Terminal and communication method

Abstract

To control a network selection trigger, or a network-to-be-selected for a user device in a roaming environment.SOLUTION: A terminal includes a receiving unit that receives signaling related to SoR (Steering of Roaming), which includes at least information indicating a preferred PLMN and information indicating a trigger for selecting a PLMN, from a first network node in a visited public land mobile network (VPLMN), and a control unit that performs PLMN selection based on the information indicating the preferred PLMN and the information indicating the trigger for selecting a PLMN. The signaling related to SoR is created by a second network node in a home public land mobile network (HPLMN), and the control unit transmits an acknowledgement to the first network node.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a terminal and a communication method.

Background Art

[0002] In 3GPP (3rd Generation Partnership Project), in order to achieve further increase in system capacity, further increase in data transmission speed, further reduction in latency in the radio section, etc., a wireless communication method called 5G or NR (New Radio) (hereinafter, this wireless communication method is referred to as "5G" or "NR") is being studied. In 5G, various wireless technologies are being studied in order to meet the requirement of achieving a throughput of 10 Gbps or more and reducing the latency in the radio section to 1 ms or less.

[0003] In NR, a network architecture including 5GC (5G Core Network) corresponding to EPC (Evolved Packet Core), which is the core network in the network architecture of LTE (Long Term Evolution), and NG-RAN (Next Generation - Radio Access Network) corresponding to E-UTRAN (Evolved Universal Terrestrial Radio Access Network), which is the RAN (Radio Access Network) in the network architecture of LTE, is being studied (for example, Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In NR, when a user equipment is connected to a network in a roaming environment and the user equipment obtains SoR (Steering of Roaming) information related to control of selecting a preferred PLMN (Public land mobile network), it has been difficult to control the timing at which PLMN selection is executed.

[0006] The present invention has been made in view of the above points, and an object thereof is to control a network selection opportunity or a network to be selected of a user equipment in a roaming environment.

Means for Solving the Problems

[0007] According to the disclosed technology, a receiving unit that receives signaling related to SoR (Steering of Roaming) including at least information indicating a preferred PLMN and information indicating an opportunity to select a PLMN from a first network node in a VPLMN (Visited Public land mobile network), and a control unit that executes PLMN selection based on the information indicating the preferred PLMN and the information indicating the opportunity to select the PLMN, wherein the signaling related to the SoR is created by a second network node in an HPLMN (Home Public land mobile network), and the control unit is provided with a terminal that transmits a confirmation response to the first network node.

Effects of the Invention

[0008] According to the disclosed technology, it is possible to control a network selection opportunity or a network to be selected of a user equipment in a roaming environment.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to the following embodiments.

[0011] In the operation of the wireless communication system according to the embodiment of the present invention, existing technologies are appropriately used. However, the existing technology is, for example, existing LTE, but is not limited to existing LTE. Further, the term "LTE" used in this specification shall have a broad meaning including LTE-Advanced, and systems after LTE-Advanced (e.g., NR), or wireless LAN (Local Area Network) unless otherwise specified.

[0012] Also, in the embodiment of the present invention, the fact that wireless parameters and the like are "configured" may mean that predetermined values are pre-configured, or that wireless parameters notified from the network node 10 or the user equipment 20 are configured.

[0013] FIG. 1 is a diagram for explaining a communication system in an embodiment of the present invention. As shown in FIG. 1, the communication system is composed of a UE which is a user equipment 20 and a plurality of network nodes 10. Hereinafter, it is assumed that one network node 10 corresponds to each function, but one network node 10 may implement a plurality of functions, or a plurality of network nodes 10 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0014] The RAN (Radio Access Network) is a network node 10 having a radio access function and is connected to a UE, an AMF (Access and Mobility Management Function), and a UPF (User plane function). The AMF is a network node 10 having functions such as the termination of the RAN interface, the termination of the NAS (Non-Access Stratum), registration management, connection management, reachability management, and mobility management. The UPF is a network node 10 having functions such as the PDU (Protocol Data Unit) session point to the outside that interconnects with the DN (Data Network), packet routing and forwarding, and QoS (Quality of Service) handling of the user plane. The UPF and the DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, a plurality of network slices may be constructed.

[0015] The AMF is connected to a UE, a RAN, an SMF (Session Management function), an NSSF (Network Slice Selection Function), a NEF (Network Exposure Function), an NRF (Network Repository Function), an AUSF (Authentication Server Function), a PCF (Policy Control Function), an AF (Application Function), a UDM (Unified Data Management), and a SEPP (Security Edge Protection Proxy). The AMF, SMF, NSSF, NEF, NRF, AUSF, PCF, AF, and UDM are network nodes 10 that are interconnected via interfaces based on their respective services, Namf, Nsmf, Nnssf, Nnef, Nnrf, Nausf, Npcf, Naf, and Nudm.

[0016] The SMF is a network node 10 having functions such as session management, UE IP (Internet Protocol) address allocation and management, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, and roaming function. The NEF is a network node 10 having a function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 10 having functions such as selection of the network slice to which the UE connects, determination of the permitted NSSAI (Network Slice Selection Assistance Information), determination of the configured NSSAI, and determination of the set of AMFs to which the UE connects. The PCF is a network node 10 having a function of performing network policy control. The AF is a network node 10 having a function of controlling the application server. The UDM is a network node 10 having functions such as generation of authentication information, user identification, and access restriction during roaming based on subscriber data. The SEPP is a non-transparent proxy that filters control plane messages between PLMNs (Public land mobile networks). The vSEPP shown in Figure 1 is the SEPP in the visited network, and the hSEPP is the SEPP in the home network. Also, the UDM can obtain information necessary for steering via the SOR-AF (Steering of Roaming application function) and Nsoraf. Furthermore, the SOR-AF can encrypt the steering information to be notified to the UE via the SP-AF (Secured Packet Application Function) and Nspaf.

[0017] As shown in FIG. 1, the UE is in a roaming environment where it is connected to the RAN and the AMF in the VPLMN (Visited PLMN). The VPLMN and the HPLMN (Home PLMN) are connected via the vSEPP and the hSEPP. The UE can communicate with the UDM of the HPLMN, for example, via the AMF of the VPLMN.

[0018] FIG. 2 is a diagram for explaining Example (1) of the SoR processing method. In FIG. 2, the SoR (Steering of Roaming) function that instructs the PLMN where the home operator is located for a roaming user in LTE is explained.

[0019] The UE selects a PLMN according to the priority PLMN list (EF_OPLMNwAcT) recorded in the USIM (Universal Subscriber Identity Module). As shown in FIG. 2, in SoR, for a roaming UE, an SMS (Short Message Service) that rewrites the PLMN list of the USIM is sent from the HSS (Home Subscriber Server) and received by the UE via the SMSC (SMS Center) and the Core NW (Core Network), thereby controlling the PLMN to which the UE should preferably roam.

[0020] FIG. 3 is a diagram for explaining Example (2) of the SoR processing method. In the SoR processing method shown in FIG. 2, the SoR function cannot be provided for SMS-incompatible terminals (for example, module terminals, etc.). Also, since no response (ACK) is returned from the terminal, the network node of the distribution source cannot recognize that the rewriting has been completed.

[0021] Therefore, in the HPLMN and VPLMN of the 5G system as shown in FIG. 1, the SoR function is realized by rewriting the PLMN list of the UE through NAS (Non-Access Stratum) signaling. By rewriting the PLMN list through NAS signaling, it becomes possible to control SMS-incompatible terminals, and the UE can return a response to the network node of the distribution source, and the UE can notify the network that the rewriting has been completed normally.

[0022] As shown in FIG. 3, the UDM in the HPLMN transmits the priority PLMN, which is the SoR information, to the AMF in the VPLMN. At this time, the UDM may obtain the priority PLMN information from the SOR-AF. The SOR-AF can determine the priority operator in consideration of various conditions such as the current number of subscribers in the circle and usage. Also, the SOR-AF may cause the SP-AF to convert the UE into a decryptable encrypted message. Subsequently, the AMF transmits the priority PLMN received from the UDM to the UE via NAS signaling. When the UE receives the priority PLMN, it transmits an ACK to the AMF.

[0023] Here, when the UE receives the SoR information and the UE performs PLMN selection during communication, the network search operates, so the call in progress is disconnected. Whether to perform PLMN selection immediately after disconnecting the call or to wait until the communication ends and then perform PLMN selection depends on the UE implementation. Therefore, it is not possible to start the PLMN selection process according to the call type or operator policy during communication. As an example where the start process of PLMN selection according to the call type during communication is required, when the call type during communication is a voice call, the disconnection should be avoided because it has a great impact on the user. Also, for example, when the call type during communication is data communication, it should be made to camp on the priority PLMN immediately after disconnection.

[0024] Also, if PLMN selection is performed immediately after an emergency call, a callback from the emergency call acceptance agency cannot be received, so it is better to avoid starting PLMN selection immediately after an emergency call.

[0025] Therefore, apply the SoR processing method as described below.

[0026] FIG. 4 is a diagram for explaining an example (1) of the SoR processing method according to an embodiment of the present invention. When notifying the priority PLMN list by NAS signaling, the home operator adds information indicating an opportunity for PLMN selection, and the UE performs PLMN selection based on the information.

[0027] As shown in FIG. 4, the UDM in the HPLMN transmits the priority PLMN, which is the SoR information, and the information indicating the PLMN selection opportunity to the AMF in the VPLMN. Subsequently, the AMF transmits the priority PLMN and the information indicating the PLMN selection opportunity received from the UDM to the UE via NAS signaling. When the UE receives the information indicating the priority PLMN and the PLMN selection opportunity, it transmits an ACK to the AMF.

[0028] The information indicating the opportunity for PLMN selection may be, for example, any of the following 1), 2), and 3).

[0029] 1) Timer value. After receiving the SoR information, the UE performs PLMN selection after the timer expires.

[0030] 2) A flag indicating whether to permit PLMN selection during communication. When the flag indicates "permit", the UE disconnects the communication and performs PLMN selection. When the flag indicates "do not permit", the UE waits until the communication ends, transitions to the idle state, and then performs PLMN selection.

[0031] 3) Set the timer value in 1) and the flag in 2) for each call type during communication. Table 1 is an example of the information set for each call type and the UE operation.

[0032]

Table 1

[0033] As shown in Table 1, when for the call type "During voice call (excluding emergency call)", the timer value T is set to 10 sec and the flag is set to 0, i.e., PLMN selection during communication is not permitted, if the UE is in the idle state 10 seconds after receiving the SoR information, it performs PLMN selection, and if it is during a voice call, it waits to perform PLMN selection until it becomes idle.

[0034] As shown in Table 1, when for the call type "During emergency call", the timer value T is set to 60 min and the flag is set to 0, i.e., PLMN selection during communication is not permitted, if the UE is in the idle state 60 minutes after receiving the SoR information, it performs PLMN selection, and if it is during an emergency call, it waits to perform PLMN selection until it becomes idle. Also, as another example, when the UE receives the SoR information for the call type "During emergency call", the UE may start the timer when the emergency call ends. That is, if the UE is in the idle state at the time when the timer expires 60 minutes after ending the emergency call, it may perform PLMN selection.

[0035] As shown in Table 1, when for the call type "During Internet communication", the timer value T is set to 0 sec and the flag is set to 1, i.e., PLMN selection during communication is permitted, the UE immediately performs PLMN selection when it receives the SoR information. At this time, if it is during Internet communication, the communication is disconnected.

[0036] Note that only the timer value in 1) above may be set, and the flag may not be set. If it is during communication when the timer expires, the communication may be disconnected uniformly and PLMN selection may be performed. Also, it may wait to perform PLMN selection until it becomes idle, or it may be implemented such that the terminal determines which operation to perform for each call type.

[0037] Note that only the flag in 2) above may be set, and the timer value may not be set. If the UE is not in communication when it receives the SoR information, it immediately performs PLMN selection. If the UE is in communication when it receives the SoR information, it immediately performs PLMN selection based on the flag or waits to perform PLMN selection until the communication ends.

[0038] Note that the call type may be other than the call types shown in Table 1. For example, the call type may be SMS. Also, for example, the call type may be defined for each application of Internet communication. Also, for example, the call type may be defined for each destination APN (Access Point Name) or DNN (Data Network Name).

[0039] FIG. 5 is a diagram for explaining an example (2) of the SoR processing method according to an embodiment of the present invention. In the example shown in FIG. 4, the timing of performing PLMN selection by the UE is controlled based on the call type during communication. On the other hand, in the example shown in FIG. 5, the network determines the call type during communication and sets the timer value in 1) above or the flag in 2) above. The UDM in the HPLMN recognizes the call type during communication and sets an appropriate timer value or a flag indicating whether to permit PLMN selection during communication.

[0040] As shown in FIG. 5, in step 1, the UDM in the HPLMN transmits the priority PLMN, which is SoR information, to the AMF in the VPLMN. Subsequently, in step 2, the AMF transmits a notification regarding the communication state to the UDM. Subsequently, in step 3, the UDM determines the timing of performing PLMN selection based on the received notification regarding the communication state and transmits a notification of the timing of performing PLMN selection to the AMF. The notification of the timing of performing PLMN selection corresponds to information indicating a PLMN selection trigger. Subsequently, in step 4, the AMF transmits the priority PLMN received from the UDM and the information indicating the PLMN selection trigger to the UE via NAS signaling. Subsequently, in step 5, when the UE receives the priority PLMN and the information indicating the PLMN selection trigger, it transmits an ACK to the AMF.

[0041] FIG. 6 is a diagram for explaining an example (3-1) of the SoR processing method according to an embodiment of the present invention. FIG. 7 is a diagram for explaining an example (3-2) of the SoR processing method according to an embodiment of the present invention. FIGS. 6 and 7 are examples of notifying the UDM in the HPLMN of the communication state from the AMF in the VPLMN every time the communication state changes during communication, and notifying the timing of performing the priority PLMN and PLMN selection at the time of SoR information transmission.

[0042] As shown in FIG. 6, when the UE starts an emergency call, the AMF in the VPLMN transmits information indicating that an emergency call is in progress to the UDM in the HPLMN.

[0043] As shown in FIG. 7, in step 1, the UDM in the HPLMN transmits a notification of the timing of performing the priority PLMN and PLMN selection, which is the SoR information, to the AMF in the VPLMN. The UDM determines the timing of performing the PLMN selection based on the notification regarding the communication state that has already been received, as shown in FIG. 6. The notification of the timing of performing the PLMN selection corresponds to the information indicating the PLMN selection trigger. Subsequently, in step 2, the AMF transmits the priority PLMN and the information indicating the PLMN selection trigger received from the UDM to the UE via NAS signaling. Subsequently, in step 3, when the UE receives the information indicating the priority PLMN and the PLMN selection trigger, the UE transmits an ACK to the AMF.

[0044] FIG. 8 is a diagram for explaining an example (4) of the SoR processing method according to an embodiment of the present invention. The network determines the call type during communication and sets the timer value in 1) above or the flag in 2) above. The AMF in the VPLMN recognizes the call type during communication and sets an appropriate timer value or a flag indicating whether to permit the PLMN selection during communication.

[0045] As shown in FIG. 8, the AMF in the VPLMN may determine the type of call in progress, etc., and determine the PLMN selection opportunity. The AMF transmits, via NAS signaling, information indicating the preferred PLMN received from the UDM and the PLMN selection opportunity determined by the AMF to the UE. Subsequently, when the UE receives the information indicating the preferred PLMN and the PLMN selection opportunity, it transmits an ACK to the AMF.

[0046] FIG. 9 is a diagram for explaining an example (5) of the SoR processing method according to an embodiment of the present invention. In FIG. 9, the operations as a communication system and the processing inside the UE are explained. According to the embodiment of the present invention, a communication system that notifies the UE not only of the preferred PLMN but also of information indicating the PLMN selection opportunity is realized.

[0047] For example, the communication system according to the embodiment of the present invention realizes the following a), b), and c). a) The network notifies the UE of information related to the PLMN selection opportunity in each communication state, and the UE determines whether to perform PLMN selection. b) The UDM in the HPLMN is notified of the communication state by the AMF in the VPLMN, and the UDM instructs the UE of an appropriate PLMN selection opportunity. c) The AMF in the roaming destination network, for example, the VPLMN, instructs the UE of an appropriate PLMN selection opportunity based on the communication state.

[0048] The operations of the functional units in the UE will be described below. The HW (Hardware) corresponds to the transmission unit 210 or the reception unit 220. The communication control unit, the OS (Operating System), or the APL (Application) corresponds to the control unit 240. In step S1 shown in FIG. 9, the HW receives NAS signaling and transmits it to the communication control unit. Subsequently, the communication control unit starts a timer, disconnects the communication, etc. according to the information on the PLMN selection opportunity (S2). Subsequently, the communication control unit transmits a network search instruction to the HW at a timing according to the information on the PLMN selection opportunity (S3). Subsequently, the HW performs a search (S4). Subsequently, the HW reports the found PLMN to the communication control unit (S5). Subsequently, the communication control unit performs PLMN selection based on the PLMN list (S6). Subsequently, the communication control unit transmits an instruction to attach to the selected PLMN to the HW (S7).

[0049] FIG. 10 is a flowchart for explaining an example (6) of the SoR processing method in the embodiment of the present invention. For example, as an example of the behavior of an IoT (Internet of Things) device, operations such as communicating at a specific time or transmitting a report at a specific time every day are assumed. Therefore, by specifying the date and time and / or cycle for executing the SoR process, the SoR process may be executed while avoiding the time when the UE targeted by the SoR is assumed to perform communication.

[0050] In step S11, the UE receives signaling related to the SoR. The signaling related to the SoR may be NAS signaling including information indicating at least the above-mentioned preferred PLMN and the PLMN selection opportunity.

[0051] In the subsequent step S12, the UE performs PLMN selection at a time or time period based on the signaling related to the received SoR. That is, the signaling related to the SoR may include information specifying the time to perform PLMN selection as information indicating a PLMN selection opportunity. This information may specify any time and period. For example, it may be an instruction to perform PLMN selection by the SoR at 13:20 every day.

[0052] Also, the signaling related to the SoR may include information specifying the date and time to perform PLMN selection as information indicating a PLMN selection opportunity. For example, this information may be an instruction to perform PLMN selection by the SoR at 13:20 on January 31, 2021.

[0053] Also, the signaling related to the SoR may include information specifying the time period and / or cycle to perform PLMN selection as information indicating a PLMN selection opportunity. For example, this information may be an instruction to perform PLMN selection by the SoR between 01:00 and 05:00. Also, this information may be an instruction to perform PLMN selection by the SoR between 01:00 and 05:00 every day.

[0054] Also, the signaling related to the SoR may include information specifying the time period and / or cycle during which PLMN selection is not to be performed as information indicating a PLMN selection opportunity. For example, this information may be an instruction not to perform PLMN selection by the SoR between 00:00 and 01:00 every day.

[0055] FIG. 11 is a flowchart for explaining an example (7) of the SoR processing method in an embodiment of the present invention. In step S21, the UE is performing voice communication and data communication. In the subsequent step S22, the UE receives signaling related to the SoR. The signaling related to the SoR may be NAS signaling including at least the above-mentioned preferred PLMN and information indicating a PLMN selection opportunity.

[0056] In the subsequent step S23, the UE may not perform PLMN selection during ongoing voice communication. In the subsequent step S24, the UE may perform PLMN selection even when data communication is ongoing at the end of voice communication. Also, in step S24, the UE may perform PLMN selection regardless of the execution state of data communication at the end of voice communication.

[0057] Note that based on the received information indicating the PLMN selection trigger, the UE may not perform PLMN selection during ongoing voice communication, or the UE may not perform PLMN selection during ongoing voice communication according to other settings or predefined specifications. Also, based on the received information indicating the PLMN selection trigger, the UE may perform PLMN selection even when data communication is ongoing at the end of voice communication, or the UE may perform PLMN selection even when data communication is ongoing at the end of voice communication according to other settings or predefined specifications.

[0058] FIG. 12 is a flowchart for explaining an example (8) of the SoR processing method according to an embodiment of the present invention. In step S31, the UE is performing data communication of a predetermined type. The data communication of a predetermined type may be, for example, communication related to telemedicine, communication related to V2X, or communication related to autonomous communication. Also, the data communication of a predetermined type may be configurable to any type of data communication.

[0059] In the subsequent step S32, the UE receives signaling related to SoR. The signaling related to SoR may be NAS signaling including at least the above-mentioned preferred PLMN and information indicating the PLMN selection trigger. The information indicating the PLMN selection trigger may include information specifying a predetermined type of data communication.

[0060] In subsequent step S33, the UE may not perform PLMN selection while a predetermined type of data communication continues. Note that based on the received information indicating a PLMN selection opportunity, the UE may not perform PLMN selection while a predetermined type of data communication continues, or the UE may not perform PLMN selection while a predetermined type of data communication continues according to other settings or predetermined specifications. Note that when the UE receives signaling related to SoR, it may be set to a state where it does not perform PLMN selection for an arbitrary period.

[0061] In subsequent step S34, when a predetermined type of data communication ends, the UE may perform PLMN selection.

[0062] FIG. 13 is a flowchart for explaining an example (9) of the SoR processing method according to an embodiment of the present invention. In step S41, the UE receives signaling related to SoR. The signaling related to SoR may be NAS signaling including at least the above-described information indicating the preferred PLMN and the PLMN selection opportunity. Further, the signaling related to SoR may include a list of preferred PLMNs and a list of preferred RATs. That is, the network may set a list of preferred PLMNs and a list of preferred RATs in the signaling related to SoR. Note that the list may be composed of one entry.

[0063] In subsequent step S42, the UE may obtain a preferred PLMN list and a preferred RAT list based on the signaling related to SoR. In subsequent step S43, the UE may prioritize the RAT first and then the PLMN. For example, when there is no preferred RAT in the topmost PLMN of the preferred PLMN list and there is a preferred RAT in another PLMN, the UE may select the other PLMN.

[0064] Note that in step S43, the UE may prioritize the PLMN first and then the RAT.

[0065] FIG. 14 is a flowchart for explaining an example (10) of the SoR processing method according to an embodiment of the present invention. In step S51, the UE receives signaling related to SoR. The signaling related to SoR may be NAS signaling including at least the above-described preferred PLMN and information indicating a PLMN selection opportunity. Further, the signaling related to SoR may include a list of preferred PLMNs and a list of preferred slice types. That is, the network may set a list of preferred PLMNs and a list of preferred slice types in the signaling related to SoR. Note that the list may be composed of one entry.

[0066] Note that the slice type may be, for example, eMBB (enhanced Mobile Broadband), URLCC (Ultra-Reliable and Low Latency Communications), mMTC (massive Machine Type Communications), V2X, or IoT.

[0067] In subsequent step S52, the UE may acquire a preferred PLMN list and a preferred slice type list based on the signaling related to SoR. In subsequent step S53, the UE may prioritize the slice type first and then the PLMN. For example, if there is no preferred slice type in the topmost PLMN in the preferred PLMN list and there is a preferred slice type in another PLMN, the UE may select the other PLMN.

[0068] Note that in step S53, the UE may prioritize the PLMN first and then the slice type.

[0069] Note that the type of the specified PLMN may be NPN (Non Public Network).

[0070] Regarding the information that can be specified in the priority PLMN list, in addition to the 3GPP access specified by information such as RAT type and PLMN ID, information indicating Non-3GPP Access (for example, WLAN, WiMax (registered trademark), fixed network, etc.) may also be included.

[0071] Also, the following SoR processing method may be executed in the embodiments of the present invention. The UE receives signaling related to SoR. The signaling related to SoR may be NAS signaling including at least the above-mentioned priority PLMN and information indicating the PLMN selection opportunity. Also, the signaling related to SoR may include information regarding the capabilities specified by UE Network Capability or UE Radio Capability. That is, the network may set the list of priority PLMNs and the priority UE Network Capability or UE Radio Capability in the signaling related to SoR. Note that the list may be composed of one entry.

[0072] Subsequently, the UE may acquire the priority PLMN list and the UE Network Capability or UE Radio Capability of the in-range network based on the signaling related to SoR. Subsequently, the UE may prioritize UE Network Capability or UE Radio Capability first and prioritize the PLMN second. For example, if there is no capability specified by the priority UE Network Capability or UE Radio Capability in the top PLMN of the priority PLMN list and there is a capability specified by the priority UE Network Capability or UE Radio Capability in another PLMN, the UE may select the other PLMN. Note that the UE may prioritize the PLMN first and prioritize the UE Network Capability or UE Radio Capability second.

[0073] According to the above embodiments, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity, thereby precisely controlling the timing for the UE to perform PLMN selection. Further, the AMF, which is a network node, can notify the UE of information indicating the preferred RAT or the preferred slice type, thereby enabling the UE to select a PLMN having the preferred RAT or the preferred slice type.

[0074] That is, it is possible to control the network selection opportunity or the network to be selected by the user equipment in a roaming environment.

[0075] (Device Configuration) Next, a functional configuration example of the network node 10 and the user equipment 20 that implement the processes and operations described so far will be described. The network node 10 and the user equipment 20 include functions for implementing the above-described embodiments. However, the network node 10 and the user equipment 20 may each be provided with only some of the functions in the embodiments.

[0076] <Network Node 10> FIG. 15 is a diagram showing an example of the functional configuration of the network node 10. As shown in FIG. 15, the network node 10 includes a transmission unit 110, a reception unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in FIG. 15 is merely an example. As long as the operations according to the embodiments of the present invention can be implemented, the functional divisions and the names of the functional units can be anything. Further, the network node 10 having a plurality of different functions in the system architecture may be composed of a plurality of network nodes 10 separated by function.

[0077] The transmission unit 110 includes a function of generating a signal to be transmitted to the user equipment 20 or another network node 10 and transmitting the signal by wire or wirelessly. The reception unit 120 includes a function of receiving various signals transmitted from the user equipment 20 or another network node 10 and acquiring information of a higher layer, for example, from the received signals.

[0078] The setting unit 130 stores setting information set in advance and various types of setting information to be transmitted to the user device 20 in a storage device, and reads it out from the storage device as necessary. The content of the setting information is, for example, subscriber information of the user device 20 and SoR information, etc.

[0079] As described in the embodiment, the control unit 140 performs processing related to communication control of the user device 20 in a roaming environment. Further, the control unit 140 performs processing related to notification of SoR information to the user device 20. A functional unit related to signal transmission in the control unit 140 may be included in the transmission unit 110, and a functional unit related to signal reception in the control unit 140 may be included in the reception unit 120.

[0080] <User device 20> FIG. 16 is a diagram showing an example of the functional configuration of the user device 20. As shown in FIG. 16, the user device 20 includes a transmission unit 210, a reception unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in FIG. 16 is merely an example. As long as the operations according to the embodiments of the present invention can be implemented, the function classification and the names of the functional units can be anything.

[0081] The transmission unit 210 creates a transmission signal from the transmission data and wirelessly transmits the transmission signal. The reception unit 220 wirelessly receives various signals and acquires signals of a higher layer from the received physical layer signals. Further, the reception unit 220 has a function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals, reference signals, etc. transmitted from the network node 10.

[0082] The setting unit 230 stores various types of setting information received from the network node 10 by the reception unit 220 in a storage device, and reads it out from the storage device as necessary. Further, the setting unit 230 also stores setting information set in advance. The content of the setting information is, for example, subscriber information and SoR information, etc.

[0083] As described in the embodiments, the control unit 240 performs processes related to communication control in a roaming environment based on SoR information. Further, the control unit 240 performs processes related to PLMN switching control when receiving SoR information. A functional unit related to signal transmission in the control unit 240 may be included in the transmission unit 210, and a functional unit related to signal reception in the control unit 240 may be included in the reception unit 220.

[0084] (Hardware Configuration) The block diagrams (FIGS. 15 and 16) used in the description of the above embodiments show blocks of functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Also, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one physically or logically combined device, or two or more physically or logically separated devices may be directly or indirectly (e.g., using wired, wireless, etc.) connected and realized using these multiple devices. The functional block may be realized by combining software with the above one device or the above multiple devices.

[0085] Functions include, but are not limited to, judgment, decision, determination, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, solution, selection, selection, establishment, comparison, assumption, expectation, regarded as, notification (broadcasting), notification (notifying), communication, forwarding, configuration, reconfiguration, allocation (allocating, mapping), assignment, etc. For example, a functional block (component) that functions as transmission is called a transmission unit or a transmitter. As described above, the realization method is not particularly limited.

[0086] For example, the network node 10, user equipment 20, etc. in an embodiment of the present disclosure may function as a computer that performs the processing of the wireless communication method of the present disclosure. FIG. 17 is a diagram showing an example of the hardware configuration of the network node 10 and the user equipment 20 according to an embodiment of the present disclosure. The above-mentioned network node 10 and user equipment 20 may physically be configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

[0087] Note that in the following description, the term "device" can be read as a circuit, device, unit, etc. The hardware configuration of the network node 10 and the user equipment 20 may be configured to include one or more of each device shown in the figure, or may be configured without including some devices.

[0088] Each function in the network node 10 and the user equipment 20 is realized by causing a predetermined software (program) to be loaded onto hardware such as the processor 1001 and the storage device 1002, so that the processor 1001 performs calculations and controls communication by the communication device 1004, or controls at least one of reading and writing data in the storage device 1002 and the auxiliary storage device 1003.

[0089] The processor 1001 controls the entire computer by operating an operating system, for example. The processor 1001 may be composed of a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic device, a register, and the like. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0090] Further, the processor 1001 reads a program (program code), software module, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes according thereto. As the program, a program for causing a computer to execute at least a part of the operations described in the above embodiments is used. For example, the control unit 140 of the network node 10 shown in FIG. 15 may be realized by a control program stored in the storage device 1002 and operating on the processor 1001. Also, for example, the control unit 240 of the user device 20 shown in FIG. 16 may be realized by a control program stored in the storage device 1002 and operating on the processor 1001. Although it has been described that the above various processes are executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. Note that the program may be transmitted from a network via a telecommunication line.

[0091] The storage device 1002 is a computer-readable recording medium and may be constituted by at least one of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may be referred to as a register, cache, main memory (main storage device), etc. The storage device 1002 can store a program (program code), software module, etc. executable for implementing the communication method according to an embodiment of the present disclosure.

[0092] The auxiliary storage device 1003 is a computer-readable recording medium, which may be constituted by at least one of, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-described storage medium may be, for example, a database, a server, or other appropriate medium including at least one of the storage device 1002 and the auxiliary storage device 1003.

[0093] The communication device 1004 is hardware (a transmission / reception device) for performing communication between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, etc. The communication device 1004 may include, for example, a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. in order to realize at least one of frequency division duplex (FDD: Frequency Division Duplex) and time division duplex (TDD: Time Division Duplex). For example, a transmission / reception antenna, an amplifier section, a transmission / reception section, a transmission line interface, etc. may be realized by the communication device 1004. The transmission / reception section may be physically or logically separated into a transmission section and a reception section.

[0094] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) for receiving an external input. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) for performing an output to the outside. Note that the input device 1005 and the output device 1006 may have an integrated configuration (e.g., a touch panel).

[0095] Also, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus or may be configured using different buses for each device.

[0096] Also, the network node 10 and the user device 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc., and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these hardware.

[0097] (Summary of Embodiment) As described above, according to the embodiment of the present invention, a receiving unit that receives signaling related to a SoR including at least information indicating a preferred PLMN and information indicating an opportunity to select a PLMN from a first network node in a VPLMN (Visited Public land mobile network), and a control unit that executes PLMN selection based on the information indicating the preferred PLMN and the information indicating the opportunity to select the PLMN, wherein the signaling related to the SoR is provided to a terminal created by a second network node in an HPLMN (Home Public land mobile network).

[0098] With the above configuration, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity, thereby precisely controlling the timing at which the UE performs PLMN selection. Also, the AMF, which is a network node, can notify the UE of information indicating the preferred RAT or the preferred slice type, enabling the UE to select a PLMN having the preferred RAT or the preferred slice type. That is, it is possible to control the network selection opportunity or the network to be selected by the user equipment in a roaming environment.

[0099] The control unit may perform PLMN selection at the time or cycle specified by the information indicating the opportunity to select the PLMN. With this configuration, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity, thereby precisely controlling the timing at which the UE performs PLMN selection. That is, the UE can perform PLMN selection at a timing when it is assumed not to be communicating.

[0100] When performing voice communication and data communication, the control unit may not perform PLMN selection during voice communication and may perform PLMN selection regardless of the execution state of data communication when the voice communication ends. With this configuration, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity, thereby precisely controlling the timing at which the UE performs PLMN selection.

[0101] The control unit may not perform PLMN selection during the execution of a specific type of data communication. With this configuration, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity, thereby precisely controlling the timing at which the UE performs PLMN selection. That is, the UE can hold off on PLMN selection while performing important data communication that would be disrupted if disconnected.

[0102] The receiving unit receives signaling related to the SoR that further includes information indicating a prioritized RAT (Radio Access Technology) or a prioritized slice type. The control unit may perform PLMN selection, first prioritizing the prioritized RAT or the prioritized slice type and second prioritizing the prioritized PLMN. The AMF, which is a network node, can notify the UE of information indicating a prioritized RAT or a prioritized slice type, enabling the UE to select a PLMN having the prioritized RAT or the prioritized slice type.

[0103] Also, according to an embodiment of the present invention, there is provided a communication system including a first network node in a VPLMN (Visited Public land mobile network), a second network node in an HPLMN (Home Public land mobile network), and a terminal. The second network node includes a transmitting unit that transmits signaling related to the SoR that at least includes information indicating a prioritized PLMN and information indicating an opportunity to select a PLMN to the first network node. The first network node includes a receiving unit that receives the signaling related to the SoR from the second network node and a transmitting unit that transmits the signaling related to the SoR to the terminal. The terminal includes a receiving unit that receives the signaling related to the SoR from the first network node and a control unit that performs PLMN selection based on the information indicating the prioritized PLMN and the information indicating the opportunity to select a PLMN.

[0104] With the above configuration, the AMF, which is a network node, can notify the UE of information related to the PLMN selection opportunity and thus precisely control the timing at which the UE performs PLMN selection. Further, the AMF, which is a network node, can notify the UE of information indicating a preferred RAT or a preferred slice type, thereby enabling the UE to select a PLMN having the preferred RAT or the preferred slice type. That is, it is possible to control the network selection opportunity or the network to be selected by a user equipment in a roaming environment.

[0105] (Supplement to the embodiment) The embodiments of the present invention have been described above. However, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, etc. Although specific numerical examples have been used for the purpose of facilitating the understanding of the invention, unless otherwise specified, those numerical values are merely examples, and any appropriate values may be used. The classification of items in the above description is not essential to the present invention, and the matters described in two or more items may be used in combination as needed, or the matters described in one item may be applied to the matters described in another item (as long as there is no contradiction). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical components. The operations of a plurality of functional units may be physically performed by one component, or the operation of one functional unit may be physically performed by a plurality of components. Regarding the processing procedures described in the embodiments, the order of processing may be changed as long as there is no contradiction. For the sake of convenience in explaining the processing, the network node 10 and the user device 20 have been described using a functional block diagram, but such devices may be implemented in hardware, software, or a combination thereof. The software that operates by the processor included in the network node 10 according to the embodiment of the present invention and the software that operates by the processor included in the user device 20 according to the embodiment of the present invention may be stored in a random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk drive (HDD), removable disk, CD-ROM, database, server, or any other appropriate storage medium, respectively.

[0106] Furthermore, the notification of information is not limited to the aspects / embodiments described in this disclosure, and other methods may be used. For example, the notification of information may be implemented by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, notification information (MIB (Master Information Block), SIB (System Information Block)), other signals, or a combination thereof. Also, the RRC signaling may be referred to as an RRC message, and for example, it may be an RRC connection setup message, an RRC connection reconfiguration message, etc.

[0107] Each aspect / embodiment described in this disclosure may be applied to at least one of systems using LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (new Radio), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth (registered trademark), other suitable systems, and next-generation systems extended based on these. Also, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A and 5G, etc.) may be applied.

[0108] The processing procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this specification may be reordered as long as there is no contradiction. For example, regarding the methods described in this disclosure, the elements of various steps are presented using an exemplary order and are not limited to the specific order presented.

[0109] The specific operations assumed to be performed by the network node 10 in this specification may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having the network node 10, it is clear that various operations performed for communication with the user equipment 20 can be performed by at least one of the network node 10 and other network nodes other than the network node 10 (for example, but not limited to, MME or S-GW, etc.). Although the case where there is one other network node other than the network node 10 is exemplified above, the other network node may be a combination of a plurality of other network nodes (for example, MME and S-GW).

[0110] The information or signals, etc. described in this disclosure can be output from an upper layer (or lower layer) to a lower layer (or upper layer). They may also be input and output via a plurality of network nodes.

[0111] The input and output information, etc. may be stored in a specific location (for example, memory) or may be managed using a management table. The input and output information, etc. can be overwritten, updated, or appended. The output information, etc. may be deleted. The input information, etc. may be transmitted to other devices.

[0112] The determination in this disclosure may be made by a value represented by 1 bit (0 or 1), or by a Boolean value (true or false), or by a numerical comparison (for example, comparison with a predetermined value).

[0113] Software, whether called software, firmware, middleware, microcode, hardware description language, or by any other name, should be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc.

[0114] Also, software, instructions, information, etc. may be transmitted and received via a transmission medium. For example, when software is transmitted from a website, server, or other remote source using at least one of wired technologies (such as coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL), etc.) and wireless technologies (such as infrared, microwave, etc.), at least one of these wired and wireless technologies is included within the definition of the transmission medium.

[0115] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc., which may be referred to throughout the above description, may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0116] In addition, for the terms described in this disclosure and the terms necessary for understanding this disclosure, they may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Also, a signal may be a message. Also, a component carrier (CC) may be referred to as a carrier frequency, a cell, a frequency carrier, etc.

[0117] The terms "system" and "network" used in this disclosure are used interchangeably.

[0118] Also, the information, parameters, etc. described in this disclosure may be represented using absolute values, relative values from a predetermined value, or using corresponding other information. For example, a radio resource may be indicated by an index.

[0119] The names used for the above-described parameters are not limiting names in any way. Furthermore, mathematical formulas, etc. using these parameters may be different from those explicitly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, the various names assigned to these various channels and information elements are not limiting names in any way.

[0120] In this disclosure, terms such as "base station (BS:Base Station)", "radio base station", "base station apparatus", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", "component carrier", etc. may be used interchangeably. The base station may also be called by terms such as macro cell, small cell, femto cell, pico cell, etc.

[0121] A base station can accommodate one or more (e.g., three) cells. When the base station accommodates a plurality of cells, the entire coverage area of the base station can be divided into a plurality of smaller areas, and each of the smaller areas can also provide communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the whole of the coverage area of at least one of a base station and a base station subsystem that provides communication services in this coverage.

[0122] In the present disclosure, terms such as "mobile station (MS)", "user terminal", "user equipment (UE)", and "terminal" can be used interchangeably.

[0123] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable term.

[0124] At least one of the base station and the mobile station may also be referred to as a transmission device, a reception device, a communication device, etc. Note that at least one of the base station and the mobile station may also be a device mounted on a moving body, the moving body itself, etc. The moving body may be a vehicle (e.g., a car, an airplane, etc.), a moving body that moves unmanned (e.g., a drone, an autonomous vehicle, etc.), or a robot (humanoid or unmanned). Note that at least one of the base station and the mobile station also includes a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0125] In addition, the base station in the present disclosure may be replaced by a user terminal. For example, for a configuration in which communication between the base station and the user terminal is replaced with communication between a plurality of user devices 20 (which may be referred to as, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.), each aspect / embodiment of the present disclosure may be applied. In this case, the functions of the above-described network node 10 may be configured as functions of the user device 20. Further, terms such as "uplink" and "downlink" may be replaced with terms corresponding to communication between terminals (for example, "side"). For example, an uplink channel, a downlink channel, etc. may be replaced with a side channel.

[0126] Similarly, the user terminal in the present disclosure may be replaced by a base station. In this case, the functions of the above-described user terminal may be configured as functions of the base station.

[0127] The terms "determining" and "deciding" as used in this disclosure may encompass a variety of operations. "Determining" and "deciding" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up (e.g., searching in a table, database, or another data structure), ascertaining, and considering something as having been "determined" or "decided". Also, "determining" and "deciding" may include considering something as having been "determined" or "decided" after receiving (e.g., receiving information), transmitting (e.g., transmitting information), inputting, outputting, accessing (e.g., accessing data in a memory), etc. Further, "determining" and "deciding" may include considering something as having been "determined" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. That is, "determining" and "deciding" may include considering that some operation has been "determined" or "decided". Also, "determining (deciding)" may be read as "assuming", "expecting", "considering", etc.

[0128] The terms "connected" or "coupled," or any variations thereof, mean any direct or indirect connection or coupling between two or more elements, and can include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "accessed." As used in this disclosure, two elements can be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as, by way of some non-limiting and non-exhaustive examples, electromagnetic energy having wavelengths in the radio frequency region, microwave region, and optical (both visible and invisible) region.

[0129] The reference signal can also be abbreviated as RS (Reference Signal) and may be called a Pilot according to the applicable standard.

[0130] As used in this disclosure, the description "based on" does not mean "based only on" unless otherwise specified. In other words, the description "based on" means both "based only on" and "based at least on."

[0131] Any reference to an element using designations such as "first," "second," etc. used in this disclosure does not generally limit the quantity or order of those elements. These designations can be used in this disclosure as a convenient way to distinguish between two or more elements. Thus, references to the first and second elements do not mean that only two elements can be employed, or that the first element must precede the second element in any way.

[0132] In the configuration of each of the above devices, "means" may be replaced with "section," "circuit," "device," etc.

[0133] In the present disclosure, when the terms "include", "including" and their variants are used, these terms are intended to be inclusive, in the same manner as the term "comprising". Further, the term "or" used in the present disclosure is not intended to be an exclusive disjunction.

[0134] In the present disclosure, for example, when articles are added by translation, such as a, an and the in English, the present disclosure may include that the nouns following these articles are in the plural form.

[0135] In the present disclosure, the term "A is different from B" may mean that "A and B are different from each other". Note that the term may also mean that "A and B are each different from C". Terms such as "separate", "coupled" and the like may also be interpreted in the same way as "different".

[0136] Each aspect / embodiment described in the present disclosure may be used alone, in combination, or switched during execution. Also, the notification of predetermined information (for example, the notification of "being X") is not limited to being explicitly performed, and may be performed implicitly (for example, without performing the notification of the predetermined information).

[0137] Note that the AMF in the present disclosure is an example of a first network node. The UDM is an example of a second network node.

[0138] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented in modified and changed forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is for illustrative purposes and has no limiting meaning for the present disclosure.

[0139] <Appendix> Regarding the embodiments described above, it can also be described as follows in the following supplementary notes.

[0140] (Supplementary Note 1) A receiving unit that receives signaling related to a SoR (System Information Request) including at least information indicating a preferred PLMN (Public Land Mobile Network) and information indicating an opportunity to select a PLMN from a first network node in a VPLMN (Visited Public land mobile network); A control unit that executes PLMN selection based on the information indicating the preferred PLMN and the information indicating the opportunity to select the PLMN, The signaling related to the SoR is for a terminal created by a second network node in an HPLMN (Home Public land mobile network).

[0141] (Supplementary Note 2) The control unit of the terminal according to Supplementary Note 1 that executes PLMN selection at a time or period specified by the information indicating the opportunity to select the PLMN.

[0142] (Supplementary Note 3) The control unit of the terminal according to Supplementary Note 1 that does not execute PLMN selection during voice communication and executes PLMN selection regardless of the execution state of data communication when voice communication ends.

[0143] (Supplementary Note 4) The control unit of the terminal according to Supplementary Note 1 that does not execute PLMN selection during execution of a specific type of data communication.

[0144] (Supplementary Note 5) The receiving unit receives the signaling related to the SoR that further includes information indicating a preferred RAT (Radio Access Technology) or a preferred slice type, The control unit of the terminal according to Supplementary Note 1 that executes PLMN selection, giving priority first to the preferred RAT or the preferred slice type and second to the preferred PLMN.

[0145] (Appendix 6) A communication system having a first network node in a VPLMN (Visited Public land mobile network), a second network node in an HPLMN (Home Public land mobile network), and a terminal, wherein the second network node has a transmission unit that transmits signaling related to a SoR (System Information Record) including at least information indicating a preferred PLMN (Public Land Mobile Network) and information indicating an opportunity to select a PLMN to the first network node, wherein the first network node has a reception unit that receives the signaling related to the SoR from the second network node, and has a transmission unit that transmits the signaling related to the SoR to the terminal, wherein the terminal has a reception unit that receives the signaling related to the SoR from the first network node, and a control unit that executes PLMN selection based on the information indicating the preferred PLMN and the information indicating the opportunity to select the PLMN.

Explanation of Signs

[0146] 10 Network node 110 Transmission unit 120 Reception unit 130 Setting unit 140 Control unit 20 User device 210 Transmission unit 220 Reception unit 230 Setting unit 240 Control unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device

Claims

1. A receiver for receiving a signaling related to Steering of Roaming (SoR), the signaling including at least information indicating a preferred PLMN and information indicating an opportunity to select a PLMN, from a first network node in a Visited Public Land Mobile Network (VPLMN); a control unit that executes a PLMN selection based on information indicating the preferred PLMN and information indicating a trigger for selecting the PLMN; the signaling related to the SoR is generated by a second network node in a Home Public Land Mobile Network (HPLMN); The control unit transmits an acknowledgement to the first network node.

2. The terminal according to claim 1 , wherein the control unit determines a timing for executing the PLMN selection based on information indicating an opportunity for selecting the PLMN.

3. The terminal according to claim 1 , wherein the control unit does not execute PLMN selection immediately after an emergency call.

4. The terminal according to claim 1 , wherein the control unit does not execute PLMN selection during ongoing voice communication.

5. 2. The terminal according to claim 1, wherein the control unit determines whether to execute PLMN selection based on a type of a call being communicated.

6. The terminal according to claim 1 , wherein the control unit selects a non public network (NPN) based on the information indicating the prioritized PLMN.

7. receiving, from a first network node in a visited public land mobile network (VPLMN), a signaling related to a steering of roaming (SoR) including at least information indicating a preferred PLMN and information indicating a trigger for selecting a PLMN; A procedure for performing PLMN selection based on the information indicating the preferred PLMN and the information indicating a trigger for selecting the PLMN, the signaling related to the SoR is generated by a second network node in a Home Public Land Mobile Network (HPLMN); A communications method, comprising the steps of: transmitting an acknowledgement to the first network node, said terminal performing said procedure.

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