unit (402) can perform channel encoding. For channel encoding, at least one of a low density parity check (LDPC) code, a convolution code, or a polar code can be used. The encoding and modulation unit (402) can generate modulation symbols by performing constellation mapping.

[0099] Although FIG. 4 of the present disclosure describes that the wireless communication unit (210) or the communication unit (310) includes an encoding and modulation unit (402), this is merely an example. For example, the control unit (240) and / or the control unit (330) may include an encoding and modulation unit (402).

[0100] According to one embodiment, the digital beamforming unit (404) may perform beamforming on a digital signal (e.g., modulation symbols). For example, the digital beamforming unit (404) may multiply the modulation symbols by beamforming weights. The beamforming weights are used to change the magnitude and phase of the signal and may be referred to as a 'precoding matrix' or a 'precoder'. The digital beamforming unit (404) may output digital beamformed modulation symbols to a plurality of transmission paths (406-1 to 406-N). At this time, according to a multiple input multiple output (MIMO) transmission technique, the modulation symbols may be multiplexed or the same modulation symbols may be provided to the plurality of transmission paths (406-1 to 406-N).

[0101] According to one embodiment, the plurality of transmission paths (406-1 to 406-N) can convert digital beamformed digital signals into analog signals. For example, each of the plurality of transmission paths (406-1 to 406-N) can include an inverse fast Fourier transform (IFFT) operation unit, a cyclic prefix (CP) insertion unit, a DAC, and / or an upconversion unit. For example, the CP insertion unit is for an orthogonal frequency division multiplexing (OFDM) scheme and can be excluded when another physical layer scheme (e.g., filter bank multi-carrier (FBMC)) is applied. That is, the plurality of transmission paths (406-1 to 406-N) can provide independent signal processing processes for the plurality of streams generated through digital beamforming. However, depending on the implementation method, some of the components of the plurality of transmission paths (406-1 to 406-N) can be used in common.

[0102] According to one embodiment, the analog beamforming unit (408) can perform beamforming on analog signals. For example, the digital beamforming unit (404) can multiply the analog signals by beamforming weights. The beamforming weights can be used to change the magnitude and phase of the signal. For example, the analog beamforming unit (440) can be configured in various ways depending on the connection structure between the plurality of transmission paths (406-1 to 406-N) and the antennas. For example, each of the plurality of transmission paths (406-1 to 406-N) can be connected to one antenna array. As another example, the plurality of transmission paths (406-1 to 406-N) can be connected to one antenna array. As yet another example, the plurality of transmission paths (406-1 to 406-N) can be adaptively connected to one antenna array or to two or more antenna arrays.

[0103] FIG. 5 is a diagram illustrating a structure of time-frequency resources of a wireless communication system according to an embodiment of the present disclosure.

[0104] Referring to FIG. 5, in the wireless resource domain according to one embodiment of the present disclosure, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol or a DFT-S-OFDM symbol, and N symb OFDM symbols or DFT-S-OFDM symbols (530) may be included in one slot (505). Unlike slots, the length of a subframe in an NR system may be defined as 1.0 ms, and the length of a radio frame (500) may be defined as 10 ms. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is a total of N BW It may include N subcarriers (525). symb , N BW Specific figures may vary depending on the system.

[0105] According to one embodiment, the basic unit of the time-frequency resource domain is a resource element (RE) (510), which can be indicated by an OFDM symbol index or a DFT-S-OFDM symbol index and a subcarrier index. A resource block (RB (515)) is N in the frequency domain. RB It can be defined as a number of consecutive subcarriers (520). In general, the minimum transmission unit of data is an RB unit, and in NR systems, it is generally N symb = 14, N RB = 12 may be

[0106] The time-frequency resource structure as shown in Fig. 5 can be applied to the Uu interface. In addition, the time-frequency resource structure as shown in Fig. 5 can be applied substantially identically or similarly to the sidelink (or PC-5).

[0107] In accordance with one embodiment of the present disclosure, when a terminal (e.g., Remote UE or remote terminal) is connected to another terminal via a sidelink relay (also referred to as Relay or Relay UE or terminal relay) to transmit and receive data, operation procedures of a terminal, a sidelink relay, and another terminal for managing an end-to-end PC5 connection established between the two terminals are described.

[0108] In one embodiment, an issue that may occur in an end-to-end PC5 connection established via a sidelink relay between two remote terminals may include an issue occurring in at least one or a combination of the PC5-S layer (e.g., PC5 ProSe layer or PC5 V2X layer), PC5-RRC layer, or PC5-PDCP layer of the end-to-end unicast connection.

[0109] For example, in an end-to-end PC5 connection established via a sidelink relay between two remote terminals, the following may be true: a problem occurs in the PC5 link establishment between the two remote terminals established at the PC5-S layer entities of the two remote terminals; a problem occurs during the transmission and reception of PC5-RRC messages at the PC5-RRC layer entities between the two remote terminals; and / or a problem occurs in the PC5-PDCP layer entities between the two remote terminals, such as an integrity protection failure.

[0110] A sidelink relay according to an embodiment of the present disclosure may be authenticated to be used in at least one or a combination of a specific service, a specific terminal, a specific sidelink flow, a specific sidelink bearer, a specific unicast link, a specific source identifier, or a specific destination identifier. The sidelink relay may configure or establish a direct connection with an authenticated terminal at the time of installation. The sidelink relay according to an embodiment of the present disclosure may configure or establish a sidelink direct connection with an authenticated terminal upon receiving a Relay discovery message from the authenticated terminal. The sidelink relay may configure or establish a sidelink direct connection with an authenticated terminal upon receiving a Relay discovery message as a response to a Relay discovery message transmitted by the sidelink relay itself from the authenticated terminal.

[0111] According to one embodiment, when a sidelink relay receives a PC5 direct link establishment request from an authenticated terminal, it can establish or establish a sidelink direct connection with the authenticated terminal.

[0112] For example, the method of PC5 direct link establishment request used by sidelink relay and terminal for relay connection can be based on PC5 direct link establishment request message (or Direct communication request message). For example, for PC5 direct link establishment request, “connection instruction via relay” can be included in general PC5 direct link establishment request message. For example, “PC5 direct link establishment message for relay use” can be defined separately in PC5 direct link establishment request message. For example, general PC5 direct link establishment request message transmitted in sidelink radio bearer (which can be denoted as SLRB) for relay use can be configured to be used.

[0113] That is, for the PC5 direct link establishment request used by the sidelink relay and the terminal for relay connection, a method in which a “connection instruction via relay” is included in the PC5 direct link establishment request message, a method in which a separately defined “PC5 direct link establishment message for relay use” is defined in the PC5 direct link establishment request message, and / or a method in which a general PC5 direct link establishment request message transmitted in the sidelink radio bearer (which may be expressed as SLRB) for relay use is used can be utilized. Of course, the method of the PC5 direct link establishment request used by the sidelink relay and the terminal for relay connection is not limited to the examples described above.

[0114] In this disclosure, the operation of a remote terminal and a sidelink relay that manage an end-to-end unicast connection established between two terminals is described, taking as an example the case where the T400 timer expires when exchanging PC5 RRC messages between two remote terminals in the PC5-RRC layer of the end-to-end unicast connection between two remote terminals and the case where an integrity protection failure occurs in the PC5-PDCP layer.

[0115] Hereinafter, FIG. 6 describes a procedure in which an end-to-end sidelink unicast connection between a terminal and another terminal is established through a sidelink relay and signaling and data are transmitted and / or received (in case that), based on the expiration of the T400 timer, the establishment of the sidelink unicast connection between the terminal and another terminal is managed through a sidelink relay.

[0116] However, the management procedure for establishing a sidelink unicast connection based on the T400 timer described in FIG. 6 is only an example and does not limit the present disclosure. For example, the T400 timer may be a waiting time until a terminal transmits a PC5 RRC message (e.g., an RRCReconfigurationSidelink message) including configuration information for establishing an end-to-end sidelink unicast connection with another terminal through a sidelink relay and receives a PC5 RRC message corresponding to a response message to the PC5 RRC message from another terminal through the sidelink relay (e.g., an RRCReconfigurationCompleteSidelink message or an RRCReconfigurationFailureSidelink message).

[0117] Although the present disclosure has described the T400 timer as the timer used to manage the end-to-end sidelink unicast connection in various embodiments, this is merely an example. For example, a separate timer (e.g., T400-indirect) may be defined to have a different value than the T400 timer for PC5 RRC message exchanges that establish an end-to-end sidelink unicast connection between terminals via a sidelink relay, and of course, a separate timer (e.g., T400-indirect timer) may be applied to the end-to-end sidelink unicast connection between two remote terminals. For example, if the T400-indirect timer is used for the end-to-end sidelink unicast connection between two remote terminals (in case that), the T400 timer may be used for the sidelink unicast connection between each remote terminal and the sidelink relay.

[0118] FIG. 6 is a diagram illustrating a signal flow for managing a terminal connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0119] Referring to FIG. 6, according to an embodiment, UE1 (600) may determine whether it can perform, configure, or establish a direct connection with UE2 (650), UE1 (600) may decide to search for a sidelink relay (630) that can support a direct connection with UE2 (650), and UE1 (600) may perform a relay discovery procedure. For example, the relay discovery procedure may also include a case where UE2 (650) searches for a sidelink relay (630) that can support a direct connection with UE1 (600). For example, the relay discovery procedure may be a procedure where UE1 (600) or UE2 (650) transmits a relay discovery message to search for a sidelink relay (630) that can support a direct connection. For example, the relay discovery procedure may correspond to a procedure in which UE1 (600) or UE2 (650) monitors the relay discovery message transmitted by the sidelink relay (630) and receives the relay discovery message from the sidelink relay (630) that can support direct connection with the counterpart terminal.

[0120] For example, the Relay discovery message may be a standalone message containing information about sidelink relay discovery, or may be a message integrated or composed into a PC5 direct link establishment request message (e.g., Direct communication request message) that UE1 (600) transmits to establish a direct connection with UE2 (650).

[0121] According to one embodiment, UE1 (600) may select a sidelink relay (630) that is determined to be capable of supporting a direct connection with UE2 (650) and perform a unicast connection procedure with the sidelink relay (630) in step 601 (PC5 unicast connection established).

[0122] According to one embodiment, the sidelink relay (630) may perform a unicast connection procedure with UE2 (650), which corresponds to the counterpart remote terminal of UE1 (600), in step 602 (PC5 unicast connection establishment). Alternatively, if UE2 (650) determines that it can establish a direct connection with UE1 (600) through the sidelink relay (630), it may perform a unicast connection procedure with the sidelink relay (630) in step 602.

[0123] According to one embodiment, if there is no need to transmit and receive user traffic between UE1 (600) and the sidelink relay (630) or between UE2 (650) and the sidelink relay (630), the SLRB configuration for transmitting and receiving user traffic, i.e., the configuration for the SL-DRB (data radio bearer), may be omitted in steps 601 and 602. In steps 601 and 602, the SLRB (sidelink radio bearer) (SL-SRB0 (signaling radio bearer), SL-SRB1, SL-SRB2, SL-SRB3) for sidelink signaling transmitted and received in the unicast connection establishment procedure between UE1 (600) and the sidelink relay (630) or between UE2 (650) and the sidelink relay (630) may have the specified SLRB configuration applied.

[0124] According to one embodiment, UE1 (600) and UE2 (650) can establish an end-to-end unicast connection (E2E (end-to-end) PC5 unicast connection established) in step 603, separately from the unicast connection (steps 601 and 602) with the sidelink relay (630). For example, the end-to-end unicast connection can be initiated from a procedure in which UE1 (600) transmits a Direct communication request message to UE2 (650) through relay transmission of the sidelink relay (630).

[0125] However, if UE1 (600) or UE2 (650) uses a PC5 direct link establishment request message (e.g., Direct communication request message) transmission procedure as a procedure for UE1 (600) to search for a sidelink relay (630) that can support connection with UE2 (650), some of the signaling messages (e.g., PC5-S (signaling) signaling message, PC5-RRC message) exchanged in the end-to-end unicast connection procedure of step 603 may be transmitted during the relay search procedure for the sidelink relay (630), and some of the signaling messages may be transmitted after the relay search procedure for the sidelink relay (630).

[0126] According to one embodiment, in the end-to-end unicast connection procedure of step 603, UE1 (600) and UE2 (650) may perform a PC5 security procedure for handling sidelink authentication and encryption key setup through relay transmission of a sidelink relay (630). For example, the end-to-end PC5 security procedure of UE1 (600) and UE2 (650) may be configured as a procedure for exchanging encryption and integrity protection algorithms and parameters to support integrity protection and encryption (integrity, verification, ciphering) to be applied to PDCP PDUs in a PDCP entity for end-to-end data or signaling (PC5-S signaling, PC5-RRC) of UE1 (600) and UE2 (650).

[0127] According to one embodiment, an E2E SLRB (sidelink radio bearer) configuration for an end-to-end unicast connection between UE1 (600) and UE2 (650) may include configuration information applicable to signaling (SL-SRB) and / or configuration information applicable to user traffic (SL-DRB) transmitted through an end-to-end unicast connection between UE1 (600) and UE2 (650) connected via a sidelink relay (630). For example, the E2E SLRB configuration may be acquired by a source remote terminal and provided to a counterpart remote terminal. For example, the E2E SLRB configuration may be acquired by a sidelink relay and provided to a source remote terminal / destination remote terminal. The E2E SLRB configuration information may be configured based on QoS (quality of service) information of signaling or user traffic transmitted and received between UE1 (600) and UE2 (650). For example, for user traffic, an E2E SLRB configuration can be configured that is mapped to information such as a QoS profile and a PQI (PC5 QoS identifier). For example, information included in the E2E SLRB configuration can include SL-SDAP (service data adaptation protocol) entity configuration information of a data bearer corresponding to user traffic, and / or SL-PDCP entity configuration information. For example, information included in the E2E SLRB configuration can include SL-PDCP entity configuration information in addition to the SL-RRC entity of a signaling bearer corresponding to signaling.

[0128] According to one embodiment, information included in an E2E SLRB configuration corresponding to an end-to-end unicast connection between UE1 (600) and UE2 (650) may include [Table 1]. For example, information included in the E2E SLRB configuration may include at least one of the information elements included in [Table 1].

[0129]

[0130] According to one embodiment, when signaling or user traffic for an end-to-end unicast connection between UE1 (600) and UE2 (650) is relayed and transmitted through a sidelink relay (630), an HbH (Hop-by-Hop) SLRB configuration applied to each of the link between UE1 (600) and the sidelink relay (630) and the link between the sidelink relay (630) and UE2 (650) may include setting information applied to each link when signaling (SL-SRB) or user traffic (SL-DRB) transmitted through the end-to-end unicast connection between UE1 (600) and UE2 (650) is transmitted through the sidelink relay (630). For example, the HbH SLRB configuration may be obtained by a source remote terminal and provided to the sidelink relay and the destination remote terminal. For example, the HbH SLRB configuration can be acquired by the relay terminal and provided to the source remote terminal and the destination remote terminal, or each remote terminal can acquire it and provide it to the sidelink relay.

[0131] According to one embodiment, HbH SLRB configuration information may be configured based on QoS information of signaling or user traffic to be transmitted and received between UE1 (600) and UE2 (650). For example, in the case of user traffic, an SLRB configuration mapped to information such as QoS profile and PQI may be configured. For example, the QoS information applied to the HbH SLRB configuration may correspond to a QoS that splits E2E QoS according to each link situation.

[0132] According to one embodiment, the operation of splitting the E2E QoS into the QoS of each link (or hop) may be performed by a source remote terminal, a relay terminal, or a serving base station. For example, information included in the HbH SLRB configuration may include at least one or a combination of SL-SRAP (sidelink relay adaption protocol) entity configuration information, SL-RLC (radio link control) entity configuration information, SL-MAC entity configuration information, or SL-PHY entity configuration information of a data bearer corresponding to user traffic. For example, information included in the HbH SLRB configuration may include at least one or a combination of SL-SRAP entity configuration information, SL-RLC entity configuration information, SL-MAC entity configuration information, or SL-PHY entity configuration information of a signaling bearer corresponding to signaling.

[0133] According to one embodiment, when signaling or user traffic corresponding to an end-to-end unicast connection between UE1 (600) and UE2 (650) is transmitted via a sidelink relay (630), information included in the HbH SLRB configuration corresponding to each link may include [Table 2]. For example, information included in the HbH SLRB configuration corresponding to each link may include at least one of the information elements included in [Table 2].

[0134]

[0135] According to one embodiment, in a direct connection between terminals, an entity for each protocol layer set for a unicast connection may be composed of an SDAP layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer for a data bearer corresponding to user traffic. An entity for each protocol layer may be composed of an RRC layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer for a signaling bearer corresponding to signaling. In contrast, as in the embodiments of [Table 1] and [Table 2], an entity for each protocol layer set for an end-to-end unicast connection between UE1 (600) and UE2 (650) and an entity for each protocol layer set for a unicast connection between UE1 (600) and a sidelink relay for relaying signaling and user traffic between UE1 (600) and UE2 (650) may be set separately. As another example, as in the embodiments of [Table 1] and [Table 2], the protocol layer entities established in the end-to-end unicast connection between UE1 (600) and UE2 (650) and the protocol layer entities established in the unicast connection between UE2 (650) and a sidelink relay for relaying signaling and user traffic between UE1 (600) and UE2 (650) can be set separately.

[0136] According to one embodiment, UE1 (600) may transmit an RRCReconfigurationSidelink message including PC5-RRC configuration information for an end-to-end unicast connection to UE2 (650) using the relay of the sidelink relay (630) in step 604 (RRCReconfigurationSidelink). For example, the RRCReconfigurationSidelink message in step 604 may correspond to a message for configuring a PC5-RRC entity while establishing an end-to-end unicast connection between UE1 (600) and UE2 (650), or may correspond to a message for configuring a PC5-RRC entity after establishing an end-to-end unicast connection between UE1 (600) and UE2 (650).

[0137] According to one embodiment, UE1 (600) may transmit an RRCReconfigurationSidelink message to UE2 (650) and start a T400 timer at step 605 (e.g., T400 started). For example, UE1 (600) may receive an RRCReconfigurationCompleteSidelink message or an RRCReconfigurationFailureSidelink message as a response message transmitted by UE2 (650) using the relay of the sidelink relay (630) before the T400 timer expires. UE1 (600) may stop the T400 timer and process the response messages received from UE2 (650).

[0138] For another example, UE1 (600) may identify or check T400 timer expiration at step 606 (e.g., T400 expired). UE1 (600) may determine that it has not received a response message from UE2 (650) until the T400 timer expires, and UE1 (600) may perform end-to-end unicast connection management procedures due to T400 timer expiration for the end-to-end unicast connection at step 607 (UE1 performs the procedures to handle E2E PC5 unicast connection problem due to T400 expiry). For example, UE1 (600) may perform PC5 RRC connection release procedures. For example, UE1 (600) may transmit a signaling message indicating that there is a problem with the end-to-end unicast connection. For example, UE1 (600) may delete configuration information configured for the end-to-end unicast connection. For example, UE1 (600) can perform a sidelink relay reselection procedure.

[0139] According to one embodiment, the operation performed by UE1 (600) in step 607 may include the examples of [Table 3]. For example, the operation performed by UE1 (600) in step 607 may include at least one of the operations described in [Table 3]. According to one embodiment, the operation performed by UE1 (600) in step 607 for the PC5 unicast connection established with the sidelink relay may include the examples of [Table 4]. For example, the operation performed for the PC5 unicast connection established with the sidelink relay may include at least one of the operations described in [Table 4].

[0140] When a problem occurs in the end-to-end unicast connection (e.g., T400 timer expiration, integrity protection failure of PDCP PDU, link establishment problem of PC5-S layer, etc.), the remote terminal can perform an end-to-end PC5 RRC connection release procedure with the opposite remote terminal. The remote terminal can send a signaling message to the sidelink relay to notify that a problem has occurred in the end-to-end unicast connection. This signaling message can be sent through a PC5-RRC message or a PC5-S signaling message of the PC5 unicast established between the remote terminal and the sidelink relay, and can notify information such as E2E PC5 RRC connection failure notification (or E2E PC5 RRC connection release notification). The remote terminal can release / delete the PC5-RRC entity and configuration information, the PC5-SDAP entity and configuration information, and / or the PC5-PDCP entity and configuration information established for the end-to-end unicast connection with the opposite remote terminal. A remote terminal can delete relay configuration information for a counterpart remote terminal (e.g., configuration information of an SRAP entity for the counterpart remote terminal, PC5-Relay RLC channel information for the counterpart remote terminal, etc.). A remote terminal (source remote terminal, destination remote terminal) can perform a sidelink relay reselection procedure.

[0141] When a remote terminal performs an end-to-end unicast connection release with another remote terminal and it is determined that it is no longer necessary to perform signaling and user traffic transmission and reception with another remote terminal using the relay transmission of the sidelink relay, i.e., when it is determined that it is no longer necessary to maintain the sidelink unicast connection for relay transmission purposes between the remote terminal and the sidelink relay, the remote terminal may perform a sidelink unicast connection release procedure for relay transmission purposes with the sidelink relay. The sidelink unicast connection release procedure for relay transmission between a remote terminal and a sidelink relay can be triggered by either the remote terminal or the sidelink relay. The sidelink unicast connection release procedure for relay transmission between a remote terminal and a sidelink relay can include the following examples: If the PC5-RRC connection with the U2U relay UE is determined to be released (corresponding to the operation of the remote terminal) (or if the PC5-RRC connection with the U2U Remote UE is determined to be released (corresponding to the operation of the sidelink relay)), the UE (remote terminal or sidelink relay) indicates upper layers to trigger PC5 unicast link release. The UE (remote terminal or sidelink relay) shall: In the procedure below, the specific destination corresponds to the sidelink relay from the perspective of the remote terminal, and the remote terminal from the perspective of the sidelink relay.1> If the PC5-RRC connection release for the specific destination is requested by upper layers or AS layer: 2> Discard the NR sidelink communication related configuration of this destination; 2> Release the DRBs of this destination if configured; (If the PC5 unicast connection configured for relay transmission between the remote terminal and the sidelink relay is not used for transmitting or receiving user traffic corresponding to the remote terminal and the sidelink relay, the DRB itself is not established. If the PC5 unicast connection configured for relay transmission between the remote terminal and the sidelink relay is used for transmitting or receiving user traffic corresponding to the remote terminal and the sidelink relay, a DRB may be established, and in this case, an operation to release the established DRB is performed.) 2> Release the SRBs of this destination (Release the PDCP entity, RLC entity, and the logical channel of the sidelink SRB for the PC5-RRC message of the specific destination); 2> Release the SRAP entity, PC5 Relay RLC channels if configured for peer Remote UE; (This action can be handled by the procedure in [Table 3] or the procedure in [Table 5]. If it is not handled by the procedure in [Table 3] or the procedure in [Table 5], the remote terminal and the sidelink relay perform this action.) 2> reset the sidelink specific MAC of this destination. 2> consider the PC5-RRC connection is released for the destination;.

[0142] Although not shown in the drawing, in the case where the procedure for disconnecting the end-to-end PC5 unicast connection between two remote terminals is performed due to the expiration of the T400 timer, the remote terminal can notify the sidelink relay of the disconnection of the end-to-end PC5 unicast connection, etc. The sidelink relay can perform an operation for processing the notification of disconnection of the end-to-end PC5 unicast connection between the two remote terminals. This will be described in detail later in FIG. 8.

[0143] In the following Figure 7, in the case of establishing a direct connection between a terminal and another terminal through a sidelink relay and transmitting and receiving signaling and data, the procedure for managing the establishment of an end-to-end sidelink unicast connection between a terminal and another terminal through a sidelink relay is explained through the case of a failure in integrity protection of a PDCP PDU operated by a PDCP entity of an end-to-end sidelink unicast connection.

[0144] FIG. 7 is a diagram illustrating a signal flow for managing a terminal connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0145] Referring to FIG. 7, UE1 (700) according to an embodiment may determine or identify whether it can perform a direct connection with UE2 (750). UE1 (700) may decide to search for a sidelink relay (730) that can support a direct connection with UE2 (750). UE1 (700) may perform a relay discovery procedure. For example, the relay discovery procedure may also include a case where UE2 (750) searches for a sidelink relay (730) that can support a direct connection with UE1 (700). For example, the relay discovery procedure may be a procedure in which UE1 (700) or UE2 (750) transmits a relay discovery message to search for a sidelink relay (730) that can support a direct connection. For example, the relay discovery procedure may correspond to a procedure in which UE1 (700) or UE2 (750) monitors the relay discovery message transmitted by the sidelink relay (730) and receives the relay discovery message from the sidelink relay (730) that can support direct connection with the counterpart terminal.

[0146] For example, the Relay discovery message may include a standalone message containing information about sidelink relay discovery. For example, the Relay discovery message may be a message integrated into a PC5 direct link establishment request message (e.g., a Direct communication request message) transmitted by UE1 (700) to establish a direct connection with UE2 (750).

[0147] According to one embodiment, UE1 (700) may select a sidelink relay (730) that is determined to support a direct connection with UE2 (750), and UE1 (700) may perform a unicast connection procedure with the sidelink relay (730) in step 701 (PC5 unicast connection established). For example, UE1 (700) may establish a unicast connection with the sidelink relay (730).

[0148] According to one embodiment, the sidelink relay (730) may perform a unicast connection procedure with UE2 (750), which corresponds to the counterpart remote terminal of UE1 (700), in step 702 (PC5 unicast connection established). For example, if UE2 (750) determines that it can establish a direct connection with UE1 (700) through the sidelink relay (730), it may perform a unicast connection procedure with the sidelink relay (730) in step 702. For example, if there is no need to transmit and receive user traffic between UE1 (700) and the sidelink relay (730) or between UE2 (750) and the sidelink relay (730), the SLRB configuration for transmitting and receiving user traffic, i.e., the SL-DRB configuration, may be omitted in steps 701 and 702.

[0149] According to one embodiment, SLRBs (SL-SRB0, SL-SRB1, SL-SRB2, SL-SRB3) for sidelink signaling transmitted and received in the unicast connection establishment procedure between UE1 (700) and the sidelink relay (730) in steps 701 and 702 may have the specified SLRB settings applied. SLRBs (SL-SRB0, SL-SRB1, SL-SRB2, SL-SRB3) for sidelink signaling transmitted and received in the unicast connection establishment procedure between UE2 (750) and the sidelink relay (730) may have the specified SLRB settings applied.

[0150] According to one embodiment, UE1 (700) and UE2 (750) can set up or establish an end-to-end unicast connection (E2E PC5 unicast connection established) in step 703, separately from the unicast connection with the sidelink relay (730) (steps 701 and 702).

[0151] For example, an end-to-end unicast connection may start with a procedure in which UE1 (700) transmits a Direct communication request message to UE2 (750) through relay transmission of a sidelink relay (730).

[0152] However, if a PC5 direct link establishment request message (e.g., Direct communication request message) transmission procedure is used by UE1 (700) or UE2 (750) as a procedure for UE1 (700) to search for a sidelink relay (730) that can support connection with UE2 (750), some of the signaling messages (e.g., PC5-S signaling message, PC5-RRC message) exchanged in the end-to-end unicast connection procedure of step 703 may be transmitted during the relay search procedure for the sidelink relay (730), and some of the signaling messages may be transmitted after the relay search procedure for the sidelink relay (730).

[0153] According to one embodiment, in the end-to-end unicast connection procedure of step 703, UE1 (700) and UE2 (750) may perform a PC5 security procedure for handling sidelink authentication and encryption key setup through relay transmission of a sidelink relay (730). For example, the end-to-end PC5 security procedure of UE1 (700) and UE2 (750) may be configured as a procedure for exchanging encryption and integrity protection algorithms and parameters to support integrity protection and encryption (integrity, verification, ciphering) to be applied to PDCP PDUs in a PDCP entity for end-to-end data or signaling (PC5-S signaling, PC5-RRC) of UE1 (700) and UE2 (750).

[0154] According to one embodiment, the E2E SLRB (sidelink radio bearer) configuration for the end-to-end unicast connection between UE1 (700) and UE2 (750) may include configuration information applied to signaling (SL-SRB) or user traffic (SL-DRB) transmitted through the end-to-end unicast connection between UE1 (700) and UE2 (750) connected via the sidelink relay (730). For example, the E2E SLRB configuration may be acquired by a source remote terminal and provided to a counterpart remote terminal. For example, the E2E SLRB configuration may be acquired by a sidelink relay and provided to a source remote terminal / destination remote terminal.

[0155] According to one embodiment, E2E SLRB configuration setting information may be configured based on QoS information of signaling or user traffic transmitted and received between UE1 (700) and UE2 (750). For example, in the case of user traffic, an E2E SLRB configuration mapped to information such as QoS profile and PQI may be configured. For example, information included in the E2E SLRB configuration may include SL-SDAP entity setting information of a data bearer corresponding to user traffic and / or SL-PDCP entity setting information. For example, information included in the E2E SLRB configuration may include SL-PDCP entity setting information in addition to the SL-RRC entity of a signaling bearer corresponding to signaling.

[0156] According to one embodiment, information included in an E2E SLRB configuration corresponding to an end-to-end unicast connection between UE1 (700) and UE2 (750) may include [Table 1]. For example, information included in the E2E SLRB configuration may include at least one of the information elements described in [Table 1].

[0157] According to one embodiment, when signaling or user traffic for an end-to-end unicast connection between UE1 (700) and UE2 (750) is relayed and transmitted through a sidelink relay (730), an HbH (Hop-by-Hop) SLRB configuration applied to each of the link between UE1 (700) and the sidelink relay (730) and the link between the sidelink relay (730) and UE2 (750) may include setting information applied to each link when signaling (SL-SRB) or user traffic (SL-DRB) transmitted through the end-to-end unicast connection between UE1 (700) and UE2 (750) is transmitted through the sidelink relay (730). For example, the HbH SLRB configuration may be obtained by a source remote terminal and provided to the sidelink relay and the destination remote terminal. For example, the HbH SLRB configuration can be obtained by the relay terminal and provided to the source remote terminal and the destination remote terminal, or each remote terminal can obtain it and provide it to the sidelink relay.

[0158] According to one embodiment, the HbH SLRB configuration setting information may be configured based on the QoS information of signaling or user traffic to be transmitted and received between UE1 (700) and UE2 (750). For example, in the case of user traffic, an SLRB configuration mapped to information such as a QoS profile or PQI may be configured. For example, the QoS information applied to the HbH SLRB configuration setting may correspond to a QoS that splits the E2E QoS according to each link situation.

[0159] According to one embodiment, the operation of splitting the E2E QoS into the QoS of each link (or hop) may be performed by a source remote terminal, a relay terminal, or a serving base station. For example, information included in the HbH SLRB configuration may include at least one or a combination of SL-SRAP entity configuration information, SL-RLC entity configuration information, SL-MAC entity configuration information, or SL-PHY entity configuration information of a data bearer corresponding to user traffic. For example, information included in the HbH SLRB configuration may include at least one or a combination of SL-SRAP entity configuration information, SL-RLC entity configuration information, SL-MAC entity configuration information, or SL-PHY entity configuration information of a signaling bearer corresponding to signaling.

[0160] According to one embodiment, when signaling or user traffic corresponding to an end-to-end unicast connection between UE1 (700) and UE2 (750) is transmitted through a sidelink relay (730), an example of information included in the HbH SLRB configuration corresponding to each link may include [Table 2]. For example, the information included in the HbH SLRB configuration may include at least one of the information elements included in [Table 2].

[0161] According to one embodiment, in a direct connection between terminals, an entity for each protocol layer set for a unicast connection may be composed of an SDAP layer, a PDCP layer, an RLC layer, a MAC layer, and / or a PHY layer for a data bearer corresponding to user traffic. In a direct connection between terminals, an entity for each protocol layer set for a unicast connection may be composed of an RRC layer, a PDCP layer, an RLC layer, a MAC layer, and / or a PHY layer for a signaling bearer corresponding to signaling. In contrast, as in the embodiments of [Table 1] and [Table 2], an entity for each protocol layer set for an end-to-end unicast connection between UE1 (700) and UE2 (750) and an entity for each protocol layer set for a unicast connection between UE1 (700) and a sidelink relay for relaying signaling and user traffic between UE1 (700) and UE2 (750) may be set separately. The protocol layer entity established in the end-to-end unicast connection between UE1 (700) and UE2 (750) and the protocol layer entity established in the unicast connection between UE2 (750) and a sidelink relay for relaying signaling and user traffic between UE1 (700) and UE2 (750) can be set separately.

[0162] According to one embodiment, if UE1 (700) determines or identifies that integrity protection processing is set for a PC5-PDCP PDU for an end-to-end unicast connection established with UE2 (750), UE2 (750) transmits a PC5-PDCP PDU using the relay of the sidelink relay (730), and UE1 (700) can determine or identify whether integrity protection has failed for a PC5-PDCP PDU received using the relay of the sidelink relay (730) in step 704 (integrity check failure indication from PDCP entity).

[0163] According to one embodiment, when UE1 (700) identifies or determines that integrity protection has failed for a PC5-PDCP (packet data convergence protocol) PDU (protocol data unit) received from UE2 (750) using the relay of the sidelink relay (730), UE1 (700) may perform end-to-end unicast connection management procedures with UE2 (750) at step 705 (UE1 performs the procedures to handle E2E PC5 unicast connection problem due to integrity check failure detection by PDCP entity). For example, when performing end-to-end unicast connection management procedures when determining or identifying that integrity protection has failed for a PC5-PDCP PDU corresponding to an end-to-end unicast connection between UE1 (700) and UE2 (750), this may actually correspond to an integrity protection failure for a PC5-PDCP PDU of a signaling bearer (e.g., SL-SRB2 and SL-SRB3) during the end-to-end unicast connection.

[0164] For example, when an integrity protection failure is determined for a PC5-PDCP PDU corresponding to an end-to-end unicast connection between UE1 (700) and UE2 (750), in the case of performing an end-to-end unicast connection management procedure, it may correspond to an integrity protection failure for at least one PC5-PDCP PDU among the signaling bearer or data bearer during the end-to-end unicast connection.

[0165] According to one embodiment, the operation performed by UE1 (700) in step 705 may include the examples of [Table 3]. For example, the operation performed by UE1 (700) in step 705 may include at least one of the operations described in [Table 3]. According to one embodiment, the operation performed by UE1 (700) in step 705 for the PC5 unicast connection established with the sidelink relay may include the examples of [Table 4]. For example, the operation performed by UE1 (700) in step 705 may include at least one of the operations described in [Table 4].

[0166] Although not shown in the drawing, in the case where a procedure for disconnecting an end-to-end PC5 unicast connection between two remote terminals is performed due to a PDCP PDU integrity protection failure, the remote terminal can notify the sidelink relay of the disconnection of the end-to-end PC5 unicast connection, etc. The sidelink relay can perform an operation for processing the notification of disconnection of the end-to-end PC5 unicast connection between the two remote terminals. This will be described with reference to FIG. 8.

[0167] FIG. 8 is a diagram illustrating a signal flow between a remote terminal and a terminal relay that manages an end-to-end connection between remote terminals in a wireless communication system that performs communication through a terminal relay according to one embodiment of the present disclosure.

[0168] Referring to FIG. 8, a remote UE (800) according to an embodiment may recognize, detect, identify, or check the occurrence of a problem in an end-to-end PC5 unicast connection with another remote UE at step 801 (E2E PC5 connection problem is detected). For example, the problem in the end-to-end PC5 unicast connection at step 801 may include at least one or a combination of a T400 timer expiration, a PC5-PDCP PDU integrity protection failure, or a link establishment failure of the PC5-S layer.

[0169] According to one embodiment, the remote terminal (800) may transmit a signaling message notifying the occurrence of a problem in the end-to-end PC5 unicast connection to the sidelink relay (830) (or relay UE_) in step 802 (E2E PC5 connection problem notification). For example, the transmitted signaling message may be delivered through a PC5-RRC message or a PC5-S signaling message corresponding to the PC5 unicast connection established between the remote terminal (800) and the sidelink relay (830). For example, the message transmitted in step 802 may include at least one or a combination of information such as identification information for the end-to-end PC5 unicast connection (e.g., layer-2 ID of the counterpart remote terminal, local ID of the counterpart remote terminal used by the SRAP entity, etc.), end-to-end PC5 unicast connection release notification, or end-to-end PC5 unicast connection failure notification.

[0170] According to one embodiment, the remote terminal (800) may perform the procedures to handle an E2E PC5 unicast connection problem in step 803. An example of the operations performed by the remote terminal (800) in step 803 may include [Table 3]. For example, the operations performed by the remote terminal (800) in step 803 may include at least one of the operations described in [Table 3].

[0171] According to one embodiment, an example of an operation performed by the remote terminal (800) in step 803 may include [Table 4]. For example, the operation performed by the remote terminal (800) in step 803 may include at least one of the operations described in [Table 4].

[0172] According to one embodiment, the sidelink relay (830) may perform an operation to handle an end-to-end PC5 unicast connection release (or failure) notification of two remote terminals based on the information of step 802 in step 804 (Relay UE performs the procedures to handle E2E PC5 unicast connection problem notification). An embodiment of the operation performed by the sidelink relay (830) in step 804 may include [Table 5]. For example, the operation performed by the sidelink relay (830) in step 804 may include at least one of the operations described in [Table 5].

[0173] According to one embodiment, when the sidelink relay (830) is connected to the serving cell in the RRC_CONNECTED state, an embodiment of the operation performed in step 804 may include [Table 6]. For example, the operation performed by the sidelink relay (830) in step 804 may include at least one of the operations described in [Table 6].

[0174] A sidelink relay may perform a procedure to delete configuration information of an SRAP entity configured for relay transmission of signaling and user traffic corresponding to a signaling bearer and a data bearer between two remote terminals. The configuration information of the SRAP entity may include, for example, at least one or a combination of an SRAP context for a destination remote terminal of an end-to-end PC5 unicast connection, or PC5 Relay RLC channels for the destination remote terminal of an end-to-end PC5 unicast connection. When the sidelink relay no longer needs to support relay transmission for a remote terminal, the sidelink relay may perform a procedure to release an SRAP entity configured for the remote terminal.

[0175]

[0176]

[0177]

[0178]

[0179]

[0180] Although not illustrated in FIG. 8, when a problem occurs in the PC5-S layer of an end-to-end unicast connection between two remote terminals according to an embodiment of the present invention, the PC5-S layer entity of the remote terminal may notify the PC5-RRC layer entity or the PC5-PDCP layer entity of the remote terminal of the problem in the end-to-end unicast connection. In addition, the PC5-RRC layer entity or the PC5-PDCP layer entity may notify the sidelink relay of the problem in the end-to-end unicast connection, as in various embodiments proposed in the present invention. Each remote terminal may perform an action when a problem occurs in the end-to-end unicast connection. The sidelink relay may perform an action when it is instructed to perform an action when a problem occurs in the end-to-end unicast connection. If the remote terminal determines it is necessary, it may perform an action to reselect a sidelink relay that can relay signaling and user traffic between the two remote terminals.

[0181] Although not shown, if a problem occurs for the PC5 unicast connection between the source remote terminal and the sidelink relay (e.g., T400 timer expires, PDCP integrity protection fails) or a problem occurs for the PC5 unicast connection between the sidelink relay and the destination remote terminal (e.g., T400 timer expires, PDCP integrity protection fails), the source remote terminal or the destination remote terminal or the sidelink relay may determine that a sidelink radio link failure has occurred for the link on which the problem occurred for the PC5 unicast connection and may trigger a sidelink relay reselection procedure.

[0182] According to one embodiment, an example of the actions performed by the remote terminal and the sidelink relay when a problem occurs in the PC5 unicast connection between the sidelink relay and the remote terminal is as shown in [Table 7].

[0183] Sidelink radio link failure related actionsIf UE is acting as a L2 U2U Remote UE and the other UE is acting as a L2 U2U Relay UE where the other UE is the destination for the PC5-RRC connection or if UE is acting as a L2 U2U Relay UE and the other UE is acting as a L2 U2U Relay UE where the other UE is the destination for the PC5-RRC connection: (i.e., per hop PC5-RRC connection)The UE shall:1> upon indication from sidelink RLC entity that the maximum number of retransmissions for a specific destination has been reached; or1> upon T400 expiry for a specific destination; or1> upon indication from MAC entity that the maximum number of consecutive HARQ DTX for a specific destination has been reached; or1> upon integrity check failure indication from sidelink PDCP entity concerning SL-SRB2 or SL-SRB3 for a specific destination:2> consider sidelink radio link failure to be detected for this destination;2> release the DRBs of this destination if configured; (For a PC5 unicast connection established for relay transmission between a sidelink relay and a remote terminal, a data bearer for transmitting user traffic may not be established, so the release procedure may not be performed. If a data bearer for transmitting user traffic is established for a PC5 unicast connection established for relay transmission between a sidelink relay and a remote terminal, the release procedure may be performed.)2> release the SRBs of this destination;2> release the PC5 Relay RLC channels for U2U relaying for peer Remote UE (When there is a counterpart remote terminal that establishes an end-to-end PC5 unicast connection using relay transmission of a remote terminal and a sidelink relay, the entity and context used for relay transmission with the counterpart remote terminal may be released / deleted. Information about the entity and context to be released / deleted (e.g., SRAP configuration information) may include, for example, information in [Table 2]);2> discard the NR sidelink communication related configuration of this destination;2> reset the sidelink specific MAC of this destination;2> consider the PC5-RRC connection is released for the destination;2> indicate the release of the PC5-RRC connection to the upper layers for this destination (i.e.PC5 is unavailable);2> if UE is in RRC_CONNECTED:3> perform the sidelink UE information for NR sidelink communication procedure;2> if UE is acting as L2 U2U Remote UE:3> release the RRC, PDCP, SDAP for its peer Remote UE (This is an example of an operation to release an end-to-end PC5 unicast connection with a peer Remote UE that has established an end-to-end PC5 unicast connection with the peer Remote UE)3> perform relay UE reselection procedure for its peer Remote UE (A procedure to reselect a sidelink relay that can relay signaling and user traffic with the peer Remote UE can be performed)NOTE: It is up to UE implementation on whether and how to indicate to upper layers to maintain the keep-alive procedure.

[0184] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0185] 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 embodiments described in the claims or specification of the present disclosure.

[0186] These programs (software modules, software) may be stored in a random access memory, a non-volatile memory including a flash memory, a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), a magnetic disc storage device, a compact disc ROM (CD-ROM), a digital versatile disc (DVD) or other forms of optical storage, a magnetic cassette, or a memory formed by a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0187] 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 LAN (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.

[0188] 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.

[0189] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

Claims

1. A method performed by a first UE (user equipment) in a wireless communication system, A step for identifying expiration of a timer associated with an end-to-end (E2E) connection for sidelink communication with a second UE via a relay UE, or failure of an integrity check of a sidelink (SL) signaling radio bearer (SRB) for the E2E connection; and A method comprising the step of discarding SRAP (sidelink relay adaption protocol) settings for the E2E connection.

2. In claim 1, A step of releasing at least one SL DRB (data radio bearer) for the E2E connection; and Further comprising the step of releasing at least one SL SRB for the E2E connection, A method wherein the above SL SRB is included in at least one SL SRB, and includes SL SRB 2 or SL SRB 3.

3. In claim 2, A method further comprising the step of releasing a PC5 RLC (radio link control) channel corresponding to at least one SL DRB.

4. In claim 1, A method further comprising a step of releasing at least one of an RRC (radio resource control) connection for the E2E connection, a PDCP (packet data convergence protocol) configuration of at least one SL SRB for the E2E connection, or a PDCP configuration of at least one SL DRB (data radio bearer) for the E2E connection.

5. In claim 1, A method further comprising the step of transmitting, to the relay UE, information associated with the release of the E2E connection.

6. In claim 5, A method wherein the information associated with the release of the E2E connection includes information about an L2 (layer 2) ID (identity) of the second UE.

7. In claim 1, A step of identifying that an expiration of a timer associated with the relay UE, a failure of an integrity check of an SL-SRB associated with the relay UE, a maximum number of PC5 RLC (radio link control) retransmissions to the relay UE have been reached, or a maximum number of continuous HARQ (hybrid automatic repeat request) discontinuous transmission (DTX) to the relay UE has been reached; and A method comprising the step of releasing at least one SL SRB associated with the relay UE.

8. In claim 7, A step of resetting the MAC (medium access control) settings associated with the above relay UE; A method further comprising the step of releasing a PC5 RLC (radio link control) channel associated with the relay UE.

9. In a wireless communication system, in the first UE (user equipment), transceiver; and A controller coupled with the above transceiver, The above controller: Identifying expiration of a timer associated with an end-to-end (E2E) connection for sidelink communication with a second UE via a relay UE, or failure of an integrity check of a sidelink (SL) signaling radio bearer (SRB) for the E2E connection, A first UE configured to discard SRAP (sidelink relay adaption protocol) settings for the above E2E connection.

10. In claim 9, The above controller: Release at least one SL DRB (data radio bearer) for the above E2E connection, is configured to release at least one SL SRB for the above E2E connection, The first UE, wherein the SL SRB is included in at least one SL SRB, including SL SRB 2 or SL SRB 3.

11. In claim 10, The above controller: A first UE configured to release a PC5 RLC (radio link control) channel corresponding to at least one SL DRB.

12. In claim 9, The above controller: A first UE configured to release at least one of an RRC (radio resource control) connection for the E2E connection, a PDCP (packet data convergence protocol) configuration of at least one SL SRB for the E2E connection, or a PDCP configuration of at least one SL DRB (data radio bearer) for the E2E connection.

13. In claim 9, The above controller: A first UE configured to transmit information associated with the release of the E2E connection to the relay UE.

14. In claim 13, The information associated with the release of the E2E connection includes information about an L2 (layer 2) ID (identity) of the second UE.

15. In claim 9, The above controller: Identifying that the timer associated with the relay UE has expired, that the integrity check of the SL-SRB associated with the relay UE has failed, that the number of PC5 RLC (radio link control) retransmissions to the relay UE has reached a maximum, or that the number of consecutive HARQ (hybrid automatic repeat request) discontinuous transmissions (DTXs) ​​to the relay UE has reached a maximum, Release at least one SL SRB associated with the above relay UE, Reset the MAC (medium access control) settings associated with the above relay UE, A first UE configured to release a PC5 RLC (radio link control) channel associated with the relay UE.

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