UE(User Equipment)

Abstract

An extension of the 5G ProSe public alarm notification relay procedure in multi-hop communication is being considered. Controlling the forwarding of alarm messages using the number of hops is being considered, but the UE behavior when the maximum number of hops is not available is unclear. [Solution] The 5G ProSe intermediate U2N relay UE receives a PROSE PC5 discovery message from the 5G ProSe multihop U2N relay UE for a multihop U2N relay discovery response, which includes the number of hops. The number of hops indicates the number of PC5 hops required for the 5G ProSe multihop remote UE to reach the network. The UE creates and stores a discovery entry which includes the received number of hops.

Description

Technical Field

[0001] This embodiment relates to a UE (User Equipment).

Background Art

[0002] In 3GPP (3rd Generation Partnership Project), the system architecture of 5GS (5G System), which is a fifth-generation (5G) mobile communication system, is being studied, and discussions are being held to support new procedures and new functions (see Non-Patent Documents 1 to 4). Currently, as one of the studies towards the specification of Release 19, discussions regarding the expansion of the ProSe (Proximity based Services) function are being held (see Non-Patent Document 5).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0004] Currently, 5GS specifies proximity wireless communication between UEs (Underground Users) in ProSe (Proximity-services). Furthermore, it specifies that remote UEs can connect to the network via U2N (UE-to-network) relay UEs. In Release 19, a U2N intermediate UE is added, and multi-hop communication is being considered in which a remote UE supporting multi-hops can connect to the network via a U2N intermediate UE and a U2N relay UE that also supports multi-hops.

[0005] Here, a 5G ProSe public alarm notification relay procedure is defined in which a U2N relay UE sends an alarm message received from the network to a remote UE. Release 19 considers extending the procedure in multi-hop communication. Controlling the forwarding of alarm messages using the number of hops is being considered, but the behavior of the UE when the maximum number of hops is not available is not yet clear.

[0006] This embodiment was made in consideration of the circumstances described above. In this embodiment, the UE behavior of a U2N relay UE and / or U2N intermediate UE that supports multi-hop communication, in determining whether or not to send an alarm message, is clarified. [Means for solving the problem]

[0007] The User Equipment (UE) of this embodiment is a UE comprising a transmitting / receiving unit and a control unit, wherein the UE is a 5G ProSe intermediate U2N relay UE, the transmitting / receiving unit sends a registration request message to the network including information indicating support for a 5G ProSe intermediate U2N (UE-to-network) relay UE, the transmitting / receiving unit receives a PROSE PC5 discovery message for a multi-hop U2N relay discovery response from the 5G ProSe multi-hop U2N relay UE, the hop count indicating the number of PC5 hops required for the 5G ProSe multi-hop remote UE to reach the network, the control unit creates and stores a discovery entry including the received hop count, and the transmitting / receiving unit sends a PROSE PC5 discovery message for a multi-hop U2N relay discovery response to the 5G ProSe multi-hop remote UE, the hop count including the received hop count plus 1. [Effects of the Invention]

[0008] This embodiment clarifies the UE behavior of a U2N relay UE and / or U2N intermediate UE that supports multi-hop communication, in determining whether or not to send an alarm message. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram illustrating the general outline of the mobile communication system (EPS / 5GS). [Figure 2] This diagram illustrates the detailed configuration of the mobile communication system (EPS / 5GS). [Figure 3] This is a diagram illustrating the equipment configuration of the UE. [Figure 4] This diagram illustrates the configuration of the access network device (gNB) in 5GS. [Figure 5] This diagram illustrates the configuration of the core network equipment (AMF / SMF / UPF) in 5GS. [Figure 6]This is a diagram for explaining the registration procedure. [Figure 7] This is a diagram for explaining the discovery procedure of Model B. [Figure 8] This is a diagram for explaining the 5G ProSe direct link establishment procedure. [Figure 9] This is a diagram for explaining the 5G ProSe direct link release procedure. [Figure 10] This is a diagram for explaining the 5G ProSe public warning notification relay procedure.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the embodiments for carrying out this example will be described with reference to the drawings. In this embodiment, as an example, the embodiment of the mobile communication system when this example is applied will be described.

[0011] [1. Overview of the System] First, FIG. 1 is a diagram for explaining the outline of the mobile communication system 1 used in each embodiment, and FIG. 2 is a diagram for explaining the detailed configuration of the mobile communication system 1.

[0012] It is described in FIG. 1 that the mobile communication system 1 is composed of UE_A1(0), access network_A80, core network_A90, PDN (Packet Data Network)_A5, access network_B120, core network_B190, and DN (Data Network)_A6.

[0013] Hereinafter, these devices and functions may be described with symbols omitted, such as UE, access network_A, core network_A, PDN, access network_B, core network_B, DN, etc.

[0014] Also, FIG. 2 shows devices / functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, UDM150, N3IWF170, etc., and interfaces connecting these devices / functions to each other.

[0015] Hereinafter, these devices / functions may be described by omitting symbols such as UE, E-UTRAN, MME, SGW, PGW-U, PGW-C, PCRF, HSS, 5G AN, AMF, UPF, SMF, PCF, UDM, N3IWF, etc.

[0016] Note that the EPS (Evolved Packet System), which is a 4G system, is composed of an access network_A and a core network_A, and may further include a UE and / or a PDN. Also, the 5GS (5G System), which is a 5G system, is composed of a UE, an access network_B and a core network_B, and may further include a DN.

[0017] A UE is a device that can be connected to network services via 3GPP access (also referred to as 3GPP access network, 3GPP AN) and / or non-3GPP access (also referred to as non-3GPP access network, non-3GPP AN). The UE may be a terminal device capable of wireless communication such as a mobile phone or a smartphone, and may be a terminal device connectable to both EPS and 5GS. The UE may be equipped with a UICC (Universal Integrated Circuit Card) or an eUICC (Embedded UICC).

[0018] Furthermore, access network_A corresponds to E-UTRAN (Evolved Universal Terrestrial Radio Access Network) and / or a wireless LAN access network. E-UTRAN has one or more eNBs (evolved Node B)45. Note that in the following, eNB45 may be written simply as eNB. If there are multiple eNBs, each eNB is connected to the others, for example, by an X2 interface. Furthermore, the wireless LAN access network has one or more access points.

[0019] Furthermore, access network_B corresponds to the 5G access network (5G AN). The 5G AN consists of NG-RAN (NG Radio Access Network) and / or non-3GPP access networks. One or more gNBs (NR NodeBs)122 are located in the NG-RAN. Note that, below, gNB122 may be written with the symbol omitted, such as gNB. A gNB is a node that provides the NR (New Radio) user plane and control plane to the UE, and is a node that connects to the 5GCN via an NG interface (including the N2 interface or N3 interface). In other words, a gNB is a base station device newly designed for 5GS and has different functions from the base station device (eNB) used in the 4G system, EPS. Also, if there are multiple gNBs, each gNB is connected to the others, for example, by an Xn interface.

[0020] Furthermore, a non-3GPP access network may be an untrusted non-3GPP access network or a trusted non-3GPP access network. Here, an untrusted non-3GPP access network may be a non-3GPP access network that does not perform security management within the access network, such as a public Wi-Fi network. On the other hand, a trusted non-3GPP access network may be an access network defined by 3GPP and may be equipped with a TNAP (trusted non-3GPP access point) and a TNGF (trusted non-3GPP Gateway function).

[0021] Furthermore, in the following, E-UTRAN and NG-RAN may be referred to as 3GPP access. Similarly, wireless LAN access networks and non-3GPP AN may be referred to as non-3GPP access. Additionally, nodes located in access network_B may be collectively referred to as NG-RAN nodes.

[0022] Furthermore, in the following, access network_A and / or access network_B and / or the devices included in access network_A and / or the devices included in access network_B may be referred to as access networks or access network devices.

[0023] Furthermore, Core Network A corresponds to EPC (Evolved Packet Core). EPC is configured with, for example, MME (Mobility Management Entity), SGW (Serving Gateway), PGW (Packet Data Network Gateway)-U, PGW-C, PCRF (Policy and Charging Rules Function), HSS (Home Subscriber Server), etc.

[0024] Furthermore, Core Network B corresponds to 5GCN (5G Core Network). 5GCN includes, for example, AMF (Access and Mobility Management Function), UPF (User Plane Function), SMF (Session Management Function), PCF (Policy Control Function), and UDM (Unified Data Management). Here, 5GCN may also be expressed as 5GC.

[0025] Furthermore, in the following, Core Network A and / or Core Network B, the devices included in Core Network A and / or Core Network B may be referred to as the Core Network, Core Network devices, or devices within the Core Network.

[0026] The core network (Core Network A and / or Core Network B) may be an IP mobile communication network operated by a Mobile Network Operator (MNO) that connects the access network (Access Network A and / or Access Network B) to the PDN and / or DN; it may be a core network for a mobile network operator that operates and manages the mobile communication system 1; or it may be a core network for a virtual mobile communication operator or virtual mobile communication service provider such as an MVNO (Mobile Virtual Network Operator) or MVNE (Mobile Virtual Network Enabler).

[0027] Furthermore, although Figure 1 shows a case where the PDN and DN are the same, they may be different. The PDN may be a Data Network (DN) that provides communication services to the UE. The DN may be configured as a packet data service network, or it may be configured for each service. In addition, the PDN may include connected communication terminals. Therefore, connecting to the PDN may also mean connecting to communication terminals or server devices located in the PDN. Furthermore, sending and receiving user data with the PDN may also mean sending and receiving user data with communication terminals or server devices located in the PDN. Note that the PDN may be referred to as DN, and the DN may be referred to as PDN.

[0028] Furthermore, in the following, access network_A, core network_A, PDN, access network_B, core network_B, DN, and / or one or more devices included therein may be referred to as a network or network device. In other words, when a network and / or network device sends and receives messages and / or performs procedures, it means that access network_A, core network_A, PDN, access network_B, core network_B, DN, and / or one or more devices included therein send and receive messages and / or perform procedures.

[0029] Furthermore, the UE can connect to the access network. The UE can also connect to the core network via the access network. In addition, the UE can connect to the PDN or DN via the access network and the core network. That is, the UE can send and receive (communicate) user data with the PDN or DN. When sending and receiving user data, non-IP communication may be used in addition to IP (Internet Protocol) communication.

[0030] Here, IP communication refers to data communication using IP, where data is sent and received via IP packets. An IP packet consists of an IP header and a payload. The payload may include data sent and received by devices and functions included in EPS or devices and functions included in 5GS. Non-IP communication refers to data communication that does not use IP, where data is sent and received in a format different from the structure of an IP packet. For example, non-IP communication may be data communication realized by sending and receiving application data without an IP header, or it may be user data sent and received by the UE with other headers such as a MAC header or an Ethernet® frame header attached.

[0031] Furthermore, access network_A, core network_A, access network_B, core network_B, PDN_A, and DN_A may include devices not shown in Figure 2. For example, core network_A and / or core network_B may include an AUSF (Authentication Server Function) or an AAA (Authentication, authorization, and accounting) server (AAA-S).

[0032] Here, AUSF is a core network device equipped with authentication functions for 3GPP access and non-3GPP access. Specifically, it is a network function unit that receives authentication requests for 3GPP access and / or non-3GPP access from the UE and executes the authentication procedure.

[0033] Furthermore, the AAA server is a device equipped with authentication, authorization, and billing functions, which connects directly or indirectly to the AUSF via other network devices. The AAA server may be a network device within the core network. However, the AAA server may not be included in core network_A and / or core network_B, but may be included in PLMN. In other words, the AAA server may be a core network device or a device located outside the core network. For example, the AAA server may be a server device within PLMN managed by a third party.

[0034] Note that in Figure 2, for the sake of simplification, only one of each device / function is shown; however, multiple similar devices / functions may be configured in the mobile communication system 1. Specifically, the mobile communication system 1 may be configured with multiple devices / functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, and / or UDM150.

[0035] UPF_A235 connects to DN, SMF, other UPFs, and access networks. UPF_A235 may also perform roles such as anchoring to intra-RAT mobility or inter-RAT mobility, packet routing and forwarding, UL CL (Uplink Classifier) ​​functionality supporting routing of multiple traffic flows to a single DN, branching point functionality supporting multi-homed PDU sessions, QoS processing for user planes, verification of uplink traffic, buffering of downlink packets, and triggering of downlink data notifications. Furthermore, UPF_A235 may also act as a relay device for transferring user data, serving as a gateway between the DN and the core network_B190. In addition, UPF_A235 may also act as a gateway for IP communication and / or non-IP communication. Moreover, UPF_A235 may have the functionality to forward IP communication and the functionality to convert between non-IP and IP communication. Furthermore, the multiple gateways that are deployed may also be gateways that connect the core network_B190 to a single DN. Note that UPF_A235 may have connectivity to other NFs and may connect to each device via other NFs.

[0036] Furthermore, a different UPF, UPF_C239 (also referred to as branching point or uplink classifier), may exist as a device or NF between UPF_A235 and the access network. If UPF_C239 exists, the PDU session between the UE and DN will be established via the access network, UPF_C239, and UPF_A235.

[0037] Furthermore, UPF130 may be the same device as UPF_A235. Note that UPF130 and UPF_A235 may be written with the symbols omitted, like UPF.

[0038] [2. Configuration of each device] Next, the configuration of each device (UE, and / or access network device, and / or core network device) used in each embodiment will be described with reference to a diagram. Each device may be configured as physical hardware, as logical (virtual) hardware configured on general-purpose hardware, or as software. Furthermore, at least some (including all) of the functions of each device may be configured as physical hardware, logical hardware, or software.

[0039] Furthermore, each memory unit (memory unit_A340, memory unit_A440, memory unit_B540, memory unit_A640, memory unit_B740) within each device / function described below is composed of, for example, semiconductor memory, SSD (Solid State Drive), HDD (Hard Disk Drive), etc. In addition, each memory unit can store not only the information originally set at the time of shipment, but also various information transmitted and received with devices / functions other than its own device / function (for example, UE, and / or access network devices, and / or core network devices, and / or PDN, and / or DN). In addition, each memory unit can store identification information, control information, flags, parameters, etc. contained in control messages transmitted and received within the various communication procedures described later. Furthermore, each memory unit may store this information for each UE. In addition, when interworking between 5GS and EPS occurs, each memory unit can store control messages and user data transmitted and received with devices / functions contained within 5GS and / or EPS. In this case, not only data transmitted and received via the N26 interface can be stored, but also data transmitted and received without using the N26 interface.

[0040] [2.1. UE Equipment Configuration] First, an example of the UE (User Equipment) configuration will be explained using Figure 3. The UE consists of a control unit_A300, an antenna 310, a transceiver_A320, and a storage unit_A340. The control unit_A300, transceiver_A320, and storage unit_A340 are connected via a bus. The transceiver_A320 is connected to the antenna 310.

[0041] The control unit_A300 is a functional unit that controls the operation and functions of the entire UE. The control unit_A300 realizes various processes in the UE by reading and executing various programs stored in the memory unit_A340 as needed.

[0042] The transceiver unit A320 is a functional unit for wireless communication with base station equipment (eNB or gNB) within the access network via an antenna. In other words, the UE can use the transceiver unit A320 to send and receive user data and / or control information between the access network equipment and / or core network equipment and / or PDN and / or DN.

[0043] Referring to Figure 2, the UE can communicate with the base station equipment (eNB) in E-UTRAN via the LTE-Uu interface using the transceiver unit A320. The UE can also communicate with the base station equipment (gNB) in 5G AN using the transceiver unit A320. Furthermore, the UE can send and receive NAS (Non-Access-Stratum) messages with the AMF via the N1 interface using the transceiver unit A320. However, since the N1 interface is logical, actual communication between the UE and the AMF takes place via the 5G AN.

[0044] Memory unit A340 is a functional unit for storing programs, user data, control information, etc., necessary for each operation of the UE.

[0045] The UE in this embodiment may be a 5G ProSe-compatible UE.

[0046] [2.2. gNB System Configuration] Next, an example of the gNB's device configuration will be explained using Figure 4. The gNB consists of a control unit_B500, an antenna 510, a network connection unit_B520, a transceiver unit_B530, and a storage unit_B540. The control unit_B500, network connection unit_B520, transceiver unit_B530, and storage unit_B540 are connected via a bus. The transceiver unit_B530 is connected to the antenna 510.

[0047] The control unit B500 is a functional unit that controls the operation and functions of the entire gNB. The control unit B500 implements various processes in the gNB by reading and executing various programs stored in the memory unit B540 as needed.

[0048] The network connection unit B520 is a functional unit that allows the gNB to communicate with the AMF and / or UPF. In other words, the gNB can use the network connection unit B520 to send and receive user data and / or control information with the AMF and / or UPF.

[0049] The transceiver unit B530 is a functional unit for wireless communication with the UE via the antenna 510. In other words, the gNB can send and receive user data and / or control information to and from the UE using the transceiver unit B530.

[0050] Referring to Figure 2, the gNB within the 5G AN can communicate with the AMF via the N2 interface and with the UPF via the N3 interface by using the network connection unit B520. Furthermore, the gNB can communicate with the UE by using the transceiver unit B530.

[0051] Memory unit B540 is a functional unit for storing programs, user data, control information, etc., necessary for each operation of the gNB.

[0052] [2.3. AMF Equipment Configuration] Next, an example of the AMF's device configuration will be explained using Figure 5. The AMF consists of a control unit_B700, a network connection unit_B720, and a storage unit_B740. The control unit_B700, network connection unit_B720, and storage unit_B740 are connected via a bus. The AMF may be a node that handles the control plane.

[0053] The control unit B700 is a functional unit that controls the operation and functions of the entire AMF. The control unit B700 implements various processes in the AMF by reading and executing various programs stored in the memory unit B740 as needed.

[0054] The network connection unit_B720 is a functional unit that allows the AMF to connect to base station equipment (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF within the 5G AN. In other words, the AMF can use the network connection unit_B720 to send and receive user data and / or control information with base station equipment (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF within the 5G AN.

[0055] Referring to Figure 2, the AMF within 5GCN can communicate with the gNB via the N2 interface, the UDM via the N8 interface, the SMF via the N11 interface, and the PCF via the N15 interface, using the network connection unit _A620. Furthermore, the AMF can send and receive NAS messages with the UE via the N1 interface using the network connection unit _A620. However, since the N1 interface is logical, actual communication between the UE and the AMF takes place via the 5G AN. Additionally, if the AMF supports the N26 interface, it can communicate with the MME via the N26 interface using the network connection unit _A620.

[0056] Memory unit B740 is a functional unit for storing programs, user data, control information, etc., necessary for each operation of the AMF.

[0057] Furthermore, the AMF has functions such as exchanging control messages with the RAN using the N2 interface, exchanging NAS messages with the UE using the N1 interface, encrypting and protecting the integrity of NAS messages, registration management (RM) function, connection management (CM) function, reachability management function, mobility management function for UEs, etc., forwarding SM (Session Management) messages between the UE and the SMF, access authentication (Access Authentication, Access Authorization) function, security anchor function (SEA), security context management (SCM), support for the N2 interface to the N3IWF (Non-3GPP Interworking Function), support for sending and receiving NAS signals with the UE via the N3IWF, and authentication of UEs connected via the N3IWF.

[0058] Furthermore, registration management manages the RM state for each UE. The RM state may be synchronized between the UE and the AMF. There are two RM states: unregistered state (RM-DEREGISTERED state) and registered state (RM-REGISTERED state). In the RM-DEREGISTERED state, the UE is not registered with the network, so the UE context in the AMF does not have valid location or routing information for that UE, and therefore the AMF cannot reach the UE. In the RM-REGISTERED state, the UE is registered with the network, so the UE can receive services that require registration with the network. Note that the RM state may also be expressed as the 5GMM state. In this case, the RM-DEREGISTERED state may be expressed as the 5GMM-DEREGISTERED state, and the RM-REGISTERED state may be expressed as the 5GMM-REGISTERED state.

[0059] In other words, 5GMM-REGISTERED means that each device may have established a 5GMM context or a PDU session context. Furthermore, when each device is 5GMM-REGISTERED, UE_A10 may start sending and receiving user data and control messages, and may respond to paging. In addition, when each device is 5GMM-REGISTERED, UE_A10 may perform registration procedures other than the registration procedure for initial registration, and / or service request procedures.

[0060] Furthermore, 5GMM-DEREGISTERED may occur even if each device has not established a 5GMM context, or if the location information of UE_A10 is not known to the network, or if the network is unreachable to UE_A10. If each device is in a 5GMM-DEREGISTERED state, UE_A10 may initiate the registration procedure, or establish a 5GMM context by executing the registration procedure.

[0061] Furthermore, connection management manages the CM state for each UE. The CM state may be synchronized between the UE and the AMF. There are two CM states: disconnected state (CM-IDLE state) and connected state (CM-CONNECTED state). In the CM-IDLE state, the UE is in the RM-REGISTERED state but does not have a NAS signaling connection established with the AMF via the N1 interface. Also, in the CM-IDLE state, the UE does not have an N2 connection or an N3 connection. On the other hand, in the CM-CONNECTED state, the UE has a NAS signaling connection established with the AMF via the N1 interface. Also, in the CM-CONNECTED state, the UE may have an N2 connection and / or an N3 connection.

[0062] Furthermore, connection management may be handled separately for CM states in 3GPP access and CM states in non-3GPP access. In this case, the CM states in 3GPP access may include an unconnected state (CM-IDLE state over 3GPP access) and a connected state (CM-CONNECTED state over 3GPP access). Furthermore, the CM states in non-3GPP access may include an unconnected state (CM-IDLE state over non-3GPP access) and a connected state (CM-CONNECTED state over non-3GPP access). Note that the unconnected state may be expressed as idle mode, and the connected state may be expressed as connected mode.

[0063] Furthermore, the CM state may be expressed as 5GMM mode. In this case, the disconnected state may be expressed as 5GMM-IDLE mode, and the connected state may be expressed as 5GMM-CONNECTED mode. Additionally, the disconnected state in 3GPP access may be expressed as 5GMM-IDLE mode over 3GPP access, and the connected state in 3GPP access may be expressed as 5GMM-CONNECTED mode over 3GPP access. Furthermore, the disconnected state in non-3GPP access may be expressed as 5GMM-IDLE mode over non-3GPP access, and the connected state in non-3GPP access may be expressed as 5GMM-CONNECTED mode over non-3GPP access. Note that 5GMM-IDLE mode may also be expressed as idle mode, and 5GMM-CONNECTED mode may also be expressed as connected mode.

[0064] Furthermore, one or more AMFs may be placed within core network_B. Also, an AMF may be a Network Function (NF) that manages one or more Network Slice Instances (NSIs). Additionally, an AMF may be a Common Control Plane Network Function (CCNF) shared among multiple NSIs.

[0065] Furthermore, N3IWF is a device and / or function placed between the non-3GPP access and 5GCN when the UE connects to 5GS via non-3GPP access.

[0066] [2.4. SMF Equipment Configuration] Next, an example of the SMF device configuration will be explained using Figure 5. The SMF consists of a control unit_B700, a network connection unit_B720, and a storage unit_B740. The control unit_B700, network connection unit_B720, and storage unit_B740 are connected via a bus. The SMF may be a node that handles the control plane.

[0067] The control unit B700 is a functional unit that controls the operation and functions of the entire SMF. The control unit B700 implements various processes in the SMF by reading and executing various programs stored in the memory unit B740 as needed.

[0068] The network connection unit B720 is a functional unit for the SMF to connect with the AMF, and / or UPF, and / or PCF, and / or UDM. In other words, the SMF can use the network connection unit B720 to send and receive user data and / or control information with the AMF, and / or UPF, and / or PCF, and / or UDM.

[0069] Referring to Figure 2, the SMF within 5GCN can communicate with the AMF via the N11 interface, the UPF via the N4 interface, the PCF via the N7 interface, and the UDM via the N10 interface by using the network connection unit A620.

[0070] Memory unit B740 is a functional unit for storing programs, user data, control information, etc., necessary for each operation of the SMF.

[0071] SMF has functions such as session management (Session Management) including establishing, modifying, and releasing PDU sessions; IP address allocation and management for UEs; UPF selection and control; UPF configuration for routing traffic to appropriate destinations; sending and receiving the SM portion of NAS messages; Downlink Data Notification; providing AN-specific (AN-specific) SM information transmitted to ANs via the N2 interface through AMF; determining the SSC mode (Session and Service Continuity mode) for sessions; and roaming functionality.

[0072] [2.5. UPF Equipment Configuration] Next, an example of the UPF's configuration will be explained using Figure 5. The UPF consists of a control unit_B700, a network connection unit_B720, and a storage unit_B740. The control unit_B700, network connection unit_B720, and storage unit_B740 are connected via a bus. The UPF may be a node that handles the control plane.

[0073] The control unit B700 is a functional unit that controls the operation and functions of the entire UPF. The control unit B700 implements various processes in the UPF by reading and executing various programs stored in the memory unit B740 as needed.

[0074] The network connection unit B720 is a functional unit that allows the UPF to connect with base station equipment (gNB), and / or SMF, and / or DN within the 5G AN. In other words, the UPF can use the network connection unit B720 to send and receive user data and / or control information with base station equipment (gNB), and / or SMF, and / or DN within the 5G AN.

[0075] Referring to Figure 2, the UPF within 5GCN can communicate with the gNB via the N3 interface, the SMF via the N4 interface, the DN via the N6 interface, and other UPFs via the N9 interface by using the network connection unit A620.

[0076] Memory unit B740 is a functional unit for storing programs, user data, control information, etc., necessary for each operation of the UPF.

[0077] UPF has functions such as acting as an anchor point for intra-RAT mobility or inter-RAT mobility, acting as an external PDU session point for interconnecting to DNs (i.e., acting as a gateway between DNs and core network B to forward user data), routing and forwarding packets, an UL CL (Uplink Classifier) ​​function that supports routing multiple traffic flows to a single DN, a branching point function that supports multi-homed PDU sessions, a QoS (Quality of Service) processing function for the user plane, an uplink traffic verification function, downlink packet buffering, and a function to trigger downlink data notification.

[0078] Furthermore, the UPF may also be a gateway for IP communication and / or non-IP communication. The UPF may also have the function of forwarding IP communication, and may also have the function of converting non-IP communication to IP communication. In addition, multiple gateways may be gateways connecting the core network B to a single DN. The UPF may also have connectivity to other NFs, and may connect to each device via other NFs.

[0079] Furthermore, the user plane refers to user data transmitted and received between the UE and the network. The user plane may be transmitted and received using a PDN connection or a PDU session. In addition, in the case of EPS, the user plane may be transmitted and received using the LTE-Uu interface and / or the S1-U interface and / or the S5 interface and / or the S8 interface and / or the SGi interface. Furthermore, in the case of 5GS, the user plane may be transmitted and received via the interface between the UE and the NG RAN and / or the N3 interface and / or the N9 interface and / or the N6 interface. Hereinafter, the user plane may be referred to as U-Plane.

[0080] Furthermore, the control plane refers to the control messages transmitted and received for communication control of the UE, etc. The control plane may be transmitted and received using the NAS (Non-Access-Stratum) signaling connection between the UE and the MME. In addition, in the case of EPS, the control plane may be transmitted and received using the LTE-Uu interface and the S1-MME interface. In addition, in the case of 5GS, the control plane may be transmitted and received using the interface between the UE and the NG RAN and the N2 interface. Hereinafter, the control plane may be referred to as the control plane or the C-Plane.

[0081] Furthermore, the U-Plane (User Plane; UP) may also be a communication channel for sending and receiving user data, and may consist of multiple bearers. Furthermore, the C-Plane (Control Plane; CP) may also be a communication channel for sending and receiving control messages, and may consist of multiple bearers.

[0082] [2.6. Description of other devices and / or functions] Next, we will describe the other devices and / or functions.

[0083] The term "network" refers to at least a portion of Access Network B, Core Network B, and DN. Furthermore, one or more devices included in at least a portion of Access Network B, Core Network B, and DN may be referred to as a network or network device.

[0084] In other words, when a network sends, receives, and / or processes messages, it may mean that devices within the network (network devices and / or control devices) send, receive, and / or process messages. Conversely, when devices within a network send, receive, and / or process messages, it may mean that the network sends, receives, and / or processes messages.

[0085] The term "network" may refer to either a PLMN (Public Land Mobile Network) or an NPN (Non-Public Network). Furthermore, "network" may also be abbreviated as "NW".

[0086] A PLMN (Public Land Mobile Network) is a communication network that provides mobile radio communication services. A PLMN is a network managed by a telecommunications operator, and the operator can be identified by the PLMN ID. A PLMN that matches the MCC (Mobile Country Code) and MNC (Mobile Network Code) of the UE's (Universal User Information System) (IMSI) may be a Home PLMN (HPLMN). Furthermore, the UE may maintain an Equivalent PLMN list in the USIM to identify one or more EPLMNs (Equivalent PLMNs). A PLMN different from the HPLMN and / or EPLMN may be a Visited PLMN (VPLMN). A PLMN that has been successfully registered by the UE may be a Registered PLMN (RPLMN).

[0087] A registration area is a set of one or more TAs assigned by the AMF to a UE. UE_A10 may move within one or more TAs included in the registration area without sending or receiving signals for tracking area updates. In other words, a registration area may be a set of information indicating an area that UE_A10 can move within without performing the tracking area update procedure. A registration area may be identified by a TAI list consisting of one or more TAIs.

[0088] A Tracking Area (TA) is one or more ranges managed by the core network that can be represented by the location information of UE_A10. A Tracking Area may consist of multiple cells. Furthermore, a Tracking Area may be the range where control messages such as paging are broadcast, or the range where UE_A10 can move without handover procedures. In addition, a Tracking Area (also called a TA) may be a routing area, a location area, or something similar. A Tracking Area may be identified by a Tracking Area Identity (TAI), which consists of a Tracking Area Code (TAC) and a Tracking Area Name Code (PLMN).

[0089] TAI (Tracking Area Identity) may be information that identifies a TA. TAI may consist of MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code).

[0090] A TA list is a list containing one or more TAs that the network has assigned to UE_A10. UE_A10 may move within one or more TAs included in the TA list without performing a tracking area update procedure. In other words, the TA list may be a set of information indicating the areas that UE_A10 can move within without performing a tracking area update procedure. Furthermore, the TA list may also be expressed as a TAI list, which consists of one or more TAIs (Tracking area identities), and hereafter, the term TAI list may refer to the TA list.

[0091] An SM (Session Management) message may be a NAS message used in procedures for SM. An SM message may also be called a NAS (Non-Access-Stratum) SM message. An SM message may be a control message sent and received between UE_A10 and SMF_A230 via AMF_A240.

[0092] An MM (Mobility Management) message may be a NAS message used for MM procedures. An MM message may be a control message sent and received between UE_A10 and AMF_A240. Furthermore, an MM message may also be referred to as a NAS MM message.

[0093] A 5GS (5G System) service may be a connectivity service provided using the core network B190.

[0094] A non-5GS service may be any service other than a 5GS service.

[0095] A PDU (Protocol Data Unit) session can be defined as the relationship between a DN (Digital Network) and an UE (User Environment) that provides PDU connectivity services, but it may also be connectivity established between the UE and an external gateway. In 5GS, the UE can send and receive user data to and from the DN using the PDU session by establishing a PDU session via access network_B and core network_B. Here, this external gateway may be UPF, SCEF, etc. The UE can use the PDU session to send and receive user data with devices such as application servers located on the DN. Each device (UE, and / or access network device, and / or core network device) may manage one or more pieces of identification information associated with the PDU session. These pieces of identification information may include one or more of the following: DNN, QoS rule, PDU session type, application identification information, NSI identification information, access network identification information, and SSC mode, or other information may be included. Furthermore, when multiple PDU sessions are established, the pieces of identification information associated with each PDU session may be the same or different.

[0096] A DNN (Data Network Name) may be identification information that identifies the core network and / or external networks such as DNs. Furthermore, the DNN can also be used as information to select gateways such as PGW / UPFs that connect to the core network B190.

[0097] PC5 is a reference point. PC5 may be a reference point between ProSe-enabled UEs. PC5 may be a reference point for 5G ProSe Direct Discovery, 5G ProSe Direct Communication, 5G ProSe U2N Relay, and / or 5G ProSe UE-to-UE Relay.

[0098] A PC5 path may be a communication channel on PC5. A PC5 path may also be a communication channel between ProSe-compatible UEs. Furthermore, a PC5 path may simply refer to PC5 itself. A PC5 path may also be referred to as a PC5 interface.

[0099] A PC5 link may be a PC5 path. A PC5 link may also be called a PC5 direct link, a 5G ProSe direct link, or a direct link. A PC5 link may simply be called a link. A PC5 link may also be a link in which a first UE connects to a third UE via zero or more second UEs.

[0100] Uu may be a wireless interface. Furthermore, Uu may be a wireless interface between a 5G AN and an UE.

[0101] A Uu path may be a communication channel on Uu. A Uu path may also be a communication channel between a 5G AN and a UE. Furthermore, a Uu path may be Uu itself. A Uu path may also be referred to as a Uu interface. A Uu path may also be referred to as a Uu link.

[0102] 5G ProSe (Proximity-based Services) may be services provided by 5GS based on mutually close UEs (Unified Entity). Furthermore, 5G ProSe may also be referred to simply as ProSe.

[0103] A 5G ProSe-enabled UE is a UE that supports 5G ProSe requirements and related procedures. A 5G ProSe-enabled UE may also be referred to as a ProSe-enabled UE.

[0104] A remote UE may be a ProSe-enabled UE that communicates with the DN via a U2N relay UE.

[0105] The remote UE may be a 5G ProSe remote UE, a 5G ProSe layer-2 remote UE, or a 5G ProSe layer-3 remote UE. Furthermore, the 5G ProSe layer-2 remote UE may be a 5G ProSe-compatible UE that communicates with the DN via a 5G ProSe layer-2 UE-to-network relay UE. Similarly, the 5G ProSe layer-3 remote UE may be a 5G ProSe-compatible UE that communicates with the DN via a 5G ProSe layer-3 UE-to-network relay UE.

[0106] A remote UE may also be referred to as a UE that operates as a remote UE.

[0107] Furthermore, the 5G ProSe layer-2 remote UE is a 5G ProSe-compatible UE that communicates with the DN via the 5G ProSe layer-2 U2N relay UE. The 5G ProSe layer-2 remote UE may also be referred to as a layer-2 remote UE.

[0108] Furthermore, a 5G ProSe layer-3 remote UE is a 5G ProSe-compatible UE that communicates with the DN via a 5G ProSe layer-3 UE-to-network relay UE. A 5G ProSe layer-3 remote UE can also be referred to as a layer-3 remote UE.

[0109] A remote UE may be any UE that has been approved to operate as a remote UE.

[0110] A U2N (UE-to-network) relay UE may be a ProSe-enabled UE that provides functionality to support the network connectivity of a remote UE.

[0111] The U2N relay UE may be a 5G ProSe U2N relay UE, a 5G ProSe layer-2 U2N relay UE, or a 5G ProSe layer-3 U2N relay UE. Furthermore, the 5G ProSe layer-2 U2N relay UE may be a 5G ProSe-compatible UE that provides functionality to support network connectivity for a 5G ProSe layer-2 remote UE via a Layer 2 protocol. Additionally, the 5G ProSe layer-3 U2N relay UE may be a 5G ProSe-compatible UE that provides functionality to support network connectivity for a 5G ProSe layer-3 remote UE via a Layer 3 protocol.

[0112] A U2N relay UE may also be referred to as a UE that operates as a U2N relay UE. Furthermore, a U2N relay UE may also be referred to as a target relay UE. Finally, a U2N relay UE may also be referred to as a U2N relay.

[0113] Furthermore, the 5G ProSe layer-2 U2N relay UE is a 5G ProSe-enabled UE that provides functionality to support network connectivity for the 5G ProSe layer-2 remote UE via the layer-2 protocol.

[0114] Furthermore, the 5G ProSe layer-3 U2N relay UE is a 5G ProSe-enabled UE that provides the functionality to support network connectivity for the 5G ProSe layer-3 remote UE via the layer-3 protocol.

[0115] Furthermore, the communication method in which a remote UE connects to the network via a U2N relay UE may be referred to as 5G ProSe UE-to-network relaying. 5G ProSe UE-to-network relaying may also be simply referred to as relaying, 5G ProSe UE-to-network relay, relay, or U2N relay.

[0116] A U2N relay UE may be any UE that has been approved to operate as a U2N relay UE.

[0117] A remote UE that supports multi-hop communication may be a ProSe-enabled UE that communicates with the DN via a U2N intermediate UE and a multi-hop U2N relay UE.

[0118] A remote UE that supports multi-hop may be a 5G ProSe remote UE supporting 5G ProSe multi-hop U2N Relay, or a 5G ProSe remote UE supporting 5G ProSe Layer-3 multi-hop U2N Relay.

[0119] Furthermore, the 5G ProSe remote UE supporting 5G ProSe Layer-3 multi-hop U2N Relay may be a 5G ProSe-compatible UE that communicates with the DN via a 5G ProSe Layer-3 U2N intermediate UE and / or a 5G ProSe U2N relay UE supporting 5G ProSe Layer-3 multi-hop U2N Relay. Furthermore, the 5G ProSe remote UE supporting 5G ProSe Layer-3 multi-hop U2N Relay may also be referred to as a multi-hop layer-3 remote UE.

[0120] A remote UE that supports multi-hop may also be referred to as a UE that operates as a multi-hop supporting remote UE. Furthermore, a remote UE that supports multi-hop may also be referred to as a multi-hop remote UE. Additionally, a multi-hop remote UE may be referred to as a 5G ProSe multi-hop remote UE.

[0121] A multi-hop remote UE may be any remote UE that supports multi-hop.

[0122] A multi-hop remote UE may be any UE that is authorized to operate as a multi-hop remote UE.

[0123] A multi-hop remote UE may also be referred to as a 5G ProSe multi-hop remote UE, a 5G ProSe multi-hop layer-2 remote UE, or a 5G ProSe multi-hop layer-3 remote UE.

[0124] A 5G ProSe multi-hop layer-2 remote UE may be a ProSe-enabled UE that communicates with a DN via zero or more 5G ProSe layer-2 intermediate UE-to-Network relay UEs and 5G ProSe multi-hop layer-2 UE-to-Network relay UEs.

[0125] A 5G ProSe multi-hop layer-3 remote UE may be a ProSe-enabled UE that communicates with a DN via zero or more 5G ProSe layer-3 intermediate UE-to-Network relay UEs and 5G ProSe multi-hop layer-3 UE-to-Network relay UEs.

[0126] A U2N (UE-to-network) relay UE that supports multi-hop can be a ProSe-enabled UE that provides functionality to support network connectivity for multi-hop remote UEs.

[0127] A U2N relay UE that supports multi-hop may be a 5G ProSe U2N relay UE supporting 5G ProSe multi-hop U2N Relay, or a 5G ProSe U2N relay UE supporting 5G ProSe Layer-3 multi-hop U2N Relay.

[0128] Furthermore, the 5G ProSe U2N relay UE supporting 5G ProSe Layer-3 multi-hop U2N Relay may be a 5G ProSe-enabled UE that provides the functionality to support network connectivity for the 5G ProSe remote UE supporting 5G ProSe Layer-3 multi-hop U2N Relay via the Layer 3 protocol. Furthermore, the 5G ProSe U2N relay UE supporting 5G ProSe Layer-3 multi-hop U2N Relay may also be referred to as a multi-hop layer-3 U2N relay UE.

[0129] A U2N relay UE that supports multi-hop may also be referred to as a UE that operates as a U2N relay UE that supports multi-hop. Furthermore, a U2N relay UE that supports multi-hop may also be referred to as a multi-hop U2N relay UE. Furthermore, a multi-hop U2N relay UE may also be referred to as a multi-hop U2N relay. Finally, a multi-hop U2N relay UE may also be referred to as a 5G ProSe multi-hop U2N relay UE.

[0130] A multi-hop U2N relay UE may be a U2N relay UE that supports multi-hop.

[0131] A multi-hop U2N relay UE may be any UE that is authorized to operate as a multi-hop U2N relay UE.

[0132] The multi-hop U2N relay UE may also be referred to as the 5G ProSe multi-hop UE-to-network relay UE, the 5G ProSe multi-hop layer-2 UE-to-network relay UE, or the 5G ProSe multi-hop layer-3 UE-to-network relay UE.

[0133] A 5G ProSe multi-hop UE-to-Network relay UE may be a 5G ProSe UE-to-network relay UE that supports 5G ProSe multi-hop UE-to-network relay.

[0134] A 5G ProSe multi-hop layer-2 UE-to-network relay UE may be a 5G ProSe layer-2 UE-to-network relay UE that supports 5G ProSe multi-hop layer-2 UE-to-network relay.

[0135] A 5G ProSe multi-hop layer-3 UE-to-network relay UE may be a 5G ProSe layer-3 UE-to-network relay UE that supports 5G ProSe multi-hop layer-3 UE-to-network relay.

[0136] A U2N (UE-to-network) intermediate UE may be a ProSe-enabled UE that provides functionality to support connectivity between a multi-hop remote UE and a multi-hop U2N relay UE.

[0137] The U2N intermediate UE may be a 5G ProSe U2N intermediate UE or a 5G ProSe layer-3 U2N intermediate UE. Furthermore, the 5G ProSe layer-3 U2N intermediate UE may be a 5G ProSe-enabled UE that provides functionality to support network connectivity for a 5G ProSe remote UE supporting a 5G ProSe Layer-3 multi-hop U2N Relay via a Layer 3 protocol and / or a 5G ProSe U2N relay UE supporting a 5G ProSe Layer-3 multi-hop U2N Relay. The 5G ProSe layer-3 U2N intermediate UE may also be referred to as a layer-3 U2N intermediate UE.

[0138] A U2N intermediate UE may also be referred to as a UE that operates as a U2N intermediate UE. A U2N intermediate UE may also be referred to as an intermediate U2N UE.

[0139] Furthermore, there may be one or more U2N intermediate UEs. For example, between a multi-hop remote UE and a multi-hop U2N relay UE, there may be a first U2N intermediate UE and a second U2N intermediate UE, from left to right.

[0140] Furthermore, the U2N intermediate UE may also be referred to as Relay participated in multi-hop U2N relaying, or as 5G ProSe Intermediate Relay. Additionally, the U2N intermediate UE may be referred to as multi-hop U2N relay UE, or as 5G ProSe multi-hop U2N relay UE. The U2N intermediate UE may also be referred to as 5G ProSe layer-3 multi-hop U2N relay UE.

[0141] Furthermore, the U2N intermediate UE may also be referred to as the 5G ProSe Intermediate U2N Relay UE or the 5G ProSe Intermediate U2N Relay.

[0142] A U2N intermediate UE may be any UE that has been authorized to operate as a U2N intermediate UE.

[0143] The U2N intermediate UE may also be referred to as the 5G ProSe intermediate UE-to-network relay UE, the 5G ProSe layer-2 intermediate UE-to-network relay UE, or the 5G ProSe layer-3 intermediate UE-to-network relay UE.

[0144] A 5G ProSe intermediate UE-to-network relay UE may be a ProSe-enabled UE that provides the functionality to support network connectivity for multi-hop remote UEs by using other ProSe-enabled UEs and a PC5 reference point. The 5G ProSe intermediate UE-to-network relay UE may be located on the path between the multi-hop remote UE and the multi-hop U2N relay UE.

[0145] A 5G ProSe layer-2 intermediate UE-to-network relay UE may be a ProSe-enabled UE that provides the ability to support connection to a network of 5G ProSe multi-hop layer-2 remote UEs using a PC5 reference point with other ProSe-enabled UEs via the layer-2 protocol.

[0146] A 5G ProSe layer-3 intermediate UE-to-network relay UE may be a ProSe-enabled UE that provides the ability to support connection to a network of 5G ProSe multi-hop layer-3 remote UEs using other ProSe-enabled UEs and PC5 reference points via the layer-3 protocol.

[0147] Multi-hop communication may refer to communication via two or more UEs. Furthermore, multi-hop communication may refer to a UE communicating with another UE or network via two or more other UEs.

[0148] For example, when a multi-hop remote UE connects to a network via one or more U2N intermediate UEs and a multi-hop U2N relay UE, this can be referred to as multi-hop communication. In this case, the multi-hop remote UE and / or U2N intermediate UE and / or multi-hop U2N relay UE may support multi-hop.

[0149] Multi-hop communication may simply be referred to as multi-hop. Furthermore, a UE that supports multi-hop may be a multi-hop UE. Also, a UE that supports multi-hop may be a UE that supports operating as a multi-hop UE.

[0150] Multi-hop communication may be UE-to-network relay multi-hop communication.

[0151] The multi-hop relay may be a 5G ProSe multi-hop U2N relay, a 5G ProSe multi-hop layer-2 U2N relay, or a 5G ProSe multi-hop layer-3 U2N relay.

[0152] Supporting multi-hop relays may mean supporting 5G ProSe multi-hop U2N relays, supporting 5G ProSe multi-hop layer-2 U2N relays, or supporting 5G ProSe multi-hop layer-3 U2N relays.

[0153] ProSeP is a 5G ProSe policy. ProSeP may be a UE policy for ProSe. ProSeP may be a UE policy for ProSe services.

[0154] A discovery entry may be information created by a U2N intermediate UE. A discovery entry may be stored by the U2N intermediate UE. A discovery entry may include RSC (Relay Service Code), Root Relay Info, Announcer Info, Hop Count, Accumulated QoS for PC5 link, NCGI, and / or RRC Container, or it may include other information.

[0155] If a U2N intermediate UE does not have a discovery entry, it may create one and store information within that entry.

[0156] [2.7. Description of Identification Information in This Embodiment] Next, the identification information transmitted, received, and / or stored and / or managed by each device in this embodiment will be described.

[0157] The first identifier may be information indicating whether or not the UE supports operating as a remote UE. The first identifier may be information indicating that the UE supports operating as a remote UE. The first identifier may be information indicating that the UE does not support operating as a remote UE.

[0158] The first identification information may indicate whether or not the UE supports operating as a layer-2 remote UE. The first identification information may indicate that the UE supports operating as a layer-2 remote UE. The first identification information may indicate that the UE does not support operating as a layer-2 remote UE.

[0159] The first identification information may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network remote UE supported". The first identification information may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network remote UE not supported".

[0160] A first identifier indicating that a UE supports operating as a layer-2 remote UE may be "Acting as a 5G ProSe layer-2 UE-to-network remote UE supported". A first identifier indicating that a UE does not support operating as a layer-2 remote UE may be "Acting as a 5G ProSe layer-2 UE-to-network remote UE not supported".

[0161] The first identification information may indicate whether or not the UE supports operating as a layer-3 remote UE. The first identification information may indicate that the UE supports operating as a layer-3 remote UE. The first identification information may indicate that the UE does not support operating as a layer-3 remote UE.

[0162] The first identification information may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network remote UE supported". The first identification information may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network remote UE not supported".

[0163] The first identification information indicating that a UE supports operating as a layer-3 remote UE may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network remote UE supported". The first identification information indicating that a UE does not support operating as a layer-3 remote UE may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network remote UE not supported".

[0164] The first identification information may be information contained in the 5GMM capability IE (Information Element). The first identification information may be UE capability information.

[0165] The second identification information may indicate whether the UE supports operating as a U2N relay UE. The second identification information may indicate that the UE supports operating as a U2N relay UE. The second identification information may indicate that the UE does not support operating as a U2N relay UE.

[0166] The second identification information may indicate whether the UE supports operating as a layer-2 U2N relay UE. The second identification information may indicate that the UE supports operating as a layer-2 U2N relay UE. The second identification information may indicate that the UE does not support operating as a layer-2 U2N relay UE.

[0167] The second identification information may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network relay UE supported". The second identification information may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network relay UE not supported".

[0168] A second identification statement indicating that a UE supports operating as a layer-2 U2N relay UE may be the statement "Acting as a 5G ProSe layer-2 UE-to-network relay UE supported". A second identification statement indicating that a UE does not support operating as a layer-2 U2N relay UE may be the statement "Acting as a 5G ProSe layer-2 UE-to-network relay UE not supported".

[0169] The second identification information may indicate whether the UE supports operating as a layer-3 U2N relay UE. The second identification information may indicate that the UE supports operating as a layer-3 U2N relay UE. The second identification information may indicate that the UE does not support operating as a layer-3 U2N relay UE.

[0170] The second identification information may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network relay UE supported". The second identification information may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network relay UE not supported".

[0171] A second identification statement indicating that a UE supports operating as a layer-3 U2N relay UE may be the statement "Acting as a 5G ProSe layer-3 UE-to-network relay UE supported". A second identification statement indicating that a UE does not support operating as a layer-3 U2N relay UE may be the statement "Acting as a 5G ProSe layer-3 UE-to-network relay UE not supported".

[0172] The second identification information may be information contained in the 5GMM capability IE (Information Element). The second identification information may be UE capability information.

[0173] The third identification information may indicate whether the UE supports operating as a multi-hop remote UE. The third identification information may indicate that the UE supports operating as a multi-hop remote UE. The third identification information may indicate that the UE does not support operating as a multi-hop remote UE.

[0174] The third identification information may indicate whether the UE supports operating as a multi-hop layer-3 remote UE. The third identification information may indicate that the UE supports operating as a multi-hop layer-3 remote UE. The third identification information may indicate that the UE does not support operating as a multi-hop layer-3 remote UE.

[0175] The third identification information may be information contained in the 5GMM capability IE (Information Element). The third identification information may be UE capability information.

[0176] The fourth identification information may indicate whether the UE supports operating as a multi-hop U2N relay UE. The fourth identification information may indicate that the UE supports operating as a multi-hop U2N relay UE. The fourth identification information may indicate that the UE does not support operating as a multi-hop U2N relay UE.

[0177] The fourth identification information may indicate whether the UE supports operating as a multi-hop layer-3 U2N relay UE. The fourth identification information may indicate that the UE supports operating as a multi-hop layer-3 U2N relay UE. The fourth identification information may indicate that the UE does not support operating as a multi-hop layer-3 U2N relay UE.

[0178] The fourth identification information may be information included in the 5GMM capability IE (Information Element). The fourth identification information may be UE capability information.

[0179] The fifth identification information may indicate whether the UE supports operating as a U2N intermediate UE. The fifth identification information may indicate that the UE supports operating as a U2N intermediate UE. The fifth identification information may indicate that the UE does not support operating as a U2N intermediate UE.

[0180] The fifth identification information may indicate whether the UE supports operating as a layer-3 U2N intermediate UE. The fifth identification information may indicate that the UE supports operating as a layer-3 U2N intermediate UE. The fifth identification information may indicate that the UE does not support operating as a layer-3 U2N intermediate UE.

[0181] The fifth identification information may be information included in the 5GMM capability IE (Information Element). The fifth identification information may be UE capability information.

[0182] The 21st identification information may be path information. The 21st identification information may be a list of User Info IDs of U2N intermediate UEs that indicate the transmission path of the message.

[0183] The 22nd identifier may be the hop count. The 22nd identifier may be information indicating the hop count. The 22nd identifier may indicate the number of hops the message has already been relayed through. The 22nd identifier may increase by 1 for each hop. The 22nd identifier may be set to 1 by the multi-hop remote UE.

[0184] The 23rd identifier may be a Hop Limit. The 23rd identifier may be information indicating a hop limit. The 23rd identifier may be an unchangeable value indicating the hop limit of a message. The 23rd identifier may be a value smaller than the maximum number of hops (pre-configured) for the multi-hop remote UE.

[0185] The 31st identification information may be path information. The 31st identification information may be a list of User Info IDs of U2N intermediate UEs on the path selected by the multi-hop U2N relay UE. The 31st identification information may be the 21st identification information selected by the multi-hop U2N relay UE. The 31st identification information may be the same as the 21st identification information.

[0186] The 31st identification information may be a list of User Info IDs of multi-hop remote UEs and User Info IDs of U2N intermediate UEs on the path selected by the multi-hop U2N relay UE. The 31st identification information may be the 21st identification information with the User Info ID of the multi-hop remote UE added. Here, the 21st identification information may be the one selected by the multi-hop U2N relay UE.

[0187] The 32nd identification information may be the hop count. The 32nd identification information may be information indicating the hop count. The 32nd identification information may indicate the number of hops between a multi-hop remote UE and a multi-hop U2N relay UE. The 32nd identification information may be the number of hops between a multi-hop remote UE and a multi-hop U2N relay UE on the path selected by the multi-hop U2N relay UE. The 32nd identification information may be the same as the 22nd identification information.

[0188] The 33rd identifier may be the hop count. The 33rd identifier may be information indicating the hop count. The 33rd identifier may be a value that reflects the number of PC5 hops it takes for a multi-hop remote UE to reach the network. The 33rd identifier may be set to 1 by a multi-hop U2N relay UE. The 33rd identifier may be incremented by 1 each time a U2N intermediate UE sends a discovery response message.

[0189] The 41st identifier may be the hop count. The 41st identifier may be information indicating the hop count. The 41st identifier may be set to 1 by a multi-hop U2N relay UE. The 41st identifier may be set to 2 by a U2N intermediate UE. The 41st identifier may be incremented by 1 each time the UE transmits a public alert notification message. In other words, based on the UE receiving a public alert notification message containing the 41st identifier, the UE may transmit and / or broadcast a public alert notification message containing the received 41st identifier plus 1 as the 41st identifier.

[0190] The 42nd identifier may be a Hop Limit. The 42nd identifier may be information indicating a hop limit. The 42nd identifier may be an unchangeable value indicating a hop limit for public alert notification messages. The 42nd identifier may be a value smaller than the maximum number of hops (pre-configured) for the U2N relay UE. The 42nd identifier may be the same as the 22nd identifier.

[0191] The 61st identifier is a reason value. The 61st identifier may be a reason value indicating that communication to the target UE is not permitted. The 61st identifier may be #1 "direct communication to the target UE not allowed". The 61st identifier may be a PC5 signalling protocol cause. The 61st identifier may be a reason value included in the PC5 signalling protocol cause IE (Information Element).

[0192] The 62nd identifier is a reason value. The 62nd identifier may be a reason value indicating a congestion state. The 62nd identifier may be #13 "congestion situation". The 62nd identifier may be a PC5 signalling protocol cause. The 62nd identifier may be a reason value included in the PC5 signalling protocol cause IE (Information Element).

[0193] The 63rd identifier is a reason value. The 63rd identifier may be a reason value indicating a failure of the 5G ProSe multi-hop UE-to-network relay UE. The 63rd identifier may be "Failure from 5G ProSe multi-hop UE-to-network relay UE". The 63rd identifier may be a PC5 signalling protocol cause. The 63rd identifier may be a reason value included in the PC5 signalling protocol cause IE (Information Element).

[0194] The 63rd identification information may be a reason value indicating that the multi-hop U2N relay UE is unavailable. The 63rd identification information may be a reason value indicating that the establishment of a link with the multi-hop U2N relay UE failed. The 63rd identification information may be a reason value indicating that the link with the multi-hop U2N relay UE has become unavailable.

[0195] [3. Description of the procedures used in each embodiment] Next, the procedures used in each embodiment will be described.

[0196] In each embodiment, the explanation will be based on the example where the HSS and UDM, PCF and PCRF, SMF and PGW-C, and UPF and PGW-U are configured as the same device (i.e., the same physical hardware, the same logical hardware, or the same software), as shown in Figure 2. However, the contents described in this embodiment are also applicable when these are configured as different devices (i.e., different physical hardware, different logical hardware, or different software). For example, data may be transmitted and received directly between them, or data may be transmitted and received via the N26 interface between the AMF and MME, or data may be transmitted and received via the UE.

[0197] [3.1. Registration Procedure] First, the registration procedure will be explained using Figure 6. This registration procedure is specific to 5GS. In this chapter, the registration procedure may be referred to simply as "this procedure."

[0198] This procedure is initiated by the UE to register with Access Network B and / or Core Network B and / or DN. The UE can execute this procedure at any time, for example, when powered on, if it is not already registered with the network. In other words, the UE can initiate this procedure at any time as long as it is in an unregistered state (RM-DEREGISTERED state).

[0199] Furthermore, the registration procedure initiated by an unregistered UE may be referred to as the "Registration procedure for initial registration."

[0200] Furthermore, each device (especially the UE and AMF) can transition to the registered state (RM-REGISTERED state) based on the completion of the registration procedure. Note that the registration status may be managed by each device for each access. Specifically, each device may independently manage the registration status for 3GPP access (registered or unregistered) and the registration status for non-3GPP access.

[0201] Furthermore, this procedure may be for updating the location registration information of the UE in the network, and / or for periodically notifying the network of the status of the UE, and / or for updating specific parameters relating to the UE in the network.

[0202] Furthermore, this procedure may be performed multiple times. In other words, after this procedure is completed, it may be started again.

[0203] The UE may initiate this procedure after performing network selection.

[0204] A UE may initiate this procedure when it moves across a Tracking Area (TA). In other words, a UE may initiate this procedure when it moves to a TA different from the one indicated in its TA list.

[0205] Furthermore, the UE may initiate this procedure periodically. Additionally, the UE may initiate this procedure based on the completion of the UE configuration update procedure.

[0206] Furthermore, UE may perform the registration procedure at any time, not limited to these.

[0207] Furthermore, even if a UE is already registered, it may initiate the registration process periodically.

[0208] Furthermore, the registration procedure performed based on the mobility of the UE and the registration procedure performed periodically may be referred to as the "Registration procedure for mobility and periodic registration update." In other words, the registration procedure for mobility and periodic registration update may be either a registration procedure performed based on the mobility of the UE or a registration procedure performed periodically.

[0209] Furthermore, the registration procedure for mobility and periodic registration renewal may be a registration procedure performed based on UE configuration updates. Furthermore, the registration procedure for mobility and periodic registration renewal may be a registration procedure performed to establish a communication channel for sending and receiving user data. Furthermore, the registration procedure for mobility and periodic registration renewal may be a registration procedure performed based on requests from the network.

[0210] Furthermore, registration procedures for mobility and periodic registration renewal may be registration procedures other than those for initial registration.

[0211] Next, we will explain each step of the registration procedure. Note that the registration procedure described below may be for initial registration or for mobility and periodic registration renewal.

[0212] First, the UE initiates the registration process by sending a Registration request message to the AMF (S800)(S802)(S804). Specifically, the UE sends an RRC message containing the Registration request message to the 5G AN (or gNB) (S800). The Registration request message is a NAS message. The RRC message may be a control message sent and received between the UE and the 5G AN (or gNB). The NAS message is processed at the NAS layer, and the RRC message is processed at the RRC layer. The NAS layer is a higher layer than the RRC layer.

[0213] Here, the UE may include the first, second, third, fourth, and / or fifth identification information in the registration request message and / or RRC message. More specifically, the UE may include the first, second, third, fourth, and / or fifth identification information in the registration request message and / or RRC message, or it may include it in a different control message, for example, a control message at a lower layer than the RRC layer (e.g., MAC layer, RLC layer, PDCP layer).

[0214] Furthermore, the UE may, by sending a registration request message, indicate to the network the content indicated by each piece of identification information, and may also indicate the UE's requests.

[0215] Furthermore, the UE may transmit each piece of identification information to the network, thereby indicating the content that each piece of identification information represents.

[0216] Specifically, if the UE supports operating as a remote UE, it may send a first identifier indicating that it supports operating as a remote UE. If the UE does not support operating as a remote UE, it may send a first identifier indicating that it does not support operating as a remote UE.

[0217] If the UE supports operating as a layer-2 remote UE, it may send a first identification indicating that it supports operating as a layer-2 remote UE. If the UE does not support operating as a layer-2 remote UE, it may send a first identification indicating that it does not support operating as a layer-2 remote UE.

[0218] If the UE supports operating as a layer-3 remote UE, it may send a first identification indicating that it supports operating as a layer-3 remote UE. If the UE does not support operating as a layer-3 remote UE, it may send a first identification indicating that it does not support operating as a layer-3 remote UE.

[0219] If the UE supports operating as a U2N relay UE, it may send a second identification indicating that it supports operating as a U2N relay UE. If the UE does not support operating as a U2N relay UE, it may send a second identification indicating that it does not support operating as a U2N relay UE.

[0220] If the UE supports operating as a layer-2 U2N relay UE, it may send a second identification indicating that it supports operating as a layer-2 U2N relay UE. If the UE does not support operating as a layer-2 U2N relay UE, it may send a second identification indicating that it does not support operating as a layer-2 U2N relay UE.

[0221] If the UE supports operating as a layer-3 U2N relay UE, it may send a second identification indicating that it supports operating as a layer-3 U2N relay UE. If the UE does not support operating as a layer-3 U2N relay UE, it may send a second identification indicating that it does not support operating as a layer-3 U2N relay UE.

[0222] If the UE supports operating as a multi-hop remote UE, it may send a third identifier indicating that it supports operating as a multi-hop remote UE. If the UE does not support operating as a multi-hop remote UE, it may send a third identifier indicating that it does not support operating as a multi-hop remote UE.

[0223] If the UE supports operating as a multi-hop layer-3 remote UE, it may send a third identification indicating that it supports operating as a multi-hop layer-3 remote UE. If the UE does not support operating as a multi-hop layer-3 remote UE, it may send a third identification indicating that it does not support operating as a multi-hop layer-3 remote UE.

[0224] If the UE supports operating as a multi-hop U2N relay UE, it may transmit a fourth identification code indicating that it supports operating as a multi-hop U2N relay UE. If the UE does not support operating as a multi-hop U2N relay UE, it may transmit a fourth identification code indicating that it does not support operating as a multi-hop U2N relay UE.

[0225] If the UE supports operating as a multi-hop layer-3 U2N relay UE, it may transmit a fourth identification code indicating that it supports operating as a multi-hop layer-3 U2N relay UE. If the UE does not support operating as a multi-hop layer-3 U2N relay UE, it may transmit a fourth identification code indicating that it does not support operating as a multi-hop layer-3 U2N relay UE.

[0226] If the UE supports operating as a U2N intermediate UE, it may send a fifth identifier indicating that it supports operating as a U2N intermediate UE. If the UE does not support operating as a U2N intermediate UE, it may send a fifth identifier indicating that it does not support operating as a U2N intermediate UE.

[0227] If the UE supports operating as a layer-3 U2N intermediate UE, it may send a fifth identifier indicating that it supports operating as a layer-3 U2N intermediate UE. If the UE does not support operating as a layer-3 U2N intermediate UE, it may send a fifth identifier indicating that it does not support operating as a layer-3 U2N intermediate UE.

[0228] Furthermore, the UE may decide whether or not to transmit each piece of identification information based on subscriber information, and / or network status, and / or user registration information, and / or context held by the UE.

[0229] When a 5G AN (or gNB) receives an RRC message containing a registration request message, it selects an AMF to forward the registration request message (S802). The 5G AN (or gNB) may select an AMF based on the information contained in the registration request message and / or the RRC message. The 5G AN (or gNB) extracts the registration request message from the received RRC message and forwards it to the selected AMF (S804).

[0230] Next, the AMF receives a registration request message from the UE via the 5G AN (gNB). The AMF may receive a registration request message containing the first, second, third, fourth, and / or fifth identification information. The AMF may receive a registration request message along with the first, second, third, fourth, and / or fifth identification information.

[0231] Furthermore, upon receiving a registration request message, the AMF may recognize the content indicated by each piece of identification information and may recognize the UE's request.

[0232] Furthermore, upon receiving each piece of identification information, the AMF may recognize the content indicated by each piece of identification information and may recognize the UE's request.

[0233] Specifically, AMF may recognize whether a UE supports operating as a remote UE if it receives the first identification information. AMF may recognize that a UE supports operating as a remote UE if it receives the first identification information indicating that it supports operating as a remote UE. AMF may recognize that a UE does not support operating as a remote UE if it receives the first identification information indicating that it does not support operating as a remote UE.

[0234] If AMF receives the first identification information, it may know whether the UE supports operating as a layer-2 remote UE. If AMF receives the first identification information indicating that the UE supports operating as a layer-2 remote UE, it may know that the UE supports operating as a layer-2 remote UE. If AMF receives the first identification information indicating that the UE does not support operating as a layer-2 remote UE, it may know that the UE does not support operating as a layer-2 remote UE.

[0235] If AMF receives the first identification information, it may know whether the UE supports operating as a layer-3 remote UE. If AMF receives the first identification information indicating that the UE supports operating as a layer-3 remote UE, it may know that the UE supports operating as a layer-3 remote UE. If AMF receives the first identification information indicating that the UE does not support operating as a layer-3 remote UE, it may know that the UE does not support operating as a layer-3 remote UE.

[0236] If AMF receives a second identification, it may determine whether the UE supports operating as a U2N relay UE. If AMF receives a second identification indicating that the UE supports operating as a U2N relay UE, it may determine that the UE supports operating as a U2N relay UE. If AMF receives a second identification indicating that the UE does not support operating as a U2N relay UE, it may determine that the UE does not support operating as a U2N relay UE.

[0237] If AMF receives the second identification information, it may recognize whether the UE supports operating as a layer-2 U2N relay UE. If AMF receives the second identification information indicating that the UE supports operating as a layer-2 U2N relay UE, it may recognize that the UE supports operating as a layer-2 U2N relay UE. If AMF receives the second identification information indicating that the UE does not support operating as a layer-2 U2N relay UE, it may recognize that the UE does not support operating as a layer-2 U2N relay UE.

[0238] If AMF receives the second identification information, it may recognize whether the UE supports operating as a layer-3 U2N relay UE. If AMF receives the second identification information indicating that the UE supports operating as a layer-3 U2N relay UE, it may recognize that the UE supports operating as a layer-3 U2N relay UE. If AMF receives the second identification information indicating that the UE does not support operating as a layer-3 U2N relay UE, it may recognize that the UE does not support operating as a layer-3 U2N relay UE.

[0239] If AMF receives third identification information, it may recognize whether the UE supports operating as a multi-hop remote UE. If AMF receives third identification information indicating that the UE supports operating as a multi-hop remote UE, it may recognize that the UE supports operating as a multi-hop remote UE. If AMF receives third identification information indicating that the UE does not support operating as a multi-hop remote UE, it may recognize that the UE does not support operating as a multi-hop remote UE.

[0240] If AMF receives third identification information, it may recognize whether the UE supports operating as a multi-hop layer-3 remote UE. If AMF receives third identification information indicating that the UE supports operating as a multi-hop layer-3 remote UE, it may recognize that the UE supports operating as a multi-hop layer-3 remote UE. If AMF receives third identification information indicating that the UE does not support operating as a multi-hop layer-3 remote UE, it may recognize that the UE does not support operating as a multi-hop layer-3 remote UE.

[0241] If AMF receives the fourth identification information, it may recognize whether the UE supports operating as a multi-hop U2N relay UE. If AMF receives the fourth identification information indicating that the UE supports operating as a multi-hop U2N relay UE, it may recognize that the UE supports operating as a multi-hop U2N relay UE. If AMF receives the fourth identification information indicating that the UE does not support operating as a multi-hop U2N relay UE, it may recognize that the UE does not support operating as a multi-hop U2N relay UE.

[0242] If AMF receives the fourth identification information, it may recognize whether the UE supports operating as a multi-hop layer-3 U2N relay UE. If AMF receives the fourth identification information indicating that the UE supports operating as a multi-hop layer-3 U2N relay UE, it may recognize that the UE supports operating as a multi-hop layer-3 U2N relay UE. If AMF receives the fourth identification information indicating that the UE does not support operating as a multi-hop layer-3 U2N relay UE, it may recognize that the UE does not support operating as a multi-hop layer-3 U2N relay UE.

[0243] If AMF receives a fifth identification, it may determine whether the UE supports operating as a U2N intermediate UE. If AMF receives a fifth identification indicating that the UE supports operating as a U2N intermediate UE, it may determine that the UE supports operating as a U2N intermediate UE. If AMF receives a fifth identification indicating that the UE does not support operating as a U2N intermediate UE, it may determine that the UE does not support operating as a U2N intermediate UE.

[0244] If AMF receives the fifth identification information, it may recognize whether the UE supports operating as a layer-3 U2N intermediate UE. If AMF receives the fifth identification information indicating that the UE supports operating as a layer-3 U2N intermediate UE, it may recognize that the UE supports operating as a layer-3 U2N intermediate UE. If AMF receives the fifth identification information indicating that the UE does not support operating as a layer-3 U2N intermediate UE, it may recognize that the UE does not support operating as a layer-3 U2N intermediate UE.

[0245] Based on each piece of identification information, the AMF may determine whether the UE is authorized to use the 5G ProSe service. Based on each piece of identification information, the AMF may or may not authorize the 5G ProSe service to be used by the UE.

[0246] The AMF may approve each piece of identification information. The AMF may transmit each piece of identification information to the PCF.

[0247] When the AMF receives a registration request message, it may perform a first conditional determination. The first conditional determination determines whether the network (or the AMF) accepts the UE's request. If the first conditional determination is true, the AMF initiates the procedure shown in Figure 6(A). If the first conditional determination is false, the AMF initiates the procedure shown in Figure 6(B).

[0248] Furthermore, the first condition determination may be performed based on the receipt of a registration request message, and / or subscriber information, and / or network capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by AMF, etc.

[0249] For example, if the network allows the UE's request, the first condition may be true. If the network does not allow the UE's request, the first condition may be false.

[0250] For example, if the network to which the UE is registered, and / or the devices within the network, support the functionality requested by the UE, the first condition may be true; if they do not support the functionality requested by the UE, the first condition may be false.

[0251] For example, if each piece of identification information is permitted, the first condition may be true. If each piece of identification information is not permitted, the first condition may be false.

[0252] Furthermore, the conditions that determine the truth or falsity of the first conditional judgment are not limited to those mentioned above.

[0253] First, let's explain the case where the first condition is true.

[0254] In the procedure shown in Figure 6(A), as a response to the registration request message, the AMF sends a Registration accept message to the UE via the 5G AN (or gNB) (S806). The Registration accept message is a NAS message transmitted and received on the N1 interface, but it is included in the RRC message transmitted and received between the UE and the 5G AN (gNB).

[0255] The AMF may indicate that the UE's request has been accepted by sending a registration acceptance message. The AMF may decide whether or not to send a registration acceptance message based on each received identification information, and / or subscriber information, and / or network capability information, and / or operator policies, and / or network status, and / or user registration information, and / or context held by the AMF.

[0256] The AMF may include in the registration acceptance message information indicating that some of the UE's requests were rejected.

[0257] Next, the UE receives a registration acceptance message from the AMF via the 5G AN (gNB) (S806).

[0258] In this case, if the UE receives a registration acceptance message, it may recognize that its request has been accepted.

[0259] If a UE receives information indicating that some of its requests have been rejected, the UE may recognize that some of its requests have been rejected.

[0260] Next, the UE may or may not send a registration completion message to the AMF via the 5G AN(gNB) as a response message to the registration acceptance message (S808). Here, the registration completion message is a NAS message sent and received on the N1 interface, but it is included in the RRC message sent and received between the UE and the 5G AN(gNB).

[0261] Next, the AMF may or may not receive a registration completion message via the 5G AN (gNB) (S808).

[0262] Each device may complete the procedure in Figure 6(A) based on the sending and receiving of a registration acceptance message and / or a registration completion message.

[0263] Next, we will explain the case where the first condition is false.

[0264] In the procedure shown in Figure 6(B), as a response to the registration request message, the AMF sends a registration rejection message to the UE via the 5G AN(gNB) (S810). Here, the registration rejection message is a NAS message sent and received on the N1 interface, but it is included in the RRC message sent and received between the UE and the 5G AN(gNB).

[0265] The AMF may indicate that the UE's request has been rejected by sending a registration rejection message. Furthermore, the AMF may send a registration rejection message that includes information indicating that the UE's request has been rejected.

[0266] Next, the UE receives a registration rejection message from the AMF via the 5G AN (gNB) (S810). Upon receiving the registration rejection message, the UE may recognize that its request has been rejected.

[0267] Each device may complete procedure (B) in this procedure based on the sending and receiving of registration rejection messages.

[0268] Each device may complete this procedure based on the completion of the procedure in Figure 6(A) or (B).

[0269] Furthermore, based on the completion of the procedure in Figure 6(A), the UE may transition to the state in which the UE is registered with the network (RM_REGISTERED state).

[0270] Furthermore, based on the completion of the procedure in Figure 6(B), the UE may either maintain the state in which it is not registered with the network (RM_DEREGISTERED state), or it may transition to the state in which it is not registered with the network.

[0271] Each device may perform processing based on the transmission and reception of each identification information upon completion of this procedure.

[0272] If the UE's request is rejected, the UE may repeat this procedure or perform network selection for a different network.

[0273] [3.2 Discovery Procedures] Next, I will explain the discovery procedure.

[0274] The discovery procedure may be either the Model A discovery procedure or the Model B discovery procedure.

[0275] The discovery procedure may be referred to as 5G ProSe direct discovery or 5G ProSe discovery.

[0276] This specification describes the Model B discovery procedure.

[0277] [3.2.1 Model B Detection Procedure] The Model B discovery procedure will be explained using Figure 7. In this chapter, the Model B discovery procedure may be referred to simply as "this procedure."

[0278] This procedure may be either a procedure for 5G ProSe U2N relay discovery using Model B, or a procedure for U2N relay discovery over a PC5 interface using Model B.

[0279] This procedure may be a procedure for multi-hop 5G ProSe UE-to-Network Relay Discovery with Model B, or multi-hop UE-to-network relay discovery over the PC5 interface with model B.

[0280] This procedure may be started after the registration procedure is completed.

[0281] This procedure may be executed multiple times. In other words, after this procedure is completed, this procedure may be executed again.

[0282] The Discovery Solicitation message may be a Solicitation message, a UE-to-Network Relay Discovery Solicitation message, a PROSE PC5 DISCOVERY message for UE-to-network relay discovery solicitation, or a PROSE PC5 DISCOVERY message for multi-hop UE-to-network relay discovery solicitation. [[ID=))]]

[0283] A Discovery Response message may be a Response message, a UE-to-Network Relay Discovery Response message, a PROSE PC5 DISCOVERY message for UE-to-network relay discovery response, or a PROSE PC5 DISCOVERY message for multi-hop UE-to-network relay discovery response.

[0284] Furthermore, the phrase "a discovery solicitation message or discovery response message is sent" can be interpreted as "a discovery solicitation message or discovery response message is broadcast."

[0285] In this procedure, the UE may be a multi-hop remote UE, a multi-hop U2N relay UE, and / or a U2N intermediate UE.

[0286] In this procedure, a UE that sends a discovery solicitation message may be referred to as a discoverer UE. In this procedure, a UE that sends a discovery response message may be referred to as a discoveree UE.

[0287] In this procedure, U2N Intermediate UE #1, U2N Intermediate UE #2, and / or U2N Intermediate UE #3 may be referred to as U2N Intermediate UE. In other words, U2N Intermediate UE may be any of U2N Intermediate UE #1, U2N Intermediate UE #2, or U2N Intermediate UE #3.

[0288] Next, we will explain each step of this procedure.

[0289] First, the multi-hop remote UE sends a discovery invitation message (S1400) (S1404). Here, the multi-hop remote UE may send the discovery invitation message to multiple U2N intermediate UEs. In other words, the multi-hop remote UE may broadcast the discovery invitation message. For example, (A-1) may occur when the discovery invitation message is received by U2N intermediate UE #1, and (B-1) may occur when the discovery invitation message is received by U2N intermediate UE #2.

[0290] For example, a multi-hop remote UE may send discovery invitation messages to U2N intermediate UE #1 and / or U2N intermediate UE #2.

[0291] Here, the multi-hop remote UE may send a discovery solicitation message containing the identification information of 21, 22, and / or 23. Alternatively, the multi-hop remote UE may send a discovery solicitation message along with the identification information of 21, 22, and / or 23.

[0292] Specifically, a multi-hop remote UE may or may not transmit the 21st identification information, including the multi-hop remote UE's User Info ID. Alternatively, a multi-hop remote UE may or may not transmit the 21st identification information, without including the multi-hop remote UE's User Info ID.

[0293] The multi-hop remote UE may set the 22nd identification information to 1 and transmit.

[0294] The multi-hop remote UE may determine and transmit the value of the 23rd identification information. The multi-hop remote UE may set the 23rd identification information to a value smaller than the (pre-configured) maximum number of hops.

[0295] Here, the multi-hop remote UE may indicate the contents of each piece of identification information to the U2N intermediate UE and / or multi-hop U2N relay UE by transmitting this identification information and / or discovery invitation messages.

[0296] Next, the U2N intermediate UE receives a discovery solicitation message from the multi-hop remote UE (S1400) (S1404). The U2N intermediate UE may also receive a discovery solicitation message containing the 21st, 22nd, and / or 23rd identification information. The U2N intermediate UE may also receive a discovery solicitation message along with the 21st, 22nd, and / or 23rd identification information.

[0297] For example, U2N intermediate UE #1 and / or U2N intermediate UE #2 may receive discovery invitation messages from the multi-hop remote UE.

[0298] Here, if the U2N intermediate UE receives these identification pieces and / or discovery solicitation messages, it may recognize the content indicated by each piece of identification piece and may store the content indicated by each piece of identification piece.

[0299] Specifically, if the U2N intermediate UE receives the 21st identification information, it may store the 21st identification information.

[0300] If the U2N intermediate UE receives the 22nd identification information, it may store the 22nd identification information.

[0301] For example, in (B-1), if U2N Intermediate UE #2 receives the 22nd identification information set to 1, it may store the 22nd identification information set to 1. Then, U2N Intermediate UE #2 may set the value to 2, which is the 22nd identification information plus 1, and transmit the 22nd identification information set to 2 to U2N Intermediate UE #3. If U2N Intermediate UE #3 receives the 22nd identification information set to 2, it may store the 22nd identification information set to 2.

[0302] When the U2N intermediate UE receives the 23rd identification information, it may store the 23rd identification information.

[0303] When the U2N intermediate UE receives the 22nd and / or 23rd identification information, if the 22nd identification information is smaller than the 23rd identification information, it may store the 22nd and / or 23rd identification information.

[0304] When the U2N intermediate UE receives the 22nd and / or 23rd identification information, if the 22nd identification information is smaller than the 23rd identification information, it may send a discovery invitation message. In other words, when the U2N intermediate UE receives the 22nd and / or 23rd identification information, if the value indicated by the 22nd identification information is greater than or equal to the value indicated by the 23rd identification information, it does not have to send a discovery invitation message. Further in other words, when the U2N intermediate UE receives the 22nd and / or 23rd identification information, if the value indicated by the 22nd identification information is greater than or equal to the value indicated by the 23rd identification information, it may drop the received discovery invitation message.

[0305] For example, in (A-1), when the U2N intermediate UE #1 receives the 22nd identification information set to 1 and the 23rd identification information set to 2, it may send a discovery invitation message to the multi-hop U2N relay UE.

[0306] For example, in (B-1), when the U2N intermediate UE #3 receives the 22nd identification information set to 2 and the 23rd identification information set to 2, it does not have to send a discovery invitation message to the multi-hop U2N relay UE.

[0307] Next, the U2N intermediate UE sends a discovery invitation message to the U2N intermediate UE or the multi-hop U2N relay UE (S1402)(S1406)(S1408). Also, the U2N intermediate UE may send a discovery invitation message including the 21st, 22nd, and / or 23rd identification information. Also, the U2N intermediate UE may send a discovery invitation message together with the 21st, 22nd, and / or 23rd identification information.

[0308] Furthermore, a U2N intermediate UE may forward discovery solicitation messages received from another U2N intermediate UE or a multi-hop remote UE. A U2N intermediate UE may also create and send a new discovery solicitation message.

[0309] For example, in (A-1), U2N intermediate UE #1 may send a discovery invitation message to the multi-hop U2N relay UE.

[0310] Furthermore, in (B-1), U2N intermediate UE #2 may send a discovery invitation message to U2N intermediate UE #3. Next, U2N intermediate UE #3 may receive a discovery invitation message from U2N intermediate UE #2. Next, U2N intermediate UE #3 may send a discovery invitation message to the multi-hop U2N relay UE.

[0311] Here, the U2N intermediate UE may indicate to the U2N intermediate UE or the multi-hop U2N relay UE what each piece of identification information represents by transmitting these identification information and / or discovery invitation messages.

[0312] Specifically, the U2N intermediate UE may transmit a 21st identification information including the User Info ID of the U2N intermediate UE. The U2N intermediate UE may transmit a 21st identification information including the User Info ID of the U2N intermediate UE to the 21st identification information received from the U2N intermediate UE or the multi-hop remote UE.

[0313] For example, in (A-1), U2N Intermediate UE #1 may transmit a 21st identifier including the User Info ID of U2N Intermediate UE #1. In other words, in (A-1), U2N Intermediate UE #1 may transmit a 21st identifier consisting of the User Info ID of U2N Intermediate UE #1. In (A-1), U2N Intermediate UE #1 may create and transmit a 21st identifier consisting of the User Info ID of U2N Intermediate UE #1.

[0314] For example, in (B-1), U2N Intermediate UE #2 may transmit the 21st identification information, including the User Info ID of U2N Intermediate UE #2. Next, U2N Intermediate UE #3 may transmit the 21st identification information, including the User Info ID of U2N Intermediate UE #3.

[0315] In other words, in (B-1), U2N Intermediate UE #2 may transmit a 21st identifier consisting of the User Info ID of U2N Intermediate UE #2. Next, U2N Intermediate UE #3 may transmit a 21st identifier consisting of the User Info ID of U2N Intermediate UE #2 and the User Info ID of U2N Intermediate UE #3.

[0316] In (B-1), U2N Intermediate UE #2 may create and transmit a 21st piece of identification information, including the User Info ID of U2N Intermediate UE #2.

[0317] The U2N intermediate UE may add 1 to the received 22nd identification information and set the value to that, then transmit the 22nd identification information.

[0318] For example, in (A-1), U2N intermediate UE #1 may transmit a 22nd identification piece set to 2 to the multi-hop U2N relay UE.

[0319] For example, in (B-1), U2N intermediate UE #2 may transmit a 22nd identification number set to 2 to U2N intermediate UE #3. U2N intermediate UE #3 may transmit a 22nd identification number set to 3 to the multi-hop U2N relay UE.

[0320] The U2N intermediate UE may transmit the received 23rd identification information without modification.

[0321] Next, the multi-hop U2N relay UE receives a discovery solicitation message from the U2N intermediate UE (S1402) (S1408). The multi-hop U2N relay UE may also receive a discovery solicitation message containing the 21st, 22nd, and / or 23rd identification information. The multi-hop U2N relay UE may also receive a discovery solicitation message along with the 21st, 22nd, and / or 23rd identification information.

[0322] For example, a multi-hop U2N relay UE may receive discovery invitation messages from U2N intermediate UE #1 and / or U2N intermediate UE #3.

[0323] For example, a multi-hop U2N relay UE may receive a discovery invitation message from U2N intermediate UE #3 after receiving a discovery invitation message from U2N intermediate UE #1.

[0324] Here, if the multi-hop U2N relay UE receives these identification pieces and / or discovery solicitation messages, it may recognize the content indicated by each piece of identification piece and may store the content indicated by each piece of identification piece.

[0325] Specifically, if a multi-hop U2N relay UE receives the 21st identification information, it may store the 21st identification information.

[0326] If a multi-hop U2N relay UE receives the 22nd identification information, it may store the 22nd identification information.

[0327] If a multi-hop U2N relay UE receives the 23rd identification information, it may store the 23rd identification information.

[0328] When a multi-hop U2N relay UE receives discovery invitation messages from multiple routes, it may select one route and send a discovery response message, or it may send discovery response messages to all routes. In other words, when a multi-hop U2N relay UE receives discovery invitation messages from multiple routes, it may select one route or not. When a multi-hop U2N relay UE receives discovery invitation messages from multiple routes, it may select one route based on the 21st identification information.

[0329] For example, if a multi-hop U2N relay UE receives discovery invitation messages from U2N intermediate UE #1 and U2N intermediate UE #3, it may choose either U2N intermediate UE #1 or U2N intermediate UE #3. In other words, if a multi-hop U2N relay UE receives discovery invitation messages from U2N intermediate UE #1 and U2N intermediate UE #3, it may choose the route multi-hop remote UE, U2N intermediate UE #1, and multi-hop U2N relay UE, or it may choose the route multi-hop remote UE, U2N intermediate UE #2, U2N intermediate UE #3, and multi-hop U2N relay UE.

[0330] If the multi-hop U2N relay UE selects U2N intermediate UE #1, it may perform the process in (A-2). Also, if the multi-hop U2N relay UE selects U2N intermediate UE #3, it may perform the process in (B-2).

[0331] The multi-hop U2N relay UE may perform the processes described in (A-2) and (B-2). In other words, the multi-hop U2N relay UE may send discovery response messages to U2N intermediate UE #1 and U2N intermediate UE #3.

[0332] Next, the multi-hop U2N relay UE sends a discovery response message (S1410)(S1414). For example, in (A-2), the multi-hop U2N relay UE may send a discovery response message to U2N intermediate UE #1 as a response to the discovery invitation message received from U2N intermediate UE #1 in (A-1). Also, in (B-2), the multi-hop U2N relay UE may send a discovery response message to U2N intermediate UE #3 as a response to the discovery invitation message received from U2N intermediate UE #3 in (B-1).

[0333] A multi-hop U2N relay UE may send a discovery response message to the selected U2N intermediate UE. In other words, a multi-hop U2N relay UE may send a discovery response message to the path to the selected multi-hop remote UE.

[0334] For example, a multi-hop U2N relay UE may send discovery response messages to U2N intermediate UE #1 and / or U2N intermediate UE #3.

[0335] For example, if a multi-hop U2N relay UE does not receive a discovery invitation message from U2N intermediate UE #3, it does not need to send a discovery response message to U2N intermediate UE #3.

[0336] Here, the multi-hop U2N relay UE may send a discovery response message containing the identification information of the 31st, 32nd, and / or 33rd. Alternatively, the multi-hop U2N relay UE may send a discovery response message along with the identification information of the 31st, 32nd, and / or 33rd.

[0337] Here, the multi-hop U2N relay UE may indicate to the U2N intermediate UE and / or multi-hop remote UE what each piece of identification information represents by transmitting these identification information and / or discovery response messages.

[0338] Specifically, the multi-hop U2N relay UE may transmit the received 21st identification information as the 31st identification information. For example, in (A-2), the multi-hop U2N relay UE may transmit the 31st identification information consisting of U2N intermediate UE #1. Also, in (B-2), the multi-hop U2N relay UE may transmit the 31st identification information consisting of U2N intermediate UE #2 and U2N intermediate UE #3.

[0339] Furthermore, the multi-hop U2N relay UE may transmit a 31st set of identification information, which includes the User Info ID of the multi-hop remote UE, along with the received 21st set of identification information. For example, in (A-2), the multi-hop U2N relay UE may transmit a 31st set of identification information consisting of the multi-hop remote UE and U2N intermediate UE #1. Also, in (B-2), the multi-hop U2N relay UE may transmit a 31st set of identification information consisting of the multi-hop remote UE, U2N intermediate UE #2, and U2N intermediate UE #3.

[0340] The multi-hop U2N relay UE may transmit the received 22nd identification information as the 32nd identification information.

[0341] The multi-hop U2N relay UE may transmit the 33rd identification information set to 1.

[0342] Next, the U2N intermediate UE receives a discovery response message from the multi-hop U2N relay UE (S1410) (S1414). The U2N intermediate UE may also receive a discovery response message containing the 31st, 32nd, and / or 33rd identification information. The U2N intermediate UE may also receive a discovery response message along with the 31st, 32nd, and / or 33rd identification information.

[0343] For example, U2N intermediate UE #1 and / or U2N intermediate UE #3 may receive discovery response messages from the multi-hop U2N relay UE.

[0344] Here, if the U2N intermediate UE receives these identification pieces and / or discovery response messages, it may recognize the content indicated by each piece of identification piece and may store the content indicated by each piece of identification piece.

[0345] Specifically, if the 31st identification information is received, the U2N intermediate UE may store the 31st identification information.

[0346] If the 32nd identification information is received, the U2N intermediate UE may store the 32nd identification information.

[0347] If the 33rd identifier is received, the U2N intermediate UE may store the 33rd identifier. If the 33rd identifier is received, the U2N intermediate UE may store the 33rd identifier in the discovery entry. In other words, if the 33rd identifier is received, the U2N intermediate UE may create and store a discovery entry containing the 33rd identifier.

[0348] For example, in (A-2), U2N intermediate UE #1 may store a 33rd identification piece that is set to 1.

[0349] For example, in (B-2), U2N Intermediate UE #3 may store the 33rd identifier, which is set to 1. Then, U2N Intermediate UE #3 may add 1 to the 33rd identifier. In other words, U2N Intermediate UE #3 may send the 33rd identifier, which is set to 2, to U2N Intermediate UE #2. U2N Intermediate UE #2 may store the 33rd identifier, which is set to 2.

[0350] Next, the U2N intermediate UE sends a discovery response message to the U2N intermediate UE or the multi-hop remote UE (S1412)(S1416)(S1418). The U2N intermediate UE may also send a discovery response message containing the 31st, 32nd, and / or 33rd identification information. The U2N intermediate UE may also send a discovery response message along with the 31st, 32nd, and / or 33rd identification information.

[0351] For example, in (A-2), U2N intermediate UE #1 may send a discovery response message to the multi-hop remote UE.

[0352] Furthermore, in (B-2), U2N intermediate UE #3 may send a discovery response message to U2N intermediate UE #2. Next, U2N intermediate UE #2 may receive the discovery response message. Next, U2N intermediate UE #2 may send a discovery response message to the multi-hop remote UE.

[0353] Furthermore, the U2N intermediate UE may forward discovery response messages received from the U2N intermediate UE or the multi-hop U2N relay UE.

[0354] Here, the U2N intermediate UE may indicate to the U2N intermediate UE or the multi-hop remote UE what each piece of identification information represents by transmitting these identification information and / or discovery response messages.

[0355] Specifically, a U2N intermediate UE may transmit a 31st identification information received from a U2N intermediate UE or a multi-hop U2N relay UE.

[0356] The U2N intermediate UE may transmit the 32nd identification information received from the U2N intermediate UE or the multi-hop U2N relay UE.

[0357] The U2N intermediate UE may transmit a value obtained by adding 1 to the 33rd identification information received from the U2N intermediate UE or the multi-hop U2N relay UE. In other words, the U2N intermediate UE may transmit a value obtained by adding 1 to the received 33rd identification information as the 33rd identification information.

[0358] For example, in (A-2), U2N intermediate UE #1 may transmit the 33rd identification information with the value 2.

[0359] For example, in (B-2), U2N intermediate UE #3 may transmit the 33rd identification information with the value 2. Subsequently, U2N intermediate UE #2, having received the 33rd identification information with the value 2, may transmit the 33rd identification information with the value 3.

[0360] Next, the multi-hop remote UE receives a discovery response message from the U2N intermediate UE (S1412)(S1418). The multi-hop remote UE may also receive a discovery response message containing the 31st, 32nd, and / or 33rd identification information. The multi-hop remote UE may also receive a discovery response message along with the 31st, 32nd, and / or 33rd identification information.

[0361] For example, a multi-hop remote UE may receive discovery response messages from U2N intermediate UE #1 and / or U2N intermediate UE #2.

[0362] Here, if the multi-hop remote UE receives these identification pieces and / or discovery response messages, it may recognize the content indicated by each piece of identification piece and may store the content indicated by each piece of identification piece.

[0363] Specifically, if the 31st identification information is received, the multi-hop remote UE may store the 31st identification information.

[0364] If the 32nd identification information is received, the multi-hop remote UE may store the 32nd identification information.

[0365] If the 33rd identification information is received, the multi-hop remote UE may store the 33rd identification information.

[0366] A multi-hop remote UE may select a U2N intermediate UE based on the receipt of a discovery response message. A multi-hop remote UE may select a route to a multi-hop U2N relay UE based on the receipt of a discovery response message. In this case, the multi-hop remote UE may select a route considering the identification information of items 31, 32, and / or 33.

[0367] Furthermore, if a multi-hop remote UE receives a discovery response message, it may select a path to a multi-hop U2N relay UE. In other words, if a multi-hop remote UE receives a discovery response message, it may select a U2N intermediate UE.

[0368] For example, if a multi-hop remote UE receives discovery response messages from U2N intermediate UE #1 and U2N intermediate UE #2, it may choose either U2N intermediate UE #1 or U2N intermediate UE #2. In other words, if a multi-hop remote UE receives discovery response messages from U2N intermediate UE #1 and U2N intermediate UE #2, it may choose the path of multi-hop remote UE, U2N intermediate UE #1, and multi-hop U2N relay UE, or it may choose the path of multi-hop remote UE, U2N intermediate UE #2, U2N intermediate UE #3, and multi-hop U2N relay UE.

[0369] Each device may complete this procedure based on the completion of the above-described process and / or the sending and receiving of discovery solicitation messages and / or discovery response messages.

[0370] Furthermore, each device may perform processing based on the identification information upon completion of this procedure.

[0371] [3.3 5G ProSE Direct Link Establishment Procedure] Next, the 5G ProSe direct link establishment procedure will be explained using Figure 8. Hereafter, the 5G ProSe direct link establishment procedure may be referred to as "this procedure."

[0372] This procedure may be a procedure for establishing a 5G ProSe direct link between two or more UEs. Here, the 5G ProSe direct link may be a Layer 2 link and / or a Layer 3 link.

[0373] Prior to the execution of this procedure, each device may have already performed the registration procedure and / or the PDU session establishment procedure and / or the discovery procedure at least once.

[0374] Furthermore, this procedure may be performed multiple times. In other words, after this procedure is completed once, a new 5G ProSe direct link establishment procedure may be performed.

[0375] Furthermore, in this procedure, the UE that sends the request message may be referred to as the "initiating UE." In other words, the initiating UE may be the UE that sends the PROSE direct link establishment request message. Additionally, UEs other than the initiating UE may be referred to as the "target UE." Furthermore, the UE that receives the request message may be referred to as the "target UE." In other words, the target UE may be the UE that sends the PROSE direct link establishment acceptance message or the PROSE direct link establishment rejection message.

[0376] Furthermore, if the multi-hop remote UE is the initiating UE, the U2N intermediate UE may be the target UE. Also, if the U2N intermediate UE is the initiating UE, the multi-hop U2N relay UE may be the target UE. In other words, this procedure may be executed between the multi-hop remote UE and the U2N intermediate UE. Also, this procedure may be executed between the U2N intermediate UE and the multi-hop U2N relay UE.

[0377] Furthermore, in this procedure, the initiating UE and the target UE may send and receive control messages on PC5.

[0378] Next, we will explain each step of this procedure.

[0379] First, the initiating UE sends a PROSE Direct Link Establishment Request message to the target UE (S1600).

[0380] Next, the target UE receives a PROSE direct link establishment request message from the initiating UE.

[0381] If the target UE receives a PROSE direct link establishment request message, it may perform a fourth conditional check. The fourth conditional check determines whether the target UE accepts the initiator UE's request. If the fourth conditional check is true, the target UE initiates procedure (A). If the fourth conditional check is false, the target UE initiates procedure (B).

[0382] Furthermore, the fourth condition determination may be performed based on the receipt of a PROSE direct link establishment request message, and / or subscriber information, and / or UE capability information, and / or operator policy, and / or network status, and / or user registration information, and / or context held by the UE, etc.

[0383] For example, if the target UE allows the initiating UE's request, the fourth condition may be true. If the target UE does not allow the initiating UE's request, the fourth condition may be false.

[0384] For example, if each piece of identification information is permitted, the fourth condition may be true. If each piece of identification information is not permitted, the fourth condition may be false.

[0385] Furthermore, the conditions that determine the truth or falsity of the fourth condition are not limited to those mentioned above.

[0386] First, let's explain the case where the fourth condition is true.

[0387] In procedure (A), the target UE sends a PROSE Direct Link Establishment Acceptance message to the initiating UE (S1602).

[0388] Next, the initiating UE receives a PROSE direct link establishment acceptance message from the target UE.

[0389] Next, we will explain the case where the fourth condition is false.

[0390] In procedure (B), the target UE sends a PROSE direct link establishment rejection message to the initiating UE (S1604). The target UE may send a PROSE direct link establishment rejection message containing the identification information of 61, 62, and / or 63.

[0391] Here, the target UE may indicate to the initiating UE what each piece of identification information represents by sending these identification information and / or a PROSE direct link establishment rejection message.

[0392] Specifically, if the target UE does not permit the request to establish a direct link, it may transmit the identification information specified in paragraph 61.

[0393] The target UE may transmit the 62nd identification information if the network is congested. The target UE may transmit the 62nd identification information if the network is congested.

[0394] If the target UE is a multi-hop U2N relay UE, the target UE may transmit the 63rd identification information.

[0395] Next, the initiating UE receives a PROSE direct link establishment rejection message from the target UE. Here, the initiating UE may receive a PROSE direct link establishment rejection message containing the identification information of 61, 62, and / or 63.

[0396] Here, if the initiating UE receives these identification pieces and / or a PROSE direct link establishment rejection message, it may recognize the content indicated by each identification piece and may store the content indicated by each identification piece.

[0397] Specifically, upon receiving identification information 61 or 62, the initiating UE may exclude a multi-hop U2N relay UE or U2N intermediate UE from the multi-hop U2N relay reselection procedure. In other words, upon receiving identification information 61 or 62, the multi-hop remote UE may exclude a multi-hop U2N relay UE or U2N intermediate UE that sent a PROSE direct link establishment rejection message from the multi-hop U2N relay reselection procedure. To put it another way, upon receiving identification information 61 or 62, the multi-hop remote UE may exclude a multi-hop U2N relay UE or U2N intermediate UE that sent a PROSE direct link establishment rejection message from the selection candidates in the multi-hop U2N relay reselection procedure.

[0398] If the 63rd identification information is received, the initiating UE may exclude the multihop U2N relay UE from the multihop U2N relay reselection procedure. In other words, if the 63rd identification information is received, the multihop remote UE may exclude the multihop U2N relay UE that sent the PROSE direct link establishment rejection message from the multihop U2N relay reselection procedure. In other words, if the 63rd identification information is received, the multihop remote UE may exclude the multihop U2N relay UE that sent the PROSE direct link establishment rejection message from the selection candidates in the multihop U2N relay reselection procedure.

[0399] The initiating UE may complete this procedure upon receiving a PROSE direct link establishment acceptance message or a PROSE direct link establishment rejection message. The target UE may complete this procedure upon sending a PROSE direct link establishment acceptance message or a PROSE direct link establishment rejection message. Each device may or may not establish a 5G ProSe direct link based on the completion of this procedure. Each device may or may not recognize that a 5G ProSe direct link has been established based on the completion of this procedure.

[0400] Furthermore, the processing of the initiating UE and target UE based on the receipt of their respective identification information may be performed after the completion of this procedure.

[0401] Upon completion of this procedure, the initiating UE and target UE may send and receive user data using the established 5G ProSe direct link.

[0402] [3.4 5G ProSE Direct Link Unlock Procedure] Next, the 5G ProSe direct link release procedure will be explained using Figure 9. Hereafter, the 5G ProSe direct link release procedure may be referred to as "this procedure."

[0403] This procedure may be a procedure for releasing a 5G ProSe direct link between two or more UEs. Here, the 5G ProSe direct link may be a Layer 2 link and / or a Layer 3 link.

[0404] In this embodiment, each device may perform the registration procedure and / or the PDU session establishment procedure and / or the discovery procedure and / or the 5G ProSe direct link establishment procedure one or more times.

[0405] Furthermore, this procedure may be performed multiple times. In other words, after this procedure is completed once, a new 5G ProSe direct link release procedure may be performed.

[0406] Furthermore, in this procedure, the UE that sends the request message may be referred to as the "initiating UE." In other words, the initiating UE may be the UE that sends the PROSE direct link release request message. Additionally, UEs other than the initiating UE may be referred to as the "target UE." Furthermore, the UE that receives the request message may be referred to as the "target UE." In other words, the target UE may be the UE that sends the PROSE direct link release acceptance message.

[0407] Furthermore, the multi-hop remote UE, U2N intermediate UE, and multi-hop U2N relay UE may be either the initiating UE or the target UE.

[0408] For example, if a multi-hop remote UE is the initiating UE, the U2N intermediate UE may be the target UE. Also, if the U2N intermediate UE is the initiating UE, the multi-hop U2N relay UE may be the target UE.

[0409] For example, if a multi-hop U2N relay UE is the initiating UE, the U2N intermediate UE may be the target UE. Also, if the U2N intermediate UE is the initiating UE, the multi-hop remote UE may be the target UE.

[0410] Furthermore, in this procedure, the initiating UE and the target UE may send and receive control messages on PC5.

[0411] Next, we will explain each step of this procedure.

[0412] First, the initiating UE sends a PROSE direct link release request message to the target UE (S1800). Here, the initiating UE may send a PROSE direct link release request message containing the identification information of items 61, 62, and / or 63.

[0413] Here, the initiating UE may indicate to the target UE what each piece of identification information represents by sending these identification information and / or a PROSE direct link release request message.

[0414] Specifically, the initiating UE may transmit the identification information specified in paragraph 61 if the direct link becomes unavailable.

[0415] The initiating UE may transmit the 62nd identification information if the network is congested.

[0416] If the initiating UE is a multi-hop U2N relay UE, the initiating UE may transmit the 63rd identification information.

[0417] Next, the target UE receives a PROSE direct link release request message from the initiating UE. Here, the target UE may receive a PROSE direct link release request message containing the identification information of 61, 62, and / or 63.

[0418] Here, if the target UE receives these identification pieces and / or a PROSE direct link release request message, it may recognize the content indicated by each identification piece and may store the content indicated by each identification piece.

[0419] Specifically, upon receiving identification information 61 or 62, the target UE may exclude the multi-hop U2N relay UE or U2N intermediate UE from the multi-hop U2N relay reselection procedure. In other words, upon receiving identification information 61 or 62, the multi-hop remote UE may exclude the multi-hop U2N relay UE or U2N intermediate UE that sent the PROSE direct link establishment rejection message from the multi-hop U2N relay reselection procedure. To put it another way, upon receiving identification information 61 or 62, the multi-hop remote UE may exclude the multi-hop U2N relay UE or U2N intermediate UE that sent the PROSE direct link establishment rejection message from the selection candidates in the multi-hop U2N relay reselection procedure.

[0420] If the target UE receives identification information No. 63, it may exclude the multi-hop U2N relay UE from the multi-hop U2N relay reselection procedure. In other words, if the multi-hop remote UE receives identification information No. 63, it may exclude the multi-hop U2N relay UE that sent the PROSE direct link establishment rejection message from the multi-hop U2N relay reselection procedure. In other words, if the multi-hop remote UE receives identification information No. 63, it may exclude the multi-hop U2N relay UE that sent the PROSE direct link establishment rejection message from the selection candidates in the multi-hop U2N relay reselection procedure.

[0421] Next, the target UE sends a PROSE direct link release acceptance message to the initiating UE (S1802). Here, the target UE may send a PROSE direct link release acceptance message if it accepts the PROSE direct link release request message from the initiating UE.

[0422] A PROSE direct link release acceptance message may be a response message to a PROSE direct link release request message. A PROSE direct link release acceptance message may indicate acceptance of the PROSE direct link release request message.

[0423] The target UE may indicate that it accepts the request of one or more initiating UEs by sending a PROSE direct link release acceptance message and / or each of the identification details.

[0424] Furthermore, the target UE may indicate that it supports or does not support each function, or that it accepts the initiator UE's request, by sending a ProSe direct link release acceptance message and / or each identification piece.

[0425] Furthermore, if multiple pieces of identification information are transmitted, two or more pieces of identification information may be transmitted as a single piece of identification information. Note that information indicating support for each function and information indicating a request to use each function may be transmitted as the same piece of identification information, or as different pieces of identification information.

[0426] Furthermore, the target UE may decide whether to include each piece of identification information in the PROSE direct link release acceptance message based on the received identification information, and / or subscriber information, and / or network capability information, and / or UE policy, and / or operator policy, and / or network status, and / or user registration information, and / or UE context, etc.

[0427] Next, the initiating UE receives a PROSE direct link release acceptance message from the target UE.

[0428] When the initiating UE receives the PROSE direct link release acceptance message and / or each piece of identification information, it may recognize that the initiating UE's request has been accepted and may store each piece of identification information.

[0429] The initiating UE may complete this procedure upon receiving a PROSE direct link release acceptance message. The target UE may complete this procedure upon sending a PROSE direct link release acceptance message. Each device may release the established 5G ProSe direct link upon completion of this procedure. Each device may recognize that the established 5G ProSe direct link has been released upon completion of this procedure.

[0430] Furthermore, the processing of the initiating UE and target UE based on the receipt of their respective identification information may be performed after the completion of this procedure.

[0431] [3.5 5G ProSe Public Alert Notification Relay Procedure] Next, the 5G ProSe public warning notification relay procedure will be explained using Figure 10. In this chapter, the 5G ProSe public warning notification relay procedure may be referred to as "this procedure".

[0432] This procedure may also be referred to as Public Warning Notification Relaying or Public Warning relaying.

[0433] This procedure may be a procedure for a U2N relay UE to broadcast alarm messages received from the network to a remote UE. The broadcast mode of 5G ProSe direct communication on PC5 may be used to broadcast the alarm messages. The remote UE may receive the broadcasted alarm messages without establishing a connection to the U2N relay UE.

[0434] Furthermore, this procedure may be a procedure for a multi-hop U2N relay UE to broadcast an alarm message received from the network to a multi-hop remote UE. The broadcast mode of 5G ProSe direct communication on PC5 may be used to broadcast the alarm message. The multi-hop remote UE may receive the broadcasted alarm message without establishing a connection to the multi-hop U2N relay UE or a U2N intermediate UE.

[0435] Furthermore, if the Model B discovery procedure is executed, this procedure may be a procedure for the multi-hop U2N relay UE to send an alarm message received from the network to the multi-hop remote UE. If the Model B discovery procedure is executed, the unicast mode of 5G ProSe direct communication on PC5 may be used to send the alarm message.

[0436] Furthermore, if the Model B detection procedure is executed, each UE does not need to send a public alert notification message. In other words, if the Model B detection procedure is executed, each UE does not need to perform this procedure.

[0437] Furthermore, in this procedure, each device may perform the registration procedure, PDU session establishment procedure, discovery procedure, and / or 5G ProSe direct link establishment procedure one or more times.

[0438] For example, Figure 10 may represent the procedure after steps (B-1) and (B-2) of the Model B discovery procedure in Figure 7 have been executed. In that case, U2N Intermediate UE #1 in Figure 10 may correspond to U2N Intermediate UE #2 in Figure 7, and U2N Intermediate UE #2 in Figure 10 may correspond to U2N Intermediate UE #3 in Figure 7.

[0439] Furthermore, this procedure may be performed multiple times. In other words, after this procedure has been completed once, it may be performed again.

[0440] In this procedure, each UE may be configured to perform this procedure.

[0441] Next, we will explain each step of this procedure. Note that "transmission" may be read as "broadcast" from now on.

[0442] First, the network broadcasts a public warning notification message (S2000). In other words, the network may send a public warning notification message to a multi-hop U2N relay UE. The network may broadcast and / or send a public warning notification message at any time.

[0443] Next, the multi-hop U2N relay UE receives a public alert notification message from the network (S2000).

[0444] Next, the multi-hop U2N relay UE broadcasts a public alert notification message (S2002). In other words, the multi-hop U2N relay UE may transmit and / or broadcast a public alert notification message to U2N intermediate UE #2. The multi-hop U2N relay UE may broadcast a public alert notification message to one or more U2N intermediate UEs.

[0445] A multi-hop U2N relay UE may decide whether to send a public alert notification message based on the 31st identification information. The multi-hop U2N relay UE may send a public alert notification message to a U2N intermediate UE or multi-hop remote UE included in the 31st identification information. The multi-hop U2N relay UE does not need to send a public alert notification message to a U2N intermediate UE or multi-hop remote UE not included in the 31st identification information.

[0446] Here, the multi-hop U2N relay UE may transmit a public alert notification message including the identification information of No. 41 and / or No. 42. Alternatively, the multi-hop U2N relay UE may transmit a public alert notification message along with the identification information of No. 41 and / or No. 42. Alternatively, the multi-hop U2N relay UE may transmit a public alert notification message that does not include the identification information of No. 41 and / or No. 42.

[0447] Specifically, the multi-hop U2N relay UE may or may not transmit the 41st identification information set to 1. In other words, the multi-hop U2N relay UE may or may not set the 41st identification information to 1.

[0448] The multi-hop U2N relay UE may or may not transmit a 42nd identifier, which is set to the value indicated by the 22nd identifier received in the Model B discovery procedure. In other words, the multi-hop U2N relay UE may or may not set the 42nd identifier to the value indicated by the 22nd identifier received in the Model B discovery procedure.

[0449] Next, U2N intermediate UE #2 receives a public alert notification message from the multi-hop U2N relay UE (S2002). Here, U2N intermediate UE #2 may receive a public alert notification message from the multi-hop U2N relay UE that includes identification information 41 and / or 42. Alternatively, U2N intermediate UE #2 may receive a public alert notification message from the multi-hop U2N relay UE along with identification information 41 and / or 42.

[0450] U2N Intermediate UE #2 may decide whether to drop the received public alert notification message based on the 31st identification information. If U2N Intermediate UE #2 receives a public alert notification message from a U2N Intermediate UE included in the 31st identification information, U2N Intermediate UE #2 does not need to drop the public alert notification message. If U2N Intermediate UE #2 receives a public alert notification message from a U2N Intermediate UE not included in the 31st identification information, U2N Intermediate UE #2 may drop the public alert notification message.

[0451] Here, if U2N Intermediate UE #2 receives these identification pieces and / or public alert notification messages, it may recognize the content indicated by each identification piece and may store the content indicated by each identification piece.

[0452] Specifically, U2N Intermediate UE #2 may decide whether to send a public alert notification message when it receives the 41st identification information. More specifically, if the value indicated by the 41st identification information is greater than the number of hops in the stored discovery entry, U2N Intermediate UE #2 does not need to send a public alert notification message. In other words, if the value indicated by the 41st identification information is less than or equal to the number of hops in the stored discovery entry, U2N Intermediate UE #2 may send a public alert notification message. Here, the number of hops in the discovery entry may be the 33rd identification information stored by U2N Intermediate UE in the Model B discovery procedure.

[0453] For example, U2N Intermediate UE #2 may send a public alert notification message if it receives a 41st identification piece indicating 1 and a hop number indicating 1 is stored in the discovery entry. For example, U2N Intermediate UE #2 does not need to send a public alert notification message if it receives a 41st identification piece indicating 2 and a hop number indicating 1 is stored in the discovery entry.

[0454] Additionally, U2N Intermediate UE #2 may drop the received public alert notification message if it does not remember the discovery entry. In other words, U2N Intermediate UE #2 may drop the received public alert notification message if it has performed the Model B discovery procedure.

[0455] Furthermore, if U2N Intermediate UE #2 does not remember the discovery entry, it may decide whether to send a public alert notification message based on a pre-configured maximum hop count. More specifically, if the value indicated by Identification 41 is greater than the pre-configured maximum hop count, U2N Intermediate UE #2 does not need to send a public alert notification message. In other words, if the value indicated by Identification 41 is less than or equal to the pre-configured maximum hop count, U2N Intermediate UE #2 may send a public alert notification message. Here, the pre-configured maximum hop count may be included in the UE policy. The pre-configured maximum hop count may be the maximum hop count for public alert notification messages. The pre-configured maximum hop count may be for the associated RSC (Relay Service Code).

[0456] U2N Intermediate UE #2 may decide whether to send a public alert notification message upon receiving identification information 41 and 42. More specifically, if the value indicated by identification information 41 is greater than or equal to the value indicated by identification information 42, U2N Intermediate UE #2 does not need to send a public alert notification message. In other words, if the value indicated by identification information 41 is less than the value indicated by identification information 42, U2N Intermediate UE #2 may send a public alert notification message.

[0457] Next, U2N Intermediate UE #2 broadcasts a public alert notification message (S2004). In other words, U2N Intermediate UE #2 may send a public alert notification message to U2N Intermediate UE #1.

[0458] U2N Intermediate UE #2 may decide whether to send a public alert notification message based on the identification information of item 31. U2N Intermediate UE #2 may send a public alert notification message to a U2N Intermediate UE or multi-hop remote UE included in the identification information of item 31. U2N Intermediate UE #2 does not need to send a public alert notification message to a U2N Intermediate UE or multi-hop remote UE not included in the identification information of item 31.

[0459] Here, U2N Intermediate UE #2 may transmit a public alert notification message containing the identification information of No. 41 and / or No. 42. Alternatively, U2N Intermediate UE #2 may transmit a public alert notification message along with the identification information of No. 41 and / or No. 42.

[0460] Specifically, U2N Intermediate UE #2 may transmit the 41st identification information with the value 2 set. In other words, U2N Intermediate UE #2 may add 1 to the received 41st identification information and transmit it.

[0461] If U2N Intermediate UE #2 has not received the 41st identification information, it may send the 41st identification information with the value 2 set.

[0462] Furthermore, U2N Intermediate UE #2 does not have to send a public alert notification message if it does not remember the discovery entry. In other words, U2N Intermediate UE #2 does not have to send a public alert notification message if it has performed the Model B discovery procedure.

[0463] U2N Intermediate UE #2 may transmit the received 42nd identification information.

[0464] Next, U2N Intermediate UE #1 receives a public alert notification message from U2N Intermediate UE #2 (S2004). Here, U2N Intermediate UE #1 may receive a public alert notification message from U2N Intermediate UE #2 that includes the 41st and / or 42nd identification information. Alternatively, U2N Intermediate UE #1 may receive a public alert notification message from U2N Intermediate UE #2 along with the 41st and / or 42nd identification information.

[0465] U2N Intermediate UE #1 may decide whether to drop the received public alert notification message based on the 31st identification information. If U2N Intermediate UE #1 receives a public alert notification message from a U2N Intermediate UE included in the 31st identification information, U2N Intermediate UE #1 does not need to drop the public alert notification message. If U2N Intermediate UE #1 receives a public alert notification message from a U2N Intermediate UE not included in the 31st identification information, U2N Intermediate UE #1 may drop the public alert notification message.

[0466] Here, if U2N Intermediate UE #1 receives these identification pieces and / or public alert notification messages, it may recognize the content indicated by each identification piece and may store the content indicated by each identification piece.

[0467] Specifically, U2N Intermediate UE #1 may decide whether to send a public alert notification message when it receives the 41st identification information. More specifically, if the value indicated by the 41st identification information is greater than the number of hops in the stored discovery entry, U2N Intermediate UE #1 does not need to send a public alert notification message. In other words, if the value indicated by the 41st identification information is less than or equal to the number of hops in the stored discovery entry, U2N Intermediate UE #1 may send a public alert notification message. Here, the number of hops in the discovery entry may be the 33rd identification information stored by U2N Intermediate UE in the Model B discovery procedure.

[0468] For example, if U2N Intermediate UE #1 receives a 41st identification number indicating 2 and the discovery entry contains a hop number indicating 2, it may send a public alert notification message. For example, if U2N Intermediate UE #1 receives a 41st identification number indicating 3 and the discovery entry contains a hop number indicating 2, it does not need to send a public alert notification message.

[0469] Additionally, U2N Intermediate UE #1 may drop the received public alert notification message if it does not remember the discovery entry. In other words, U2N Intermediate UE #1 may drop the received public alert notification message if it has performed the Model B discovery procedure.

[0470] Furthermore, if U2N Intermediate UE #1 does not remember the discovery entry, it may decide whether to send a public alert notification message based on a pre-configured maximum hop count. More specifically, if the value indicated by Identification 41 is greater than the pre-configured maximum hop count, U2N Intermediate UE #1 does not need to send a public alert notification message. In other words, if the value indicated by Identification 41 is less than or equal to the pre-configured maximum hop count, U2N Intermediate UE #1 may send a public alert notification message. Here, the pre-configured maximum hop count may be included in the UE policy. The pre-configured maximum hop count may be the maximum hop count for the public alert notification message. The pre-configured maximum hop count may be for the associated RSC (Relay Service Code).

[0471] U2N Intermediate UE #1 may decide whether to send a public alert notification message if it receives identification information 41 and 42. More specifically, if the value indicated by identification information 41 is greater than or equal to the value indicated by identification information 42, U2N Intermediate UE #1 does not need to send a public alert notification message. In other words, if the value indicated by identification information 41 is less than the value indicated by identification information 42, U2N Intermediate UE #1 may send a public alert notification message.

[0472] Next, U2N Intermediate UE #1 broadcasts a public alert notification message (S2006). In other words, U2N Intermediate UE #1 may send a public alert notification message to the multi-hop remote UE.

[0473] U2N Intermediate UE #1 may decide whether to send a public alert notification message based on the identification information of item 31. U2N Intermediate UE #1 may send a public alert notification message to a U2N Intermediate UE or multi-hop remote UE included in the identification information of item 31. U2N Intermediate UE #1 does not need to send a public alert notification message to a U2N Intermediate UE or multi-hop remote UE not included in the identification information of item 31.

[0474] Here, U2N Intermediate UE #1 may transmit a public alert notification message containing the 41st identification information. Alternatively, U2N Intermediate UE #1 may transmit a public alert notification message along with the 41st identification information.

[0475] Specifically, U2N Intermediate UE #1 may transmit the 41st identification information with the value 3 set. In other words, U2N Intermediate UE #1 may add 1 to the received 41st identification information and transmit it.

[0476] Furthermore, U2N Intermediate UE #1 does not have to send a public alert notification message if it does not remember the discovery entry. In other words, U2N Intermediate UE #1 does not have to send a public alert notification message if it has performed the Model B discovery procedure.

[0477] Next, the multi-hop remote UE receives a public alert notification message (S2006) from U2N intermediate UE #1.

[0478] When multiple pieces of identification information are transmitted, two or more pieces of identification information may be transmitted as a single piece of identification information. Furthermore, information indicating support for each function and information indicating a request to use each function may be transmitted as the same piece of identification information, or as different pieces of identification information.

[0479] Furthermore, each device may decide whether to include each identification information in the PROSE direct link release acceptance message based on the received identification information, and / or subscriber information, and / or network capability information, and / or UE policy, and / or operator policy, and / or network status, and / or user registration information, and / or UE context, etc.

[0480] Each device may complete this procedure based on the sending and receiving of public alert notification messages.

[0481] [4. Variant] The program running on the device according to this embodiment may be a program that controls the Central Processing Unit (CPU), etc., to make the computer function in order to realize the functions of the embodiment according to this embodiment. The program or the information handled by the program is temporarily stored in volatile memory such as Random Access Memory (RAM), non-volatile memory such as flash memory, a Hard Disk Drive (HDD), or other storage system.

[0482] Furthermore, a program for realizing the functions of the embodiment related to this embodiment may be recorded on a computer-readable recording medium. This can also be realized by loading the program recorded on this recording medium into a computer system and executing it. The term "computer system" here refers to a computer system built into the device, and includes hardware such as an operating system and peripheral devices. The term "computer-readable recording medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a medium that dynamically holds a program for a short period of time, or any other computer-readable recording medium.

[0483] Furthermore, each functional block or feature of the apparatus used in the embodiments described above may be implemented or executed by an electrical circuit, such as an integrated circuit or a combination of integrated circuits. An electrical circuit designed to perform the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, a conventional processor, controller, microcontroller, or state machine. The aforementioned electrical circuits may consist of digital circuits or analog circuits. Also, if advances in semiconductor technology lead to the emergence of integrated circuit technologies that replace current integrated circuits, one or more aspects of this embodiment may use new integrated circuits based on such technologies.

[0484] It should be noted that this embodiment is not limited to the embodiments described above. Although one example of a device is described in this embodiment, this embodiment is not limited to this and can be applied to stationary or non-movable electronic devices installed indoors or outdoors, such as terminal devices or communication devices for AV equipment, kitchen equipment, cleaning and washing machines, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0485] Although embodiments of this embodiment have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment and includes design changes and the like that do not depart from the gist of this embodiment. Furthermore, this embodiment can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this embodiment. In addition, configurations in which elements described in each of the above embodiments that produce similar effects are substituted for each other are also included. [Explanation of symbols]

[0486] 1. Mobile communication systems 10 UE_A 30 PGW-U 32 PGW-C 35 SGW 40 MME 45 eNB 50 HSS 60 PCRF 80 Access Network_A(E-UTRAN) 90 Core Network_A 120 Access Network_B(5G AN) 122 gNB 130 UPF 132 SMF 140 AMF 150 UDM 160 PCF 190 Core Network_B 235 UPF_A 239 UPF_C

Claims

1. A UE (User Equipment) comprising a transmitting / receiving unit and a control unit, The aforementioned UE is a 5G ProSe intermediate U2N relay UE, The transmitting / receiving unit sends a registration request message to the network, which includes information indicating that it supports 5G ProSe intermediate U2N (UE-to-network) relay UE. The transmitting / receiving unit receives a PROSE PC5 discovery message from the 5G ProSe multi-hop U2N relay UE for a multi-hop U2N relay discovery response, including the number of hops. The aforementioned hop count indicates the number of PC5 hops required for the 5G ProSe multi-hop remote UE to reach the network. The control unit creates and stores a discovery entry, which includes the number of hops received. The transmitting / receiving unit transmits a PROSE PC5 discovery message to the 5G ProSe multi-hop remote UE for a multi-hop U2N relay discovery response, which includes the number of hops obtained by adding 1 to the number of hops received. A UE characterized by the following:

2. The aforementioned transmitting and receiving unit receives a public alert notification message including the hop count from the 5G ProSe multi-hop U2N relay UE. If the number of hops in the public alert notification message is greater than the number of hops in the stored discovery entry, the transmitting / receiving unit will not transmit the public alert notification message. The UE according to feature 1.

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