Method and apparatus for direct communication between terminals based on terminal relay in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. According to one embodiment of the present disclosure, a method of a first user equipment (UE) providing proximity based services (ProSe) in a wireless communication system comprises the steps of: receiving a plurality of relay discovery request messages from a plurality of second UEs providing a ProSe UE-to-UE relay function; selecting a third UE among the plurality of second UEs; and transmitting a plurality of relay discovery response messages to the plurality of second UEs, wherein the plurality of relay discovery response messages include a user information identifier (ID) of the third UE.

Description

Method and device for direct communication between terminals based on terminal relay in a wireless communication system

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and device for searching for a terminal relay when performing direct communication between terminals via the terminal relay.

[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 band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band (Above 6GHz) called millimeter wave (mmWave) such as 28GHz and 39GHz. In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and ultra-low latency 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 ultra-wideband services (eMBB: enhanced Mobile Broadband), ultra-reliable / ultra-low-latency communications (URLLC: Ultra-Reliable Low-Latency Communications), and massive Machine-Type Communications (mMTC), including 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 sub-carrier 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 codes for reliable transmission of control information, L2 pre-processing, and specific services. Standardization has been progressed for network slicing, which provides specialized, dedicated networks.

[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 (IIoT: Industrial Internet of Things) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) to provide nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) to simplify random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture: SBA, Service-based Interface: SBI) 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] When such 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, which will require enhanced functions and performance of 5G mobile communication systems and integrated operation of 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 antennas, and large scale antennas, 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, and AI (Artificial Intelligence) from the design stage and internalize end-to-end AI support functions to realize system optimization, and ultra-high-performance communication and computing resources to realize services with complexity that exceeds the limits of terminal computing capabilities. It could serve as a basis for the development of next-generation distributed computing technologies.

[0008] The present disclosure aims to provide a method and device for searching for a terminal relay when performing direct communication between terminals through a terminal relay in a wireless communication system.

[0009] The technical problems to be achieved in the present invention 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 invention belongs from the description below.

[0010] According to one embodiment of the present disclosure, a method of a first user equipment (UE) providing ProSe (Proximity based services) in a wireless communication system comprises: receiving a plurality of relay discovery request messages from a plurality of second UEs providing a ProSe UE-to-UE relay function; selecting a third UE among the plurality of second UEs; and transmitting at least one relay discovery response message to the plurality of second UEs, wherein the plurality of relay discovery response messages include a user info identifier (ID) of the third UE.

[0011] According to one embodiment of the present disclosure, a method of a second UE (user equipment) providing a ProSe (Proximity based services) UE-to-UE relay function in a wireless communication system comprises the steps of: transmitting a relay discovery request message to a first UE providing a ProSe function; and receiving a relay discovery response message from the first UE; wherein the relay discovery response message includes a user info identifier (ID) of a third UE, which is one of a plurality of UEs providing a ProSe UE-to-UE relay function that have transmitted a plurality of relay discovery request messages to the first UE.

[0012] According to one embodiment of the present disclosure, a method of a first user equipment (UE) providing ProSe (Proximity based services) in a wireless communication system comprises: a transceiver; and at least one processor; wherein the at least one processor is configured to receive a plurality of relay discovery request messages from a plurality of second UEs providing a ProSe UE-to-UE relay function, select a third UE among the plurality of second UEs, and transmit a plurality of relay discovery response messages to the plurality of second UEs, wherein the plurality of relay discovery response messages include a user info identifier (ID) of the third UE.

[0013] According to one embodiment of the present disclosure, a second UE (user equipment) providing a ProSe (Proximity based services) UE-to-UE relay function in a wireless communication system comprises: a transceiver; and at least one processor; wherein the at least one processor is configured to transmit a relay discovery request message to a first UE providing a ProSe function, and to receive a relay discovery response message from the first UE, wherein the relay discovery response message includes a user info identifier (ID) of a third UE that is one of a plurality of UEs providing a ProSe UE-to-UE relay function that have transmitted a plurality of relay discovery request messages to the first UE.

[0014] One embodiment of the present invention provides a device and method capable of effectively providing a service in a wireless communication system.

[0015] One embodiment of the present invention can provide a method and device capable of directly transmitting user data between terminals in a wireless communication system.

[0016] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0017] FIG. 1 is a diagram showing an example of a configuration of a wireless communication system according to an embodiment of the present disclosure, and FIG. 1 exemplifies the configuration of a 5G system.

[0018] FIG. 2 is a diagram illustrating a 5G ProSe (proximity based services) UE-to-UE Relay structure according to an embodiment of the present disclosure.

[0019] FIG. 3 is a diagram illustrating a 5G ProSe UE-to-UE Relay Discovery Model B scheme according to an embodiment of the present disclosure.

[0020] FIG. 4 is a diagram illustrating a procedure of a 5G ProSe UE-to-UE Relay Discovery Model B scheme according to one embodiment of the present disclosure.

[0021] FIG. 5 is a diagram illustrating a procedure in which a terminal uses a separate request message in a 5G ProSe UE-to-UE Relay Discovery Model B scheme according to one embodiment of the present disclosure.

[0022] FIG. 6 is a diagram showing the configuration of a terminal according to an embodiment of the present disclosure.

[0023] Hereinafter, preferred embodiments of the present invention 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 throughout the accompanying drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted.

[0024] In describing the embodiments herein, 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 invention 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.

[0025] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0026] The advantages and features of the present disclosure, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments are provided only to ensure that the disclosure of the present disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0027] Furthermore, when describing the present disclosure, detailed descriptions of related functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0028] Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B (gNB), an eNode B (eNB), a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, the downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and the uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although LTE, LTE-A, or 5G systems may be described below as examples, embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, this may include the fifth-generation mobile communication technology (5G, new radio, NR) developed after LTE-A. The term "5G" below may also encompass existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications, as determined by a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure.

[0029] At this time, it will be understood that each block of the processing flow diagrams and combinations of the flow diagrams 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 flow diagram 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 flow diagram 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).

[0030] 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.

[0031] 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 regenerate one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, the components and '~ units' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card. Additionally, in the embodiment, '~bu' may include one or more processors.

[0032] Wireless communication systems are evolving from providing voice-oriented services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards such as 3GPP's HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE's 802.16e.

[0033] As a representative example of the above broadband wireless communication system, the LTE system adopts the Orthogonal Frequency Division Multiplexing (OFDM) method in the downlink (DL) and the Single Carrier Frequency Division Multiple Access (SC-FDMA) method in the uplink (UL). The uplink refers to a wireless link in which a terminal (User Equipment (UE) or Mobile Station (MS)) transmits data or control signals to a base station (eNode B, gNode B, or base station (BS)), and the downlink refers to a wireless link in which a base station transmits data or control signals to a terminal. The above multiple access method can distinguish the data or control information of each user by allocating and operating the time-frequency resources for transmitting data or control information to each user so that they do not overlap, that is, so as to achieve orthogonality.

[0034] As the future communications system beyond LTE, 5G communication systems must be able to freely reflect the diverse needs of users and service providers. Therefore, they must support services that simultaneously satisfy these diverse requirements. Services being considered for 5G communication systems include enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), and Ultra-Reliable Low Latency Communication (URLLC).

[0035] eMBB aims to provide data transmission rates that are significantly higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to support a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. Furthermore, 5G communication systems must simultaneously provide the peak data rate and an increased user-perceived data rate for terminals. To meet these requirements, improvements in various transmission and reception technologies, including improved multi-input, multi-output (MIMO) transmission technology, are required. Furthermore, while LTE transmits signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, 5G communication systems can meet the data transmission rates required by 5G communication systems by using a wider frequency bandwidth than 20 MHz in the 3-6 GHz or higher 6 GHz band.

[0036] At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide the IoT, mMTC requires supporting large-scale terminal connections within a cell, improved terminal coverage, enhanced battery life, and reduced terminal costs. The IoT requires the ability to support a large number of terminals (e.g., 1,000,000 terminals / km^2) within a cell, as it provides communication capabilities through the attachment of various sensors and devices. Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in shadow areas, such as basements, beyond the reach of cells. Therefore, they may require wider coverage than other services provided by 5G communication systems. Terminals supporting mMTC must be inexpensive, and since frequent battery replacement is unlikely, they may require extremely long battery lifespans, such as 10 to 15 years.

[0037] Finally, URLLC refers to cellular-based wireless communication services used for specific mission-critical purposes. Examples include remote control of robots or machinery, industrial automation, unmanned aerial vehicles (UAVs), remote health care, and emergency alerts. Therefore, URLLC communications must offer extremely low latency and high reliability. For example, services supporting URLLC must meet air interface latency requirements of less than 0.5 milliseconds and a packet error rate (PER) of less than 10^-5. Therefore, for services supporting URLLC, 5G systems must provide shorter transmission time intervals (TTIs) than other services, and design requirements may require the allocation of extensive resources in the frequency band to ensure communication link reliability.

[0038] The three 5G services—eMBB, URLLC, and mMTC—can be multiplexed and transmitted within a single system. To meet the differing requirements of each service, different transmission and reception techniques and parameters can be used. Of course, 5G is not limited to the three services described above.

[0039] In this disclosure, phrases such as "A and / or B", "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can each include any one of the items listed together in that phrase, or all possible combinations thereof. Terms such as "first", "second", or "first" or "second" may be used merely to distinguish the corresponding component from other corresponding components and do not limit the corresponding components in any other respect (e.g., importance or order).

[0040] Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a Node B, a BS (Base Station), an eNB (eNode B), a gNB (gNode B), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In addition, the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel form to the embodiments of the present disclosure described below. In addition, the embodiments of the present disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure at the discretion of a person having skilled technical knowledge.

[0041] In the present disclosure, network technology may refer to standard specifications defined by the International Telecommunication Union (ITU) or 3GPP (e.g., TS 23.501, TS 23.502, TS 23.503, etc.), and components included in the network structure of Fig. 1 may each mean a physical entity, or may mean software performing an individual function, or hardware combined with software. Reference symbols shown as Nx, such as N1, N2, N3, ... in the drawings, represent known interfaces between NFs in a 5G core network (CN), and since a related description may refer to the standard specification (TS 23.501), a detailed description will be omitted.

[0042] In the following description, terms used to identify connection nodes, terms referring to network entities (NEs) or network functions (NFs), terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0043] For convenience of explanation, some terms and names defined in the 3rd generation partnership project long-term evolution (3GPP) standards may be used. However, the present disclosure is not limited to these terms and names, and can be equally applied to systems conforming to other standards.

[0044] FIG. 1 is a diagram showing an example of a configuration of a wireless communication system according to an embodiment of the present disclosure, and FIG. 1 exemplifies the configuration of a 5G system.

[0045] Referring to FIG. 1, a 5G network may include at least one of the network entities (NE) or network functions (NF) described below.

[0046] (R)AN ((Radio) Access Network) is an entity that performs wireless resource allocation of a terminal, and may be at least one of an eNode B, a Node B, a BS (Base Station), an NG-RAN (Next Generation Radio Access Network), a 5G-AN (5G Access Network), a 5G NR (5G New Radio), a radio access unit, a base station controller, or a node on a network.

[0047] The terminal may include a UE (User Equipment), NG UE (Next Generation UE), MS (Mobile Station), cellular phone, smartphone, computer, IoT (Internet of Things) device, or multimedia system capable of performing communication functions.

[0048] Furthermore, while the embodiments of the present disclosure are described below using a 5G system as an example, the embodiments of the present disclosure can also be applied to other communication systems with similar technical backgrounds. Furthermore, the embodiments of the present disclosure can be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure.

[0049] As wireless communication systems evolve from 4G to 5G, a new core network (CN) called the Next Generation Core (NG Core) or 5GC (5G Core Network) is being defined. This new core network virtualizes all existing network entities (NEs) into network functions (NFs). According to one embodiment of the present disclosure, a network function may refer to a network entity, a network component, or a network resource.

[0050] According to one embodiment of the present disclosure, 5GC may include NFs illustrated in FIG. 1. Of course, the present invention is not limited to the example illustrated in FIG. 1, and 5GC may include more or fewer NFs than the NFs illustrated in FIG. 1.

[0051] The Access and Mobility Management Function (AMF) may be a network function that manages the access and mobility of a terminal (UE). For example, AMF may perform network functions such as terminal registration, connection, reachability, mobility management, access verification, authentication, and mobility event generation.

[0052] A Session Management Function (SMF) may be a network function that manages a Packet Data Network (PDN) connection provided to a user equipment (UE). A PDN connection may be referred to as a Protocol Data Unit (PDU) Session. For example, an SMF may perform network functions such as session management through the establishment, modification, and release of sessions and the maintenance of tunnels between the User Plane Function (UPF) and the RAN, selection and control of the User Plane (UPF), control of traffic processing in the UPF, and control of charging data collection.

[0053] PCF (Policy Control Function) may be a network function that applies the mobile carrier's service policy, charging policy, and PDU Session policy to the terminal.

[0054] Unified Data Management (UDM) can be a network function that stores subscriber information. For example, UDM can perform functions such as generating authentication information for 3GPP security, processing user identifiers (User IDs), managing a list of network functions supporting UEs, and managing subscription information.

[0055] The Network Exposure Function (NEF) may provide information about a terminal to a server outside the 5G network. Additionally, NEF may provide the information necessary for 5G network services and store it in the Unified Data Repository (UDR).

[0056] The User Plane Function (UPF) may function as a gateway that transmits user data (PDU) to the Data Network (DN). More specifically, the UPF may process data so that it can transmit data transmitted by a terminal to an external network or transmit data received from an external network to the terminal. For example, the UPF may perform network functions such as serving as an anchor between Radio Access Technologies (RATs), packet routing and forwarding, packet inspection, user plane policy application, traffic usage report generation, and buffering.

[0057] NRF (Network Repository Function) can store the profiles of NFs and perform the function of discovering NFs.

[0058] AUSF (Authentication Server Function) can perform terminal authentication in 3GPP access networks and non-3GPP access networks.

[0059] NSSF (Network Slice Selection Function) can perform the function of selecting a Network Slice Instance provided to a terminal.

[0060] The Network Data Analytics Function (NWDAF) collects data from multiple NFs (Network Functions) to ensure efficient operation of the 5GC network. This data is analyzed using a machine learning (ML) model, and the results are provided to the NFs, helping them provide efficient network services.

[0061] An Application Function (AF) can communicate with a network operator to enable external servers (Application Servers) to utilize network services provided by the operator's network. Depending on the deployment entity, AFs can be categorized as internal AFs and external AFs. Internal AFs deployed by network operators can communicate directly with network functions (NFs) within the operator's network. AFs deployed by third-party service providers (3rd-party service providers) must go through an NEF to communicate with NFs within the operator's network.

[0062] DN (Data Network) can be a data network where terminals transmit and receive data to use network operator services or third-party services.

[0063] The terminal may include an IoT device. The IoT device may include a device that does not use battery power or operates with very little power, and such IoT devices are referred to as ambient IoT devices (or simply Ambient IoT).

[0064] In the 3GPP system, a conceptual link connecting NFs within a 5G system is defined as a reference point. The following illustrates a reference point included in the 5G system architecture depicted in Figure 1.

[0065] - N1: Reference point between UE and AMF

[0066] - N2: Reference point between (R)AN and AMF

[0067] - N3: Reference point between (R)AN and UPF

[0068] - N4: Reference point between SMF and UPF

[0069] - N5: Reference point between PCF and AF

[0070] - N6: Reference point between UPF and DN

[0071] - N7: Reference point between SMF and PCF

[0072] - N8: Reference point between UDM and AMF

[0073] - N9: Reference point between two core UPFs

[0074] - N10: Reference point between UDM and SMF

[0075] - N11: Reference point between AMF and SMF

[0076] - N12: Reference point between AMF and AUSF

[0077] - N13: Reference points between UDM and AUSF

[0078] - N14: Reference point between two AMFs

[0079] Additionally, in 3GPP systems, the 5G system architecture may include service-based interfaces such as the following examples.

[0080] - Nnssf: Service-based interface by NSSF

[0081] - Nnssaaf: Service-based interface by NSSAAF (Network Slice-Specific Authentication and Authorization Function)

[0082] - Nnef: Service-based interface by NEF

[0083] - Nausf: Service-based interface by AUSF

[0084] - Nnrf: Service-based interface by NRF

[0085] - Namf: Service-based interface by AMF

[0086] - Npcf: Service-based interface by PCF

[0087] - Nsmf: Service-based interface by SMF

[0088] - Nupf: Service-based interface by UPF

[0089] - Nudm: Service-based interface by UDM

[0090] - Naf: Service-based interface by AF

[0091] - Nasaf: Service-based interface by AUSF

[0092] - Neasdf: Service-based interface by EASDF (Edge Application Server Discovery Function)

[0093] - Nnwdaf: Service-based interface by NWDAF

[0094] According to one embodiment of the present disclosure, 5G ProSe (Proximity-based Services) defines a form of communication that enables direct communication between nearby 5G ProSe-enabled terminals without going through a network. In this case, if direct communication is not possible due to a large distance between two 5G ProSe-enabled terminals, relay communication via 5G ProSe Relay is also possible. The present disclosure proposes a method for resolving issues related to a method for 5G ProSe-enabled terminals to search for 5G ProSe Relay for communication using 5G ProSe Relay.

[0095] FIG. 2 is a diagram illustrating a 5G ProSe (Proximity based Services) UE-to-UE Relay structure according to an embodiment of the present disclosure.

[0096] Referring to FIG. 2, both the 5G ProSe End UE and the 5G ProSe UE-to-UE Relay are 5G ProSe enabled UEs. The 5G ProSe End UE can communicate with the counterpart 5G ProSe End UE using the 5G ProSe UE-to-UE Relay, and the 5G ProSe UE-to-UE Relay can provide a data relay service to enable 5G ProSe End UEs to communicate. In addition, the 5G ProSe enabled UEs can use the PC5 interface to transmit data and signaling.

[0097] FIG. 3 is a diagram illustrating a 5G ProSe UE-to-UE Relay Discovery Model B scheme according to an embodiment of the present disclosure.

[0098] Figure 3 illustrates a Model B scheme in which a 5G ProSe End UE transmits a Discovery Solicitation message to search for a 5G ProSe UE-to-UE Relay. The 5G ProSe UE-to-UE Relay Discovery Solicitation message may include a Type of Discovery Message, its own User Info ID, an RSC (Relay Service Code), and the other party's User Info ID.

[0099] The Type of Discovery Message can indicate the type of message being transmitted. The User Info ID refers to the value configured in the 5G ProSe End UE and 5G ProSe UE-to-UE Relay for 5G ProSe UE-to-UE Relay Discovery. The RSC can be used to identify the connectivity service provided by the 5G ProSe UE-to-UE Relay.

[0100] The 5G ProSe UE-to-UE Relay that receives the Discovery Solicitation message transmitted by the 5G ProSe End UE can check the RSC included in the message to confirm whether it is a connectivity service it provides and then relay it again.

[0101] When a 5G ProSe End UE relayed by a 5G ProSe UE-to-UE Relay receives a Discovery Solicitation message, the other party's 5G ProSe End UE can check the RSC and the other party's User Info ID included in the received message and, if the message sent to itself is correct, generate and send a 5G ProSe UE-to-UE Relay Discovery Response message.

[0102] FIG. 4 is a diagram illustrating a procedure of a 5G ProSe UE-to-UE Relay Discovery Model B scheme according to one embodiment of the present disclosure.

[0103] At step 410, the (discoverer) 5G ProSe End UE-1 may perform a 5G ProSe UE-to-UE Relay Discovery Model B procedure to communicate with the (discoveree) 5G ProSe End UE-2. To this end, the 5G ProSe End UE-1 may transmit a 5G ProSe UE-to-UE Relay Discovery Solicitation message.

[0104] In one embodiment, the 5G ProSe UE-to-UE Relay Discovery Solicitation message may include at least one of a Type of Discovery Message, a User Info ID of UE-1, a User Info ID of UE-2, and an RSC. In one embodiment, in order to transmit a message, a value arbitrarily set by the Source Layer-2 ID value may be assigned, and a Default ID value may be set for the Destination Layer-2 ID value. In one embodiment, the Layer-2 ID value may be an address value that 5G ProSe enabled UEs use to confirm whether a message received is a message sent to itself. In particular, since the Default ID value means Broadcast, if the Default ID value is assigned to the destination (Destination Layer-2 ID) address, all terminals can receive this message. A message transmitted by 5G ProSe End UE-1 can be received by 5G ProSe UE-to-UE Relay-1, 5G ProSe UE-to-UE Relay-2, and 5G ProSe UE-to-UE Relay-3.

[0105] Afterwards, 5G ProSe UE-to-UE Relay-1, 5G ProSe UE-to-UE Relay-2, and 5G ProSe UE-to-UE Relay-3, which have received the 5G ProSe UE-to-UE Relay Discovery Solicitation message transmitted by 5G ProSe End UE-1, can check the message. At this time, each relay can check the RSC value in the message.

[0106] In step 420, each Relay checks whether it is an RSC that it serves, and if it is the same as the RSC value that it serves, it re-creates and retransmits the 5G ProSe UE-to-UE Relay Discovery Solicitation message, and if it is not the same as the RSC value, it can ignore this message. For example, in FIG. 4, Relay-1 and Relay-2 retransmit the 5G ProSe UE-to-UE Relay Discovery Solicitation message because they support the RSC service, but Relay-3 does not support it, so it can ignore this message and not retransmit it. The 5G ProSe UE-to-UE Relay Discovery Solicitation message that the Relay retransmits may include at least one of the following information.

[0107] - Type of Discovery Message, User Info ID of discoverer 5G ProSe End UE (UE-1), User Info ID of discoveree 5G ProSe End UE (UE-2), User Info ID of 5G ProSe UE-to-UE Relay, and RSC.

[0108] To transmit a 5G ProSe UE-to-UE Relay Discovery Solicitation message, the Source Layer-2 ID value can be assigned a value of its own choice and the Destination Layer-2 ID value can be set to the Default ID value. In addition, the Relay can store the Source Layer-2 ID value and RSC value of UE-1 to provide retransmission services.

[0109] At step 420, the (discoveree) 5G ProSe End UE (UE-2) can receive the 5G ProSe UE-to-UE Relay Discovery Solicitation message retransmitted by Relay-1 and Relay-2. The 5G ProSe End UE-2 can receive the message and check the RSC value and the User Info ID of the discoveree 5G ProSe End UE (UE-2). The UE-2 can check whether the RSC value is the same as the value of the service to which it has subscribed and check the User Info ID value to determine whether the message is sent to it.

[0110] In step 430, the 5G ProSe End UE-2 may transmit a 5G ProSe UE-to-UE Relay Discovery Response message to the Relay that transmitted the message, selecting one of the messages received from multiple Relays or multiple Relays. The method of selecting one of the multiple 5G ProSe UE-to-UE Relay Discovery Solicitation messages received by the UE-2 may be selected by considering at least one of the strength of the received message signal and the time at which the message was received. The 5G ProSe UE-to-UE Relay Discovery Response message transmitted by the UE-2 may include at least one of the following information.

[0111] - Type of Discovery Message, User Info ID of discoverer 5G ProSe End UE, User Info ID of discoveree 5G ProSe End UE, and RSC.

[0112] In order to transmit a 5G ProSe UE-to-UE Relay Discovery Response message, UE-2 may assign a value arbitrarily set by itself to the Source Layer-2 ID value and assign the Source Layer-2 ID value of its received 5G ProSe UE-to-UE Relay Discovery Solicitation message to the Destination Layer-2 ID value. That is, the 5G ProSe UE-to-UE Relay Discovery Response message may be transmitted as a unicast toward a specific Relay, rather than a broadcast. In the present embodiment, for example, the address of Relay-2 (e.g., the Source Layer-2 ID of the 5G ProSe UE-to-UE Relay Discovery Solicitation message transmitted by Relay 2) may be assigned to the Destination Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Response message. The message is sent to Relay-1 and Relay-2, but since the destination address is Relay-2, only Relay-2 receives it and Relay-1 can ignore it.

[0113] At step 440, Relay-2, which receives the 5G ProSe UE-to-UE Relay Discovery Response message transmitted by 5G ProSe End UE-2, may generate a 5G ProSe UE-to-UE Relay Discovery Response message and transmit it to the discoverer 5G ProSe End UE (UE-1). The 5G ProSe UE-to-UE Relay Discovery Response message may include at least one of the following information:

[0114] - Type of Discovery Message, User Info ID of discoveree 5G ProSe End UE, User Info ID of 5G ProSe UE-to-UE Relay and RSC.

[0115] To transmit a 5G ProSe UE-to-UE Relay Discovery Response message, the Relay can assign a value it arbitrarily sets to the Source Layer-2 ID value. To set the Destination Layer-2 ID value, the User Info ID of the discoverer 5G ProSe End UE and RSC included in the 5G ProSe UE-to-UE Relay Discovery Response message can be checked, and the Source Layer-2 ID value of the 5G ProSe End UE-1 saved in step 420 can be used. Therefore, the 5G ProSe UE-to-UE Relay Discovery Response message can be transmitted unicast to the (discoverer) 5G ProSe End UE (UE-1).

[0116] In step 420 of the above 5G ProSe UE-to-UE Relay Discovery Model B scheme, when 5G ProSe UE-to-UE Relay-1 and 5G ProSe UE-to-UE Relay-2 transmit a UE-to-UE Relay Discovery Solicitation message to 5G ProSe End UE-2, the Source Layer-2 ID of the UE-to-UE Relay Discovery Solicitation message may be set to the same value and transmitted. This is because the 5G ProSe UE-to-UE Relay assigns a value of its own choice to the Source Layer-2 ID value when transmitting the UE-to-UE Relay Discovery Solicitation message, and therefore, this value is not a unique value. In other words, the Source Layer-2 ID values ​​included in the UE-to-UE Relay Discovery Solicitation message transmitted by another Relay may be duplicated.

[0117] In step 420, the 5G ProSe End UE-2 may receive multiple UE-to-UE Discovery Solicitation messages from multiple 5G ProSe UE-to-UE Relays. At this time, the 5G ProSe End UE-2 may select one UE-to-UE Discovery Solicitation message by considering at least one of the strength of the received message signal and the time at which the message was received, and transmit a UE-to-UE Discovery Response message to the 5G ProSe UE-to-UE Relay that transmitted the message. In order to transmit the 5G ProSe UE-to-UE Relay Discovery Response message, the 5G ProSe End UE-2 may assign a value arbitrarily set by itself to the Source Layer-2 ID value and may assign the Source Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Solicitation message it received to the Destination Layer-2 ID value. That is, the above 5G ProSe UE-to-UE Relay Discovery Solicitation message can be transmitted as a unicast to a specific relay rather than a broadcast.

[0118] 5G ProSe UE-to-UE Relay-1 and 5G ProSe UE-to-UE Relay-2, which receive the above message, can both identify that this message is a message destined for them. This is because, since the two relays used the same Source Layer-2 ID when transmitting the UE-to-UE Discovery Solicitation message in step 420, 5G ProSe End UE-2 used the same Source Layer-2 ID as the Destination Layer-2 ID when transmitting the UE-to-UE Discovery Response message. Accordingly, in step 440, not only 5G ProSe UE-to-UE Relay-2 but also 5G ProSe UE-to-UE Relay-1 can transmit the UE-to-UE Relay Discovery Response message toward 5G ProSe End UE-1.

[0119] This may mean that 5G ProSe End UE-1 cannot determine which Relay to use for communication with 5G ProSe End UE-2, which may result in the 5G ProSe UE-to-UE Relay Discovery procedure not functioning properly.

[0120] In order to solve this problem, the procedure in FIG. 4 can be performed as follows.

[0121] At step 420, the (discoveree) 5G ProSe End UE (UE-2) can receive the 5G ProSe UE-to-UE Relay Discovery Solicitation message retransmitted by Relay-1 and Relay-2. The 5G ProSe End UE-2 can receive the message and check the RSC value and the User Info ID of the discoveree 5G ProSe End UE (UE-2). The 5G ProSe End UE-2 can check whether the RSC value is the same as the RSC value of the service to which it has subscribed and check the User Info ID value to determine whether the message was sent to it.

[0122] In step 430, the 5G ProSe End UE-2 may select one of the messages received from multiple Relays or one of the multiple Relays that transmitted the messages and transmit a 5G ProSe UE-to-UE Relay Discovery Response message to the Relay that transmitted the message. The method of selecting one of the multiple 5G ProSe UE-to-UE Relay Discovery Solicitation messages received by the 5G ProSe End UE-2 or one of the multiple Relays that transmitted the messages may be selected by considering at least one of the strength of the received message signal and the time at which the message was received. The 5G ProSe UE-to-UE Relay Discovery Response message transmitted by the 5G ProSe End UE-2 may include at least one of the following information:

[0123] - Type of Discovery Message, User Info ID of discoverer 5G ProSe End UE, User Info ID of discoveree 5G ProSe End UE, and RSC.

[0124] In one embodiment, the 5G ProSe End UE-2 may add the User Info ID of the selected 5G ProSe UE-to-UE Relay to the 5G ProSe UE-to-UE Relay Discovery Response message. In one embodiment, the 5G ProSe End UE-2 may also add an Indication to Layer-2 requesting 5G ProSe UE-to-UE Relays to further verify the User Info ID of the 5G ProSe UE-to-UE Relay of the upper Layer. In this case, if the Source Layer-2 ID of two or more 5G ProSe UE-to-UE Relay Discovery Solicitations among the received 5G ProSe UE-to-UE Relay Discovery Solicitation messages is the same, the Indication may be added to Layer-2 and the User Info ID of the ProSe UE-to-UE Relay may be added to the 5G ProSe UE-to-UE Relay Discovery Response message.

[0125] In order to transmit the above 5G ProSe UE-to-UE Relay Discovery Response message, the 5G ProSe End UE-2 may assign a value arbitrarily set by itself to the Source Layer-2 ID value and assign the Source Layer-2 ID value of its received 5G ProSe UE-to-UE Relay Discovery Solicitation message to the Destination Layer-2 ID value. That is, the 5G ProSe UE-to-UE Relay Discovery Response message may be transmitted as a unicast toward a specific Relay, not a broadcast. In the present embodiment, for example, the address of Relay-2 may be assigned to the Source Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Response message. The 5G ProSe UE-to-UE Relay Discovery Response message is transmitted to Relay-1 and Relay-2, but since the destination address is Relay-2, only Relay-2 may receive it and Relay-1 may ignore it.

[0126] In one embodiment, the 5G ProSe UE-to-UE Relay may check the Destination Layer-2 ID and, if the message is directed to itself, additionally check the User Info ID of the 5G ProSe UE-to-UE Relay. In one embodiment, the User Info ID of the 5G ProSe UE-to-UE Relay may be additionally checked depending on whether an indication requests verification of the User Info ID of the 5G ProSe UE-to-UE Relay.

[0127] If the two Relays assign the same Source Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Solicitation message, and the destination addresses of each 5G ProSe UE-to-UE Relay Discovery Relay Response message destined for Relay-1 and Relay-2 are the same, the destination Relays cannot be distinguished using only the Destination Layer-2 ID. However, by using the globally unique User Info ID of the 5G ProSe UE-to-UE Relay, the destination Relays of each 5G ProSe UE-to-UE Relay Discovery Response message can be distinguished. That is, even if the destination addresses of each 5G ProSe UE-to-UE Relay Discovery Response message destined for Relay-1 and Relay-2 are the same, since the User Info ID value of 5G ProSe UE-to-UE Relay is Relay-2, only Relay-2 receives the 5G ProSe UE-to-UE Relay Discovery Response message and Relay-1 can ignore it.

[0128] FIG. 5 is a diagram illustrating a procedure in which a terminal uses a separate request message in the 5G ProSe UE-to-UE Relay Discovery Model B scheme. Steps 510 and 520 of FIG. 5 may be performed in the same manner as steps 410 and 420 illustrated in FIG. 4.

[0129] In step 525, if the 5G ProSe End UE-2 confirms that the Source Layer-2 IDs of the multiple UE-to-UE Relay Discovery Solicitation messages received in step 520 are the same, the 5G ProSe End UE-2 may transmit a UE-to-UE L2-ID Resolving Request message to the relays. The UE-to-UE L2-ID Resolving Request message transmitted by the 5G ProSe End UE-2 may include the following values.

[0130] - Type of Discovery Message, User Info ID of 5G ProSe UE-to-UE Relay and RSC.

[0131] In order to transmit the above UE-to-UE L2-ID Resolving Request message, the Source Layer-2 ID value can be assigned a value arbitrarily set by the UE, and the Destination Layer-2 ID value can be assigned the Source Layer-2 ID value of the received 5G ProSe UE-to-UE Relay Discovery Solicitation message. That is, the UE-to-UE L2-ID Resolving Request message can be transmitted as a unicast to a specific relay, rather than as a broadcast.

[0132] 5G ProSe UE-to-UE Relay-1 and 5G ProSe UE-to-UE Relay-2, which received the above UE-to-UE L2-ID Resolving Request message, can confirm that the Source Layer-2 ID of the UE-to-UE Relay Discovery Solicitation message transmitted in step 520 is in conflict. Each Relay can generate a UE-to-UE L2-ID Resolving Response message and transmit it to 5G ProSe End UE-2. The message can include the following values.

[0133] - Type of Discovery Message, User Info ID of 5G ProSe UE-to-UE Relay and RSC.

[0134] The 5G ProSe UE-to-UE Relay-1 and 5G ProSe UE-to-UE Relay-2 may assign a value arbitrarily set by themselves to the Source Layer-2 ID value in order to transmit the UE-to-UE L2-ID Resolving Response message and may assign the Source Layer-2 ID value of the UE-to-UE L2-ID Resolving Request message they received to the Destination Layer-2 ID value. That is, the UE-to-UE L2-ID Resolving Request message is transmitted as a unicast toward a specific Relay, not a broadcast. In this case, Relay 1 and Relay 2 may assign an arbitrary value different from the arbitrary value assigned to the Source Layer-2 ID value of the UE-to-UE Relay Discovery solicitation message transmitted in step 520 to the Source Layer-2 ID value of the UE-to-UE L2-ID Resolving Response message.

[0135] In step 530, the 5G ProSe UE-to-UE Relay-1 and the 5G ProSe UE-to-UE Relay-2 that received the UE-to-UE L2-ID Resolving Request message may retransmit the 5G ProSe UE-to-UE Relay Discovery Solicitation message. In one embodiment, the 5G ProSe UE-to-UE Relay-1 and the 5G ProSe UE-to-UE Relay-2 that received the UE-to-UE L2-ID Resolving Request message may perform only one of transmitting the UE-to-UE L2-ID Resolving Response message in step 525 and retransmitting the 5G ProSe UE-to-UE Relay Discovery Solicitation message in step 530.

[0136] 5G ProSe End UE-2 can receive the retransmitted 5G ProSe UE-to-UE Relay Discovery Solicitation message and check the RSC value and the User Info ID of the discoveree 5G ProSe End UE (UE-2). 5G ProSe End UE-2 can check whether the RSC value of the 5G ProSe UE-to-UE Relay Discovery Solicitation message is the same as the RSC value of the service it has subscribed to and check the User Info ID value to determine whether the message was sent to it.

[0137] In step 540, UE-2 may select one of the messages received from multiple Relays and transmit a 5G ProSe UE-to-UE Relay Discovery Response message to the Relay that transmitted the message. 5G ProSe End UE-2 may select one of the received multiple 5G ProSe UE-to-UE Relay Discovery Solicitation messages by considering at least one of the signal strength of the received message and the time at which the message was received. The 5G ProSe UE-to-UE Relay Discovery Response message transmitted by 5G ProSe End UE-2 may include the following values.

[0138] - Type of Discovery Message, User Info ID of discoverer 5G ProSe End UE, User Info ID of discoveree 5G ProSe End UE, and RSC.

[0139] In order to transmit the above 5G ProSe UE-to-UE Relay Discovery Response message, UE-2 can assign a value arbitrarily set by itself to the Source Layer-2 ID value and assign the Source Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Solicitation message received in its step 530 to the Destination Layer-2 ID value. That is, this 5G ProSe UE-to-UE Relay Discovery Response message is not transmitted as a broadcast, but as a unicast toward a specific Relay. In this embodiment, for example, the address of Relay-2 can be assigned to the Destination Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Solicitation message. Relay-1 and Relay-2 receive the message, but since the destination address is Relay-2, only Relay-2 can receive it and Relay-1 can ignore it.

[0140] If the UE-to-UE Relay L2-ID Resolving Request / Response message is transmitted and received with the relays in step 525, the 5G ProSe End UE-2 may assign the Source Layer-2 ID value of the UE-to-UE Relay L2-ID Resolving Response message it received to the Destination Layer-2 ID value of the 5G ProSe UE-to-UE Relay Discovery Response message.

[0141] FIG. 6 is a diagram showing the configuration of a terminal according to an embodiment of the present disclosure.

[0142] The terminal illustrated in FIG. 6 may include the 5G ProSe End UE and 5G ProSe UE-to-UE Relay described in FIG. 2. That is, all of the terminals illustrated in FIG. 6 are 5G ProSe enabled UEs. If they are 5G ProSe End UEs, they can communicate with the counterpart 5G ProSe End UE using 5G ProSe UE-to-UE Relay, and if they are 5G ProSe UE-to-UE Relays, they can provide a data relay service so that 5G ProSe End UEs can communicate.

[0143] A terminal according to one embodiment of the present disclosure may include a processor (620) that controls the overall operation of the terminal, a transceiver (600) including a transmitter and a receiver, and a memory (610). Of course, the present invention is not limited to the above example, and the terminal may include more or fewer components than those illustrated in FIG. 6.

[0144] According to one embodiment of the present disclosure, the transceiver (600) can transmit and receive signals with network entities or other terminals. The signals transmitted and received with the network entities may include control information and data. In addition, the transceiver (600) can receive signals via a wireless channel, output them to the processor (620), and transmit the signals output from the processor (620) via the wireless channel.

[0145] According to one embodiment of the present disclosure, the processor (620) can control the terminal to perform any one of the operations of the above-described embodiments. Meanwhile, the processor (620), the memory (610), and the transceiver (600) do not necessarily have to be implemented as separate modules, and of course, they can be implemented as a single component in the form of a single chip. In addition, the processor (620) and the transceiver (600) can be electrically connected. In addition, the processor (620) can be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor.

[0146] According to one embodiment of the present disclosure, the memory (610) can store data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the memory (610) provides the stored data upon request of the processor (620). The memory (610) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (610). In addition, the processor (620) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (610).

[0147] If the terminal is a 5G ProSe End UE (first UE), the at least one processor may control receiving a plurality of relay discovery request messages from a plurality of second UEs that provide a ProSe UE-to-UE relay function. The at least one processor may select a third UE among the plurality of second UEs. The at least one processor may control transmitting a plurality of relay discovery response messages to the plurality of second UEs. The plurality of relay discovery response messages may include a user information identifier (ID) of a third UE among the plurality of second UEs that transmitted the first relay discovery request message.

[0148] In one embodiment, the plurality of relay discovery response messages may include an indication requesting additional verification of the user information ID in the relay discovery response message.

[0149] In one embodiment, the at least one processor may identify whether duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in a plurality of relay discovery request messages received from the plurality of second UEs. In one embodiment, the at least one processor may control transmission of an L2-ID request message to at least two second UEs among the plurality of second UEs if duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in the plurality of relay discovery request messages.

[0150] In one embodiment, the at least one processor may control receiving L2-ID response messages or relay discovery request messages from at least two second UEs among the plurality of second UEs in response to the L2-ID request message.

[0151] In one embodiment, multiple Source Layer-2 IDs of the L2-ID response messages or relay discovery request messages may be assigned values ​​different from the assigned duplicate values.

[0152] If the terminal is a 5G ProSe UE-to-UE Relay (second UE), the at least one processor may control to transmit a relay discovery request message to a first UE providing a ProSe function. The at least one processor may control to receive a relay discovery response message from the first UE. In one embodiment, the relay discovery response message may include a user information identifier (ID) of a third UE, which is one of a plurality of UEs providing a ProSe UE-to-UE relay function that have transmitted a plurality of relay discovery request messages to the first UE. In one embodiment, the third UE may be a UE that has transmitted a relay discovery request message selected by the first UE.

[0153] In one embodiment, the plurality of relay discovery response messages may include an indication requesting additional verification of a user information ID in the relay discovery response message. In one embodiment, the at least one processor may control receiving an L2-ID request message from the first UE when a plurality of relay discovery request messages are transmitted to the first UE and duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in the plurality of relay discovery request messages.

[0154] In one embodiment, the at least one processor may control the first UE to receive an L2-ID response message or a relay discovery request message.

[0155] In one embodiment, multiple Source Layer-2 IDs of the L2-ID response message or relay discovery request message may be assigned values ​​different from the assigned duplicate values.

[0156] It should be noted that the aforementioned configuration diagrams, examples of control / data signal transmission methods, examples of operational procedures, and configuration diagrams are not intended to limit the scope of the present disclosure. That is, not all components, entities, or operational steps described in the embodiments of the present disclosure should be construed as essential components for implementing the disclosure, and implementations may be made within a scope that does not detract from the essence of the disclosure even if only some components are included. Furthermore, each embodiment may be combined and operated as needed. For example, parts of the methods proposed in the present disclosure may be combined to operate network entities and terminals.

[0157] The operations of the base station or terminal described above can be realized by providing a memory device storing the corresponding program code in any component within the base station or terminal device. That is, the control unit of the base station or terminal device can execute the operations described above by reading and executing the program code stored in the memory device using a processor or CPU (Central Processing Unit).

[0158] The various components and modules of the entity, base station or terminal device described in this specification may be operated using hardware circuits, such as logic circuits based on complementary metal oxide semiconductors, firmware, software and / or hardware and firmware and / or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates and application-specific semiconductors.

[0159] 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.

[0160] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0161] Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

[0162] 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.

[0163] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is obvious that various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the following claims but also by equivalents of the scope of the claims. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, each of the above embodiments can be combined and operated with each other as needed. For example, parts of the methods proposed in the present disclosure can be combined with each other to operate a base station and a terminal. In addition, although the above embodiments have been presented based on a 5G, NR system, other modifications based on the technical idea of ​​the above embodiments can be implemented with other systems such as LTE, LTE-A, and LTE-A-Pro systems.

[0164] 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. In a method of a first UE (user equipment) providing ProSe (Proximity based services) in a wireless communication system, A step of receiving a plurality of relay discovery request messages from a plurality of second UEs providing a ProSe UE-to-UE relay function; a step of selecting a third UE among the plurality of second UEs; and a step of transmitting a plurality of relay search response messages to the plurality of second UEs; A method characterized in that the plurality of relay search response messages include a user info identifier (ID) of the third UE.

2. A method according to claim 1, characterized in that the plurality of relay search response messages include an indication requesting additional verification of the user information ID in the plurality of relay search response messages.

3. In paragraph 1, A step of identifying whether duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in a plurality of relay discovery request messages received from the plurality of second UEs; and A method characterized in that it further includes a step of transmitting L2-ID request messages to at least two second UEs among the plurality of second UEs when duplicate values ​​are assigned to the plurality of Source Layer-2 IDs included in the plurality of relay search request messages.

4. In paragraph 3, A method characterized by comprising: receiving L2-ID response messages or second relay discovery request messages from at least two second UEs among the plurality of second UEs in response to the L2-ID request messages.

5. A method according to claim 4, characterized in that a value different from the assigned duplicate value is assigned to a plurality of Source Layer-2 IDs of the L2-ID response messages or the second relay discovery request messages.

6. In a method of a second UE (user equipment) providing a ProSe (Proximity based services) UE (user equipment)-to-UE relay function in a wireless communication system, A step of transmitting a relay discovery request message to a first UE providing ProSe functionality; and A step of receiving a relay search response message from the first UE; A method characterized in that the relay discovery response message includes a user information identifier (ID) of a third UE, which is one of a plurality of UEs providing a ProSe UE-to-UE relay function that transmitted a plurality of relay discovery request messages to the first UE.

7. A method according to claim 6, characterized in that the relay search response message includes an indication requesting additional verification of the user information ID in the relay search response message.

8. In paragraph 6, If duplicate values ​​are assigned to multiple Source Layer-2 IDs included in the above multiple relay search request messages, A method further comprising: receiving an L2-ID request message from the first UE.

9. In paragraph 8, A method characterized by comprising the step of receiving an L2-ID response message or a second relay discovery request message from the first UE.

10. A method according to claim 9, characterized in that a plurality of Source Layer-2 IDs of the L2-ID response message or the second relay search request message are assigned values ​​different from the assigned duplicate values.

11. In a first UE (user equipment) providing ProSe (Proximity based services) in a wireless communication system, Transmitter and receiver; and At least one processor; comprising: Receive multiple relay discovery request messages from multiple second UEs that provide ProSe UE-to-UE relay functionality, Selecting a third UE from among the plurality of second UEs, and configured to transmit a plurality of relay search response messages to the plurality of second UEs, A first UE, characterized in that the plurality of relay search response messages include a user info identifier (ID) of the third UE.

12. In the 11th paragraph, the first UE is characterized in that the plurality of relay search response messages include an indication requesting additional verification of the user information ID in the relay search response message.

13. In the 11th paragraph, the at least one processor, Identify whether duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in a plurality of relay discovery request messages received from the plurality of second UEs, and A first UE characterized in that, when duplicate values ​​are assigned to a plurality of Source Layer-2 IDs included in the plurality of relay search request messages, it is configured to transmit L2-ID request messages to at least two second UEs among the plurality of second UEs.

14. In a second UE (user equipment) that provides ProSe (Proximity based services) UE (user equipment)-to-UE relay function in a wireless communication system, Transmitter and receiver; and At least one processor; comprising: Transmit a relay discovery request message to a first UE that provides ProSe functionality, and configured to receive a relay search response message from the first UE, A second UE, characterized in that the relay discovery response message includes a user information identifier (ID) of a third UE, which is one of a plurality of UEs providing a ProSe UE-to-UE relay function that transmitted a plurality of relay discovery request messages to the first UE.

15. In paragraph 14, the at least one processor, If duplicate values ​​are assigned to multiple Source Layer-2 IDs included in the above multiple relay search request messages, A second UE, characterized in that it is configured to receive an L2-ID request message from the first UE.

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