UE(user equipment)

Abstract

To clarify various kinds of information required for establishment of a communication path for multi-hop communication and maintenance and update of the established communication path, to provide a means for transmitting and receiving a control message including the information between UEs, and to execute behavior and processing of each UE based on the message.SOLUTION: In a direct link establishment procedure, a TargetEndUE #2 receives a ProSe direct link establishment request message from a third UE-to-UE relay UE #3, transmits a response message to the ProSe direct link establishment request message to the third UE-to-UE relay UE S906, starts a first timer with the transmission of a ProSe direct link establishment accept message, and stops the first timer S910 when a ProSe direct link establishment complete message is received from the third UE-to-UE relay UE S926 before the first timer expires.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to UE (User Equipment). [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project: registered trademark) is studying the system architecture of 5GS (5G System), a fifth-generation (5G) mobile communication system, and is discussing how to support new procedures and new functions (see Non-Patent Documents 1 to 4). In Release 19 of the 5G standard, architecture for expanding the Proximity-based Services (ProSe) function, procedures for communication and control, etc. are being studied (see Non-Patent Document 4). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 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) [Non-patent document 2] 3GPP TS 24.554 V18.5.1 (2024-06); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Proximity-services (ProSe) in 5G System (5GS) protocol aspects; Stage 3 (Release 18) [Non-patent document 3] 3GPP TS 24.501 V18.7.0 (2024-06); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3; (Release 18) [Non-patent document 4] 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) Summary of the Invention [Problem to be solved by the invention]

[0004] In 5GS (5G System), Proximity-services (ProSe) is being considered to realize close-proximity wireless communication between UEs. Furthermore, Release 19 of the 5G standard considers multi-hop communication between UEs via multiple relay UEs.

[0005] On the other hand, the establishment of communication paths for multi-hop communication, the various information required to maintain and update established communication paths, the transmission and reception of control messages containing this information between UEs, and the behavior and processing of each UE based on these messages are not clear.

[0006] One aspect of this embodiment has been made in consideration of the above circumstances, and its purpose is to clarify various information required for establishing a communication path for multi-hop communication and for maintaining and updating the established communication path, and further to provide a means for transmitting and receiving control messages containing this information between each UE, and a method for executing the behavior and processing of each UE based on this message. [Means for solving the problem]

[0007] A UE (User Equipment) of one aspect of this embodiment is a UE having a transceiver unit and a control unit, the UE being a target End UE, wherein the transceiver unit receives a ProSe direct link establishment request message from a third UE-to-UE relay UE in a direct link establishment procedure, the transceiver unit includes first information in a ProSe direct link establishment accept message, which is a response message to the ProSe direct link establishment request message, and transmits the message to the third UE-to-UE relay UE, the first information being information indicating a request for transmission of a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message, the control unit starts a first timer in conjunction with the transmission of the ProSe direct link establishment accept message, and if the transceiver unit receives the ProSe direct link establishment completion message from the third UE-to-UE relay UE before the first timer expires, the control unit stops the first timer.A UE (User Equipment) according to one aspect of the present embodiment is a UE including a transceiver unit and a controller, the UE being a target End UE, wherein the transceiver unit receives a ProSe direct link establishment request message from a source End UE via two or more UE-to-UE relay UEs in a direct link establishment procedure, the transceiver unit includes second information in a ProSe direct link establishment accept message that is a response message to the ProSe direct link establishment request message, and transmits the ProSe direct link establishment accept message to the source End UE via two or more UE-to-UE relay UEs, the second information being information indicating a request for transmission of a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message, the control unit starts a second timer in association with the transmission of the ProSe direct link establishment accept message, and the transceiver unit transmits the ProSe direct link establishment completion message to the source End UE via two or more UE-to-UE relay UEs by the time the second timer expires. When the direct link establishment procedure is received from the UE via two or more UE-to-UE relay UEs, the control unit recognizes that the direct link establishment procedure has been successful and stops the second timer. [Effects of the Invention]

[0008] According to one aspect of this embodiment, various information required to establish a communication path for multi-hop communication is clarified, and a means for transmitting and receiving control messages including the information between UEs, and a method for executing the behavior and processing of each UE based on the message are provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an outline of a mobile communication system (EPS / 5GS). [Figure 2] FIG. 1 is a diagram illustrating the detailed configuration of a mobile communication system (EPS / 5GS). [Figure 3] FIG. 1 is a diagram illustrating the device configuration of a UE. [Figure 4]A diagram explaining the configuration of an access network device (gNB) in 5GS. [Figure 5] A diagram explaining the configuration of core network devices (AMF / SMF / UPF) in 5GS. [Figure 6] FIG. 1 is a diagram illustrating a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery. [Figure 7] FIG. 10 is a diagram illustrating a configuration example of ProSe Layer-3 multi-hop UE-to-UE Relay communication. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a best mode for carrying out one aspect of this embodiment will be described with reference to the drawings. In this embodiment, as an example, an embodiment of a mobile communication system to which one aspect of this embodiment is applied will be described.

[0011] [1. System Overview] First, FIG. 1 is a diagram for explaining an outline 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. As shown in FIG.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] A 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). A 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. A UE may include a UICC (Universal Integrated Circuit Card) or an eUICC (Embedded UICC). Note that a UE may be referred to as a user device or a terminal device.

[0018] 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.

[0019] 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 Node Bs) 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.

[0020] 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).

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] Furthermore, in this specification, core network _A, and / or core network _B, and / or devices included in core network _A, and / or devices included in core network _B may be referred to as core networks, or core network devices, or devices within core networks, or networks, or NWs. In other words, for example, when referring to networks or NWs in this specification, it may mean core network _A or core network _B.

[0026] The core network (core network _A and / or core network _B) may be an IP mobile communication network operated by a mobile network operator (MNO) that connects the access network (access network _A and / or access network _B) to the PDN and / or DN, 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).

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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. The payload 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, added.

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The UPF_A235 is connected to the DN, the SMF, other UPFs, and the access network. The UPF_A235 may perform functions such as anchoring for intra-RAT 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 the function of forwarding IP communication and the function of 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.

[0036] Note that UPF_C239 (also referred to as a branching point or uplink classifier), which is a UPF different from UPF_A235, may exist as a device or NF between UPF_A235 and the access network. When UPF_C239 exists, a PDU session between the UE and the DN is established via the access network, UPF_C239, and UPF_A235.

[0037] 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.

[0038] [2. Configuration of each device] Next, the configuration of each device (UE, and / or access network device, and / or core network device) used in each embodiment will be described with reference to 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.

[0039] 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 that was 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.

[0040] [2.1. UE Device Configuration] 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.

[0041] The control unit _A300 is a functional unit that controls the operation and functions of the entire UE.The control unit _A300 realizes various processing in the UE by reading and executing various programs stored in the memory unit _A340 as necessary.

[0042] 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.

[0043] 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.

[0044] The memory unit _A340 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the UE.

[0045] [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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The memory unit _B540 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the gNB.

[0051] [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. The AMF may also be a network device. In other words, for example, in this specification, a network device may mean an AMF.

[0052] 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 necessary.

[0053] 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. That is, the AMF can use the network connection unit _B720 to transmit 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. In other words, for example, the network connection unit may be a transceiver unit.

[0054] 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.

[0055] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. necessary for each operation of the AMF.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] [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.

[0066] 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 necessary.

[0067] 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.

[0068] 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.

[0069] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the SMF.

[0070] 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.

[0071] [2.5. UPF device configuration] Next, an example of the device configuration of the UPF 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.

[0072] 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 necessary.

[0073] 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.

[0074] 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.

[0075] The memory unit _B740 is a functional unit for storing programs, user data, control information, etc. required for each operation of the UPF.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 2.6. Description of Other Devices and / or Functions Next, other devices and / or functions will be described.

[0082] The PCF has a function to provide policy rules.

[0083] The UDM also has functions such as authentication credential processing, user identification processing, access authentication, registration / mobility management, and subscription management.

[0084] The PCRF is connected to the PGW and / or PDN and has a function of managing QoS for data delivery. For example, it manages the QoS of the communication path between the UE_A10 and the PDN. Furthermore, the PCRF may be a device that creates and / or manages PCC (Policy and Charging Control) rules and / or routing rules used by each device when transmitting and receiving user data.

[0085] The HSS is connected to the MME and / or SCEF and has a function of managing subscriber information. The subscriber information of the HSS is referred to, for example, when controlling access to the MME. Furthermore, the HSS may be connected to a location management device different from the MME.

[0086] [3. Explanation of terms and identification information used in each embodiment] Next, highly specialized terms and identification information used in each embodiment will be explained in advance.

[0087] [3.1. Explanation of terms used in each embodiment] Next, highly specialized terms used in each embodiment will be explained.

[0088] A network refers to at least a portion of an access network _B, a core network _B, and a DN. Furthermore, one or more devices included in at least a portion of an access network _B, a core network _B, and a DN may be referred to as a network or a network device. In other words, when a network transmits, receives, and / or processes messages, it may mean that devices within the network (network devices and / or control devices) transmit, receive, receive, and / or process messages. Conversely, when a device within the network transmits, receives, receives, and / or processes messages, it may mean that the network transmits, receives, receives, and / or processes messages.

[0089] An SM (Session Management) message (also referred to as a NAS (Non-Access-Stratum) SM message) may be a NAS message used in a procedure for SM (SM procedure), and may be a control message transmitted and received between UE_A10 and SMF_A230 via AMF_A240. Furthermore, the SM message may include a PDU session establishment request message, a PDU session establishment accept message, a PDU session establishment reject message, a PDU session modification request message, a PDU session modification command message, a PDU session modification complete message, a PDU session modification command reject message, a PDU session modification reject message, a PDU session release request message, a PDU session release reject message, a PDU session release command message, a PDU session release complete message, etc. Furthermore, the procedure for SM or the SM procedure may include a PDU session establishment procedure, a PDU session modification procedure, and a UE-requested PDU session release procedure.Each procedure may be initiated from the UE or from the NW.

[0090] An MM (Mobility management) message (also referred to as an NAS MM message) may be an NAS message used in procedures for MM, and may be a control message transmitted and received between UE_A10 and AMF_A240. Furthermore, the MM message may include a registration request message, a registration accept message, a registration reject message, a de-registration request message, a de-registration accept message, a configuration update command message, a configuration update complete message, a service request message, a service accept message, a service reject message, a notification message, a notification response message, etc. Furthermore, the procedures for MM or MM procedures may include a registration procedure, a de-registration procedure, a generic UE configuration update procedure (also simply referred to as a UE configuration update procedure), an authentication and / or authorization procedure, a service request procedure, a paging procedure, and a notification procedure.

[0091] The 5GS (5G System) service is a connection service provided using the core network _B190. Furthermore, the 5GS service may be a service different from the EPS service or a service similar to the EPS service.

[0092] Non-5GS services may be services other than 5GS services, and may include EPS services and / or non-EPS services.

[0093] PDN (Packet Data Network) type indicates the type of PDN connection, and can be IPv4, IPv6, IPv4v6, or non-IP. If IPv4 is specified, it indicates that data will be sent and received using IPv4. If IPv6 is specified, it indicates that data will be sent and received using IPv6. If IPv4v6 is specified, it indicates that data will be sent and received using either IPv4 or IPv6. If non-IP is specified, it indicates that communication will not be via IP, but via a communication method other than IP.

[0094] A PDU (Protocol Data Unit / Packet Data Unit) session can be defined as an association between a DN that provides PDU connectivity services 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.

[0095] 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. Furthermore, the DNN may be equivalent to an APN (Access Point Name).

[0096] The PDU (Protocol Data Unit / Packet Data Unit) session type indicates the type of PDU session, and can be IPv4, IPv6, Ethernet, or Unstructured. If IPv4 is specified, it indicates that data will be sent and received using IPv4. If IPv6 is specified, it indicates that data will be sent and received using IPv6. If Ethernet is specified, it indicates that Ethernet frames will be sent and received. Ethernet may also indicate that communication using IP is not performed. If Unstructured is specified, it indicates that data will be sent and received to an application server or the like in the DN using Point-to-Point (P2P) tunneling technology. As the P2P tunneling technology, for example, UDP / IP encapsulation technology may be used. In addition to the above, the PDU session type may also include IP. IP can be specified if the UE is capable of using both IPv4 and IPv6.

[0097] 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 Subscriber Identity) may be a Home PLMN (HPLMN). Furthermore, a UE may store an Equivalent HPLMN list (also referred to as equivalent HPLMN) in its USIM to identify one or more Equivalent HPLMNs (EPLMNs). A PLMN that is different from the HPLMN and / or EPLMN may be a Visited PLMN (VPLMN). A PLMN to which a UE has successfully registered may be a Registered PLMN (RPLMN).

[0098] A tracking area is a single or multiple ranges managed by the core network that can be represented by the location information of UE_A10. Note that 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 may be a routing area, a location area, or anything similar. Hereinafter, a tracking area may be a TA (Tracking Area). A tracking area may be identified by a TAI (Tracking Area Identity) consisting of a TAC (Tracking area code) and a PLMN.

[0099] A registration area is a collection 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.

[0100] The Current TAI is the TAI broadcast by the selected PLMN in the cell where the UE is located or camped, or if the cell is a satellite NG-RAN cell that broadcasts multiple Tracking Area Codes (TACs) in the selected PLMN, the UE NAS layer may select the current TAI from multiple Tracking Area Codes (TACs) in the selected PLMN.

[0101] The UE ID is information for identifying a UE. For example, the UE ID may be a SUCI (Subscription Concealed Identifier), a SUPI (Subscription Permanent Identifier), a GUTI (Globally Unique Temporary Identifier), an IMEI (International Mobile Subscriber Identity), an IMEISV (IMEI Software Version), or a TMSI (Temporary Mobile Subscriber Identity). Alternatively, the UE ID may be other information set in an application or a network. Furthermore, the UE ID may be information for identifying a user.

[0102] PC5 is a reference point. PC5 may be a reference point between ProSe-enabled UEs. PC5 may be a reference point for 5G ProSe Direct Discovery, 5G ProSe Direct Communication, 5G ProSe UE-to-Network Relay, and / or 5G ProSe UE-to-UE Relay.

[0103] 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.

[0104] In addition, 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.

[0105] Uu may be a radio interface, and Uu may be a radio interface between a 5G AN and a UE.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] The initiating UE may be the UE that sends the PROSE direct link establishment request message.

[0110] The target UE may be the UE that sends the PROSE direct link establishment acceptance message.

[0111] An End UE may be a ProSe-enabled UE that communicates with another ProSe-enabled UE via a U2U relay UE. An End UE may be a ProSe-enabled UE that communicates with another ProSe-enabled UE via a U2U relay UE. In this specification, a 5G ProSe End UE is also simply referred to as an End UE.

[0112] The end UE may be a 5G ProSe end UE, a 5G ProSe layer-2 end UE, or a 5G ProSe layer-3 end UE. Note that the 5G ProSe layer-2 end UE may be a 5G ProSe capable UE that communicates with other 5G ProSe capable UEs via a 5G ProSe layer-2 UE-to-UE relay UE. Also, the 5G ProSe layer-3 end UE may be a 5G ProSe capable UE that communicates with other 5G ProSe capable UEs via a 5G ProSe layer-3 UE-to-UE relay UE.

[0113] An End UE may be referred to as a UE operating as an End UE. More specifically, an End UE may include a source End UE and a destination End UE (also referred to as a target End UE). Here, the source End UE may be an end UE that transmits a request message. Also, here, the target End UE may be an end UE that receives the request message. Here, the source End UE is also referred to as a source End UE. Also, here, the destination End UE is also referred to as a target End UE. Also, here, the source End UE and / or the destination End UE are also simply referred to as End UE. Furthermore, End UEs that perform direct communication via a communication path using a multi-hop U2U relay may be a source End UE and a target End UE, and are also referred to as an End UE and another End UE in this specification.

[0114] Also, a 5G ProSe layer-2 end UE is a 5G ProSe-enabled UE that communicates with another 5G ProSe-enabled UE via a 5G ProSe layer-2 U2U relay UE.

[0115] Also, a 5G ProSe layer-3 end UE is a 5G ProSe-enabled UE that communicates with another 5G ProSe-enabled UE via a 5G ProSe layer-3 U2U relay UE.

[0116] A U2U (UE-to-UE) relay UE may be a ProSe-enabled UE that provides functionality to support connectivity between two end UEs. One or more U2U relay UEs may be ProSe-enabled UEs that provide functionality to support connectivity between two end UEs.

[0117] A UE-to-UE relay (U2U Relay) UE may be a 5G ProSe U2U relay UE, a 5G ProSe layer-2 U2U relay UE, or a 5G ProSe layer-3 U2U relay UE. In this specification, 5G ProSe UE-to-UE Relay is also simply referred to as U2U Relay or U2U Relay UE. Furthermore, in this specification, when describing multiple U2U Relay UEs, each U2U Relay UE is also referred to as U2U Relay UE#1, U2U Relay UE#2, etc. to distinguish them from one another.

[0118] Here, the 5G ProSe layer-2 U2U relay UE may be a 5G ProSe-enabled UE that provides the function of supporting a connection between two 5G ProSe layer-2 end UEs via a layer 2 protocol.

[0119] Also, here, the 5G ProSe layer-3 U2U relay UE may be a 5G ProSe-enabled UE that provides a function of supporting a connection between two 5G ProSe layer-3 end UEs via a layer 3 protocol.

[0120] A U2U relay UE may be referred to as a UE that operates as a U2U relay UE. A U2U relay UE may be referred to as a U2U relay.

[0121] In addition, 5G ProSe layer-2 U2U relay UE is a 5G ProSe-enabled UE that provides the capability to support connectivity between two 5G ProSe layer-2 end UEs via layer-2 protocols.

[0122] In addition, 5G ProSe layer-3 U2U relay UE is a 5G ProSe-enabled UE that provides the capability to support connectivity between two 5G ProSe layer-3 end UEs via layer-3 protocols.

[0123] A discovery procedure may be a procedure that uses NR radio signals to detect and identify other nearby UEs.

[0124] The discovery procedure may be a 5G ProSe direct discovery procedure, a 5G ProSe UE-to-network relay discovery procedure, or a 5G ProSe UE-to-UE relay discovery procedure. The discovery procedure may also be referred to as 5G ProSe direct discovery or 5G ProSe discovery.

[0125] Multi-hop communication may refer to communication via two or more UEs. Also, multi-hop communication may refer to communication between a UE and another UE or a network via two or more other UEs. More specifically, for example, multi-hop communication may refer to communication between End UEs via two or more UE-to-UE Relay UEs.

[0126] For example, the embodiments described in Figures 6 and 7 may be multi-hop communication. More specifically, the embodiments described in Figures 6 and 7 may be examples in which a source end UE connects to a target end UE via two U2U relay UEs, establishes a communication path for multi-hop communication, and performs multi-hop communication. Here, the source end UE, and / or the target end UE, and / or each of U2U relay UE #1 to U2U relay UE #7 described in Figures 6 and 7 may support multi-hop communication.

[0127] Here, the multi-hop communication may be UE-to-network relay multi-hop communication or UE-to-UE relay multi-hop communication.

[0128] Furthermore, a UE that supports multi-hop communication may be a multi-hop UE. Furthermore, a UE that supports multi-hop communication may be a UE that supports operating as a multi-hop UE. More specifically, for example, a UE that supports multi-hop communication may be a UE-to-UE Relay UE and / or a UE-to-Network Relay UE. Or, for example, a UE that supports multi-hop communication may be a UE-to-UE Relay UE and / or a UE-to-Network Relay UE and / or an End UE.

[0129] The application layer ID is an identifier that identifies a 5G ProSe-enabled UE within the context of a particular application.

[0130] A Relay Service Code (RCS) may be information used to identify the connection service provided by U2U-relay and / or U2N relay and the authorized users to whom the U2U-relay and / or U2N relay provides the service. In this specification, the Relay Service Code (RCS) may also be referred to as an RCS.

[0131] Furthermore, for example, the relay service code may be information for identifying communication or communication service between End UEs via a multi-hop communication path via two or more U2U-relay UEs.

[0132] In addition, the relay service code may select security policies and information required for authentication and authorization between the End UE and the U2U relay UE.

[0133] Furthermore, the relay service code may be information included in configuration parameters for U2U-relay and / or U2N relay. The relay service code may be information included in configuration parameters for U2U-relay and / or U2N relay. The relay service code may be information included in configuration parameters for End UE.

[0134] The user info ID may be configured for Model A or Model B Group Member Discovery, 5G ProSe U2N Relay Discovery, and 5G ProSe U2U Relay Discovery for public safety or commercial applications based on the policy of the HPLMN or via the ProSe application server.

[0135] The application layer ID may be an identifier that identifies a 5G ProSe capable UE within the context of a particular application.

[0136] Furthermore, the application layer ID may be used as information indicating an End UE included in a ProSe direct link establishment request message in a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery, which will be described later. More specifically, for example, Source user info indicating a source End UE may be the application ID of the source End UE. Also, for example, Target user info indicating a target End UE may be the application ID of the source End UE.

[0137] Here, the application layer ID of the target End UE may be an ID to be included in the ProSe direct link establishment request message if the source End UE is provided by a higher layer or is known based on the Target End UE layer-2 ID.

[0138] Here, if the source End UE and the target End UE can communicate via previous direct communication or a direct communication path, and the ProSe direct link establishment procedure is for direct communication between the source End UE and the target End UE, the layer-2 ID of the target End UE (i.e., the layer-2 ID of the target End UE) may be included as information indicating the target End UE. Here, the ProSe direct link establishment procedure for direct communication between the source End UE and the target End UE may be a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery, which will be described later.

[0139] In other words, the information indicating the target End UE included in the ProSe direct link establishment request message may be Target user info, which is the application ID of the source End UE, and / or Target end UE layer-2 ID, which is the layer-2 ID of the target End UE.

[0140] ProSeP may be a 5G ProSe policy or information indicating or including a 5G ProSe policy. ProSeP may also be provided from the network to the U2U-relay and / or End UE in a network-requested UE policy management procedure and / or a UE-requested ProSeP provision procedure, which will be described later. ProSeP may also be information determined by the PCF and provided to the U2U-relay and / or End UE.

[0141] OLSR (Optimized Link State Routing Protocol) or OLSRv2 (Optimized Link State Routing Protocol Version 2) is a proactive routing protocol for mobile ad-hoc network environments, specified by the Mobile ad-hoc Network (MANET) Working Group of the IETF (Internet Engineering Task Force).

[0142] Here, a proactive routing protocol may be a routing protocol in which the terminals constituting the mobile ad hoc network exchange information in advance to determine a communication path before user communication is performed.

[0143] Currently, standardization is being promoted for use as a routing protocol for establishing a communication path between two End UEs when sending and receiving IP (Internet Protocol) type traffic in Layer-3 Multi-hop UE-to-UE Relay communications.

[0144] The communication path via the 5G ProSe layer-3 multi-hop UE-to-UE relay may be a communication path for direct communication between End UEs via one or more U2U Relay UEs, where the End UEs may be a source End UE and a target End UE, and the communication path via the 5G ProSe layer-3 multi-hop UE-to-UE relay may be a communication path for direct communication established between the source End UE and the target End UE via one or more U2U Relays.

[0145] In this specification, 5G ProSe layer-3 multi-hop UE-to-UE relay is also referred to as ProSe layer-3 multi-hop UE-to-UE relay, ProSe layer-3 multi-hop U2U relay, or simply multi-hop U2U relay.

[0146] [3.2. Description of Identification Information in Each Embodiment] Next, the identification information used in each procedure of each embodiment will be described. Note that each piece of identification information may be control information, and will be referred to as control information or simply information in this specification. Also, the name of each UE in the description of each piece of identification information may be based on the description in Figure 6 and / or Figure 7.

[0147] In this embodiment, the first identification information is a relay indication. Here, the relay indication indicated by the twentieth identification information may be information indicating that “The PROSE DIRECT LINK ESTABLISHMENT REQUEST message cannot be forwarded by a 5G ProSe UE-to-UE relay UE,” i.e., that the PROSE direct link establishment request message cannot be forwarded by a U2U Relay UE.

[0148] Alternatively, the relay indication indicated by the first identification information may be information indicating that "The PROSE DIRECT LINK ESTABLISHMENT REQUEST message can be forwarded by a 5G ProSe UE-to-UE relay UE," i.e., that the PROSE direct link establishment request message can be forwarded by a U2U Relay UE.

[0149] More specifically, for example, a U2U Relay UE that receives a message including a relay indication indicated by the first identification information may determine whether to relay the message in consideration of the content of the relay indication. Here, the message including the twentieth identification information may be a ProSe Direct Link Establishment Request message. Furthermore, the U2U relay UE may determine whether to forward the ProSe Direct Link Establishment Request message in consideration of the first, second, and / or third identification information.

[0150] In other words, the content or parameters of the relay indication indicated by the first identification information may be used to indicate whether the U2U relay UE forwards the ProSe direct link establishment request message.

[0151] Furthermore, the U2U Relay UE may determine the content of the first identification information to be included in the message based on the relay indication indicated by the received first identification information and the second and third identification information. Alternatively, the U2U Relay UE may determine whether to include the first identification information in the message based on the relay indication indicated by the received first identification information and one or more of the second to seventh identification information described below.

[0152] The second identification information in this embodiment is the maximum number of hops between End UEs. That is, the second identification information may be the maximum number of U2U relay UEs that can be passed through when establishing a direct communication path between End UEs, or the maximum number of paths between each End UE and one or more U2U relay UEs. Furthermore, the second identification information may be the maximum number of U2U relay UEs that can be passed through in direct communication between End UEs.

[0153] More specifically, the second identification information may be the maximum number of hops between two End UEs attempting ProSe Layer-3 multi-hop UE-to-UE Relay communication, or may be a value determined by the UE based on or taking into consideration a ProSe Policy (ProSeP) provided by the network.

[0154] Also, for example, the maximum hop count indicated by the second identification information may be the maximum number of U2U relay UEs between the source End UE and the destination End UE. More specifically, for example, if the maximum hop count indicated by the second identification information is "3," the source End UE may be able to transfer the ProSe direct link establishment request message to the destination End UE via a maximum of three U2U relay UEs. Furthermore, based on relay selection by the destination End UE, a communication path may be established between the source End UE and the destination End UE via the U2U relay UE.

[0155] The third identification information in this embodiment may be the number of hops from the End UE, i.e., the third identification information may be the number of U2U relay UEs through which the message transmitted from the source End UE has passed.

[0156] More specifically, for example, when a U2U relay UE receives a message including third identification information #1, it may forward the message taking into account the first and second identification information, and may forward a message including third identification information #2, which is the third identification information #1 plus "1".

[0157] Here, the number of hops from the End UE indicated by the third identification information may be the number of U2U relay UEs included in the fourth identification information.

[0158] More specifically, for example, if the number of hops indicated by the third identification information is "3," this may mean that the signal has passed through three U2U relay UEs from the source End UE. Furthermore, the number of IDs of U2U relay UEs included in the fourth identification information in this case may be three.

[0159] The third identification information may be information indicating a value equal to or less than the second identification information. Furthermore, if the value indicated by the third identification information is equal to the value indicated by the second information, the U2U relay UE that forwards the ProSe direct link establishment request message does not need to include the first identification information.

[0160] The fourth identification information in this embodiment is information indicating the IDs of one or more UE-to-UE relay UEs through which the ProSe direct link establishment request message transmitted by the source End UE is forwarded.

[0161] Here, the ID of the U2U relay UE included in the fourth identification information may be the User info ID of the U2U relay UE. In this specification, unless otherwise specified, the ID of the U2U relay UE included in the fourth identification information may be the User info ID of the U2U relay UE.

[0162] Furthermore, the U2U relay UE may add the ID of the U2U relay UE that receives and forwards the ProSe direct link establishment request message to the fourth identification information included in the ProSe direct link establishment request message received from the source End UE.

[0163] More specifically, for example, when a U2U relay UE receives a message including third identification information #1, it may forward the message by adding its own ID to the third identification information #1 and forwarding the message to include third identification information #2.

[0164] Here, for example, when the End UE or U2U relay UE includes the fourth identification information in the DCR, the End UE or U2U relay UE does not need to include the third identification information in the same message. In other words, for example, the End UE or U2U relay UE may recognize, store, or process the number of IDs of the U2U relay UE included in the third identification information included in the DCR as the number of hops. That is, The fifth identification information in this embodiment may be information indicating the quality of a connection or link between an End UE and a U2U relay UE, or between a U2U relay UE and another U2U relay UE. Furthermore, the fifth identification information may be information associated with or related to the fourth identification information. In other words, the fifth identification information may be information indicating the quality of a connection or link of a U2U relay UE or a previous hop of a target End UE.

[0165] More specifically, the fifth identification information may be, for example, PC5 signal strength, or information indicating link metrics, or information indicating the latency of the connection or link, but is not limited to these.

[0166] A U2U relay UE that receives a ProSe direct link establishment request message including the fifth identification information may add its own ID to the fourth identification information, and may add information indicating the quality of the connection or link between the fifth identification information and the U2U relay one hop before or the source End UE to the fifth information, include it in the ProSe direct link establishment request message, and forward it to the U2U relay UE or End UE.

[0167] Furthermore, the target End UE that has received the ProSe direct link establishment request message including the fifth identification information may select an optimal communication path between the End UEs, taking into consideration the quality of the connection or link between the source End UE and the U2U relay UE, and / or between the U2U relays, and / or between the U2U relay UE and the target End UE, which are indicated by the fifth identification information. The selection of the communication path by the Target End UE will be described in detail later.

[0168] The sixth identification information in this embodiment may be timestamp information indicating the time when the Direct Communication Request (DCR) message or the PROSE direct link establishment request message was created. Furthermore, the sixth identification information may be information associated with or related to the fourth identification information.

[0169] More specifically, for example, the sixth identification information may be information indicating a timestamp indicating the time at which the ProSe direct link establishment request message was created, associated with the ID of one or more UE-to-UE relay UEs (U2U relay UEs) included in the first identification information.

[0170] Here, the source End UE may or may not include the sixth information in the direct link establishment request message.

[0171] The seventh identification information in this embodiment is information indicating the expiration date of at least one of the fourth and fifth identification information.

[0172] The source End UE or the target End UE may recognize the expiration date of one or more of the fourth to fifth identification information based on the seventh identification information, and based on this recognition, may initiate a procedure to update each identification information that has reached its expiration date.

[0173] Furthermore, the seventh identification information may be an identification information determined by the network, or the source End UE, or a network policy, or a UE policy, or a local policy.

[0174] The tenth identification information in this embodiment may be information indicating a request for transmission of a response message to the ProSe direct link establishment accept message, where the response message to the ProSe direct link establishment accept message may be, for example, a ProSe direct link establishment completion message.

[0175] The first timer in this embodiment is a timer that is started or executed by the End UE or the U2U relay UE together with or accompanying the transmission or forwarding of the ProSe direct link establishment accept message. More specifically, for example, the first timer may be a timer that is stopped when the End UE receives a response message to the ProSe direct link establishment accept message from the U2U relay that transmitted the ProSe direct link establishment accept message. Also, for example, the first timer may be a timer that is stopped when the U2U relay UE receives a response message to the ProSe direct link establishment accept message from the U2U relay or End UE that forwarded the ProSe direct link establishment accept message.

[0176] In addition, the response message to the ProSe direct link establishment acceptance message may be a ProSe direct link establishment completion message.

[0177] Here, each message transmitted by the source End UE or End UE#1 and / or the target End UE or End UE#2 does not have to include the fourth to seventh identification information, or each message transmitted by the source End UE or End UE#1 and / or the target End UE or End UE#2 may include the fourth to seventh identification information.

[0178] The second timer in this embodiment is a timer that is started or executed by the End UE together with or accompanying the transmission or forwarding of the ProSe direct link establishment accept message. More specifically, for example, the second timer may be a timer that is stopped when the End UE receives a response message to the ProSe direct link establishment accept message via one or more U2U relay UEs from the other End UE that transmitted the ProSe direct link establishment accept message.

[0179] Here, the second timer may be a timer that is not started or executed in the U2U relay UE.

[0180] The 21st identification information in this embodiment is information indicating a request to update one or more pieces of information among the first to seventh identification information. Here, in a procedure for updating one or more pieces of information among the first to seventh identification information, an End UE may request one or more U2U relay UEs or the other End UE to update one or more pieces of information among the first to seventh identification information by transmitting the 21st identification information and the like to the other End UE via the established direct communication path by the ProSe Layer-3 multi-hop U2U relay.

[0181] The 21st identification information may request updating of one or more pieces of information among the first to seventh identification information, or may request updating of one or more pieces of information among the fourth to seventh identification information. Details of the procedure for updating one or more pieces of information among the first to seventh identification information will be described later.

[0182] The 22nd identification information in this embodiment is the updated fourth identification information. That is, the 22nd identification information may be information indicating the IDs of one or more UE-to-UE relay UEs through which the ProSe direct link establishment request message or the ProSe direct link modification request message transmitted by End UE#1 or End UE#2 is forwarded, or may be information indicating the IDs of one or more UE-to-UE relay UEs different from the fourth identification information.

[0183] More specifically, for example, the 22nd identification information may be the updated fourth identification information in a procedure for updating one or more of the fourth to seventh identification information, which is initiated when the End UE sends a request message including the 21st identification information.

[0184] In addition, if there is no change in the procedure, the fourth identification information and the twenty-second identification information may be information indicating the ID of one or more UE-to-UE relay UEs.

[0185] The 23rd identification information in this embodiment is the updated 5th identification information, that is, the 23rd identification information may be information representing the quality of the connection or link between the End UE and the U2U relay UE, or between the U2U relay UE and another U2U relay UE, or may be information representing the quality of the connection or link between the End UE and the U2U relay UE, or between the U2U relay UE and another U2U relay UE, which is different from the 5th identification information.

[0186] More specifically, for example, the 23rd identification information may be the updated 5th identification information in a procedure for updating one or more of the 4th to 7th identification information, which is initiated when the End UE sends a request message including the 21st identification information.

[0187] Furthermore, if there are no changes in the procedure, the fifth identification information and the twenty-third identification information may be information representing the quality of the connection or link between the same End UE and U2U relay UE, or between the U2U relay UE and another U2U relay UE.

[0188] The 24th identification information in this embodiment is the updated 6th identification information. That is, the 24th identification information may be timestamp information indicating the time when a Direct Communication Request (DCR) message or a PROSE direct link establishment request message was created, or may be timestamp information indicating the time when a Direct Communication Request (DCR) message or a PROSE direct link establishment request message different from the 6th identification information was created.

[0189] More specifically, for example, the 24th identification information may be the updated 6th identification information in a procedure for updating one or more of the 4th to 7th identification information, which is initiated when the End UE sends a request message including the 21st identification information.

[0190] Furthermore, if there are no changes in the procedure, the sixth identification information and the twenty-fourth identification information may be the same Direct Communication Request (DCR) message or timestamp information indicating the time when the PROSE direct link establishment request message was created.

[0191] The 25th identification information in this embodiment is the updated seventh identification information. That is, the 25th identification information may be information indicating the expiration date of one or more of the fourth to fifth identification information, or may be information indicating the expiration date of one or more of the fourth to fifth identification information that is different from the seventh identification information.

[0192] More specifically, for example, the 25th identification information may be the updated 6th identification information in a procedure for updating one or more of the 4th to 7th identification information, which is initiated when the End UE sends a request message including the 21st identification information.

[0193] In addition, if there are no changes in the procedure, the seventh identification information and the twenty-fifth identification information may be information indicating the expiration date of one or more of the same fourth to fifth identification information.

[0194] Details of the behavior of the UE and the network based on one or a combination of the above identification information 1 to 23 are not limited to those described in this chapter, but are also described in Chapter 4 and / or Chapter 5.

[0195] [4. Description of procedures used in each embodiment] Next, procedures used in each embodiment will be described. Here, the procedures used in each embodiment may include a 5G ProSe UE-to-UE Relay communication procedure using joint discovery and a communication path update procedure for ProSe Layer-3 multi-hop UE-to-UE Relay communication.

[0196] Note that each procedure described in this chapter may be executed or initiated after the source End UE, target End UE, and one or more UE-to-UE Relay UEs (U2U Relay UEs) complete the registration procedure, and / or the network-requested UE policy management procedure, and / or the UE-requested ProSeP provision procedure. Here, the source End UE and / or the target End UE are also simply referred to as End UE. Note that the names of each UE in the description of each procedure may be based on the descriptions in Figure 6 and / or Figure 7.

[0197] More specifically, for example, during the registration procedure, the source End UE, the target End UE, and one or more U2U relay UEs may be authorized or permitted by the network or AMF to use the ProSe Layer-3 multi-hop UE-to-UE Relay communication service.

[0198] More specifically, for example, a ProSe Layer-3 multi-hop UE-to-UE Relay communication service in which a source End UE, a target End UE, and one or more U2U relay UEs have been approved or authorized by a network or AMF may be a Layer-3 multi-hop UE-to-UE Relay service that uses a MANET (Mobile Ad-hoc Network) routing protocol in transmitting and receiving IP type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication, and / or a Layer-3 multi-hop UE-to-UE Relay service for Ethernet type or Unstructured type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication.

[0199] Furthermore, for example, in a network-requested UE policy management procedure and / or a UE-requested ProSeP provisioning procedure performed after the completion of the registration procedure, the source End UE, the target End UE, and one or more U2U relay UEs may be provided with ProSeP for ProSe Layer-3 multi-hop UE-to-UE Relay service or communication from the network or PCF.

[0200] More specifically, for example, ProSeP for ProSe Layer-3 multi-hop UE-to-UE Relay service or communication may be ProSeP when a MANET (Mobile Ad-hoc Network) routing protocol is used in transmitting and receiving IP type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication, and / or ProSeP when a Layer-3 multi-hop UE-to-UE Relay is used in transmitting and receiving Ethernet type or Unstructured type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication.

[0201] 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.

[0202] 4.1 5G ProSe UE-to-UE Relay Communication Procedure with Integrated Discovery The 5G ProSe UE-to-UE Relay communication procedure using integrated discovery will be described with reference to Figures 6 and 7. In this section, the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery will also be referred to as this procedure. The 5G ProSe UE-to-UE Relay communication procedure using integrated discovery may also be a procedure that combines the U2U relay discovery procedure and the direct link establishment procedure.

[0203] In this section, an example will be shown using Figure 6 in which a communication path consisting of five UEs, namely, a source End UE, U2U Relay UE #1, U2U Relay UE #2, U2U Relay UE #3, and a destination End UE, is established, and user data is transmitted and received over the path. The number of hops between the end UEs shown in Figure 6 may be four based on the number of paths, and the third identification information included in the direct link establishment request message transmitted by the source End UE in this case may be "1." Alternatively, the number of hops between the end UEs shown in Figure 6 may be three based on the number of U2U relay UEs, and the third identification information included in the direct link establishment request message transmitted by the source End UE in this case may be "0."

[0204] This procedure may be a procedure for 5G Prose UE-to-UE Relay communication by joint discovery via Layer-3 UE-to-UE Relay, or may be a procedure for establishing a communication path for multi-hop communication between End UEs via two or more UE-to-UE Relays.

[0205] This procedure may be performed multiple times. In other words, after this procedure is completed, it may be started again.

[0206] In this procedure, the UE that transmits the request message may be referred to as the initiating UE. In other words, the initiating UE may be the UE that transmits the PROSE direct link establishment request message. That is, the initiating UE in this procedure may be an End UE and / or a U2U Relay UE. In addition, the PROSE direct link establishment request message may be a Direct Communication Request (DCR) message.

[0207] A UE other than the initiating UE may be referred to as a target UE. A UE that receives the request message may be referred to as a target UE. In other words, the target UE may be a UE that sends a PROSE direct link establishment accept message or a PROSE direct link establishment reject message.

[0208] Furthermore, in this procedure, the End UE (source End UE or destination End UE) and the U2U Relay UE, and / or the U2U Relay and the U2U Relay UE may transmit and receive various control messages or user data via PC5.

[0209] Next, each step of this procedure will be described.

[0210] Here, this procedure may be executed after each UE completes the registration procedure. Also, this procedure may be initiated in a state where a service is authorized for each UE and parameters are provisioned for each UE. More specifically, for example, this procedure may be initiated in a state where an End UE is authorized and provisioned with parameters for using a service provided by the U2U Relay UE. Also, this procedure may be initiated in a state where the U2U Relay UE is authorized and provisioned with parameters for providing a service to relay traffic between two End UEs.

[0211] First, a Direct Communication Request (DCR) message is repeatedly broadcast and forwarded by each UE from a source End UE via U2U Relay #1, U2U Relay #2, and U2U Relay #3 until it reaches a destination End UE (S900 to S906). Here, in this specification, the DCR message is also simply referred to as DCR. Note that in this specification, the Direct Communication Request (DCR) message, the direct communication request message, and the ProSe Direct Link Establishment Request (PROSE DIRECT LINK ESTABLISHMENT REQUEST) message may be the same. In other words, in this specification, the Direct Communication Request (DCR) message may be read as a ProSe Direct Link Establishment Request message. In this specification, the ProSe Direct Link Establishment Request message may be read as a Direct Communication Request (DCR). In this specification, the ProSe direct link establishment request message is also simply referred to as a direct link establishment request message.

[0212] Here, in steps S900 to S906 of this procedure, each Direct Communication Request message (DCR) sent and received may include one or more of the first to tenth identification information.

[0213] More specifically, for example, each direct communication request message transmitted by the source End UE or End UE#1 may include one or more of the first to third and tenth identification information. In other words, for example, each direct communication request message transmitted by the source End UE or End UE#1 may be transmitted without including the fourth to seventh identification information. In other words, each direct communication request message (DCR) transmitted and received between U2U relay UEs, or between a U2U relay UE and a target End UE or End UE#2, may include one or more of the first to tenth identification information.

[0214] Furthermore, in steps S900 to S906 of this procedure, the U2U relay UE that receives the DCR may determine the content of the first identification information or whether to include the first identification information, taking into account one or more of the first to tenth identification information.

[0215] Furthermore, the third to seventh identification information included in the DCR may be changed or updated by the U2U relay UE that receives the DCR. More specifically, for example, when the U2U relay UE that receives the DCR forwards the DCR to the U2U relay UE or End UE, the U2U relay UE may add "1" to the third identification information included in the received message before forwarding. One or more of the fourth to seventh identification information may also be changed or updated and forwarded by the U2U relay UE that relays or forwards the message.

[0216] Also, in S900 to S906 of this procedure, a U2U relay UE that receives a DCR message including first identification information or a DCR message not including first identification information indicating that the message cannot be forwarded may recognize that the message cannot be forwarded or that the message cannot be forwarded.

[0217] More specifically, first, the source End UE broadcasts a DCR#1 message, and U2U Relay UE#1 receives DCR#1. Next, U2U Relay #1 broadcasts DCR#2, and U2U Relay UE#2 receives DCR#2. Next, U2U Relay UE#2, which has received DCR#2, broadcasts DCR#3, and U2U Relay UE#3 receives DCR#3. Furthermore, U2U Relay UE#3, which has received DCR#3, may broadcast DCR#4, and the destination End UE may receive DCR#4.

[0218] Furthermore, DCR#2 may be a message based on DCR#1, or may be a message generated by U2U Relay UE#1 by modifying the contents of DCR#1 received by DCR#1. As described above, DCR#2 may be a message generated by U2U Relay UE by modifying or updating the contents of specific identification information included in DCR#1. More specifically, for example, the 22nd identification information included in DCR#2 may be a value obtained by adding 1 to the value indicated by the 22nd identification information included in DCR#1. That is, U2U Relay UE#1 may add 1 to the value indicating the number of hops from the source End UE, which is included in the received DCR#1. Furthermore, U2U Relay UE#1 may generate DCR#2 including fourth identification information obtained by adding its own ID (e.g., UE ID, etc.) and / or address, etc., to the fourth identification information included in DCR#1.

[0219] Similarly to DCR#2, DCR#3 may also be a message modified by U2U Relay UE#2 in the same manner. Here, U2U Relay UE#2 may generate DCR#3 including fourth identification information obtained by adding its own ID or address to the fourth identification information included in DCR#2.

[0220] Here, the list of IDs or addresses of U2U Relays included in each DCR may be used by the U2U Relay UE or the destination End UE to recognize the route to the source End UE. Furthermore, when a U2U Relay UE receives a broadcasted DCR including its own ID or address, it may ignore or discard the message.

[0221] Furthermore, in steps S900 to S906 of this procedure, each U2U relay UE that receives a message including a list including an RSC and / or one or more identification information from the fourth to seventh identification information may store this information in association with or corresponding to the RSC.

[0222] Here, one or more of the fourth to seventh identification information may be included as a list in, for example, a direct communication request message (DCR). More specifically, for example, the list may be a list in which one or more of the fourth to seventh identification information are listed in one line. Furthermore, in S900 to S906 of this procedure, a U2U relay UE through which the DCR passes may add one or more of the fourth to seventh identification information to the list when forwarding a message.

[0223] In other words, one or more of the fourth to seventh identification information may be identification information that is added to a list of one or more of the fourth to seventh identification information contained in a message (e.g., a DCR) for each U2U relay UE through which the message passes.

[0224] Next, the target End UE or End UE#2 that has received the DCR (DCR#3) may perform or start relay selection, route selection, or path selection (S908), where the relay selection may be performed according to signal strength, and / or local policy, and / or operator policy per Relay Service Code (RSC), etc.

[0225] More specifically, for example, the target End UE or End UE#2 may perform or initiate relay selection, route selection, or path selection taking into account the RSC included in the direct link establishment request message and / or one or more of the first to seventh identification information.

[0226] Here, each UE may be able to recognize the route from the source End UE to the target End UE using a list consisting of one or more of the fourth to seventh identification information added by each U2U relay UE.

[0227] More specifically, for example, the list composed of one or more pieces of identification information from the fourth to seventh pieces of identification information may be information indicating a route or a communication path between a source End UE or End UE #1 and a target End UE or End UE #2. That is, each End UE may perform relay selection, route selection, or path selection based on information in the list composed of one or more pieces of identification information from the fourth to seventh pieces of identification information. Furthermore, when the expiration date indicated by the seventh identification information included in the list composed of one or more pieces of identification information from the fourth to seventh pieces of identification information has expired or is expected to expire, or is about to expire, the End UE may initiate or perform a procedure to update the list composed of one or more pieces of identification information from the fourth to seventh pieces of identification information.

[0228] In addition, the relay selection, route selection, or path selection in this procedure may be an operation of selecting a U2U Relay UE to send a response or response message when the target End UE or end UE#2 receives DCRs sent from the same source End UE or end UE#1 from multiple different U2U Relays.

[0229] Note that FIG. 6 may be an example in which the destination End UE selects U2U Relay #3.

[0230] Next, the destination End UE may transmit a response message to the direct link establishment request message (DCR) to the U2U Relay UE#2 selected in the relay selection (S910). Here, the response message to the DCR may be a direct link establishment accept message or a direct link establishment reject message. In this specification, unless otherwise specified, the response message to the DCR may be a direct link establishment accept message. Note that the response message to the DCR transmitted by the destination End UE may be transmitted by unicast.

[0231] Upon receiving the response message for the DCR from the destination End UE, the U2U Relay UE #3 may forward the response message to the U2U Relay UE #2 (S912). Note that the forwarding in this step may be performed by unicast.

[0232] Here, the direct link accept message transmitted by End UE#2 may include one or more of the first to seventh identification information.

[0233] Here, the fourth identification information included in the DCR transmitted and received in S912 may not include any information. Also, the DCR transmitted and received in S912 does not need to include the fourth identification information.

[0234] Next, the U2U Relay UE #2 may forward the response message received from the U2U Relay UE #3 to the U2U Relay UE #1 (S914).

[0235] Next, the U2U Relay UE #1 may forward the response message received from the U2U Relay UE #2 to the source End UE (S916).

[0236] Note that the transfers in steps S910 to S916 may be transmitted by unicast.

[0237] Here, the destination End UE or End UE#1 may not include one or more of the first to tenth identification information in the response message to the DCR transmitted and received at S910 to S916. Alternatively, the destination End UE may include one or more of the first to tenth identification information in the response message to the DCR transmitted and received at S910 to S916.

[0238] When the received response message to the DCR includes the tenth identification information, the source End UE or End UE#1 may recognize that it is requested to transmit a response message to the response message to the DCR to the target End UE or End UE#2. Here, the response message to the DCR may be a direct link establishment acceptance message. Furthermore, the response message to the direct link establishment acceptance message may be, for example, but is not limited to, a direct link establishment complete (ProSe direct link establishment complete) message.

[0239] The source End UE or End UE #1 that receives the direct link establishment acceptance message including the 10th identification information may send, for example, a direct link establishment completion message to one or more U2U relay UEs as a response message to the direct link establishment acceptance message, addressed to the target End UE or End UE #2 (S920 to S926).

[0240] Here, the transmission and reception of a response message to the direct link establishment accept message from End UE#1 to End UE#2 via one or more U2U relay UEs may be processed or transmitted and received in the same manner as the transmission and reception of the direct link establishment accept message (DCA) (S910 to S920). Note that the direct link establishment completion message may include RSC and / or zero or more identification information from the first to seventh identification information.

[0241] Here, the direct link establishment accept message transmitted from the End UE to the U2U relay UE does not need to include at least the fourth to seventh identification information. More specifically, for example, the target End UE or End UE#2 does not need to include the fourth to seventh identification information in the direct link establishment accept message (DCA) transmitted to the U2U relay UE#3.

[0242] Furthermore, whether or not to send and receive the direct link establishment completion message may be determined based on the 10th identification information included in End UE#2, may be determined based on network policy, may be determined according to UE policy or UE support, and is not limited to these.

[0243] Furthermore, the destination End UE may include a list of U2U Relay IDs or addresses in the DCR (DCR#4) received by the destination End UE in a response message to the DCR transmitted in S916. U2U Relay UE #3 and U2U Relay UE #2 that have received response messages including a list of U2U Relay IDs or addresses in S912 to S916 may forward the response messages based on the list of U2U Relay IDs or addresses, i.e., the fourth identification information.

[0244] Here, by including one or more of the identification information from the fourth to the seventh in the direct link establishment acceptance message, a list consisting of one or more of the identification information from the fourth to the seventh, indicating the route or communication path between the source End UE or End UE#1 and the target End UE or End UE#2, may be transmitted to End UE#1.

[0245] In addition, End UE#1 may store a list consisting of one or more of the fourth to seventh identification information indicating the route or communication path between the source End UE or End UE#1 and the target End UE or End UE#2.

[0246] In addition, U2U relay UE#1 to #3 may or may not store a list consisting of one or more of the fourth to seventh identification information indicating the route or communication path between the source End UE or End UE#1 and the target End UE or End UE#2.

[0247] Furthermore, a list consisting of one or more of the fourth to seventh identification information indicating a route or communication path between the source End UE or End UE#1 and the target End UE or End UE#2 may be stored in each UE in association with the RSC. That is, even if there is direct communication between the same combination of End UEs, if the RSC is different, it may be recognized as a different service or a different path.

[0248] If the response message to the DCR sent from the destination End UE is a direct link establishment acceptance message, a communication path may be established between the source End UE and the destination End UE via U2U Relay UE#1 and U2U Relay UE#2.

[0249] In this embodiment, the established communication path between the end UEs may be capable of transmitting and receiving any type of traffic, such as IP (Internet Protocol), Ethernet, or Unstructured. Note that the source end UE may indicate to each UE in a direct link establishment request message which type of traffic connectivity is to be established.

[0250] Furthermore, the source End UE and the destination End UE may perform data communication or user communication or user data communication of any type of IP (Internet Protocol), Ethernet, or Unstructured via the communication path established via U2U Relay UE #1 and U2U Relay UE #2 (S930).

[0251] This may complete the procedure. More specifically, this procedure may be completed when End UE#1 receives a direct link establishment acceptance message (S916). Alternatively, this procedure may be completed when End UE#2 receives a response message to the direct link establishment acceptance message (S926).

[0252] In addition, the ProSe direct link establishment request message or direct communication request message transmitted and received in S900 to S906 of this procedure may be transmitted by broadcast at the discretion of each UE.

[0253] Furthermore, messages transmitted and received in steps S910 to S916 and / or steps S920 to S926 of this procedure may be transferred by unicast between each UE (U2U Relay UE or End UE). Here, the messages transmitted and received in steps S910 to S916 may be ProSe direct link establishment accept messages or ProSe direct link establishment reject messages. Furthermore, user data transmission and reception between End UEs via two or more U2U Relay UEs may be transmitted and received by unicast for each segment (between a pair of two U2U Relays).

[0254] On the other hand, in steps S900 to S906 of this procedure, if the U2U Relay UE and / or End UE receives a DCR and recognizes that the DCR message cannot be forwarded or that the message cannot be forwarded, it may send a direct link establishment rejection message addressed to the source End UE to the source U2U Relay UE or source End UE of the DCR message.

[0255] 6 may be a communication path update procedure for 5G ProSe Layer-3 multi-hop UE-to-UE Relay communication, and may be a procedure executed after S930. Details of the communication path update procedure for 5G ProSe Layer-3 multi-hop UE-to-UE Relay communication will be described in the next section.

[0256] [4.2 Communication Path Update Procedure for 5G ProSe Layer-3 Multi-hop UE-to-UE Relay Communication] Next, a communication path update procedure for 5G ProSe Layer-3 multi-hop UE-to-UE Relay communication will be described with reference to Figures 6 and 7. In this chapter, the communication path update procedure for 5G ProSe Layer-3 multi-hop UE-to-UE Relay communication will also be referred to as this procedure.

[0257] This procedure may be initiated or executed after a communication path for Layer-3 multi-hop UE-to-UE Relay communication via one or more U2U Relay UEs is established between End UE#1 and End UE#2 in Chapter 4.1. In other words, this procedure may be executed as S904 in Fig. 6.

[0258] Here, this procedure may be a procedure that is initiated by End UE#1 in a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery, and is executed or started after End UE#2 accepts and transmits and receives a direct link establishment request message including identification information 1 to 7 via U2U relay UE#1 to UE#3.

[0259] In addition, End UE#1 or End UE#2 may start this procedure based on the seventh identification information included in a list consisting of one or more of the fourth to seventh identification information, which indicate the route or communication path between the source End UE or End UE#1 and the target End UE or End UE#2.

[0260] More specifically, when End UE#1 or End UE#2 recognizes that the expiration date indicated by the seventh identification information included in or associated with a list consisting of one or more of the fourth to seventh identification information has expired or is expected to expire or is about to expire, it may initiate or execute this procedure to update the list consisting of one or more of the fourth to seventh identification information.

[0261] Based on the seventh identification information, End UE#1 or End UE#2 that executes or starts this procedure may transmit an update request message including the tenth identification information to the End UE with which direct communication has been established. Here, the update request message may be a direct link establishment request message or a direct link modification request message.

[0262] Note that the update request message in this procedure may be transmitted and received between each UE in the same manner as in S900 to S906 or S910 to S916 in Fig. 9. Here, when End UE#1 initiates or executes this procedure, the update request message may be transmitted and received in the same manner as in S900 to S906. Alternatively, when End UE#2 initiates or executes this procedure, the update request message may be transmitted and received in the same manner as in S910 to S916.

[0263] Here, the update request message may include first to tenth identification information. More specifically, for example, the first to seventh identification information included in the update request message may be the same as the first to seventh identification information included in the direct link request message transmitted by the source End UE or End UE#1 in the 5G ProSe UE-to-UE Relay communication procedure using joint discovery.

[0264] Furthermore, each U2U Relay UE or End UE that receives an update request message including the tenth identification information recognizes that it is necessary to update a list consisting of one or more of the fourth to seventh identification information indicating the route or communication path between the source End UE or End UE #1 and the target End UE or End UE #2, and may process one or more of the fourth to seventh identification information in the same manner as S900 to S906 in the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery.

[0265] While the direct communication path between the End UEs is established, each End UE may execute this procedure at each expiration date based on the seventh identification information.

[0266] 5. Embodiment Next, each embodiment of this embodiment will be described. Note that each embodiment described in this chapter is based on the definitions of terms and various identification information explained in Chapter 3, and the procedures explained in Chapter 4. Also, in this chapter, each embodiment described in this chapter will be referred to as each embodiment of this chapter, or simply each embodiment. Note that the name of each UE in the explanation of each embodiment may be based on the description in Figure 6 and / or Figure 7.

[0267] Here, each embodiment described in this chapter may be an embodiment that is executed or initiated when the source End UE, the target End UE, and one or more UE-to-UE Relay UEs (U2U Relay UEs) have completed the registration procedure, and / or the network-requested UE policy management procedure, and / or the UE-requested ProSeP provision procedure.

[0268] More specifically, for example, during the registration procedure, the source End UE, the target End UE, and one or more U2U relay UEs may be authorized or permitted by the network or AMF to use the ProSe Layer-3 multi-hop UE-to-UE Relay communication service.

[0269] More specifically, for example, a ProSe Layer-3 multi-hop UE-to-UE Relay communication service in which a source End UE, a target End UE, and one or more U2U relay UEs have been approved or authorized by a network or AMF may be a Layer-3 multi-hop UE-to-UE Relay service that uses a MANET (Mobile Ad-hoc Network) routing protocol in transmitting and receiving IP type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication, and / or a Layer-3 multi-hop UE-to-UE Relay service for Ethernet type or Unstructured type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication.

[0270] Furthermore, for example, in a network-requested UE policy management procedure and / or a UE-requested ProSeP provisioning procedure performed after the completion of the registration procedure, the source End UE, the target End UE, and one or more U2U relay UEs may be provided with ProSeP for ProSe Layer-3 multi-hop UE-to-UE Relay service or communication from the network or PCF.

[0271] More specifically, for example, ProSeP for ProSe Layer-3 multi-hop UE-to-UE Relay service or communication may be ProSeP when a MANET (Mobile Ad-hoc Network) routing protocol is used in transmitting and receiving IP type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication, and / or ProSeP when a Layer-3 multi-hop UE-to-UE Relay is used in transmitting and receiving Ethernet type or Unstructured type traffic in ProSe Layer-3 multi-hop UE-to-UE Relay communication.

[0272] Furthermore, unless otherwise specified, each embodiment described in each section of this chapter may be executed individually and independently, or may be executed by combining the procedures of one or more embodiments described in each section, or may be executed in any order.

[0273] More specifically, for example, each UE of this embodiment may execute the fifth and sixth embodiments after executing the first to third embodiments.

[0274] Each embodiment will be described below.

[0275] 5.1. First embodiment The first embodiment of this example will be described with reference to Figure 6 and / or Figure 7. Hereinafter, in this section, the first embodiment will also be referred to as the present embodiment.

[0276] In this embodiment, the target End UE receives a ProSe direct link establishment request message from the U2U relay UE#3 in a direct link establishment procedure or a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery (S906). Here, the Target End UE in this embodiment may select a path via the U2U relay UE#3 in relay selection performed based on the received one or more DCRs (S908).

[0277] Next, the target End UE transmits a ProSe direct link establishment accept message to the U2U relay UE#3 as a response message to the ProSe direct link establishment request message received from the U2U relay UE#3 (S910).

[0278] Here, the target End UE includes the tenth identification information in the ProSe direct link establishment accept message and transmits it to the U2U relay UE #3. Here, the tenth identification information may be information indicating a request to transmit a response message to the ProSe direct link establishment accept message. More specifically, for example, the tenth identification information may be information indicating a request to transmit a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message.

[0279] Furthermore, the target End UE may start or run a first timer in conjunction with the transmission of the ProSe direct link establishment accept message. If the target End UE receives a response message to the ProSe direct link establishment accept message from the U2U relay UE #3 before the first timer expires (S926), the target End UE may stop the first timer.

[0280] More specifically, for example, the target End UE may start or run a first timer in conjunction with the transmission of the ProSe direct link establishment accept message. If the target End UE receives a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message from the U2U relay UE #3 before the first timer expires (S926), the target End UE may stop the first timer.

[0281] In addition, if the target End UE does not receive, for example, a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message from the UE-to-UE relay UE#3 before the first timer expires, the target End UE may resend the ProSe direct link establishment acceptance message to the UE-to-UE relay UE#3.

[0282] Here, the direct link acceptance message transmitted and received by each UE in this embodiment may include one or more of the first to seventh identification information.

[0283] In addition, if the first timer expires and retransmission is repeated multiple times, the target End UE may recognize that the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using joint discovery has failed, or that the transmission of the ProSe direct link establishment accept message has failed.

[0284] [5.2. Second embodiment] A second embodiment of this example will be described below. Hereinafter, in this section, the second embodiment will also be referred to as this embodiment.

[0285] In this embodiment, the U2U relay UE #3 receives a ProSe direct link establishment accept message #1 from the target end UE in a direct link establishment procedure or a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery.

[0286] Here, the U2U relay UE #3 receives a ProSe direct link establishment accept message #1 including tenth identification information from the target End UE. Here, the tenth identification information may be information indicating a request to transmit a response message to the ProSe direct link establishment accept message. More specifically, for example, the tenth identification information may be information indicating a request to transmit a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message.

[0287] The U2U relay UE #3 transmits a response message to the ProSe direct link establishment accept message #1 to the target End UE based on the tenth identification information received from the target End UE and included in the ProSe direct link establishment accept message #1.

[0288] Furthermore, the U2U relay UE#3 transmits the ProSe direct link establishment accept message#1 as a ProSe direct link establishment accept message#2 to the U2U relay UE#2, including the tenth identification information. Here, the U2U relay UE#3 starts a first timer along with the ProSe direct link establishment accept message#2. If the U2U relay UE#3 receives a response message to the ProSe direct link establishment accept message from the U2U relay UE#2 before the first timer expires, the U2U relay UE#3 may stop the first timer.

[0289] More specifically, for example, the U2U relay UE #3 transmits the ProSe direct link establishment accept message #1 as a ProSe direct link establishment accept message #2 to the U2U relay UE #2, including the tenth identification information. Here, the U2U relay UE #3 starts a first timer along with the ProSe direct link establishment accept message #2. If the U2U relay UE #3 receives a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message from the U2U relay UE #2 before the first timer expires, the U2U relay UE #3 may stop the first timer.

[0290] In addition, if the U2U relay UE#3 does not receive, for example, a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message from the UE-to-UE relay UE#2 before the first timer expires, the U2U relay UE#3 may resend the ProSe direct link establishment acceptance message to the UE-to-UE relay UE#2.

[0291] Here, the direct link acceptance message transmitted and received by each UE in this embodiment may include one or more of the first to seventh identification information.

[0292] Furthermore, if the first timer expires and retransmission is repeated multiple times, the U2U relay UE#3 may recognize that the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery has failed, or that the transfer of the ProSe direct link establishment acceptance message has failed.

[0293] Note that the ProSe direct link establishment acceptance message #2 described in this section may be the ProSe direct link establishment acceptance message #1 forwarded by the U2U relay UE, or may be the same message with some of the identification information and other contents replaced.

[0294] 5.3. Third embodiment The third embodiment of this example will be described with reference to Fig. 6 and / or Fig. 7. Hereinafter, in this section, the third embodiment will also be referred to as the present embodiment.

[0295] In the present embodiment, the target End UE receives a ProSe direct link establishment request message (DCR) from the source End UE via the U2U relay UE#3 in a direct link establishment procedure or a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery (S906). The target End UE may select a path via the U2U relay UE#3 in relay selection performed based on one or more received DCRs (S908).

[0296] Next, the target End UE transmits a ProSe direct link establishment acceptance message to the source End UE via the U2U relay UE #3, etc. as a response message to the ProSe direct link establishment request message received from the U2U relay UE #3 (S910 to S916).

[0297] Here, the target End UE includes the tenth identification information in a ProSe direct link establishment accept message, which is a response message to the ProSe direct link establishment request message, and transmits the message to the source End UE via U2U relay UE #3. Here, the tenth identification information may be information indicating a request to transmit a response message to the ProSe direct link establishment accept message. More specifically, for example, the tenth identification information may be information indicating a request to transmit a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message.

[0298] Furthermore, the target End UE may start or run a second timer in conjunction with the transmission of the ProSe direct link establishment accept message. If the target End UE receives a response message to the ProSe direct link establishment accept message from the source End UE via U2U relay UE #3 or the like before the second timer expires (S920 to S926), the target End UE may stop the second timer.

[0299] More specifically, for example, the target End UE may start or run a second timer in conjunction with the transmission of the ProSe direct link establishment accept message. If the target End UE receives a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment accept message from the source End UE via U2U relay UE #3 or the like before the second timer expires (S920 to S926), the target End UE may stop the second timer.

[0300] Here, the direct link acceptance message transmitted and received by each UE in this embodiment may include one or more of the first to seventh identification information.

[0301] Furthermore, for example, if the target End UE in this embodiment does not receive, for example, a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message from the UE-to-UE relay UE #3 before the second timer expires, the target End UE may recognize that the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure by integrated discovery has failed, or that the establishment of a Layer-3 multi-hop direct link with the source End UE has failed.

[0302] Or, for example, if the target End UE in this embodiment does not receive, for example, a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message from the UE-to-UE relay UE#3 before the second timer expires, the target End UE may resend the ProSe direct link establishment acceptance message to the UE-to-UE relay UE#3.

[0303] Furthermore, the source End UE that receives the ProSe direct link establishment accept message including the tenth identification information may recognize that it is requested to send, for example, a ProSe direct link establishment completion message to the target End UE as a response message to the ProSe direct link establishment accept message, and may further send, for example, a ProSe direct link establishment completion message to the target End UE as a response message to the ProSe direct link establishment accept message.

[0304] [5.4. Fourth embodiment] A fourth embodiment of this example will be described. In this section, the fourth embodiment will also be referred to as this embodiment.

[0305] Here, this embodiment may be an embodiment that starts in a state where the direct link establishment procedure of the first to third embodiments or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery has been accepted and completed, i.e., a state where the source End UE or End UE#1 has received a direct link establishment accept message and / or a target End UE or End UE#2 has received and completed a direct link establishment complete message. More specifically, this embodiment may be an embodiment that starts in a state where, for example, the target End UE or End UE#2 has transmitted a direct link establishment accept message to the source End UE or End UE#1, and the source End UE or End UE#1 has received the direct link establishment accept message, thereby completing the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery. Alternatively, for example, this embodiment may be an embodiment that starts when the target End UE or End UE#2 transmits a direct link establishment acceptance message to the source End UE or End UE#1, the source End UE or End UE#1 receives the direct link establishment acceptance message, and the target End UE or End UE#2 receives, for example, a direct link establishment as a response message to the direct link establishment acceptance message, and the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery is completed.

[0306] In this embodiment, the U2U relay UE #3 receives a ProSe direct link establishment request message #1 from the U2U relay UE #2 during a direct link establishment procedure or a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery, the ProSe direct link establishment request message #1 including any one or more of the first to seventh identification information.

[0307] Here, the first identification information may be a relay indication. The second identification information may be information indicating the maximum number of hops in communication between End UEs, or information indicating the maximum number of U2U relay UEs through which the message transmitted from the source End UE passes. The fourth identification information may be information indicating IDs of one or more UE-to-UE relay UEs through which the ProSe direct link establishment request message transmitted by the source End UE passes. The fifth identification information may be information included in the fourth identification information and indicating the quality of the connection or link between the End UE and the U2U relay UE, or between the U2U relay UE and each UE associated with another U2U relay UE, and may be, for example, information indicating PC5 signal strength associated with or related to IDs of one or more UE-to-UE relay UEs. Furthermore, the sixth identification information may be information indicating a timestamp that indicates a time when the ProSe direct link establishment request message was created, and that is associated with the ID of one or more UE-to-UE relay UEs included in the fourth identification information. Furthermore, the seventh identification information may be information indicating an expiration date of any one or more of the fourth and fifth identification information.

[0308] The ProSe direct link establishment request message #2 containing the first to third identification information and the 22nd to 25th identification information is forwarded to the target End UE instead of the first to seventh identification information contained in the ProSe direct link establishment request message #1 received from the U2U relay UE #2.

[0309] Here, the third identification information included in the ProSe direct link establishment request message #2 may be a value obtained by adding "1" to the third identification information included in the ProSe direct link establishment request message #1. Furthermore, the 22nd identification information may be information obtained by adding, to the fourth identification information, the ID of the U2U relay UE, i.e., the User info ID of the U2U relay UE #3, for example, as the ID of the U2U relay UE #3. Furthermore, the 23rd identification information may be information indicating, for example, PC5 signal strength, which is information indicating the quality of the connection or link between the U2U relay UE #2 and the U2U relay UE #3 and which is associated with or correlated to the ID of the U2U relay UE #3 and which is added to the fourth identification information. Furthermore, the 24th identification information may be information indicating a timestamp, which is the time at which the ProSe direct link establishment request message #2 was generated, which is associated with or correlated to the ID of the U2U relay UE #3 and added to the fourth identification information. Furthermore, the 25th information may be information indicating the expiration date of one or more of the 4th to 6th identification information that is added to the 4th identification information and corresponds to or is associated with the ID of U2U relay UE #3.

[0310] [5.5. Fifth embodiment] The fifth embodiment of this example will be described with reference to Figures 6 and 7. In this section, the fifth embodiment will also be referred to as the present embodiment.

[0311] Here, this embodiment may be an embodiment that starts in a state where the direct link establishment procedure of the first to third embodiments or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery has been accepted and completed, i.e., a state where the source End UE or End UE#1 has received a direct link establishment accept message and / or a target End UE or End UE#2 has received and completed a direct link establishment complete message. More specifically, this embodiment may be an embodiment that starts in a state where, for example, the target End UE or End UE#2 has transmitted a direct link establishment accept message to the source End UE or End UE#1, and the source End UE or End UE#1 has received the direct link establishment accept message, thereby completing the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery. Alternatively, for example, this embodiment may be an embodiment that starts when the target End UE or End UE#2 transmits a direct link establishment acceptance message to the source End UE or End UE#1, the source End UE or End UE#1 receives the direct link establishment acceptance message, and the target End UE or End UE#2 receives, for example, a direct link establishment as a response message to the direct link establishment acceptance message, and the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery is completed.

[0312] In this embodiment, the target End UE or End UE #2 receives a ProSe direct link establishment request message #1 including any one or more of the first to seventh identification information from the U2U relay UE #3 in a direct link establishment procedure or a 5G ProSe UE-to-UE Relay communication procedure using integrated discovery.

[0313] Here, the first identification information may be a relay indication. The second identification information may be information indicating the maximum number of hops in communication between End UEs or information indicating the maximum number of U2U relay UEs through which a message transmitted from a source End UE passes. The third identification information may be information indicating the number of U2U relay UEs through which a message transmitted from a source End UE passes.

[0314] Furthermore, the fourth identification information may be information indicating IDs of one or more UE-to-UE relay UEs via which the ProSe direct link establishment request message transmitted by the source End UE has been sent. Furthermore, the fifth identification information may be information included in the fourth identification information and indicating the quality of a connection or link between the End UE and the U2U relay UE, or between the U2U relay UE and each UE associated with another U2U relay UE, and may be, for example, information indicating a PC5 signal strength associated with or related to the ID of one or more UE-to-UE relay UEs. Furthermore, the sixth identification information may be information indicating a timestamp indicating the time when the ProSe direct link establishment request message was created, and associated with the ID of one or more UE-to-UE relay UEs included in the fourth identification information. Furthermore, the seventh identification information may be information indicating the expiration date of one or more of the fourth and fifth identification information.

[0315] Furthermore, in the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure by integrated discovery, the target End UE may receive a ProSe direct link establishment request message #2 including any one or more of the first to seventh identification information from the U2U relay UE #5, or may receive a ProSe direct link establishment request message #3 including any one or more of the first to seventh identification information from the U2U relay UE #7. Note that here, any one or more of the first to seventh identification information included in the ProSe direct link establishment request messages #1 to #3 may indicate different values ​​or information.

[0316] In other words, for example, any one or more of the first to seventh identification information included in the ProSe direct link establishment request message #1 received by the target End UE or End UE #2 from the U2U relay UE #3 may be different from any one or more of the first to seventh identification information included in the ProSe direct link establishment request message #2 received by the target End UE or End UE #2 from the U2U relay UE #5. Also, for example, any one or more of the first to seventh identification information included in the ProSe direct link establishment request message #1 received by the target End UE or End UE #2 from the U2U relay UE #3 may be different from any one or more of the first to seventh identification information included in the ProSe direct link establishment request message #3 received by the target End UE or End UE #2 from the U2U relay UE #7.

[0317] More specifically, for example, the fourth identification information included in the ProSe direct link establishment request messages #1 to #3 may be different from each other. More specifically, for example, the fourth identification information included in the ProSe direct link establishment request message #1 may include the IDs of U2U relay UE #1, U2U relay UE #2, and U2U relay UE #3, in that order. Also, for example, the fourth identification information included in the ProSe direct link establishment request message #2 may include the IDs of U2U relay UE #4 and U2U relay UE #5, or the IDs of U2U relay UE #1, U2U relay UE #2, and U2U relay UE #5, in that order. Also, for example, the fourth identification information included in the ProSe direct link establishment request message #3 may include the IDs of U2U relay UE #6 and U2U relay UE #7, in that order.

[0318] The Target End UE may select a communication path for Layer-3 multi-hop UE-to-UE Relay communication via one or more U2U relay UEs or a U2U relay UE to be established between the source End UE or End UE#1 and the target End UE or End UE#2, taking into consideration the first to seventh identification information included in the received one or more ProSe direct link establishment request messages.

[0319] Note that the relay selection by the target End UE or End UE#2 may be performed based on ProSeP provided by the network or PCF.

[0320] More specifically, for example, if the ProSeP provided to the target End UE or End UE#2 includes content instructing that relay selection be performed taking into account the number of hops, the target End UE or End UE#2 may perform relay selection based on the number of hops indicated by the third identification information for each route or the number of U2U relay UEs included in the fourth identification information.

[0321] Furthermore, for example, if the ProSeP provided to the target End UE or End UE#2 includes content instructing that relay selection be performed taking into consideration the quality of the link or connection, the target End UE or End UE#2 may perform relay selection based on the number of U2U relay UEs included in the fifth identification information. Here, if the fifth identification information is information indicating PC5 signal strength, the target end UE or end UE#2 performing relay selection may derive an index indicating the quality of the end-to-end connection or link for each route by adding up scores calculated from the PC5 signal strength for each segment between the End UEs, and perform relay selection based on the index.

[0322] [5.6. Sixth embodiment] The sixth embodiment of this example will be described with reference to Fig. 6 and / or Fig. 7. In this section, the sixth embodiment will also be referred to as the present embodiment.

[0323] Here, this embodiment may be an embodiment that starts in a state where the direct link establishment procedure of the first to third embodiments or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery has been accepted and completed, i.e., a state where the source End UE or End UE#1 has received a direct link establishment accept message and / or a target End UE or End UE#2 has received and completed a direct link establishment complete message. More specifically, this embodiment may be an embodiment that starts in a state where, for example, the target End UE or End UE#2 has transmitted a direct link establishment accept message to the source End UE or End UE#1, and the source End UE or End UE#1 has received the direct link establishment accept message, thereby completing the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery. Alternatively, for example, this embodiment may be an embodiment that starts when the target End UE or End UE#2 transmits a direct link establishment acceptance message to the source End UE or End UE#1, the source End UE or End UE#1 receives the direct link establishment acceptance message, and the target End UE or End UE#2 receives, for example, a direct link establishment as a response message to the direct link establishment acceptance message, and the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery is completed.

[0324] The target End UE or End UE#2 in this embodiment may store any one or more of the first to seventh identification information included in the ProSe direct link establishment request message received from the U2U relay UE in the direct link establishment procedure or the 5G ProSe UE-to-UE Relay communication procedure using integrated discovery.

[0325] Next, in a procedure for updating one or more of the identification information from the first to seventh identification information based on the seventh identification information, the target End UE or End UE#2 may send a link change request message or a direct communication request message including the 21st identification information to the source End UE or End UE#1 via one or more U2U relay UEs that constitute the established direct communication path.

[0326] Here, the first identification information may be a relay indication. The second identification information may be information indicating the maximum number of hops in communication between End UEs or information indicating the maximum number of U2U relay UEs through which a message transmitted from a source End UE passes. The third identification information may be information indicating the number of U2U relay UEs through which a message transmitted from a source End UE passes.

[0327] Furthermore, the fourth identification information may be information indicating IDs of one or more UE-to-UE relay UEs via which the ProSe direct link establishment request message transmitted by the source End UE has been sent. Furthermore, the fifth identification information may be information included in the fourth identification information and indicating the quality of a connection or link between the End UE and the U2U relay UE, or between the U2U relay UE and each UE associated with another U2U relay UE, and may be, for example, information indicating a PC5 signal strength associated with or corresponding to the ID of one or more UE-to-UE relay UEs. Furthermore, the sixth identification information may be information indicating a timestamp that indicates the time when the ProSe direct link establishment request message was created and that is associated with the ID of one or more UE-to-UE relay UEs included in the fourth identification information. Furthermore, the seventh identification information may be information indicating the expiration date of one or more of the identification information from the fourth to fifth identification information. Furthermore, the identification information of the twenty-first identification information may be identification information indicating a request to update one or more of the identification information from the first to seventh identification information.

[0328] The procedure for updating one or more of the first to seventh identification information may be the procedure or process described in the communication path update procedure for 5G ProSe Layer-3 multi-hop UE-to-UE relay communication described in Chapter 4.2. Also, here, the request message including the 21st identification information may be a link change request message and / or a direct link establishment request message described in Chapter 4.2.

[0329] Subsequently, the target End UE or End UE #2 receives a ProSe direct link modification accept message, a ProSe direct establishment modification ACK (ACKnowledgement) message, or a ProSe direct link establishment accept message including one or more identification information items among the 22nd to 25th identification information items from End UE #1 via one or more U2U relay UEs. Here, the ProSe direct link modification accept message or the ProSe direct establishment modification ACK message may be a response message to the ProSe direct link modification request message. Also, the ProSe direct link establishment accept message may be a response message to the ProSe direct link establishment request message.

[0330] Here, the 22nd identification information may be the updated fourth identification information, the 23rd identification information may be the updated fifth identification information, the 24th identification information may be the updated sixth identification information, and the 25th identification information may be the updated seventh identification information.

[0331] The target End UE or End UE#2 may replace or update any one or more of the first to seventh identification information stored therein with one or more of the received identification information of the 22nd to 25th identification information, and store the replaced information. Note that the updating or replacement of any one or more of the first to seventh identification information with one or more of the 22nd to 25th identification information may mean replacing or updating the content indicated by the corresponding identification information. 6. Variations The program that runs on the device according to one aspect of 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 one aspect of 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 another storage device system.

[0332] A program for realizing the functions of an embodiment according to one aspect of this example 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 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.

[0333] 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.

[0334] 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 stationary or non-movable electronic devices installed indoors or outdoors, such as terminal devices or communication devices for AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0335] 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 embodiment, and design modifications within the scope of this example are also included. Furthermore, various modifications of this example are possible 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. [Explanation of symbols]

[0336] 1. Mobile communication systems 10 UE_A 30 PGW-U 32 PGW-C 35 SGW 40 MME 45 eNB 50 HSS 60 PCRF 80 Access Network_A (E-UTRAN) 90 Core Network_A 120 Access Network_B (5G AN) 122 gNB 130 UPF 132 SMF 140 AMF 150 UDM 160 PCF 190 Core Network_B 235 UPF_A 239 UPF_C

Claims

1. A UE (User Equipment) including a transceiver unit and a control unit, The UE is a target End UE, the transceiver unit receives a ProSe direct link establishment request message from a third UE-to-UE relay UE in a direct link establishment procedure; the transceiver unit includes first information in a ProSe direct link establishment accept message, which is a response message to the ProSe direct link establishment request message, and transmits the ProSe direct link establishment accept message to the third UE-to-UE relay UE; the first information is information indicating a request to transmit a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message, the control unit starts a first timer in response to transmission of a ProSe direct link establishment acceptance message; If the transceiver unit receives the ProSe direct link establishment completion message from the third UE-to-UE relay UE before the first timer expires, the control unit stops the first timer. A UE characterized by:

2. If the transceiver unit does not receive the ProSe direct link establishment completion message from the third UE-to-UE relay UE before the first timer expires, The transceiver unit retransmits the ProSe direct link establishment accept message to the third UE-to-UE relay UE.

2. The UE of claim 1 .

3. A UE (User Equipment) including a transceiver unit and a control unit, The UE is a target End UE, the transceiver unit receives a ProSe direct link establishment request message from a source End UE via two or more UE-to-UE relay UEs in a direct link establishment procedure; the transceiver unit includes second information in a ProSe direct link establishment accept message, which is a response message to the ProSe direct link establishment request message, and transmits the ProSe direct link establishment accept message to the source End UE via two or more UE-to-UE relay UEs; the second information is information indicating a request to transmit a ProSe direct link establishment completion message as a response message to the ProSe direct link establishment acceptance message, The control unit starts a second timer in response to the transmission of the ProSe direct link establishment acceptance message; If the transceiver unit receives the ProSe direct link establishment completion message from the source End UE via two or more UE-to-UE relay UEs before the second timer expires, the control unit recognizes that the direct link establishment procedure has been successful and stops the second timer. A UE characterized by:

4. If the transceiver unit does not receive the ProSe direct link establishment completion message from the source End UE via two or more UE-to-UE relay UEs before the first timer expires, The control unit recognizes that the direct link establishment procedure has failed or that establishment of a Layer-3 multi-hop direct link with the source End UE has failed.

4. The UE according to claim 3,

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