User equipment (UE)

Abstract

In the present invention, in an additional parameter announcement procedure, a U2N intermediate UE transmits, to a remote UE, a PROSE PC5 discovery message for relay discovery additional information, if a timer has not expired. In a discovery procedure model B for signal strength measurement, if the U2N intermediate UE does not receive a PROSE PC5 discovery message for a U2N relay discovery response after the maximum number of permitted retransmissions has been reached, the U2N intermediate UE triggers a U2N relay reselection procedure.

Description

UE (User Equipment)

[0001] This embodiment relates to UE (User Equipment). This application claims priority to Japanese Patent Application No. 2024-110822, filed on July 10, 2024, the contents of which are incorporated herein by reference.

[0002] The 3GPP (3rd Generation Partnership Project, registered trademark) is studying the system architecture of the 5G System (5GS), a fifth-generation (5G) mobile communication system, and is discussing how to support new procedures and new functions (see Non-Patent Documents 1 to 3). Currently, as part of the study toward the specification of Release 19, discussions are underway regarding the extension of ProSe (Proximity-based Services) functions (see Non-Patent Document 4).

[0003] 3GPP TS 23.304 V19.0.0 (2024-06); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Proximity based Services (ProSe) in the 5G System (5GS); (Release 18)3GPP TS 24.554 V18.4.0 (2024-03); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Proximity-services (ProSe) in 5G System (5GS) protocol aspects; Stage 3 (Release 18)3GPP TS 24.501 V18.6.0 (2024-03); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (Release 18)3GPP TR 23.700-03 V1.0.0 (2024-06); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on system enhancement for Proximity based Services (ProSe) in the 5G System (5GS); Phase 3 (Release 19)

[0004] Currently, 5GS specifies proximity wireless communication between UEs in ProSe (Proximity-services). It also specifies that a remote UE connects to a network via a U2N (UE-to-network) relay UE. Release 19 adds U2N intermediate UE, and considers multi-hop communication in which a remote UE connects to a network via a U2N intermediate UE and a U2N relay UE.

[0005] The application of the additional parameter announcement procedure to multi-hop communication is also being considered. However, it is not clear what kind of timers U2N intermediate UEs should manage in the additional parameter announcement procedure, and how they should operate using the timers.

[0006] In addition, it is not clear what timers the U2N intermediate UE manages in the discovery procedure model B for signal strength measurement, and how it operates using the timers.

[0007] This embodiment has been made in consideration of the above circumstances. In this embodiment, the timers managed by the U2N intermediate UE and the operation of the U2N intermediate UE using the timers in the additional parameter announcement procedure are clarified. Furthermore, the timers managed by the U2N intermediate UE and the operation of the U2N intermediate UE using the timers in the discovery procedure model B for signal strength measurement are clarified.

[0008] A UE (User Equipment) of this embodiment is a UE including a transceiver unit and a controller, and the UE is a UE operating as a first 5G ProSe (Proximity based Services) intermediate U2N (UE-to-network) relay UE, the transceiver unit receives a PROSE additional parameter announcement response message including a first timer value and a second timer value from a 5G ProSe U2N relay UE, the controller starts a second timer using the second timer value, the transceiver unit transmits a PROSE additional parameter announcement response message including the first timer value to a second 5G ProSe intermediate U2N relay UE, and if the second timer has not expired, the transceiver unit transmits a PROSE PC5 discovery message for relay discovery additional information to the second 5G ProSe intermediate U2N relay UE, the first timer value is a timer value of a first timer, and the first timer is a timer value of the 5G ProSe remote relay UE. The second timer is a timer for controlling a PROSE additional parameter announcement request message transmitted by a UE, the second timer value is a timer value of a second timer, and the second timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the 5G ProSe intermediate relay UE.

[0009] A UE (User Equipment) of this embodiment is a UE including a transceiver unit and a controller, and the UE is a UE operating as a 5G ProSe (Proximity based Services) U2N (UE-to-network) relay UE, the transceiver unit receives a PROSE additional parameter announcement request message from a 5G ProSe intermediate U2N relay UE, the controller determines a first timer value and a second timer value and starts a third timer, the transceiver unit transmits a PROSE additional parameter announcement response message including the first timer value and the second timer value to the 5G ProSe intermediate U2N relay UE, and if the third timer has not expired, the transceiver unit transmits a PROSE PC5 discovery message for relay discovery additional information to the 5G ProSe intermediate U2N relay UE, the first timer value is a timer value of a first timer, and the first timer is a timer value of the 5G ProSe remote The third timer is a timer for controlling a PROSE additional parameter announcement request message transmitted by a UE, the second timer value is a timer value of a second timer, the second timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the 5G ProSe intermediate relay UE, and the third timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the transceiver unit.

[0010] According to this embodiment, the timers managed by the U2N intermediate UE and the operation of the U2N intermediate UE using the timers in the additional parameter announcement procedure are clarified. Furthermore, the timers managed by the U2N intermediate UE and the operation of the U2N intermediate UE using the timers in the discovery procedure model B for signal strength measurement are clarified.

[0011] FIG. 1 is a diagram illustrating an overview of a mobile communication system (EPS / 5GS). FIG. 2 is a diagram illustrating a detailed configuration of a mobile communication system (EPS / 5GS). FIG. 3 is a diagram illustrating a device configuration of a UE. FIG. 4 is a diagram illustrating a configuration of an access network device (gNB) in 5GS. FIG. 5 is a diagram illustrating a configuration of a core network device (AMF / SMF / UPF) in 5GS. FIG. 6 is a diagram illustrating a registration procedure. FIG. 7 is a diagram illustrating a discovery procedure model B for signal strength measurement. FIG. 8 is a diagram illustrating an additional parameter announcement procedure. FIG. 9 is a diagram illustrating a 5G ProSe direct link establishment procedure.

[0012] Hereinafter, a mode for carrying out the present embodiment will be described with reference to the drawings. In this embodiment, as an example, an embodiment of a mobile communication system to which the present embodiment is applied will be described.

[0013] [1. System Overview] First, FIG. 1 is a diagram for explaining an overview of a mobile communication system 1 used in each embodiment, and FIG. 2 is a diagram for explaining a detailed configuration of the mobile communication system 1.

[0014] FIG. 1 shows that the mobile communication system 1 is composed of UE_A10, access network _A80, core network _A90, PDN (Packet Data Network) _A5, access network _B120, core network _B190, and DN (Data Network) _A6.

[0015] In the following, these devices and functions may be referred to by abbreviating the symbols, such as UE, access network_A, core network_A, PDN, access network_B, core network_B, DN, etc.

[0016] Figure 2 also shows devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, UDM150, and N3IWF170, as well as interfaces that connect these devices and functions to each other.

[0017] In the following, these devices and functions may be referred to by abbreviated symbols such as UE, E-UTRAN, MME, SGW, PGW-U, PGW-C, PCRF, HSS, 5G AN, AMF, UPF, SMF, PCF, UDM, N3IWF, etc.

[0018] The 4G system EPS (Evolved Packet System) includes an access network _A and a core network _A, but may further include a UE and / or a PDN. The 5G system 5GS (5G System) includes a UE, an access network _B, and a core network _B, but may further include a DN.

[0019] The UE is a device that can connect to a network service via 3GPP access (also referred to as a 3GPP access network, or 3GPP AN) and / or non-3GPP access (also referred to as a non-3GPP access network, or 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 that can connect to both EPS and 5GS. The UE may include a UICC (Universal Integrated Circuit Card) or an eUICC (Embedded UICC).

[0020] Furthermore, access network_A corresponds to an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) and / or a wireless LAN access network. One or more eNBs (evolved Node Bs) 45 are deployed in the E-UTRAN. Note that, hereinafter, the eNB 45 may be referred to by abbreviating the symbol eNB. If there are multiple eNBs, the eNBs are connected to each other, for example, via an X2 interface. Furthermore, one or more access points are deployed in the wireless LAN access network.

[0021] Furthermore, access network_B corresponds to a 5G access network (5G AN). The 5G AN is composed of an NG-RAN (NG Radio Access Network) and / or a non-3GPP access network. One or more gNBs (NR NodeBs) 122 are deployed in the NG-RAN. Note that, hereinafter, the symbol for gNB 122 may be abbreviated, such as gNB. The gNB is a node that provides the NR (New Radio) user plane and control plane to UEs and connects to the 5GCN via an NG interface (including an N2 interface or an N3 interface). In other words, the 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. Furthermore, when there are multiple gNBs, the gNBs are connected to each other, for example, via an Xn interface.

[0022] Furthermore, the non-3GPP access network may be an untrusted non-3GPP access network or a trusted non-3GPP access network. Here, the 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 wireless LAN. On the other hand, the trusted non-3GPP access network may be an access network specified by 3GPP, and may include a trusted non-3GPP access point (TNAP) and a trusted non-3GPP gateway function (TNGF).

[0023] In the following, E-UTRAN and NG-RAN may be referred to as 3GPP access. Also, wireless LAN access networks and non-3GPP AN may be referred to as non-3GPP access. Also, nodes located in access network_B may be collectively referred to as NG-RAN nodes.

[0024] Furthermore, in the following, access network _A, and / or access network _B, and / or devices included in access network _A, and / or devices included in access network _B may be referred to as access networks or access network devices.

[0025] The core network_A corresponds to an EPC (Evolved Packet Core), which includes, for example, an MME (Mobility Management Entity), an SGW (Serving Gateway), a PGW (Packet Data Network Gateway)-U, a PGW-C, a PCRF (Policy and Charging Rules Function), and an HSS (Home Subscriber Server).

[0026] Furthermore, the core network_B corresponds to a 5G Core Network (5GCN). In the 5GCN, for example, an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), a Policy Control Function (PCF), a Unified Data Management (UDM), etc. are arranged. Here, the 5GCN may be expressed as a 5GC.

[0027] In addition, in the following, core network _A and / or core network _B, devices included in core network _A, and / or devices included in core network _B may be referred to as core networks, core network devices, or devices within the core network.

[0028] 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, or 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).

[0029] Also, while FIG. 1 illustrates a case where the PDN and the DN are the same, they may be different. The PDN may be a DN (Data Network) that provides communication services to the UE. The DN may be configured as a packet data service network, or may be configured for each service. Furthermore, the PDN may include a connected communication terminal. Therefore, connecting to the PDN may mean connecting to a communication terminal or a server device located in the PDN. Furthermore, transmitting and receiving user data to and from the PDN may mean transmitting and receiving user data to and from a communication terminal or a server device located in the PDN. The PDN may be referred to as the DN, and the DN may be referred to as the PDN.

[0030] In addition, hereinafter, at least a portion of the access network _A, the core network _A, the PDN, the access network _B, the core network _B, and the DN, and / or one or more devices included therein may be referred to as a network or a network device. In other words, when a network and / or a network device sends or receives a message and / or performs a procedure, it means that at least a portion of the access network _A, the core network _A, the PDN, the access network _B, the core network _B, and the DN, and / or one or more devices included therein send or receive a message and / or perform a procedure.

[0031] The UE can also connect to an access network. The UE can also connect to a core network via the access network. The UE can also connect to a PDN or DN via the access network and the core network. That is, the UE can transmit and receive (communicate) user data with the PDN or DN. When transmitting and receiving user data, not only IP (Internet Protocol) communication but also non-IP communication can be used.

[0032] Here, IP communication refers to data communication using IP, and data is transmitted and received using IP packets. An IP packet consists of an IP header and a payload portion. The payload portion may include data transmitted 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, and data is transmitted and received in a format different from the IP packet structure. For example, non-IP communication may be data communication achieved by transmitting and receiving application data without an IP header, or it may be user data transmitted and received by a UE with a different header such as a MAC header or an Ethernet (registered trademark) frame header.

[0033] In addition, access network _A, core network _A, access network _B, core network _B, PDN_A, and DN_A may be configured with devices not shown in Fig. 2. For example, core network _A and / or core network _B may include an AUSF (Authentication Server Function) and an AAA (Authentication, authorization, and accounting) server (AAA-S).

[0034] Here, the AUSF is a core network device having an authentication function for 3GPP access and non-3GPP access, specifically, a network function unit that receives an authentication request for 3GPP access and / or non-3GPP access from a UE and executes the authentication procedure.

[0035] The AAA server is a device that has authentication, authorization, and accounting functions and is connected to the AUSF directly or indirectly via another network device. The AAA server may be a network device within the core network. The AAA server may not be included in the core network _A and / or core network _B, but may be included in the PLMN. In other words, the AAA server may be a core network device or a device outside the core network. For example, the AAA server may be a server device within the PLMN managed by a third party.

[0036] 2, for the sake of simplicity, each device and function is shown one by one, but multiple similar devices and functions may be configured in the mobile communication system 1. Specifically, the mobile communication system 1 may be configured with multiple devices and functions such as UE_A10, E-UTRAN80, MME40, SGW35, PGW-U30, PGW-C32, PCRF60, HSS50, 5G AN120, AMF140, UPF130, SMF132, PCF160, and / or UDM150.

[0037] The UPF_A235 is connected to the DN, the SMF, other UPFs, and the access network. The UPF_A235 may perform functions such as an anchor for intra-RAT mobility or inter-RAT mobility, packet routing and forwarding, an UL CL (Uplink Classifier) ​​function that supports routing of multiple traffic flows for one DN, a branching point function that supports multi-homed PDU sessions, QoS processing for the user plane, verification of uplink traffic, buffering of downlink packets, and a trigger function for downlink data notification. The UPF_A235 may also be a relay device that forwards user data as a gateway between the DN and the core network_B190. The UPF_A235 may also be a gateway for IP communication and / or non-IP communication. The UPF_A235 may also have a function for forwarding IP communication and a function for converting non-IP communication to IP communication. Furthermore, multiple gateways may be gateways that connect the core network _B190 to a single DN. Note that UPF_A235 may have connectivity with other NFs and may be connected to each device via other NFs.

[0038] Between UPF_A235 and the access network, UPF_C239 (also called a branching point or uplink classifier), which is a UPF different from UPF_A235, may exist as a device or NF. When UPF_C239 exists, a PDU session between the UE and the DN will be established via the access network, UPF_C239, and UPF_A235.

[0039] Furthermore, the UPF 130 may be the same device as the UPF_A 235. Note that the UPF 130 and the UPF_A 235 may be written with the symbols omitted, such as UPF.

[0040] [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 the drawings. Each device may be configured as physical hardware, as logical (virtual) hardware configured on general-purpose hardware, or as software. Furthermore, at least a part (including all) of the functions of each device may be configured as physical hardware, logical hardware, or software.

[0041] Note that each memory unit (memory unit_A340, memory unit_A440, memory unit_B540, memory unit_A640, memory unit_B740) in each device / function mentioned below is configured with, for example, a semiconductor memory, a solid state drive (SSD), a hard disk drive (HDD), etc. Furthermore, each memory unit can store not only information originally set at the time of shipment, but also various information transmitted and received between devices / functions other than the device / function itself (e.g., UE, and / or access network device, and / or core network device, and / or PDN, and / or DN). Furthermore, each memory unit can store identification information, control information, flags, parameters, etc. included in control messages transmitted and received in various communication procedures described below. Furthermore, each memory unit may store this information for each UE. Furthermore, when interworking between 5GS and EPS is performed, each memory unit can store control messages and user data transmitted and received between 5GS and / or devices / functions included in EPS. At this time, not only those transmitted and received via the N26 interface but also those transmitted and received without going through the N26 interface can be stored.

[0042] [2.1. Device configuration of UE] First, an example of the device configuration of UE (User Equipment) will be explained using Figure 3. The UE is composed of a control unit _A300, an antenna 310, a transceiver unit _A320, and a memory unit _A340. The control unit _A300, the transceiver unit _A320, and the memory unit _A340 are connected via a bus. The transceiver unit _A320 is connected to the antenna 310.

[0043] The control unit _A300 is a functional unit that controls the operation and functions of the entire UE. The control unit _A300 realizes various processing in the UE by reading and executing various programs stored in the memory unit _A340 as necessary.

[0044] The transceiver unit _A320 is a functional unit for wireless communication with a base station device (eNB or gNB) in the access network via an antenna. That is, the UE can use the transceiver unit _A320 to transmit and receive user data and / or control information between an access network device, and / or a core network device, and / or a PDN, and / or a DN.

[0045] Explaining in detail with reference to Figure 2, the UE can communicate with a base station device (eNB) in the E-UTRAN via the LTE-Uu interface by using the transceiver unit _A320. The UE can also communicate with a base station device (gNB) in the 5G AN by using the transceiver unit _A320. The UE can also transmit and receive AMF and NAS (Non-Access-Stratum) messages via the N1 interface by using the transceiver unit _A320. However, since the N1 interface is logical, in reality, communication between the UE and the AMF is performed via the 5G AN.

[0046] The memory unit _A340 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the UE.

[0047] The UE in this embodiment may be a 5G ProSe-enabled UE.

[0048] [2.2. gNB Device Configuration] Next, an example of the gNB device configuration will be described using Figure 4. The gNB is composed of a control unit _B500, an antenna 510, a network connection unit _B520, a transceiver unit _B530, and a memory unit _B540. The control unit _B500, the network connection unit _B520, the transceiver unit _B530, and the memory unit _B540 are connected via a bus. The transceiver unit _B530 is connected to the antenna 510.

[0049] The control unit _B500 is a functional unit that controls the operation and functions of the entire gNB. The control unit _B500 realizes various processes in the gNB by reading and executing various programs stored in the memory unit _B540 as necessary.

[0050] The network connection unit _B520 is a functional unit for the gNB to communicate with the AMF and / or UPF. That is, the gNB can send and receive user data and / or control information between the AMF and / or UPF using the network connection unit _B520.

[0051] The transceiver unit _B530 is a functional unit for wireless communication with the UE via the antenna 510. That is, the gNB can transmit and receive user data and / or control information to and from the UE using the transceiver unit _B530.

[0052] 2, a gNB in ​​a 5G AN can communicate with an AMF via an N2 interface by using a network connection unit _B 520, and can communicate with a UPF via an N3 interface, and can communicate with a UE by using a transceiver unit _B 530.

[0053] The memory unit _B540 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the gNB.

[0054] [2.3. AMF Device Configuration] Next, an example of the AMF device configuration will be explained using Figure 5. The AMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The AMF may be a node that handles the control plane.

[0055] The control unit _B700 is a functional unit that controls the operation and functions of the entire AMF. The control unit _B700 realizes various processing in the AMF by reading and executing various programs stored in the memory unit _B740 as needed.

[0056] The network connection unit _B720 is a functional unit for the AMF to connect to a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF in a 5G AN. In other words, the AMF can use the network connection unit _B720 to send and receive user data and / or control information between a base station device (gNB), and / or SMF, and / or PCF, and / or UDM, and / or SCEF in a 5G AN.

[0057] Explaining in detail with reference to FIG. 2, the AMF in the 5GCN can communicate with a gNB via the N2 interface by using the network connection unit _A620, can communicate with a UDM via the N8 interface, can communicate with an SMF via the N11 interface, and can communicate with a PCF via the N15 interface. The AMF can also send and receive NAS messages with a UE via the N1 interface by using the network connection unit _A620. However, since the N1 interface is logical, communication between the UE and the AMF is actually performed via a 5G AN. Furthermore, if the AMF supports the N26 interface, it can communicate with an MME via the N26 interface by using the network connection unit _A620.

[0058] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the AMF.

[0059] 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) functions, connection management (CM) functions, reachability management functions, mobility management functions for UEs, etc., transferring SM (Session Management) messages between the UE and the SMF, access authentication (Access Authorization) functions, security anchor functionality (SEA), security context management (SCM), a function to support the N2 interface for the N3IWF (Non-3GPP Interworking Function), a function to support sending and receiving NAS signals with the UE via the N3IWF, and a function to authenticate UEs connected via the N3IWF.

[0060] In addition, registration management manages the RM state for each UE. The RM state may be synchronized between the UE and the AMF. The RM state includes an unregistered state (RM-DEREGISTERED state) and a registered state (RM-REGISTERED state). In the RM-DEREGISTERED state, the UE is not registered with the network, and therefore the UE context in the AMF does not have valid location information or routing information for the UE, and therefore the AMF cannot reach the UE. In the RM-REGISTERED state, the UE is registered with the network, and therefore the UE can receive services that require registration with the network. Note that the RM state may also be expressed as a 5GMM state. In this case, the RM-DEREGISTERED state may be expressed as a 5GMM-DEREGISTERED state, and the RM-REGISTERED state may be expressed as a 5GMM-REGISTERED state.

[0061] In other words, 5GMM-REGISTERED may be a state in which each device has established a 5GMM context or a PDU session context. When each device is 5GMM-REGISTERED, UE_A10 may start transmitting and receiving user data and control messages, or may respond to paging. Furthermore, 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.

[0062] Furthermore, 5GMM-DEREGISTERED may be a state in which each device has not established a 5GMM context, a state in which UE_A10's location information is not known to the network, or a state in which UE_A10 is unreachable from the network. Note that when each device is 5GMM-DEREGISTERED, UE_A10 may initiate a registration procedure or may establish a 5GMM context by performing the registration procedure.

[0063] In addition, connection management manages the CM state for each UE. The CM state may be synchronized between the UE and the AMF. The CM state includes a non-connected state (CM-IDLE state) and a 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. In the CM-IDLE state, the UE does not have an N2 interface connection or an N3 interface 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. In the CM-CONNECTED state, the UE may have an N2 interface connection and / or an N3 interface connection.

[0064] Furthermore, in connection management, the CM state in 3GPP access and the CM state in non-3GPP access may be managed separately. In this case, the CM state in 3GPP access may include a non-connected state in 3GPP access (CM-IDLE state over 3GPP access) and a connected state in 3GPP access (CM-CONNECTED state over 3GPP access). Furthermore, the CM state in non-3GPP access may include a non-connected state in non-3GPP access (CM-IDLE state over non-3GPP access) and a connected state in non-3GPP access (CM-CONNECTED state over non-3GPP access). Note that the non-connected state may be expressed as an idle mode, and the connected state mode may be expressed as a connected mode.

[0065] The CM state may be expressed as a 5GMM mode. In this case, the unconnected state may be expressed as a 5GMM-IDLE mode, and the connected state may be expressed as a 5GMM-CONNECTED mode. Furthermore, the unconnected state in 3GPP access may be expressed as a 5GMM-IDLE mode over 3GPP access, and the connected state in 3GPP access may be expressed as a 5GMM-CONNECTED mode over 3GPP access. Furthermore, the unconnected state in non-3GPP access may be expressed as 5GMM unconnected mode in non-3GPP access (5GMM-IDLE mode over non-3GPP access), and the connected state in non-3GPP access may be expressed as 5GMM connected mode in non-3GPP access (5GMM-CONNECTED mode over non-3GPP access). Note that the 5GMM unconnected mode may be expressed as idle mode, and the 5GMM connected mode may be expressed as connected mode.

[0066] In addition, one or more AMFs may be placed in the core network _B. In addition, the AMF may be a Network Function (NF) that manages one or more Network Slice Instances (NSIs). In addition, the AMF may be a Common Control Plane Network Function (CCNF) shared among multiple NSIs.

[0067] In addition, the N3IWF is a device and / or function located between the non-3GPP access and the 5GCN when the UE connects to the 5GS via the non-3GPP access.

[0068] [2.4. SMF Device Configuration] Next, an example of the SMF device configuration will be explained using Figure 5. The SMF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The SMF may be a node that handles the control plane.

[0069] The control unit _B700 is a functional unit that controls the operation and functions of the entire SMF. The control unit _B700 realizes various processing in the SMF by reading and executing various programs stored in the memory unit _B740 as needed.

[0070] 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 send and receive user data and / or control information between the AMF, and / or UPF, and / or PCF, and / or UDM using the network connection unit _B720.

[0071] Explaining in more detail with reference to Figure 2, the SMF in the 5GCN can communicate with the AMF via the N11 interface, with the UPF via the N4 interface, with the PCF via the N7 interface, and with the UDM via the N10 interface by using the network connection unit _A620.

[0072] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the SMF.

[0073] The SMF has session management functions such as establishing, modifying, and releasing PDU sessions, IP address allocation for UEs and its management, UPF selection and control, UPF configuration for routing traffic to the appropriate destination, sending and receiving the SM portion of NAS messages, Downlink Data Notification, providing AN-specific (for each AN) SM information to be sent to the AN via the N2 interface via the AMF, determining the SSC mode (Session and Service Continuity mode) for the session, and roaming functions.

[0074] [2.5. UPF Device Configuration] Next, an example of the UPF device configuration will be explained using Figure 5. The UPF is composed of a control unit _B700, a network connection unit _B720, and a memory unit _B740. The control unit _B700, the network connection unit _B720, and the memory unit _B740 are connected via a bus. The UPF may be a node that handles the control plane.

[0075] The control unit _B700 is a functional unit that controls the operation and functions of the entire UPF.The control unit _B700 realizes various processing in the UPF by reading and executing various programs stored in the memory unit _B740 as needed.

[0076] The network connection unit _B720 is a functional unit for the UPF to connect to a base station device (gNB), and / or SMF, and / or DN within the 5G AN. In other words, the UPF can use the network connection unit _B720 to transmit and receive user data and / or control information between the base station device (gNB), and / or SMF, and / or DN within the 5G AN.

[0077] Explaining in more detail with reference to Figure 2, a UPF in a 5GCN can communicate with a gNB via the N3 interface, with an SMF via the N4 interface, with a DN via the N6 interface, and with other UPFs via the N9 interface by using the network connection unit _A620.

[0078] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

[0079] The UPF has functions such as an anchor point for intra-RAT mobility or inter-RAT mobility, an external PDU session point for interconnecting to DNs (i.e., a gateway between DNs and core network_B that forwards user data), packet routing and forwarding, an UL CL (Uplink Classifier) ​​function that supports routing of multiple traffic flows to one 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 notifications.

[0080] The UPF may also be a gateway for IP communication and / or non-IP communication. The UPF may also have a function for forwarding IP communication and a function for converting non-IP communication and IP communication. Furthermore, multiple gateways may be gateways that connect the core network_B to a single DN. The UPF may also have connectivity with other NFs and may be connected to each device via other NFs.

[0081] The user plane refers to user data transmitted and received between a UE and a network. The user plane may be transmitted and received using a PDN connection or a PDU session. Furthermore, 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 the U-Plane.

[0082] Furthermore, the control plane refers to control messages transmitted and received to control UE communications, etc. The control plane may be transmitted and received using a Non-Access-Stratum (NAS) signaling connection between the UE and the MME. Furthermore, in the case of EPS, the control plane may be transmitted and received using the LTE-Uu interface and the S1-MME interface. Furthermore, 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.

[0083] Furthermore, the U-Plane (User Plane; UP) may be a communication path for transmitting and receiving user data and may be composed of multiple bearers. Furthermore, the C-Plane (Control Plane; CP) may be a communication path for transmitting and receiving control messages and may be composed of multiple bearers.

[0084] [2.6. Description of Other Devices and / or Functions] Next, other devices and / or functions will be described.

[0085] The network refers to at least a portion of the access network _B, the core network _B, and the DN. Furthermore, one or more devices included in at least a portion of the access network _B, the core network _B, and the DN may be referred to as a network or a network device.

[0086] That is, when a network transmits, receives, and / or processes messages, it may mean that devices in the network (network devices and / or control devices) transmit, receive, and / or process messages. Conversely, when a device in the network transmits, receives, receives, and / or processes messages, it may mean that the network transmits, receives, receives, and / or processes messages.

[0087] The network may refer to a public land mobile network (PLMN) or a non-public network (NPN). The network may also be referred to as a NW.

[0088] A PLMN (Public Land Mobile Network) is a communication network that provides mobile radio communication services. A PLMN is a network managed by an operator, which is a communications carrier, and the operator can be identified by a PLMN ID. A PLMN that matches the MCC (Mobile Country Code) and MNC (Mobile Network Code) of a UE's IMSI (International Mobile Subscription Identity) may be a Home PLMN (HPLMN). Furthermore, the UE may store an Equivalent PLMN list in its USIM to identify one or more Equivalent PLMNs (EPLMNs). A PLMN different from the HPLMN and / or EPLMN may be a Visited PLMN (VPLMN). A PLMN to which the UE has successfully registered may be a Registered PLMN (RPLMN).

[0089] A registration area is a set of one or more TAs assigned to a UE by the AMF. Note that while UE_A10 is moving within one or more TAs included in the registration area, it may be able to move without sending or receiving signals for tracking area update. In other words, a registration area may be a group of information indicating areas in which UE_A10 can move without performing a tracking area update procedure. A registration area may be identified by a TAI list consisting of one or more TAIs.

[0090] A tracking area (TA) is a single or multiple ranges managed by the core network that can be represented by the location information of UE_A10. A tracking area may be composed of multiple cells. Furthermore, a tracking area may be an area in which control messages such as paging are broadcast, or an area in which UE_A10 can move without performing a handover procedure. Furthermore, a tracking area (also referred to as a TA) may be a routing area, a location area, or anything similar. A tracking area may be identified by a tracking area identity (TAI) consisting of a tracking area code (TAC) and a PLMN.

[0091] A tracking area identity (TAI) may be information that identifies a TA. The TAI may be composed of a mobile country code (MCC), a mobile network code (MNC), and a tracking area code (TAC).

[0092] A TA list is a list that includes one or more TAs assigned by the network to UE_A10. Note that UE_A10 may be able to move without performing a tracking area update procedure while moving within one or more TAs included in the TA list. In other words, UE_A10 may use the TA list as a group of information indicating areas in which UE_A10 can move without performing a tracking area update procedure. Note that the TA list may also be expressed as a TAI list consisting of one or more TAIs (Tracking area identities), and hereinafter, the TAI list may refer to the TA list.

[0093] The NG-RAN Cell Global ID (NCGI) or NR Cell Global Identity (NR Cell Global Identity) may be information that identifies an NG-RAN cell. The NCGI may be a combination of a PLMN Identifier (PLMN-Id) and an NR Cell Identity (NCI). The NCGI may be globally unique.

[0094] An SM (Session Management) message may be a NAS message used in a procedure for SM. The SM message may also be referred to as a NAS (Non-Access-Stratum) SM message. The SM message may be a control message transmitted and received between UE_A10 and SMF_A230 via AMF_A240.

[0095] An MM (Mobility management) message may be a NAS message used in procedures for MM. The MM message may be a control message transmitted and received between UE_A10 and AMF_A240. Note that the MM message may also be referred to as a NAS MM message.

[0096] 5GS (5G System) service may be a connection service provided using core network _B190.

[0097] A non-5GS service may be a service other than a 5GS service.

[0098] A PDU (Protocol Data Unit) session can be defined as an association between a DN providing a PDU connectivity service and a UE, but it may also be connectivity established between a UE and an external gateway. In 5GS, a UE can transmit and receive user data to and from a DN by establishing a PDU session via an access network _B and a core network _B. Here, this external gateway may be a UPF, SCEF, or the like. The UE can transmit and receive user data to and from a device such as an application server located in the DN using the PDU session. Note that each device (UE, and / or access network device, and / or core network device) may manage one or more pieces of identification information associated with a PDU session. Note that this identification information may include one or more of a DNN, a QoS rule, a PDU session type, an application identification information, an NSI identification information, an access network identification information, and an SSC mode, or may further include other information. Furthermore, when multiple PDU sessions are established, the identification information associated with each PDU session may be the same or different.

[0099] The DNN (Data Network Name) may be identification information for identifying a core network and / or an external network such as a DN. Furthermore, the DNN can also be used as information for selecting a gateway such as a PGW / UPF that connects the core network B190.

[0100] 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, and 5G ProSe UE-to-Network Relay.

[0101] The PC5 path may be a communication path on the PC5. The PC5 path may also be a communication path between ProSe-enabled UEs. The PC5 path may also refer to the PC5. The PC5 path may also be referred to as a PC5 interface.

[0102] The PC5 link may be a PC5 path. The PC5 link may be referred to as a PC5 direct link, a 5G ProSe direct link, or a direct link. The PC5 link may simply be referred to as a link.

[0103] Uu may be a radio interface, and Uu may be a radio interface between a 5G AN and a UE.

[0104] The Uu path may be a communication path on the Uu. The Uu path may also be a communication path between the 5G AN and the UE. The Uu path may also refer to the Uu. The Uu path may also be referred to as a Uu interface. The Uu path may also be referred to as a Uu link.

[0105] 5G Proximity-based Services (ProSe) may be services provided by 5GS based on UEs being in close proximity to each other. 5G ProSe may also be referred to as ProSe.

[0106] A 5G ProSe-enabled UE may be a UE that supports 5G ProSe requirements and related procedures. A 5G ProSe-enabled UE may also be referred to as a ProSe-capable UE.

[0107] The remote UE may be a ProSe-enabled UE that communicates with the DN via a U2N relay UE.

[0108] 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. Note that the 5G ProSe layer-2 remote UE may be a 5G ProSe capable UE that communicates with the DN via a 5G ProSe layer-2 UE-to-network relay UE. Also, the 5G ProSe layer-3 remote UE may be a 5G ProSe capable UE that communicates with the DN via a 5G ProSe layer-3 UE-to-network relay UE.

[0109] A remote UE may also be referred to as a UE acting as a remote UE.

[0110] Furthermore, a 5G ProSe layer-2 remote UE is a 5G ProSe-enabled UE that communicates with a DN via a 5G ProSe layer-2 U2N relay UE, and may be referred to as a layer-2 remote UE.

[0111] Also, a 5G ProSe layer-3 remote UE is a 5G ProSe-enabled UE that communicates with a DN via a 5G ProSe layer-3 UE-to-network relay UE. The 5G ProSe layer-3 remote UE may also be referred to as a layer-3 remote UE.

[0112] A U2N (UE-to-network) relay UE may be a ProSe-enabled UE that provides functionality to support network connectivity for remote UEs.

[0113] 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. Note that the 5G ProSe layer-2 U2N relay UE may be a 5G ProSe capable UE that provides functionality to support network connectivity for 5G ProSe layer-2 remote UEs via a layer 2 protocol. Also, the 5G ProSe layer-3 U2N relay UE may be a 5G ProSe capable UE that provides functionality to support network connectivity for 5G ProSe layer-3 remote UEs via a layer 3 protocol.

[0114] A U2N relay UE may be referred to as a UE that operates as a U2N relay UE, a U2N relay UE may be referred to as a target relay UE, and a U2N relay UE may be referred to as a U2N relay.

[0115] In addition, 5G ProSe layer-2 U2N relay UE is a 5G ProSe-enabled UE that provides the functionality to support the network connectivity of 5G ProSe layer-2 remote UE via layer-2 protocol.

[0116] In addition, 5G ProSe layer-3 U2N relay UE is a 5G ProSe-enabled UE that provides the functionality to support the network connectivity of 5G ProSe layer-3 remote UE via layer-3 protocol.

[0117] Note that a communication mode in which a remote UE connects to a network via a U2N relay UE may be referred to as 5G ProSe UE-to-network relaying. 5G ProSe UE-to-network relaying may simply be referred to as relaying, 5G ProSe UE-to-network relay, relay, or U2N relay.

[0118] A U2N (UE-to-network) intermediate UE may be a ProSe-enabled UE that provides functionality to support connectivity between a remote UE and a U2N relay UE.

[0119] The U2N intermediate UE may be a 5G ProSe U2N intermediate UE, a 5G ProSe layer-2 U2N intermediate UE, or a 5G ProSe layer-3 U2N intermediate UE. Note that the 5G ProSe layer-2 U2N intermediate UE may be a 5G ProSe capable UE that provides functionality to support connection to a network for a 5G ProSe layer-2 remote UE via a layer 2 protocol and / or a 5G ProSe layer-2 UE-to-network relay UE. Also, the 5G ProSe layer-3 U2N intermediate UE may be a 5G ProSe capable UE that provides functionality to support connection to a network for a 5G ProSe layer-3 remote UE via a layer 3 protocol and / or a 5G ProSe layer-2 UE-to-network relay UE.

[0120] A U2N intermediate UE may be referred to as a UE that acts as a U2N intermediate UE. A U2N intermediate UE may be referred to as an intermediate U2N UE.

[0121] In addition, the 5G ProSe layer-2 U2N intermediate UE may be a 5G ProSe-enabled UE that provides functionality to support connectivity between a 5G ProSe layer-2 remote UE and a 5G ProSe layer-2 U2N relay UE via a layer-2 protocol.

[0122] In addition, the 5G ProSe layer-3 U2N intermediate UE may be a 5G ProSe-enabled UE that provides functionality to support connectivity between a 5G ProSe layer-3 remote UE and a 5G ProSe layer-3 U2N relay UE via a layer-3 protocol.

[0123] There may be one or more U2N intermediate UEs. For example, there may be a first U2N intermediate UE and a second U2N intermediate UE between the remote UE and the U2N relay UE, in this order from the left.

[0124] Furthermore, a U2N intermediate UE may be referred to as a Relay participated in multi-hop U2N relaying or as a 5G ProSe Intermediate Relay. Furthermore, a U2N intermediate UE may be referred to as a multi-hop U2N relay UE or as a 5G ProSe multi-hop U2N relay UE. A U2N intermediate UE may be referred to as a 5G ProSe layer-2 multi-hop U2N relay UE or as a 5G ProSe layer-3 multi-hop U2N relay UE.

[0125] Multi-hop communication may refer to communication via two or more UEs, or a UE communicating to another UE or a network via two or more other UEs.

[0126] For example, a remote UE connecting to a network via one or more U2N intermediate UEs and U2N relay UEs may be referred to as multi-hop communication, where the remote UE, the U2N intermediate UE, and / or the U2N relay UE may support multi-hop.

[0127] Multi-hop communication may be simply referred to as multi-hop. Also, 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.

[0128] The multi-hop communication may be a UE-to-network relay multi-hop communication.

[0129] In addition, a UE that supports multi-hop U2N relay UE may be a UE that supports operating as a U2N intermediate UE.

[0130] In addition, a UE that supports multi-hop may be a UE that supports multi-hop U2N relay UE.

[0131] Supporting multi-hop or multi-hop functionality may mean supporting operation as a U2N intermediate UE.

[0132] [2.7. Description of Identification Information in This Embodiment] Next, the identification information transmitted, received, stored, and / or managed by each device in this embodiment will be described.

[0133] The first identification information may be information indicating whether the UE supports operating as a remote UE. The first identification information may be information indicating that the UE supports operating as a remote UE. The first identification information may be information indicating that the UE does not support operating as a remote UE.

[0134] The first identification information may be information indicating whether the UE supports operating as a layer-2 remote UE. The first identification information may be information indicating that the UE supports operating as a layer-2 remote UE. The first identification information may be information indicating that the UE does not support operating as a layer-2 remote UE.

[0135] 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".

[0136] The first identification information indicating that the UE supports operating as a layer-2 remote UE may be "Acting as a 5G ProSe layer-2 UE-to-network remote UE supported". The first identification information indicating that the 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".

[0137] The first identification information may be information indicating whether the UE supports operating as a layer-3 remote UE. The first identification information may be information indicating that the UE supports operating as a layer-3 remote UE. The first identification information may be information indicating that the UE does not support operating as a layer-3 remote UE.

[0138] 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".

[0139] The first identification information indicating that the 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 the 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".

[0140] The first identification information may be information included in a 5GMM capability information element (IE). The first identification information may be UE capability information.

[0141] The second identification information may be information indicating whether the UE supports operating as a U2N relay UE. The second identification information may be information indicating that the UE supports operating as a U2N relay UE. The second identification information may be information indicating that the UE does not support operating as a U2N relay UE.

[0142] The second identification information may be information indicating whether the UE supports operating as a layer-2 U2N relay UE. The second identification information may be information indicating that the UE supports operating as a layer-2 U2N relay UE. The second identification information may be information indicating that the UE does not support operating as a layer-2 U2N relay UE.

[0143] 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".

[0144] The second identification information indicating that the UE supports operating as a layer-2 U2N relay UE may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network relay UE supported". The second identification information indicating that the UE does not support operating as a layer-2 U2N relay UE may be information indicating "Acting as a 5G ProSe layer-2 UE-to-network relay UE not supported".

[0145] The second identification information may be information indicating whether the UE supports operating as a layer-3 U2N relay UE. The second identification information may be information indicating that the UE supports operating as a layer-3 U2N relay UE. The second identification information may be information indicating that the UE does not support operating as a layer-3 U2N relay UE.

[0146] 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".

[0147] The second identification information indicating that the UE supports operating as a layer-3 U2N relay UE may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network relay UE supported". The second identification information indicating that the UE does not support operating as a layer-3 U2N relay UE may be information indicating "Acting as a 5G ProSe layer-3 UE-to-network relay UE not supported".

[0148] The second identification information may be information included in a 5GMM capability information element (IE). The second identification information may be UE capability information.

[0149] The third identification information may be information indicating whether the UE supports operating as a U2N intermediate UE. The third identification information may be information indicating that the UE supports operating as a U2N intermediate UE. The third identification information may be information indicating that the UE does not support operating as a U2N intermediate UE.

[0150] The third identification information may be information indicating whether the UE supports operating as a layer-2 U2N intermediate UE. The third identification information may be information indicating that the UE supports operating as a layer-2 U2N intermediate UE. The third identification information may be information indicating that the UE does not support operating as a layer-2 U2N intermediate UE.

[0151] The third identification information may be information indicating whether the UE supports operating as a layer-3 U2N intermediate UE. The third identification information may be information indicating that the UE supports operating as a layer-3 U2N intermediate UE. The third identification information may be information indicating that the UE does not support operating as a layer-3 U2N intermediate UE.

[0152] The third identification information may be information included in a 5GMM capability information element (IE). The third identification information may be UE capability information.

[0153] The fourth identification information may be information indicating that the UE supports multi-hop. The fourth identification information may be information indicating that the UE does not support multi-hop. The fourth identification information may be information indicating whether the UE supports multi-hop.

[0154] The fourth identification information may be information indicating that the UE supports operating as a multi-hop UE. The fourth identification information may be information indicating that the UE does not support operating as a multi-hop UE. The fourth identification information may be information indicating whether the UE supports operating as a multi-hop UE.

[0155] The fourth identification information may be information indicating that the UE supports multi-hop. The fourth identification information may be information indicating that the UE does not support multi-hop. The fourth identification information may be information indicating whether the UE supports multi-hop.

[0156] The fourth identification information may be information included in a 5GMM capability information element (IE). The fourth identification information may be UE capability information.

[0157] The thirtieth identification information is a timer value. The thirtieth identification information may be a timer value of a fifth timer. The timer value of the fifth timer may be referred to as a fifth timer value.

[0158] The fifth timer may be a timer for controlling a PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message sent by the remote UE. The fifth timer may be T5106.

[0159] The fifth timer value may be determined by the U2N relay UE or by the U2N intermediate UE. The fifth timer value may be shorter than the third timer value. The fifth timer value may be smaller than the fourth timer value. In other words, the period of the fifth timer may be shorter than the period of the fourth timer.

[0160] The UE that has received the 30th identification information may set the timer value indicated by the 30th identification information in the corresponding timer. The detailed operation will be described later.

[0161] The 31st identification information is a timer value. The 31st identification information may be a timer value of a fourth timer. The timer value of the fourth timer may be referred to as a fourth timer value.

[0162] The fourth timer may be a timer for controlling a PROSE PC5 discovery message for relay discovery additional information sent by a U2N intermediate UE. The fourth timer may be a timer different from T5106 and T5107.

[0163] The fourth timer value may be determined by the U2N relay UE or by the U2N intermediate UE. The fourth timer value may be greater than the fifth timer value. Also, the fourth timer value may be smaller than the third timer value. In other words, the period of the fourth timer may be longer than the period of the fifth timer. Also, in other words, the period of the fourth timer may be shorter than the period of the third timer.

[0164] The UE that has received the 31st identification information may set the timer value indicated by the 31st identification information in the corresponding timer. The detailed operation will be described later.

[0165] The 32nd identification information may be information indicating an NCGI (NG-RAN Cell Global ID). The 32nd identification information may be information indicating an NCGI of a cell serving a U2N relay UE. The 32nd identification information may be information indicating an NCGI of a cell serving a U2N intermediate UE. The 32nd identification information may be an NCGI Information Element (IE).

[0166] Here, the 32nd identity of the U2N relay UE may be the NCGI of the cell serving the U2N relay UE. The 32nd identity of the U2N intermediate UE may be the NCGI of the cell serving the U2N intermediate UE.

[0167] The 33rd identification information may be information indicating a Tracking Area Identity (TAI). The 33rd identification information may be information indicating a TAI of a cell serving a U2N relay UE. The 33rd identification information may be information indicating a TAI of a cell serving a U2N intermediate UE. The 33rd identification information may be a TAI Information Element (IE). The 33rd identification information may be a Relay TAI IE.

[0168] Here, the 33rd identity of the U2N relay UE may be the TAI of the cell serving the U2N relay UE, and the 33rd identity of the U2N intermediate UE may be the TAI of the cell serving the U2N intermediate UE.

[0169] The 34th identification information is information indicating a cause value. The 34th identification information may be a cause value indicating that a 5G ProSe direct link already exists. The 34th identification information may be #21 (5G ProSe direct link already exists). Note that the 34th identification information may be a cause value included in a PC5 signaling protocol cause Information Element (IE).

[0170] The 35th identification information is a timer value. The 35th identification information may be a timer value of a third timer. The timer value of the third timer may be referred to as a third timer value.

[0171] The third timer may be a timer for controlling a PROSE PC5 discovery message for relay discovery additional information sent by a U2N relay UE. The third timer may be T5107.

[0172] The third timer value may be determined by the U2N relay UE. The third timer value may be greater than the fifth timer value. Also, the third timer value may be greater than the fourth timer value. In other words, the period of the third timer may be longer than the period of the fifth timer. Also, the period of the third timer may be shorter than the period of the fourth timer.

[0173] The UE that has received the 35th identification information may set the timer value indicated by the 35th identification information in the corresponding timer. The detailed operation will be described later.

[0174] [3. Description of Procedures Used in Each Embodiment] Next, procedures used in each embodiment will be described.

[0175] In each embodiment, as shown in FIG. 2, the HSS and UDM, PCF and PCRF, SMF and PGW-C, and UPF and PGW-U are each configured as the same device (i.e., the same physical hardware, the same logical hardware, or the same software). However, the contents described in this embodiment are also applicable to cases where 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 these devices, 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.

[0176] [3.1. Registration Procedure] First, the registration procedure will be explained using Figure 6. The registration procedure is a procedure under 5GS. In this chapter, the registration procedure may be referred to as this procedure.

[0177] This procedure is a procedure for the UE to initiate registration with the access network _B and / or the core network _B and / or the DN. If the UE is not registered with the network, it can execute this procedure at any time, for example, when it is powered on. In other words, if the UE is in the unregistered state (RM-DEREGISTERED state), it can start this procedure at any time.

[0178] The registration procedure initiated by a UE in an unregistered state may be referred to as a registration procedure for initial registration.

[0179] Furthermore, each device (particularly the UE and the AMF) can transition to a registered state (RM-REGISTERED state) based on completion of the registration procedure. Note that the registration state may be managed by each device for each access. Specifically, each device may independently manage the registration state (registered state or unregistered state) for 3GPP access and the registration state for non-3GPP access.

[0180] Furthermore, the procedure may be a procedure 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 from the UE, and / or for updating certain parameters related to the UE in the network.

[0181] This procedure may be performed multiple times. In other words, after this procedure is completed, it may be started again.

[0182] The UE may initiate this procedure after performing network selection.

[0183] The UE may initiate this procedure when it performs mobility across TAs (Tracking Areas). In other words, the UE may initiate this procedure when it moves to a TA different from the TA indicated in the TA list it holds.

[0184] Additionally, the UE may initiate this procedure periodically. Additionally, the UE may initiate this procedure based on the completion of a UE Configuration Update procedure.

[0185] However, the UE may perform the registration procedure at any timing, not limited to these.

[0186] Additionally, the UE may periodically initiate a registration procedure even when in a registered state.

[0187] The registration procedure performed based on the mobility of the UE and the registration procedure performed periodically may be referred to as a registration procedure for mobility and periodic registration update. In other words, the registration procedure for mobility and periodic registration update may be a registration procedure performed based on the mobility of the UE or a registration procedure performed periodically.

[0188] Furthermore, the registration procedures for mobility and periodic registration updates may be registration procedures performed based on a configuration update of the UE, or may be registration procedures performed to establish a communication path for transmitting and receiving user data, or may be registration procedures performed based on a request from the network.

[0189] Furthermore, the registration procedures for mobility and periodic registration updates may be registration procedures other than the registration procedure for initial registration.

[0190] Next, each step of the registration procedure will be described. Note that the registration procedure described below may be a registration procedure for initial registration, or a registration procedure for mobility and periodic registration update.

[0191] First, the UE starts the registration procedure by transmitting a registration request message to the AMF (S800) (S802) (S804). Specifically, the UE transmits an RRC message including a registration request message to the 5G AN (or gNB) (S800). The registration request message is an NAS message. The RRC message may be a control message transmitted and received between the UE and the 5G AN (or gNB). The NAS message is processed in the NAS layer, and the RRC message is processed in the RRC layer. The NAS layer is a layer higher than the RRC layer.

[0192] Here, the UE may transmit the first and / or second and / or third and / or fourth identification information by including it in a registration request message and / or an RRC message. More specifically, the UE may transmit the first and / or second and / or third and / or fourth identification information by including it in a registration request message and / or an RRC message, or may transmit the first and / or second and / or third and / or fourth identification information by including it in a control message different from these, for example, a control message of a layer lower than the RRC layer (for example, a MAC layer, an RLC layer, or a PDCP layer).

[0193] In addition, the UE may transmit a registration request message to indicate to the network the contents indicated by each piece of identification information or to indicate the UE's request.

[0194] Furthermore, the UE may transmit each piece of identification information to indicate to the network what each piece of identification information represents.

[0195] Specifically, if the UE supports operating as a remote UE, it may transmit first identification information indicating that it supports operating as a remote UE. If the UE does not support operating as a remote UE, it may transmit first identification information indicating that it does not support operating as a remote UE.

[0196] If the UE supports operating as a layer-2 remote UE, it may transmit first identification information 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 transmit first identification information indicating that it does not support operating as a layer-2 remote UE.

[0197] If the UE supports operating as a layer-3 remote UE, it may transmit first identification information 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 transmit first identification information indicating that it does not support operating as a layer-3 remote UE.

[0198] If the UE supports operating as a U2N relay UE, it may send second identification information 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 second identification information indicating that it does not support operating as a U2N relay UE.

[0199] If the UE supports operating as a layer-2 U2N relay UE, it may send second identification information 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 second identification information indicating that it does not support operating as a layer-2 U2N relay UE.

[0200] If the UE supports operating as a layer-3 U2N relay UE, it may send second identification information 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 second identification information indicating that it does not support operating as a layer-3 U2N relay UE.

[0201] If the UE supports operating as a U2N intermediate UE, it may transmit third identification information indicating that it supports operating as a U2N intermediate UE. If the UE does not support operating as a U2N intermediate UE, it may transmit third identification information indicating that it does not support operating as a U2N intermediate UE.

[0202] If the UE supports multi-hop, the UE may transmit fourth identification information indicating that it supports multi-hop. If the UE does not support multi-hop, the UE may transmit fourth identification information indicating that it does not support multi-hop.

[0203] If the UE supports operating as a multi-hop UE, it may transmit fourth identification information indicating that it supports multi-hop. If the UE does not support operating as a multi-hop UE, it may transmit fourth identification information indicating that it does not support multi-hop.

[0204] In addition, the UE may decide whether to transmit each identification information based on subscription information, and / or network status, and / or user registration information, and / or context held by the UE, etc.

[0205] When a 5G AN (or gNB) receives an RRC message including a registration request message, it selects an AMF to which to forward the registration request message (S802). Note that the 5G AN (or gNB) may select an AMF based on information included 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 the registration request message to the selected AMF (S804).

[0206] Next, the AMF receives a registration request message from the UE via the 5G AN (gNB). The AMF may receive the registration request message including the first, and / or second, and / or third, and / or fourth identification information.

[0207] Furthermore, by receiving a registration request message, the AMF may recognize the contents indicated by each identification information or may recognize the UE's request.

[0208] Furthermore, by receiving each identification information, the AMF may recognize the content indicated by each identification information and may recognize the UE's request.

[0209] Specifically, the AMF may recognize that the UE supports operating as a remote UE when receiving first identification information indicating that the UE supports operating as a remote UE. The AMF may recognize that the UE does not support operating as a remote UE when receiving first identification information indicating that the UE does not support operating as a remote UE.

[0210] The AMF may recognize that the UE supports operating as a layer-2 remote UE if the AMF receives first identification information indicating that the UE supports operating as a layer-2 remote UE. The AMF may recognize that the UE does not support operating as a layer-2 remote UE if the AMF receives first identification information indicating that the UE does not support operating as a layer-2 remote UE.

[0211] The AMF may recognize that the UE supports operating as a layer-3 remote UE if it receives first identification information indicating that the UE supports operating as a layer-3 remote UE. The AMF may recognize that the UE does not support operating as a layer-3 remote UE if it receives first identification information indicating that the UE does not support operating as a layer-3 remote UE.

[0212] The AMF may recognize that the UE supports operating as a U2N relay UE if the AMF receives second identification information indicating that the UE supports operating as a U2N relay UE. The AMF may recognize that the UE does not support operating as a U2N relay UE if the AMF receives second identification information indicating that the UE does not support operating as a U2N relay UE.

[0213] The AMF may recognize that the UE supports operating as a layer-2 U2N relay UE if the AMF receives second identification information indicating that the UE supports operating as a layer-2 U2N relay UE. The AMF may recognize that the UE does not support operating as a layer-2 U2N relay UE if the AMF receives second identification information indicating that the UE does not support operating as a layer-2 U2N relay UE.

[0214] The AMF may recognize that the UE supports operating as a layer-3 U2N relay UE if the AMF receives second identification information indicating that the UE supports operating as a layer-3 U2N relay UE. The AMF may recognize that the UE does not support operating as a layer-3 U2N relay UE if the AMF receives second identification information indicating that the UE does not support operating as a layer-3 U2N relay UE.

[0215] If the AMF receives the third identification information, it may recognize that the UE supports or does not support operating as a U2N intermediate UE.

[0216] Furthermore, when the AMF receives the fourth identification information, it may recognize that the UE supports or does not support multi-hop. When the AMF receives the fourth identification information, it may recognize that the UE supports or does not support operating as a multi-hop UE.

[0217] The AMF may determine whether the UE is authorized to use the 5G ProSe service based on the first, and / or second, and / or third, and / or fourth identification information. The AMF may or may not approve the 5G ProSe service used by the UE based on the first, and / or second, and / or third, and / or fourth identification information.

[0218] The AMF may approve the first, and / or second, and / or third, and / or fourth identities. The AMF may send the first, and / or second, and / or third, and / or fourth identities to the PCF.

[0219] When the AMF receives the registration request message, the AMF may perform a first condition determination. The first condition determination is for determining whether the network (or the AMF) accepts the UE's request. If the first condition determination is true, the AMF starts the procedure of (A) in Figure 6. If the first condition determination is false, the AMF starts the procedure of (B) in Figure 6.

[0220] 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 the AMF, etc.

[0221] For example, if the network allows the UE's request, the first condition determination may be true. If the network does not allow the UE's request, the first condition determination may be false.

[0222] For example, if the network to which the UE is registered and / or a device within the network supports the function requested by the UE, the first condition determination may be true, and if the network to which the UE is registered and / or a device within the network does not support the function requested by the UE, the first condition determination may be false.

[0223] For example, if each identification is authorized, the first condition determination may be true, and if each identification is not authorized, the first condition determination may be false.

[0224] The conditions for determining whether the first condition determination is true or false do not have to be limited to the above-mentioned conditions.

[0225] First, the case where the first condition is true will be described.

[0226] In the procedure of (A) in Figure 6, as a response message to the registration request message, the AMF sends a registration accept message to the UE via the 5G AN (or gNB) (S806). Note that the registration accept message is a NAS message transmitted and received on the N1 interface, but is transmitted and received between the UE and the 5G AN (gNB) in the form of an RRC message.

[0227] The AMF may indicate that the UE's request has been accepted by sending a registration accept message. The AMF may determine whether to send the registration accept message based on the received identification information, 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 the AMF, etc.

[0228] The AMF may send a registration acceptance message including information indicating that some of the UE's requests have been rejected.

[0229] Next, the UE receives a registration acceptance message from the AMF via the 5G AN (gNB) (S806).

[0230] Here, if the UE receives the registration accept message, it may recognize that the UE's request has been accepted.

[0231] If the UE receives information indicating that some of the UE's requests have been rejected, the UE may recognize that some of the UE's requests have been rejected.

[0232] 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 an NAS message transmitted and received on the N1 interface, but is included in an RRC message and transmitted and received between the UE and the 5G AN (gNB).

[0233] Next, the AMF may or may not receive a registration completion message via the 5G AN (gNB) (S808).

[0234] Each device may complete the procedure of FIG. 6(A) based on sending and receiving the registration acceptance message and / or the registration completion message.

[0235] Next, a case where the first condition determination is false will be described.

[0236] In the procedure of (B) in Figure 6, the AMF sends a registration reject message to the UE via the 5G AN (gNB) as a response message to the registration request message (S810). Here, the registration reject message is a NAS message transmitted and received on the N1 interface, but is included in an RRC message and transmitted and received between the UE and the 5G AN (gNB).

[0237] The AMF may indicate that the UE's request has been rejected by sending a registration rejection message. Further, the AMF may send a registration rejection message including information indicating that the UE's request has been rejected.

[0238] Next, the UE receives a registration rejection message from the AMF via the 5G AN (gNB) (S810). When the UE receives the registration rejection message, it may recognize that the UE's request has been rejected.

[0239] Each device may complete procedure (B) in this procedure based on sending and receiving the registration rejection message.

[0240] Each device may complete this procedure based on the completion of the procedure in (A) or (B) of FIG.

[0241] Upon completion of the procedure in FIG. 6(A), the UE may transition to a state in which the UE is registered in the network (RM_REGISTERED state).

[0242] Furthermore, based on the completion of the procedure in (B) of Figure 6, the UE may maintain a state in which the UE is not registered in the network (RM_DEREGISTERED state), or may transition to a state in which the UE is not registered in the network.

[0243] Upon completion of this procedure, each device may perform processing based on the transmission and reception of each identification information.

[0244] If the UE's request is rejected, the UE may perform this procedure again or may perform network selection for a different network.

[0245] [3.2 Discovery Procedure Model B for Signal Strength Measurement] Discovery procedure model B for signal strength measurement will be explained using Fig. 7. In this chapter, discovery procedure model B for signal strength measurement may be referred to as this procedure.

[0246] The discovery procedure model B for signal strength measurement may be discovery procedure model B or may be a discovery procedure.

[0247] This procedure may be referred to as PROSE PC5 DISCOVERY message signal strength measurement.

[0248] The procedure may be a procedure for measuring signal strength between UEs. The procedure may be a procedure for measuring signal strength of a PC5 link between UEs.

[0249] The discovery procedure may be a 5G ProSe direct discovery procedure, a 5G ProSe U2N relay discovery procedure, or a UE-to-network relay discovery procedure over a PC5 interface.

[0250] The discovery procedure may also be referred to as 5G ProSe direct discovery or 5G ProSe discovery.

[0251] This procedure may be a Procedure for 5G ProSe U2N Relay Discovery with Model B or a UE-to-network relay discovery over PC5 interface with model B.

[0252] This procedure may be initiated after the network selection and / or registration procedure and / or 5G ProSe direct link establishment procedure is completed.

[0253] This procedure may be performed multiple times, i.e., after the procedure is completed, the procedure may be started again.

[0254] In this procedure, the first control message may be a PROSE PC5 DISCOVERY message signal strength measurement, or a Solicitation message, a U2N relay discovery solicitation message, or a PROSE PC5 DISCOVERY message for UE-to-network relay discovery solicitation.

[0255] In this procedure, the second control message may be a Response message, or a U2N Relay Discovery Response message, or a PROSE PC5 DISCOVERY message for UE-to-network relay discovery response.

[0256] In this procedure, the UE may be a remote UE, a U2N relay UE, or a U2N intermediate UE.

[0257] In this procedure, a UE that transmits the first control message may be referred to as a discoverer UE, and a UE that transmits the second control message may be referred to as a discoveree UE.

[0258] In this procedure, there may be one or more U2N intermediate UEs. When there are two or more U2N intermediate UEs, for example, there may be a first U2N intermediate UE and a second U2N intermediate UE.

[0259] Here, for example, in FIG. 7, the discoverer UE is a U2N intermediate UE, and the discoveree UE is a U2N relay UE.

[0260] A discoverer UE may be a remote UE. A discoveree UE may be a U2N relay UE. If there are two or more U2N intermediate UEs, the discoverer UE may be the first U2N intermediate UE and the discoveree UE may be the second U2N intermediate UE.

[0261] In other words, in Fig. 7, U2N intermediate UE may be read as remote UE, and U2N relay UE may be read as U2N intermediate UE. Also, in Fig. 7, if there are two or more U2N intermediate UEs, U2N intermediate UE may be read as first U2N intermediate UE, and U2N relay UE may be read as second U2N intermediate UE.

[0262] Next, each step of this procedure will be described. In each step of this procedure described below, U2N intermediate UE may be replaced with remote UE, and U2N relay UE may be replaced with U2N intermediate UE. Also, U2N intermediate UE may be replaced with first U2N intermediate UE, and U2N relay UE may be replaced with second U2N intermediate UE.

[0263] First, the U2N intermediate UE establishes a PC5 link with the U2N relay UE (S1000). The U2N intermediate UE may establish the PC5 link using a 5G ProSe direct link establishment procedure.

[0264] Next, the U2N intermediate UE starts a first timer (S1002).

[0265] Specifically, the U2N intermediate UE may start a first timer every time it establishes a PC5 link with a U2N relay UE. The U2N intermediate UE may start the first timer after receiving a PROSE direct link establishment accept message from the U2N relay UE. The U2N intermediate UE may start the first timer after completing the PROSE direct link establishment procedure.

[0266] The first timer may be a timer used to trigger periodic PROSE PC5 discovery message signal strength measurements. The first timer may be a timer used to trigger periodic this procedure between a U2N intermediate UE and a U2N relay UE. The first timer may be a timer different from T5109, T5111, and T5113. The first timer may be a periodic measurement timer.

[0267] The U2N intermediate UE may start the first timer using or setting the first timer value to the first timer. The first timer value may be any value. The first timer value may be left to the implementation.

[0268] If the first timer expires, the U2N intermediate UE may send a first control message to the U2N relay UE (S1004).

[0269] If the first timer has not expired, the U2N intermediate UE may not send the first control message to the U2N relay UE. In other words, if the first timer is stopped before the first timer expires, the U2N intermediate UE may not send the first control message to the U2N relay UE.

[0270] The first timer may be stopped when the PC5 link is released. The first timer may be stopped when the PC5 link between the U2N intermediate UE and the U2N relay UE is released.

[0271] Next, the U2N intermediate UE may start a second timer (S1006).

[0272] Specifically, the U2N intermediate UE may start a second timer based on the transmission of the first control message. The U2N intermediate UE may start the second timer if the first control message is used to trigger the procedure.

[0273] The second timer may be a retransmission timer. The second timer may be a timer used by the U2N intermediate UE to repeatedly retransmit the first control message. The first timer may be a timer different from T5108, T5110, and T5112.

[0274] The U2N intermediate UE may start the second timer with or set the second timer value, which may be a value indicating 2 seconds.

[0275] Next, the U2N relay UE may receive a first control message from the U2N intermediate UE (S1004).

[0276] The U2N relay UE may not be able to receive the first control message from the U2N intermediate UE. The U2N relay UE may not be able to receive the first control message due to, for example, weak radio wave strength.

[0277] Next, the U2N relay UE may send a second control message to the U2N intermediate UE (S1008). The U2N relay UE may send the second control message in response to the first control message.

[0278] More specifically, the U2N relay UE may transmit the second control message if it receives the first control message, and may not transmit the second control message if it fails to receive the first control message.

[0279] Next, the U2N intermediate UE may resend the first control message to the U2N relay UE (S1010). In other words, the U2N intermediate UE may send the first control message to the U2N relay UE.

[0280] More specifically, if the second timer expires, the U2N intermediate UE may resend the first control message and restart the second timer. More specifically, if the U2N intermediate UE has not received the second control message (S1008) and the second timer expires, the U2N intermediate UE may resend the first control message and restart the second timer. The U2N intermediate UE may resend the first control message every time the second timer expires.

[0281] When the U2N intermediate UE receives the second control message (S1008), the U2N intermediate UE may not retransmit the first control message. When the U2N intermediate UE receives the second control message, the U2N intermediate UE may stop the second timer and start the first timer.

[0282] Next, the U2N relay UE may receive a first control message from the U2N intermediate UE (S1010).

[0283] The U2N relay UE may not be able to receive the first control message from the U2N intermediate UE. The U2N relay UE may not be able to receive the first control message due to, for example, weak radio wave strength.

[0284] Next, the U2N relay UE may send a second control message to the U2N intermediate UE (S1012). The U2N relay UE may send the second control message in response to the first control message.

[0285] More specifically, the U2N relay UE may transmit the second control message if it receives the first control message, and may not transmit the second control message if it fails to receive the first control message.

[0286] Next, if the U2N intermediate UE has not received the second control message (S1012) and the second timer expires, the U2N intermediate UE may resend the first control message and restart the second timer. The U2N intermediate UE may resend the first control message every time the second timer expires.

[0287] When the U2N intermediate UE receives the second control message (S1012), the U2N intermediate UE may not retransmit the first control message. When the U2N intermediate UE receives the second control message, the U2N intermediate UE may stop the second timer and start the first timer.

[0288] When the U2N intermediate UE retransmits the first control message (S1010), the U2N intermediate UE may increment a first counter. The first counter may be a counter for counting the number of times the first control message is retransmitted.

[0289] The U2N intermediate UE may trigger a relay reselection procedure if it does not receive the second control message after the maximum number of allowed retransmissions has been reached. In other words, the U2N intermediate UE may trigger a relay reselection procedure if it does not receive the second control message after the number of retransmissions of the first control message has reached the maximum number of allowed retransmissions. In yet other words, the U2N intermediate UE may trigger a relay reselection procedure if it does not receive the second control message after the first counter has reached the maximum number of allowed retransmissions.

[0290] The relay reselection procedure may be a procedure in which a U2N intermediate UE reselects a U2N relay UE. The relay reselection procedure may be a procedure in which a U2N intermediate UE reselects a U2N relay UE when the serving U2N relay UE becomes unsuitable. The relay reselection procedure may also be referred to as a U2N relay reselection procedure.

[0291] The U2N intermediate UE may not retransmit the first control message after the maximum number of allowed retransmissions has been reached. In other words, the U2N intermediate UE may not retransmit the first control message after the first counter has reached the maximum number of allowed retransmissions.

[0292] The U2N intermediate UE may retransmit the first control message as long as the maximum number of allowed retransmissions has not been reached. In other words, the U2N intermediate UE may retransmit the first control message as long as the first counter has not reached the maximum number of allowed retransmissions.

[0293] In the relay reselection procedure, the U2N intermediate UE may reselect a new U2N relay UE that is different from the U2N relay UE that currently establishes the PC5 link.

[0294] [3.3 Additional Parameter Announcement Procedure] Next, the additional parameter announcement procedure will be described with reference to Fig. 8. In this chapter, the additional parameter announcement procedure may be referred to as this procedure.

[0295] This procedure may be a procedure for a remote UE to obtain an NG-RAN Cell Global ID (NCGI) and / or a Tracking Area Identity (TAI) of a cell serving a U2N relay UE and / or a U2N intermediate UE.

[0296] This procedure may be initiated after the network selection and / or registration and / or discovery procedures have been completed.

[0297] The discovery procedure may be a 5G ProSe direct discovery procedure, a 5G ProSe U2N relay discovery procedure, or a UE-to-network relay discovery procedure over a PC5 interface.

[0298] The discovery procedure may also be referred to as 5G ProSe direct discovery or 5G ProSe discovery.

[0299] The discovery procedure may be a Procedure for 5G ProSe U2N Relay Discovery with Model A or a UE-to-network relay discovery over PC5 interface with model A.

[0300] The discovery procedure may be a Procedure for 5G ProSe U2N Relay Discovery with Model B or a UE-to-network relay discovery over PC5 interface with model B.

[0301] This procedure may be performed multiple times, i.e., after the procedure is completed, the procedure may be started again.

[0302] Note that while Figure 8 illustrates a communication mode with only one U2N intermediate UE, there may be two or more U2N intermediate UEs. In other words, although Figure 8 illustrates a communication mode with two hops to the destination, this procedure may also be implemented when there are three or more hops to the destination. When there are two or more U2N intermediate UEs, the U2N intermediate UEs may be referred to as, for example, a first U2N intermediate UE and a second U2N intermediate UE, from left to right.

[0303] Next, each step of this procedure will be described.

[0304] First, the remote UE transmits a PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message to the U2N intermediate UE (S1200).

[0305] Also, if there are two or more U2N intermediate UEs, the remote UE may send a PROSE additional parameter announcement request message to the first U2N intermediate UE.

[0306] Next, the U2N intermediate UE receives a PROSE additional parameter announcement request message from the remote UE (S1200).

[0307] Also, if there are two or more U2N intermediate UEs, the first U2N intermediate UE may receive a PROSE additional parameter announcement request message from the remote UE.

[0308] Next, the U2N intermediate UE sends a PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message to the U2N relay UE (S1202). When the U2N intermediate UE receives the PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message from the remote UE, the U2N intermediate UE may send the PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message to the U2N relay UE.

[0309] The U2N intermediate UE may forward the received PROSE additional parameter announcement request message to the U2N relay UE.

[0310] Also, when there are two or more U2N intermediate UEs, the first U2N intermediate UE may send a PROSE additional parameter announcement request message to the second U2N intermediate UE. The second U2N intermediate UE may send a PROSE additional parameter announcement request message to the U2N relay UE. When the first U2N intermediate UE receives the PROSE additional parameter announcement request message from the remote UE, it may send a PROSE additional parameter announcement request message to the second U2N intermediate UE. When the second U2N intermediate UE receives the PROSE additional parameter announcement request message from the first U2N intermediate UE, it may send a PROSE additional parameter announcement request message to the U2N relay UE.

[0311] The first U2N intermediate UE may forward the received PROSE additional parameter announcement request message to the second U2N intermediate UE. The second U2N intermediate UE may forward the received PROSE additional parameter announcement request message to the U2N relay UE.

[0312] Next, the U2N relay UE receives a PROSE additional parameter announcement request message from the U2N intermediate UE (S1202).

[0313] Also, when there are two or more U2N intermediate UEs, a second U2N intermediate UE may receive a PROSE additional parameter announcement request message from a first U2N intermediate UE. A U2N relay UE may receive a PROSE additional parameter announcement request message from a second U2N intermediate UE.

[0314] Next, the U2N relay UE transmits a PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT RESPONSE message to the U2N intermediate UE (S1204).

[0315] Also, if there are two or more U2N intermediate UEs, the U2N relay UE may send a PROSE additional parameter announcement response message to the second U2N intermediate UE.

[0316] The U2N relay UE may send a PROSE additional parameter announcement response message including the 30th, and / or 31st, and / or 35th identification information.

[0317] The U2N relay UE may determine a 30th identity and include the 30th identity in the PROSE additional parameter announcement response message. The U2N relay UE may determine a 31st identity and include the 31st identity in the PROSE additional parameter announcement response message. The U2N relay UE may determine a 35th identity and include the 35th identity in the PROSE additional parameter announcement response message.

[0318] Next, the U2N relay UE starts a third timer (S1206).

[0319] Specifically, the U2N relay UE may start a third timer when sending a PROSE additional parameter announcement response message (S1204). The U2N relay UE may start a third timer when receiving a PROSE additional parameter announcement request message (S1202).

[0320] The third timer may be a timer for controlling a PROSE PC5 discovery message for relay discovery additional information sent by a U2N relay UE. The third timer may be T5107.

[0321] The U2N relay UE may start the third timer using or setting the third timer value to the third timer. The third timer value may be determined by the U2N relay UE. The third timer value may be greater than the fifth timer value. The third timer value may be greater than the fourth timer value.

[0322] The U2N relay UE may determine the third timer value taking into account the fourth and / or fifth timer values. In other words, the U2N relay UE may determine the third timer value taking into account the thirtieth and / or thirtieth identification information to be transmitted. For example, the U2N relay UE may determine the third timer value to be greater than the fourth timer value. In other words, the U2N relay UE may set the third timer value to be greater than the fourth timer value. For example, the U2N relay UE may determine the third timer value to be greater than the fifth timer value. In other words, the U2N relay UE may set the third timer value to be greater than the fifth timer value.

[0323] The U2N relay UE may transmit a PROSE PC5 discovery message for relay discovery additional information until a third timer expires. The U2N relay UE may transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identities of the U2N relay UE until a third timer expires. Here, the U2N relay UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcements in the serving PLMN if the UE is served by the NG-RAN.

[0324] If the third timer has not expired, the U2N relay UE may periodically send a PROSE PC5 discovery message for relay discovery additional information. If the third timer has not expired, the U2N relay UE may periodically send a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identities of the U2N relay UE. Here, the U2N relay UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcements in the serving PLMN if the UE is served by NG-RAN.

[0325] If the third timer has not expired and the U2N relay UE detects camping on a new serving cell, the U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information. If the third timer has not expired and the U2N relay UE detects camping on a new serving cell, the U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information including a 32nd identity of the U2N relay UE. Here, the U2N relay UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcement in the serving PLMN if the UE is served by an NG-RAN.

[0326] If the third timer has not expired and the U2N relay UE detects that it has entered a new tracking area, the U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information. If the third timer has not expired and the U2N relay UE detects that it has entered a new tracking area, the U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information including a 33rd identity of the U2N relay UE. Here, the U2N relay UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcement in the serving PLMN if the UE is served by NG-RAN.

[0327] If the third timer expires, the U2N relay UE may not send a PROSE PC5 discovery message for relay discovery additional information. If the third timer expires, the U2N relay UE may not send a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the U2N relay UE.

[0328] Next, the U2N intermediate UE receives a PROSE additional parameter announcement response message from the U2N relay UE (S1204).

[0329] Also, if there are two or more U2N intermediate UEs, the second U2N intermediate UE may receive a PROSE additional parameter announcement response message from the U2N relay UE.

[0330] The U2N intermediate UE may receive a PROSE additional parameter announcement response message including the 30th, and / or 31st, and / or 35th identification information.

[0331] When the U2N intermediate UE receives the 30th identification information, it may recognize and / or store the fifth timer value. When the U2N intermediate UE receives the 31st identification information, it may recognize and / or store the fourth timer value. When the U2N intermediate UE receives the 35th identification information, it may recognize and / or store the third timer value.

[0332] Next, the U2N intermediate UE sends a PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message to the remote UE (S1208). When the U2N intermediate UE receives the PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message from the U2N relay UE, the U2N intermediate UE may send the PROSE ADDITIONAL PARAMETERS ANNOUNCEMENT REQUEST message to the remote UE.

[0333] The U2N intermediate UE may forward the received PROSE additional parameter announcement response message to the remote UE.

[0334] The U2N intermediate UE may send a PROSE additional parameter announcement response message including the 30th, and / or 31st, and / or 35th identification information.

[0335] The U2N intermediate UE may determine a 30th identity and include the 30th identity in the PROSE additional parameter announcement response message. The U2N intermediate UE may determine a 31st identity and include the 31st identity in the PROSE additional parameter announcement response message.

[0336] Also, when there are two or more U2N intermediate UEs, the second U2N intermediate UE may send a PROSE additional parameter announcement response message to the first U2N intermediate UE. The first U2N intermediate UE may send a PROSE additional parameter announcement response message to the remote UE. When the second U2N intermediate UE receives the PROSE additional parameter announcement response message from the U2N relay UE, it may send a PROSE additional parameter announcement response message to the first U2N intermediate UE. When the first U2N intermediate UE receives the PROSE additional parameter announcement response message from the second U2N intermediate UE, it may send a PROSE additional parameter announcement response message to the remote UE.

[0337] The second U2N intermediate UE may forward the received PROSE additional parameter announcement request message to the first U2N intermediate UE. The first U2N intermediate UE may forward the received PROSE additional parameter announcement request message to the remote UE.

[0338] The first and second U2N intermediate UEs may send PROSE additional parameter announcement response messages including the 30th, and / or 31st, and / or 35th identification information.

[0339] The first and second U2N intermediate UEs may determine a 30th identity and include the 30th identity in the PROSE additional parameter announcement response message. The first and second U2N intermediate UEs may determine a 31st identity and include the 31st identity in the PROSE additional parameter announcement response message.

[0340] Next, the U2N intermediate UE may start a fourth timer (S1210).

[0341] Specifically, the U2N intermediate UE may start a fourth timer when sending a PROSE additional parameter announcement response message (S1208). The U2N intermediate UE may start a fourth timer when receiving a PROSE additional parameter announcement request message (S1200). The U2N intermediate UE may start a fourth timer when receiving a PROSE additional parameter announcement response message (S1204).

[0342] The fourth timer may be a timer for controlling a PROSE PC5 discovery message for relay discovery additional information sent by a U2N intermediate UE. The fourth timer may be a timer different from T5106 and T5107.

[0343] The U2N intermediate UE may start the fourth timer using the fourth timer value or by setting the fourth timer value. The fourth timer value may be determined by the U2N relay UE or the U2N intermediate UE. In other words, the U2N intermediate UE may determine the fourth timer value by itself or may determine the fourth timer value using the received 31st identification information. The fourth timer value may be greater than the fifth timer value. The fourth timer value may be less than the third timer value. The U2N intermediate UE may start the fourth timer using the received 31st identification information.

[0344] The U2N intermediate UE may determine the fourth timer value taking into account the third and / or fifth timer values. In other words, the U2N intermediate UE may determine the fourth timer value taking into account the received thirtieth and / or thirty-fifth identification information. For example, the U2N intermediate UE may determine the fourth timer value to be greater than the fifth timer value. In other words, the U2N intermediate UE may set the fourth timer value to be greater than the fifth timer value. For example, the U2N intermediate UE may determine the fourth timer value to be smaller than the third timer value. In other words, the U2N intermediate UE may set the fourth timer value to be smaller than the third timer value.

[0345] The U2N intermediate UE may transmit a PROSE PC5 discovery message for relay discovery additional information until a fourth timer expires. The U2N intermediate UE may transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identities of the U2N intermediate UE until a fourth timer expires. Here, the U2N intermediate UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcements in the serving PLMN if the UE is served by the NG-RAN.

[0346] If the fourth timer has not expired, the U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information. If the fourth timer has not expired, the U2N intermediate UE may periodically send a PROSE PC5 discovery message for relay discovery additional information. If the fourth timer has not expired, the U2N intermediate UE may periodically send a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identities of the U2N intermediate UE. Here, the U2N intermediate UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcements in the serving PLMN if the UE is served in NG-RAN.

[0347] If the fourth timer has not expired and the U2N intermediate UE detects camping on the new serving cell, the U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information. If the fourth timer has not expired and the U2N intermediate UE detects camping on the new serving cell, the U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information including the 32nd identity of the U2N intermediate UE. Here, the U2N intermediate UE may be authorized to perform discovery procedure model A (5G ProSe direct discovery Model A) announcements in the serving PLMN if the UE is served in the NG-RAN.

[0348] If the fourth timer has not expired and the U2N intermediate UE detects that it has entered a new tracking area, the U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information. If the fourth timer has not expired and the U2N intermediate UE detects that it has entered a new tracking area, the U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information including a 33rd identity of the U2N intermediate UE. Here, the U2N intermediate UE may be authorized to perform a discovery procedure model A (5G ProSe direct discovery Model A) announcement in the serving PLMN if the UE is served in an NG-RAN.

[0349] If the fourth timer expires, the U2N intermediate UE may not transmit a PROSE PC5 discovery message for relay discovery additional information. If the fourth timer expires, the U2N intermediate UE may not transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the U2N intermediate UE.

[0350] Next, the remote UE receives a PROSE additional parameter announcement response message from the U2N intermediate UE (S1208).

[0351] Also, if there are two or more U2N intermediate UEs, the remote UE may receive a PROSE additional parameter announcement response message from the first U2N intermediate UE.

[0352] The remote UE may receive a PROSE additional parameter announcement response message including the 30th, and / or 31st, and / or 35th identification information.

[0353] The remote UE may recognize and / or store the fifth timer value when it receives the 30th identification. The remote UE may recognize and / or store the fourth timer value when it receives the 31st identification. The remote UE may recognize and / or store the third timer value when it receives the 35th identification.

[0354] Next, the remote UE may start a fifth timer (S1212).

[0355] Specifically, the remote UE may start a fifth timer when receiving the PROSE additional parameter announcement response message (S1208).

[0356] The fifth timer may be a timer for controlling a PROSE additional parameter announcement request message sent by the remote UE. The fifth timer may be T5106.

[0357] The remote UE may start the fifth timer using or setting the fifth timer value to the fifth timer. The fifth timer value may be determined by the U2N relay UE or the U2N intermediate UE. The fifth timer value may be smaller than the third timer value. The fifth timer value may be smaller than the fourth timer value. The remote UE may start the fifth timer using the received thirtieth identity.

[0358] When the fifth timer expires and the remote UE needs to obtain the 32nd and / or 33rd identity information of the U2N relay UE, the remote UE may initiate this procedure. In other words, when the fifth timer expires and the remote UE needs to obtain the 32nd and / or 33rd identity information of the U2N relay UE, the remote UE may send a PROSE additional parameter announcement request message.

[0359] If the fifth timer has not expired, the remote UE may not initiate this procedure, in other words, if the fifth timer has not expired, the remote UE may not send a PROSE additional parameter announcement request message.

[0360] Next, the U2N relay UE transmits a PROSE PC5 DISCOVERY message for relay discovery additional information to the U2N intermediate UE (S1214).

[0361] Also, if there are two or more U2N intermediate UEs, the U2N relay UE may send a PROSE PC5 discovery message to the second U2N intermediate UE for relay discovery additional information.

[0362] The U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information. The U2N relay UE may send a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the U2N relay UE.

[0363] Next, the U2N intermediate UE receives a PROSE PC5 discovery message for relay discovery additional information from the U2N relay UE (S1214).

[0364] Also, if there are two or more U2N intermediate UEs, the second U2N intermediate UE may receive a PROSE PC5 discovery message for relay discovery additional information from the U2N relay UE.

[0365] The U2N intermediate UE may receive a PROSE PC5 discovery message for relay discovery additional information that includes the 32nd and / or 33rd identities. The U2N intermediate UE may receive a PROSE PC5 discovery message for relay discovery additional information that includes the 32nd and / or 33rd identities of the U2N relay UE.

[0366] Next, the U2N intermediate UE sends a PROSE PC5 DISCOVERY message for relay discovery additional information to the remote UE (S1216). When the U2N intermediate UE receives the PROSE PC5 DISCOVERY message for relay discovery additional information from the U2N relay UE, the U2N intermediate UE may send the PROSE PC5 DISCOVERY message for relay discovery additional information to the remote UE.

[0367] The U2N intermediate UE may forward the PROSE PC5 discovery message for relay discovery additional information received from the U2N relay UE to the remote UE.

[0368] The U2N intermediate UE may transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the received U2N relay UE. The U2N intermediate UE may transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the U2N intermediate UE. The U2N intermediate UE may transmit a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information of the U2N intermediate UE.

[0369] Also, when there are two or more U2N intermediate UEs, the second U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information to the first U2N intermediate UE. The first U2N intermediate UE may send a PROSE PC5 discovery message for relay discovery additional information to the remote UE. When the second U2N intermediate UE receives a PROSE PC5 discovery message for relay discovery additional information from the U2N relay UE, it may send a PROSE PC5 discovery message for relay discovery additional information to the first U2N intermediate UE. When the first U2N intermediate UE receives a PROSE PC5 discovery message for relay discovery additional information from the second U2N intermediate UE, it may send a PROSE PC5 discovery message for relay discovery additional information to the remote UE.

[0370] The second U2N intermediate UE may forward the received PROSE PC5 discovery message for the relay discovery additional information to the first U2N intermediate UE. The first U2N intermediate UE may forward the received PROSE PC5 discovery message for the relay discovery additional information to the remote UE.

[0371] The first and second U2N intermediate UEs may send PROSE PC5 discovery messages for relay discovery additional information including the 32nd and / or 33rd identification information.

[0372] Next, the remote UE receives a PROSE PC5 discovery message for relay discovery additional information from the U2N intermediate UE (S1216).

[0373] Also, if there are two or more U2N intermediate UEs, the remote UE may receive a PROSE PC5 discovery message for relay discovery additional information from the first U2N intermediate UE.

[0374] The remote UE may receive a PROSE PC5 discovery message for relay discovery additional information including the 32nd and / or 33rd identification information.

[0375] The remote UE may recognize and / or store the 32nd and / or 33rd identities of the received U2N relay UE. The remote UE may recognize and / or store the 32nd and / or 33rd identities of the received U2N intermediate UE.

[0376] [3.4 5G ProSe direct link establishment procedure] Next, the 5G ProSe direct link establishment procedure will be described with reference to Fig. 9. Hereinafter, the 5G ProSe direct link establishment procedure may be referred to as this procedure.

[0377] The procedure may be for establishing a 5G ProSe direct link between two or more UEs, where the 5G ProSe direct link may be a Layer 2 link and / or a Layer 3 link.

[0378] Note that before this procedure is executed, each device may have performed the registration procedure, and / or the PDU session establishment procedure, and / or the discovery procedure one or more times.

[0379] This procedure may be performed multiple times, i.e., after this procedure is completed once, a new 5G ProSe direct link establishment procedure may be performed.

[0380] 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. A UE other than the initiating UE may be referred to as the target UE. A 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 accept message or the PROSE direct link establishment reject message.

[0381] Note that when the remote UE is the initiating UE, the U2N intermediate UE may be the target UE. Also, when the U2N intermediate UE is the initiating UE, the U2N relay UE may be the target UE. That is, this procedure may be performed between the remote UE and the U2N intermediate UE. Also, this procedure may be performed between the U2N intermediate UE and the U2N relay UE.

[0382] 9 illustrates a communication mode with only one U2N intermediate UE, but two or more U2N intermediate UEs may exist. In other words, while FIG. 9 illustrates a communication mode with two hops to the destination, this procedure may also be implemented when there are three or more hops to the destination.

[0383] In this procedure, the initiating UE and the target UE may transmit and receive control messages on PC5.

[0384] Next, each step of this procedure will be described.

[0385] First, the remote UE may send a PROSE DIRECT LINK ESTABLISHMENT REQUEST message to the U2N intermediate UE (S1400).

[0386] Next, the U2N intermediate UE may receive a PROSE direct link establishment request message from the remote UE (S1400).

[0387] Next, the U2N intermediate UE may send a PROSE direct link establishment request message to the U2N relay UE (S1402).

[0388] Next, the U2N relay UE may receive a PROSE direct link establishment request message from the U2N intermediate UE (S1402).

[0389] Next, (A) of FIG. 9 will be described.

[0390] The U2N relay UE may send a PROSE DIRECT LINK ESTABLISHMENT ACCEPT message to the U2N intermediate UE (S1404). Here, the U2N relay UE may send the PROSE DIRECT LINK ESTABLISHMENT ACCEPT message if it accepts the PROSE DIRECT LINK ESTABLISHMENT REQUEST message from the remote UE and / or the U2N intermediate UE.

[0391] Next, the U2N intermediate UE may receive a PROSE direct link establishment acceptance message from the U2N relay UE (S1404).

[0392] If the PROSE Direct Link Establishment Accept message is received, the U2N intermediate UE may know that the request has been accepted.

[0393] Next, the U2N intermediate UE may send a PROSE direct link establishment accept message to the remote UE (S1406). The U2N intermediate UE may forward the PROSE direct link establishment accept message received from the U2N relay UE to the remote UE.

[0394] Next, the remote UE may receive a PROSE direct link establishment acceptance message from the U2N intermediate UE (S1406).

[0395] If the PROSE Direct Link Establishment Accept message is received, the remote UE may know that the request has been accepted.

[0396] Next, (B) of FIG. 9 will be described.

[0397] The U2N relay UE may send a PROSE DIRECT LINK ESTABLISHMENT REJECT message to the U2N intermediate UE (S1410). Here, the U2N relay UE may send the PROSE DIRECT LINK ESTABLISHMENT REJECT message when rejecting the PROSE DIRECT LINK ESTABLISHMENT REQUEST message from the remote UE and / or the U2N intermediate UE.

[0398] The U2N relay UE may send a PROSE direct link establishment rejection message including the 34th identification information. More specifically, if the procedure is for direct communication between the U2N intermediate UE and the U2N relay UE integrating a discovery procedure, and / or if a direct link between the U2N intermediate UE and the U2N relay UE already exists, and / or if the data type unit is IP or Ethernet, the U2N relay UE may send a PROSE direct link establishment rejection message including the 34th identification information.

[0399] Next, the U2N intermediate UE may receive a PROSE direct link establishment rejection message from the U2N relay UE (S1410).

[0400] If a PROSE Direct Link Establishment Reject message is received, the U2N intermediate UE may know that the request has been rejected.

[0401] The U2N intermediate UE may receive a PROSE direct link establishment rejection message including the 34th identification information.

[0402] Upon receiving the 34th identification information, the U2N intermediate UE may perform a 5G ProSe direct link change procedure with the remote UE. More specifically, if the procedure is for direct communication between the U2N intermediate UE and the U2N relay UE and / or upon receiving the 34th identification information, the U2N intermediate UE may perform a 5G ProSe direct link change procedure with the remote UE.

[0403] Next, the U2N intermediate UE may send a PROSE direct link establishment rejection message to the remote UE (S1412). The U2N intermediate UE may forward the PROSE direct link establishment rejection message received from the U2N relay UE to the remote UE.

[0404] Next, the remote UE may receive a PROSE direct link establishment rejection message from the U2N intermediate UE (S1412).

[0405] If a PROSE Direct Link Establishment Reject message is received, the remote UE may recognize that the request has been rejected.

[0406] Furthermore, "when each piece of identification information is received" may be read as "when a PROSE direct link establishment rejection message is received."

[0407] The initiating UE may complete this procedure based on receiving a PROSE direct link establishment accept message or a PROSE direct link establishment reject message. The target UE may complete this procedure based on sending a PROSE direct link establishment accept message or a PROSE direct link establishment reject message. Each device may or may not establish a 5G ProSe direct link based on completion of this procedure. Each device may or may not recognize that a 5G ProSe direct link has been established based on completion of this procedure.

[0408] Note that the processing based on the reception of the identification information of the initiating UE and the target UE may be performed after the completion of this procedure.

[0409] Upon completion of this procedure, the initiating UE and the target UE may transmit and receive user data using the established 5G ProSe direct link.

[0410] 9A, the U2N intermediate UE may be in a state of being connected to the remote UE, and the U2N relay UE may be in a state of being connected to the U2N intermediate UE.

[0411] In addition, the remote UE may connect to the network via a U2N intermediate UE and a U2N relay UE. In other words, the remote UE may connect to the network using a ProSe direct link between the remote UE and the U2N intermediate UE, a ProSe direct link between the U2N intermediate UE and the U2N relay UE, and a PDU session between the U2N relay UE and the network.

[0412] In addition, the U2N intermediate UE may connect to the network via the U2N relay UE. In other words, the U2N intermediate UE may connect to the network using a ProSe direct link between the U2N intermediate UE and the U2N relay UE and a PDU session between the U2N relay UE and the network.

[0413] The U2N relay UE may also send a second control message to the network (S1408). More specifically, the U2N relay UE may send the second control message to notify the network that the U2N intermediate UE is connected to the U2N relay UE. The U2N relay UE may also send the second control message to notify the network that the U2N intermediate UE is disconnected from the U2N relay UE. The U2N relay UE may send the second control message to the network based on completion of the 5G ProSe direct link establishment procedure.

[0414] In addition, the U2N relay UE may send a second control message to notify the network that the U2N intermediate UE connected to the remote UE is connected to the U2N relay UE, and in addition, the U2N relay UE may send a second control message to notify the network that the U2N intermediate UE connected to the remote UE is disconnected from the U2N relay UE.

[0415] The U2N relay UE may also send a second control message to notify the network that the remote UE is connected to the U2N relay UE via the U2N intermediate UE, and the U2N relay UE may also send a second control message to notify the network that the remote UE is disconnected from the U2N relay UE via the U2N intermediate UE.

[0416] The second control message may be a remote UE report message, a U2N intermediate UE report message, or a message with a different name. The second control message may be a message for notifying the network that the U2N intermediate UE is connected to the U2N relay UE or that the U2N intermediate UE is disconnected from the U2N relay UE. The second control message may be a message sent to the network to notify the connection or disconnection of the U2N intermediate UE. The second control message may be a message for notifying whether the remote UE is connected to the U2N intermediate UE. Furthermore, the network may be an AMF and / or an SMF.

[0417] [4. Modifications] The program that runs on the device according to this embodiment may be a program that controls a central processing unit (CPU) or the like to cause a computer to function so as to realize the functions of the embodiment according to this embodiment. The program or information handled by the program is temporarily stored in a volatile memory such as a random access memory (RAM), a non-volatile memory such as a flash memory, a hard disk drive (HDD), or other storage device system.

[0418] A program for realizing the functions of the embodiments according to the present invention may be recorded on a computer-readable recording medium. The program may be read into a computer system and executed. The term "computer system" as used herein refers to a computer system built into a device, including hardware such as an operating system and peripheral devices. The term "computer-readable recording medium" may also refer to a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a medium that dynamically stores a program for a short period of time, or any other computer-readable recording medium.

[0419] Additionally, each functional block or feature of the device used in the above-described embodiments may be implemented or performed by an electrical circuit, such as an integrated circuit or multiple integrated circuits. The 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, or a conventional processor, controller, microcontroller, or state machine. The electrical circuit may be composed of digital circuits or analog circuits. Furthermore, as advances in semiconductor technology emerge, one or more aspects of the present embodiments may utilize new integrated circuit technologies that replace current integrated circuits.

[0420] It should be noted that this example is not limited to the above-described embodiment. In the embodiment, one example of a device is described, but this example is not limited to this and can be applied to terminal devices or communication devices such as stationary or non-movable electronic devices installed indoors or outdoors, for example, AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0421] Although the embodiment of this example has been described in detail above with reference to the drawings, the specific configuration is not limited to this example, and design modifications within the scope of the gist of this example are also included. Furthermore, this example 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 example. Furthermore, configurations in which elements described in each of the above embodiments are substituted with elements that achieve the same effect are also included.

[0422] The present invention can be used in, for example, a communication system, a communication device (for example, a mobile phone device, a base station device, a wireless LAN device, or a sensor device), an integrated circuit (for example, a communication chip), or a program.

[0423] 1 Mobile communication system 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) including a transceiver unit and a controller, the UE operating as a first 5G ProSe (Proximity based Services) intermediate U2N (UE-to-network) relay UE, the transceiver unit receiving a PROSE additional parameter announcement response message including a first timer value and a second timer value from a 5G ProSe U2N relay UE, the controller starting a second timer using the second timer value, the transceiver unit transmitting a PROSE additional parameter announcement response message including the first timer value to a second 5G ProSe intermediate U2N relay UE, if the second timer has not expired, the transceiver unit transmitting a PROSE PC5 discovery message for relay discovery additional information to the second 5G ProSe intermediate U2N relay UE, the first timer value being a timer value of a first timer, the first timer being a timer value of the 5G ProSe remote relay UE, The UE is characterized in that: the second timer is a timer for controlling a PROSE additional parameter announcement request message transmitted by the UE; the second timer value is a timer value of a second timer; and the second timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the 5G ProSe intermediate relay UE.

2. A UE (User Equipment) including a transceiver unit and a control unit, wherein the UE operates as a 5G ProSe (Proximity based Services) U2N (UE-to-network) relay UE, the transceiver unit receives a PROSE additional parameter announcement request message from a 5G ProSe intermediate U2N relay UE, the control unit determines a first timer value and a second timer value, and starts a third timer, the transceiver unit transmits a PROSE additional parameter announcement response message including the first timer value and the second timer value to the 5G ProSe intermediate U2N relay UE, and if the third timer has not expired, the transceiver unit transmits a PROSE PC5 discovery message for relay discovery additional information to the 5G ProSe intermediate U2N relay UE, the first timer value is a timer value of a first timer, and the first timer is a timer for controlling a PROSE additional parameter announcement request message transmitted by the 5G ProSe remote UE, the second timer value is a timer value of a second timer, the second timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the 5G ProSe intermediate relay UE, and the third timer is a timer for controlling a PROSE PC5 discovery message for relay discovery additional information transmitted by the transceiver unit.

Images