Communication device and method

Abstract

One aspect of the present disclosure includes a method for a user equipment (UE). The method includes receiving a first message from a communication device in a first public land mobile network (PLMN). The first message includes first information indicating that a registration procedure is required and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or an area in which the UE is included in the group or in which service is provided for the UE. The third information indicates the second PLMN in which the UE needs to perform the registration procedure. The method includes transmitting a second message. The second message includes a registration request message and at least one of the second information and the third information.

Description

[Technical Field]

[0001] The present disclosure relates to a method for a User Equipment (UE), a method for a first communication device, a UE and a first communication device, etc. [Background technology]

[0002] According to 3GPP® TR 22.877 [2], the 3GPP SA1 group captures new service requirements for subscriber management, as summarized below: The 5G system shall be able to support mechanisms for forwarding signaling traffic related to UEs of certain subscribers from their HPLMN to a target PLMN, e.g., to enable further handling of those UEs by the target PLMN. The forwarding mechanism shall minimize signaling traffic in the HPLMN, e.g., by using efficient means for forwarding traffic from selected UEs.

[0003] This service requirement stems from the fact that a PLMN operator may have a special relationship with another PLMN operator for each subscriber. For example, suppose one PLMN operator acquires another PLMN operator, and the other PLMN operator provides a unique service to its subscribers. In this case, those subscribers should continue to have the unique service from the network within the other PLMN operator, even though they belong to one PLMN. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TR 21.905: “Vocabulary for 3GPP Specifications”.V17.1.0(2021-12) [Non-patent document 2] 3GPP TR 22.877: “Study on Roaming Value-Added Services”.V19.0.0(2022-12) [Non-patent document 3] 3GPP TS 23.501: “System architecture for the 5G System (5GS)”.V18.0.0(2022-12) [Non-patent document 4] 3GPP TS 23.502: “Procedures for the 5G System (5GS)”.V18.0.0(2022-12) [Non-Patent Document 5] 3GPP TS 23.503: “Policy and charging control framework for the 5G System(5GS)Stage 2”.V18.0.0(2022-12) [Non-patent document 6] 3GPP TS 24.501: “Non-Access-Stratum (NAS) protocol for 5G System (5GS) Stage 3”.V18.1.0 (2022-12) [Non-Patent Document 7] 3GPP TS 23.122: "Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode".V18.1.0 (2022-12) Summary of the Invention [Problem to be solved by the invention]

[0005] According to the latest 3GPP mobility management functionality, as defined for example in 3GPP TS 23.501 [3], an operator cannot steer a UE to move to another PLMN while the UE is in the home network environment, i.e., the UE must stay in the HPLMN as long as it can discover the HPLMN.

[0006] This is a limitation in the 3GPP standard(s) when an operator wants to move a UE to another PLMN while the UE is within the coverage of the HPLMN. Therefore, for example, due to this limitation, the latest 3GPP specification(s) may not meet new service requirements, and this limitation prevents operators from achieving flexible service deployment scenarios, for example, based on business relationships between operators.

[0007] For example, the present disclosure focuses on the following limitations as operational issues in the latest 3GPP mobility management functions: Due to these limitations, for example, the latest 3GPP specification(s) may not meet new service requirements, and therefore the latest 3GPP functions need to be improved:

[0008] Operational Issues: According to the latest 3GPP mobility management functionality, the AMF in the HPLMN of the UE cannot relocate to another AMF from a PLMN different from the HPLMN of the UE. In addition, according to the latest 3GPP functionality, the AMF in the HPLMN of the UE cannot contact an SMF in a PLMN different from the HPLMN of the UE, and cannot perform communication to establish PDU session(s) between the HPLMN and the PLMN different from the HPLMN of the UE. [Means for solving the problem]

[0009] A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; The third information indicates a second PLMN with which the UE needs to perform a registration procedure; and sending a second message, The second message includes a registration request message and at least one of the second information and the third information.

[0010] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a user equipment (UE); the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; Sending a second message to the second communication device, the second message including a registration request message.

[0011] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a second communication device; the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and sending a second message to the UE; The second message includes third information indicating that a registration procedure is required and at least one of the first information and the second information.

[0012] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: communicating with a second communication device; and sending a message to the second communication device; the message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure.

[0013] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving 5G-GUTI; and sending the 5G-GUTI and fourth information indicating that a registration procedure is required to the UE.

[0014] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message from a second communication device in a second PLMN; The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and and transmitting the 5G-GUTI.

[0015] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving 5G-GUTI; Transmitting 5G-GUTI; and sending, to the UE, fourth information indicating that a registration procedure is required.

[0016] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving 5G-GUTI; Transmitting 5G-GUTI; and sending, to the UE, fourth information indicating that a registration procedure is required.

[0017] A method for a User Equipment (UE), the method comprising: receiving a message from a communication device in a first Public Land Mobile Network (PLMN); The message includes information indicating that a registration procedure is required and a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and and performing a registration procedure based on the 5G-GUTI.

[0018] A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and receiving a second message, the second message includes information indicating that a registration procedure is required; and and performing a registration procedure based on the 5G-GUTI.

[0019] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and performing a procedure for establishing a PDU session.

[0020] A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and receiving a second message, the second message includes information indicating that a registration procedure is required; and and performing a registration procedure based on the 5G-GUTI.

[0021] 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and transmitting a second message to a third communication device in the first PLMN to establish a PDU session.

[0022] User equipment (UE) means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; the third information indicating a second PLMN with which the UE needs to perform a registration procedure; a means for transmitting a second message, the means comprising: The second message includes a registration request message and at least one of the second information and the third information.

[0023] a first communication device in a first Public Land Mobile Network (PLMN); A means for receiving a first message from a user equipment (UE), the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; and means for transmitting a second message to the second communication device, the second message including a registration request message.

[0024] a first communication device in a first Public Land Mobile Network (PLMN); means for receiving a first message from a second communication device, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; A means for transmitting a second message to the UE, The second message includes means for including third information indicating that a registration procedure is required and at least one of the first information and the second information.

[0025] a first communication device in a first Public Land Mobile Network (PLMN); means for communicating with a second communication device; means for sending a message to a second communication device; the message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure.

[0026] a first communication device in a first Public Land Mobile Network (PLMN); a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; means for transmitting a second message to a second communication device, the second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); a means for receiving 5G-GUTI; and means for transmitting the 5G-GUTI and fourth information indicating that a registration procedure is required to the UE.

[0027] a first communication device in a first Public Land Mobile Network (PLMN); a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; means for transmitting a second message to a second communication device, the second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); a means for receiving 5G-GUTI; a means for transmitting 5G-GUTI; and means for transmitting fourth information to the UE indicating that a registration procedure is required.

[0028] User equipment (UE) means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and means for receiving a second message, the second message includes information indicating that a registration procedure is required; and means for performing a registration procedure based on the 5G-GUTI.

[0029] a first communication device in a first Public Land Mobile Network (PLMN); a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; and means for sending a second message to the second communication device to instruct the second communication device to perform a registration procedure for the UE.

[0030] a first communication device in a first Public Land Mobile Network (PLMN); means for receiving a first message from a second communication device in a second PLMN for performing a registration procedure for the user equipment; and means for performing a registration procedure.

[0031] a first communication device in a first Public Land Mobile Network (PLMN); a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE; means for selecting a second communication device in a second PLMN based on the first information and the second information; and means for transmitting a third message to the second communication device to establish the PDU session.

[0032] a first communication device in a first Public Land Mobile Network (PLMN); means for receiving a Protocol Data Unit (PDU) session establishment message from a second communication device in a second PLMN; and means for performing a procedure for establishing a PDU session.

[0033] a first communication device in a first Public Land Mobile Network (PLMN); means for receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and means for transmitting a second message to a third communication device in the first PLMN to establish a PDU session. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a signaling diagram of a first example of the first embodiment. [Figure 2] FIG. 10 is a signaling diagram of a second example of the first embodiment. [Figure 3] FIG. 10 is a signaling diagram of a third example of the first embodiment. [Figure 4] FIG. 10 is a signaling diagram of a fourth example of the first embodiment. [Figure 5] FIG. 10 is a signaling diagram of a fifth example of the first embodiment. [Figure 6] FIG. 10 is a signaling diagram of a sixth example of the first embodiment. [Figure 7] FIG. 10 is a signaling diagram of a seventh example of the first embodiment. [Figure 8]FIG. 10 is a signaling diagram of an eighth example of the first embodiment. [Figure 9] FIG. 10 is a signaling diagram of a first example of the second embodiment. [Figure 10] FIG. 10 is a signaling diagram of a second example of the second embodiment. [Figure 11] FIG. 10 is a signaling diagram of a third example of the second embodiment. [Figure 12] FIG. 10 is a signaling diagram of a fourth example of the second embodiment. [Figure 13] FIG. 1 is a diagram illustrating a system overview. [Figure 14] FIG. 2 is a block diagram showing a UE. [Figure 15] FIG. 1 is a block diagram illustrating an (R)AN node. [Figure 16] FIG. 1 illustrates a system overview of an (R)AN node based on the O-RAN architecture. [Figure 17] FIG. 2 is a block diagram showing an RU. [Figure 18] FIG. 1 is a block diagram showing a DU. [Figure 19] FIG. 2 is a block diagram showing a CU. [Figure 20] FIG. 2 is a block diagram illustrating an AMF. [Figure 21] FIG. 2 is a block diagram illustrating an SMF. [Figure 22] FIG. 2 is a block diagram illustrating a PCF. [Figure 23] FIG. 2 is a block diagram illustrating an AUSF. [Figure 24] FIG. 2 is a block diagram illustrating a UDM. [Figure 25] FIG. 1 is a block diagram illustrating an NSSF. DETAILED DESCRIPTION OF THE INVENTION

[0035] Abbreviation For the purposes of this document, 3GPP TR 21.905 (Non-Patent Document 1) and the following abbreviations apply: Abbreviations defined in this document take precedence over definitions of the same abbreviations in 3GPP TR 21.905 (Non-Patent Document 1). 4G-GUTI 4G Globally Unique Temporary UE Identity 5GC 5G Core Network 5GLAN 5G Local Area Network 5GS 5G System 5G-AN 5G Access Network 5G-AN PDB 5G Access Network Packet Delay Budget 5G-EIR 5G-Equipment Identity Register 5G-GUTI 5G Globally Unique Temporary Identifier 5G-BRG 5G Broadband Residential Gateway 5G-CRG 5G Cable Residential Gateway 5G GM 5G Grand Master 5G-RG 5G Residential Gateway 5G-S-TMSI 5G S-Temporary Mobile Subscription Identifier 5G VN 5G Virtual Network 5QI 5G QoS Identifier AF Application Function AMF Access and Mobility Management Function AMF-G Geographically selected Access and Mobility Management Function AMF-NG Non-Geographically selected Access and Mobility Management Function ANDSF Access Network Discovery and Selection Function ARFCN Absolute radio-frequency channel number AS Access Stratum ASN Abstract Syntax Notation ATSSS Access Traffic Steering,Switching,Splitting ATSSS-LL ATSSS Low-Layer AuC Authentication Centre AUSF Authentication Server Function AUTN Authentication token BCCH Broadcast Control Channel BMCA Best Master Clock Algorithm BSF Binding Support Function CAG Closed Access Group CAPIF Common API Framework for 3GPP northbound APIs CHF Charging Function CN PDB Core Network Packet Delay Budget CP Control Plane DAPS Dual Active Protocol Stacks DL Downlink DN Data Network DNAI DN Access Identifier DNN Data Network Name DRX Discontinuous Reception DS-TT Device-side TSN translator ePDG evolved Packet Data Gateway EBI EPS Bearer Identity EPS Evolved Packet System EUI Extended Unique Identifier FAR Forwarding Action Rule FN-BRG Fixed Network Broadband RG FN-CRG Fixed Network Cable RG FN-RG Fixed Network RG FQDN Fully Qualified Domain Name GFBR Guaranteed Flow Bit Rate GMLC Gateway Mobile Location Centre G-PDU GTP encapsulated user Plane Data Unit GPS Global Positioning System GPSI Generic Public Subscription Identifier GUAMI Globally Unique AMF Identifier GUTI Globally Unique Temporary UE Identity HPLMN Home Public Land Mobile Network HR Home Routed(roaming) HSS Home Subscriber Server IAB Integrated access and backhaul IPsec Internet Protocol Security IMEI / TAC IMEI Type Allocation Code IMSI International Mobile Subscriber Identity IPUPS Inter PLMN UP Security I-SMF Intermediate SMF I-UPF Intermediate UPF LADN Local Area Data Network LBO Local Break Out(roaming) LMF Location Management Function LoA Level of Automation LPP LTE Positioning Protocol LRF Location Retrieval Function MCC Mobile country code MCX Mission Critical Service MDBV Maximum Data Burst Volume ME Mobile Equipment MFBR Maximum Flow Bit Rate MICO Mobile Initiated Connection Only MINT Minimization of service interruption MITM Man In the Middle MME Mobility Management Entity MNC Mobile Network Code MOCN Multiple Operator Core Network MPS Multimedia Priority Service MPTCP Multi-Path TCP Protocol MT Mobile Termination N3IWF Non-3GPP InterWorking Function N3GPP Non-3GPP access N5CW Non-5G-Capable over WLAN NAI Network Access Identifier NAS Non-Access-Stratum NEF Network Exposure Function NF Network Function NGAP Next Generation Application Protocol NID Network identifier NMEA National Marine Electronics Association NPN Non-Public Network NR New Radio NSAG Network Slice Access Stratum Group NRF Network Repository Function NSI ID Network Slice Instance Identifier NSSAA Network Slice-Specific Authentication and Authorization NSSAAF Network Slice-Specific Authentication and Authorization Function NSSAI Network Slice Selection Assistance Information NSSF Network Slice Selection Function NSSP Network Slice Selection Policy NSSRG Network Slice Simultaneous Registration Group NW-TT Network-side TSN translator NWDAF Network Data Analytics Function PCF Policy Control Function PCO Protocol Configuration Options PCRF Policy and Charging Rules Function PDB Packet Delay Budget PDR Packet Detection Rule PDU Protocol Data Unit PEI Permanent Equipment Identifier PER Packet Error Rate PFD Packet Flow Description PLMN Public Land Mobile Network PNI-NPN Public Network Integrated Non-Public Network PPD Paging Policy Differentiation PPF Paging Proceed Flag PPI Paging Policy Indicator PSA PDU Session Anchor PTP Precision Time Protocol QFI QoS Flow Identifier QoE Quality of Experience RACS Radio Capabilities Signalling optimisation (R)AN (Radio)Access Network RAT Radio Access Technology RG Residential Gateway RIM Remote Interference Management RQA Reflective QoS Attribute RQI Reflective QoS Indication RRC Radio Resource Control RSN Redundancy Sequence Number RSRP Reference Signal Received Power RSRQ Reference Signal Received Quality RVAS Roaming Value Added Service SA NR Standalone New Radio SBA Service Based Architecture SBI Service Based Interface SCP Service Communication Proxy SD Slice Differentiator SEAF Security Anchor Functionality SENSE Signal Level Enhanced Network Selection SEPP Security Edge Protection Proxy SGW Serving Gateway SIB System Information Block SINR Signal to Interference plus Noise Ratio SMF Session Management Function SMSF Short Message Service Function SN Sequence Number SN name Serving Network Name SNPN Stand-alone Non-Public Network S-NSSAI Single Network Slice Selection Assistance Information SOR Steering Of Roaming SSC Session and Service Continuity SSCMSP Session and Service Continuity Mode Selection Policy SST Slice / Service Type SUCI Subscription Concealed Identifier SUPI Subscription Permanent Identifier SV Software Version TAU Tracking Area Update TEID Tunnel Endpoint Identifier TMSI Temporary Mobile Subscriber Identity TNAN Trusted Non-3GPP Access Network TNAP Trusted Non-3GPP Access Point TNGF Trusted Non-3GPP Gateway Function TNL Transport Network Layer TNLA Transport Network Layer Association TSC Time Sensitive Communication TSCAI TSC Assistance Information TSN Time Sensitive Networking TSN TSN Grand Master TSP Traffic Steering Policy TT TSN Translator TWIF Trusted WLAN Interworking Function UCMF UE radio Capability Management Function UDM Unified Data Management UDR Unified Data Repository UDSF Unstructured Data Storage Function UE User Equipment UL Uplink UL CL Uplink Classifier UPF User Plane Function UPSI UE Policy Section Identifier URLLC Ultra Reliable Low Latency Communication URRP-AMF UE Reachability Request Parameter for AMF URSP UE Route Selection Policy USIM User Services Identity Module VID VLAN Identifier VLAN Virtual Local Area Network VPLMN Visited Public Land Mobile Network W-5GAN Wireline 5G Access Network W-5GBAN Wireline BBF Access Network W-5GCAN Wireline 5G Cable Access Network W-AGF Wireline Access Gateway Function

[0036] definition For the purposes of this document, the terms and definitions in 3GPP TR 21.905 [1] and below apply. Terms defined in this document take precedence over any definition of the same term in 3GPP TR 21.905 [1].

[0037] Citation List [1]3GPP TR 21.905: “Vocabulary for 3GPP Specifications”.V17.1.0(2021-12) [2]3GPP TR 22.877: “Study on Roaming Value-Added Services”.V19.0.0(2022-12) [3]3GPP TS 23.501: “System architecture for the 5G System(5GS)”.V18.0.0(2022-12) [4]3GPP TS 23.502: “Procedures for the 5G System (5GS)”.V18.0.0(2022-12) [5]3GPP TS 23.503: “Policy and charging control framework for the 5G System(5GS)Stage 2”.V18.0.0(2022-12) [6]3GPP TS 24.501: “Non-Access-Stratum (NAS) protocol for 5G System (5GS) Stage 3”.V18.1.0 (2022-12) [7] 3GPP TS 23.122: “Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode”.V18.1.0 (2022-12)

[0038] general Those skilled in the art will understand that elements in the figures are illustrated for simplicity and may not necessarily be drawn to scale. Further, with respect to the configuration of a device, one or more components of the device may be represented in the figures by conventional symbols, and the figures may show only certain details relevant to an understanding of aspects of the present disclosure so as not to obscure the figures with details that will be readily apparent to one of ordinary skill in the art having the benefit of the description herein. For the purposes of promoting an understanding of the principles of the present disclosure, reference will be made to the embodiments illustrated in the drawings and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended. Such changes and further modifications in the illustrated systems, and such further applications of the principles of the present disclosure as would normally occur to one skilled in the art, are to be construed as being within the scope of the present disclosure.

[0039] The terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that includes a list of steps does not include only those steps, but may also include other steps that are not expressly listed or inherent in such process or method. Similarly, the term "comprises...a" precedes one or more devices or entities or subsystems or elements or structures or components, and does not, without further constraints, exclude the presence of other devices, subsystems, elements, structures, components, additional devices, additional subsystems, additional elements, additional structures, or additional components. Throughout this specification, the appearances of the phrases "in an embodiment," "in another embodiment," and similar language may, but do not necessarily, all refer to the same embodiment.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The systems, methods, and examples provided herein are illustrative only and are not intended to be limiting.

[0041] In the following specification and claims, reference will be made to a number of terms that may be defined to have the following meanings: The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. As used herein, information is associated with data and knowledge, as data is meaningful information and represents values ​​attributed to parameters. Further knowledge represents an understanding of abstract or concrete concepts. It should be noted that this exemplary system is simplified to facilitate explanation of the subject matter of the present disclosure and is not intended to limit the scope of the present disclosure. Other devices, systems, and configurations may be used in addition to or instead of the system to implement aspects disclosed herein, and all such aspects are considered to be within the scope of the present disclosure.

[0042] Each aspect described below (e.g., the first aspect, the second aspect, the first example of the first aspect, the second example of the first aspect, the third example of the first aspect, the fourth example of the first aspect, the fifth example of the first aspect, the sixth example of the first aspect, the seventh example of the first aspect, the eighth example of the first aspect, the first example of the second aspect, the second example of the second aspect, the third example of the second aspect, the fourth example of the second aspect, and variant(s) of each aspect) and elements included in each aspect may be implemented independently or in any combination with others. These aspects include novel features that are different from each other. Therefore, these aspects contribute to achieving different objectives or solving different problems and to obtaining different advantages from each other.

[0043] Any list described in the following aspects includes at least one parameter or multiple parameters.

[0044] Although this disclosure includes mechanisms for steering a UE to another PLMN while the UE is in a home network environment (e.g., HPLMN) in 5GS, all mechanisms in this disclosure may also be applied to EPS. When all mechanisms in this disclosure are applied to EPS, the following terminology conversions apply: gNB → eNodeB AMF → MME NGAP → S1AP Any NGAP message → each S1AP message Registration request message → Attach request message or TAU request message Any AMF service-related message (e.g., Namf_Communication_NonUeN2InfoNotify) →GTP-C message Any UDM service-related message (e.g., Nudm_SDM_Notification) → DIAMETER message 5G-GUTI → GUTI 5G-S-TMSI → S-TMSI

[0045] The phrase "A and / or B" may mean "at least one of A and B" in this disclosure. In this disclosure, user(s), subscriber(s), UE(s), and similar term(s) may have the same meaning. These terms may be interchangeable.

[0046] An exemplary object of the present disclosure is to provide a method and apparatus that can solve the above problems.

[0047] A method for a user equipment (UE) according to an example aspect of the present disclosure includes receiving a first message from a communication device in a first public land mobile network (PLMN). The first message includes first information indicating that a registration procedure is required and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or an area in which the UE is included in the group or in which service is provided for the UE. The third information indicates the second PLMN in which the UE needs to perform the registration procedure. The method includes transmitting a second message. The second message includes a registration request message and at least one of the second information and the third information.

[0048] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message from a User Equipment (UE). The first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device. The segment indicates a group of subscribers, or an area in which the UE is included in the group or in which service is provided for the UE. The second information indicates a second PLMN with which the UE needs to perform a registration procedure. The method includes selecting a second communication device in the second PLMN based on the first information and the second information. The method includes transmitting a second message to the second communication device. The second message includes the registration request message.

[0049] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message from a second communication device. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The method includes transmitting a second message to the UE. The second message includes third information indicating that a registration procedure is required and at least one of the first information and the second information.

[0050] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes communicating with a second communication device. The method includes transmitting a message to the second communication device. The message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates the second PLMN with which the UE needs to perform a registration procedure.

[0051] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The method includes selecting a second communication device in the second PLMN based on the first information and the second information. The method includes transmitting a second message to the second communication device. The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI). The method includes receiving the 5G-GUTI. The method includes transmitting the 5G-GUTI and fourth information indicating that a registration procedure is required to the UE.

[0052] According to an example aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a message from a second communication device in a second PLMN, the message including information requesting assignment of a 5G Globally Unique Temporary Identifier (5G-GUTI). The method includes transmitting the 5G-GUTI.

[0053] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The method includes selecting a second communication device in the second PLMN based on the first information and the second information. The method includes transmitting a second message to the second communication device. The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI). The method includes receiving the 5G-GUTI. The method includes transmitting the 5G-GUTI. The method includes transmitting fourth information to the UE indicating that a registration procedure is required.

[0054] A method for a user equipment (UE) according to an example aspect of the present disclosure includes receiving a message from a communication device in a first public land mobile network (PLMN). The message includes information indicating that a registration procedure is required and a 5G globally unique temporary identifier (5G-GUTI). The 5G-GUTI is assigned in a second PLMN. The method includes performing the registration procedure based on the 5G-GUTI.

[0055] A method for a user equipment (UE) according to an example aspect of the present disclosure includes receiving a first message from a communication device in a first public land mobile network (PLMN). The first message includes a 5G globally unique temporary identifier (5G-GUTI). The 5G-GUTI is assigned in a second PLMN. The method includes receiving a second message. The second message includes information indicating that a registration procedure is required. The method includes performing the registration procedure based on the 5G-GUTI.

[0056] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The method includes selecting a second communication device in the second PLMN based on the first information and the second information. The method includes transmitting a second message to the second communication device to instruct the second communication device to perform a registration procedure for the UE.

[0057] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving, from a second communication device in a second PLMN, a first message for performing a registration procedure for the user equipment. The method includes performing the registration procedure.

[0058] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The method includes receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE. The method includes selecting a second communication device in the second PLMN based on the first information and the second information. The method includes transmitting a third message for establishing the PDU session to the second communication device.

[0059] According to an exemplary aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN, the method including performing a procedure for establishing the PDU session.

[0060] According to an example aspect of the present disclosure, a method for a first communication device in a first Public Land Mobile Network (PLMN) includes receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN, and transmitting a second message for establishing the PDU session to a third communication device in the first PLMN.

[0061] A user equipment (UE) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message from a communication device in a first public land mobile network (PLMN). The first message includes first information indicating that a registration procedure is required and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or an area in which the UE is included in the group or in which service is provided for the UE. The third information indicates the second PLMN in which the UE needs to perform the registration procedure. The at least one hardware processor is configured to transmit a second message. The second message includes a registration request message and at least one of the second information and the third information.

[0062] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message from a User Equipment (UE). The first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device. The segment indicates a group of subscribers, or an area in which the UE is included in the group or in which service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to select a second communication device in the second PLMN based on the first information and the second information. The at least one hardware processor is configured to transmit a second message to the second communication device. The second message includes the registration request message.

[0063] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message from a second communication device. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to send a second message to the UE. The second message includes third information indicating that a registration procedure is required and at least one of the first information and the second information.

[0064] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to communicate with a second communication device. The at least one hardware processor is configured to send a message to the second communication device. The message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates the second PLMN with which the UE needs to perform a registration procedure.

[0065] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to select a second communication device in the second PLMN based on the first information and the second information. The at least one hardware processor is configured to send a second message to the second communication device. The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI). The at least one hardware processor is configured to receive the 5G-GUTI. The at least one hardware processor is configured to send the 5G-GUTI and fourth information indicating that a registration procedure is required to the UE.

[0066] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a message from a second communication device in a second PLMN. The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI). The at least one hardware processor is configured to transmit the 5G-GUTI.

[0067] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to select a second communication device in the second PLMN based on the first information and the second information. The at least one hardware processor is configured to send a second message to the second communication device. The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI). The at least one hardware processor is configured to receive the 5G-GUTI. The at least one hardware processor is configured to transmit the 5G-GUTI. The at least one hardware processor is configured to transmit fourth information to the UE indicating that a registration procedure is required.

[0068] A user equipment (UE) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a message from a communication device in a first public land mobile network (PLMN). The message includes information indicating that a registration procedure is required and a 5G globally unique temporary identifier (5G-GUTI). The 5G-GUTI is assigned in a second PLMN. The at least one hardware processor is configured to perform the registration procedure based on the 5G-GUTI.

[0069] A user equipment (UE) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message from a communication device in a first public land mobile network (PLMN). The first message includes a 5G globally unique temporary identifier (5G-GUTI). The 5G-GUTI is assigned in a second PLMN. The at least one hardware processor is configured to receive a second message.

[0070] The second message includes information indicating that a registration procedure is required. The at least one hardware processor is configured to perform the registration procedure based on the 5G-GUTI.

[0071] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to select a second communication device in the second PLMN based on the first information and the second information. The at least one hardware processor is configured to send a second message to the second communication device to instruct the second communication device to perform a registration procedure for the UE.

[0072] According to an exemplary aspect of the present disclosure, a first communication device in a first Public Land Mobile Network (PLMN) includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message for performing a registration procedure for a UE from a second communication device in a second PLMN. The at least one hardware processor is configured to perform the registration procedure.

[0073] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory. The at least one hardware processor is configured to receive a first message. The first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN. The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area where service is provided for the UE. The second information indicates a second PLMN in which the UE needs to perform a registration procedure. The at least one hardware processor is configured to receive a second message for establishing a Protocol Data Unit (PDU) session from the UE. The at least one hardware processor is configured to select a second communication device in the second PLMN based on the first information and the second information. The at least one hardware processor is configured to transmit a third message for establishing the PDU session to the second communication device.

[0074] According to an exemplary aspect of the present disclosure, a first communication device in a first Public Land Mobile Network (PLMN) includes at least one memory and at least one hardware processor coupled to the at least one memory, the at least one hardware processor configured to receive a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN, and the at least one hardware processor configured to perform a procedure for establishing the PDU session.

[0075] A first communication device in a first Public Land Mobile Network (PLMN) according to an exemplary aspect of the present disclosure includes at least one memory and at least one hardware processor coupled to the at least one memory, the at least one hardware processor configured to receive a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN, and the at least one hardware processor configured to transmit a second message for establishing the PDU session to a third communication device in the first PLMN.

[0076] First Aspect This aspect includes a mechanism for (re)selecting an AMF (e.g., AMF 7002) based on subscription data in a UDM (e.g., UDM 75). A segment is maintained by the UDM (e.g., UDM 75) for each subscriber. The segment may indicate a group of subscriber(s) who are eligible to have unique service(s) provided by a specified PLMN (e.g., a specified PLMN2, or PLMN2) to which the AMF (e.g., AMF 7002) belongs. The segment may indicate a group of subscriber(s) who are eligible to have the unique service(s) and / or an area in which the unique service(s) are provided. The segment may indicate a name of a group of subscriber(s) and / or a name of an area. The segment may indicate an area in the specified PLMN in which the subscriber(s) (or UE(s)) need to camp. The segment may indicate an area in the specified PLMN where the subscriber(s) (or UE(s)) need to perform a registration procedure. The segment may be indicated by a particular IMSI range of the USIM(s). For example, a group of subscriber(s) may be indicated by a particular IMSI range. For example, the subscriber(s) eligible to have the unique service(s) provided by the specified PLMN may be identified by a value(s) within the particular IMSI range. For example, at least one of the subscriber(s) eligible to have the unique service(s) provided by the specified PLMN may be identified by an IMSI (or IMSI range) including an MCC set to "AAA" (e.g., "AAA" may indicate a country), an MNC set to "BB" (e.g., "BB" may indicate an operator. For example, the operator may be PLMN1 or PLMN2 in this disclosure. "BB" indicates PLMN1 or PLMN2 in this disclosure), and an MSIN set to one of "9000000000" to "9999999999." The unique service may be referred to as a Roaming Value Added Service (RVAS) or any other designation for a service provided by a designated entity that is not an HPLMN.

[0077] For example, this aspect includes mechanisms that can solve the above-mentioned challenges (eg, the identified problems outlined as operational issues in the problem statement).

[0078] First example of the first aspect: FIG. 1 includes an example of AMF (re)selection by NG-RAN (e.g., NG-RAN5) based on segment and / or PLMN identifier. Figure 1: AMF (re)selection by NG-RAN5 based on segment and / or PLMN identifier The detailed process of the first example of the first embodiment is described below with reference to FIG.

[0079] Step 0. The UDM 75 maintains (or stores) subscription data for each user(s). For example, the UDM 75 may maintain information about segments. For example, the UDM 75 may maintain information indicating whether the user(s) (or UE(s)) are included in a segment. For example, the UDM 75 may maintain information indicating whether the user(s) (or UE(s)) are included in the above-mentioned specific IMSI range. For example, the UDM 75 may maintain information indicating whether the user(s) (or UE(s)) are user(s) (or UE(s)) included in the above-mentioned specific IMSI range. For example, the UDM 75 may maintain information indicating whether unique service(s) in a specific PLMN are provided to the user(s) (or UE(s)). For example, if a segment indicates an area that provides unique service(s), UDM75 may hold information indicating whether user(s) (or UE(s)) are user(s) (or UE(s)) within the segment (or area). User(s) (or UE(s)) may be indicated by user identifier (ID)(s). For example, UDM75 may hold information indicating whether user(s) (or UE(s)) are eligible to have unique service(s). For example, UDM75 may hold information indicating that UE3, described below, is associated with a segment set to "X." X may be the name of the segment. For example, UDM75 may hold information indicating that UE3 is included in a segment set to "X." For example, UDM75 may hold information indicating that UE3 is included in a group of subscriber(s) named "X." For example, UDM75 may hold information indicating that UE3 is included in a particular IMSI range named "X." For example, UDM 75 may hold information indicating that UE 3 is contained in or belongs to an area named "X" in which unique service(s) are provided. UDM75 may be included in PLMN1.

[0080] For example, UDM 75 in PLMN1 may hold information about PLMN2. For example, UDM 75 may hold a target PLMN identifier for each user(s). Target PLMN identifiers are described below. For example, for UE3 described below, UDM 75 may hold information indicating that UE3 is included in segment "X" and / or information indicating that the target PLMN identifier for UE3 is PLMN2. X may be the name of a segment.

[0081] For example, UDM 75 may hold information indicating that UE 3 has, is included in, or belongs to a particular IMSI range, as described above. For example, PLMN 1 may be a PLMN that covers an entire country area (e.g., PLMN 1 has a coverage area that can cover the entire country area), and PLMN 2 may be included in PLMN 1 (e.g., the coverage area of ​​PLMN 2 may be included in the coverage area of ​​PLMN 1) or may cover a particular area of ​​a country (e.g., PLMN 2 has a coverage area that can cover a particular area or portion of a country). PLMN 1 may be different from PLMN 2.

[0082] Step 1. The UE 3 sends a registration request message including a user ID and a segment support indication to the AMF 7001 via the NG-RAN 5. The user ID indicates the user identifier of the UE 3. The user ID may be the SUCI, 5G-GUTI, PEI, or information identifying the UE 3. The segment support indication indicates to the AMF 7001 that the UE 3 supports the AMF (re)selection function based on segment information. The NG-RAN 5 may include an NG-RAN node(s), an (R)AN node(s), a gNB(s), etc. The NG-RAN 5 and the AMF 7001 may be included in the PLMN 1. "The UE 3 supports the AMF (re)selection function based on segment information" may mean that the UE 3 can send the segment support indication. "XXX (where XXX is a node, e.g., UE, AMF, NG-RAN, etc.) supports the AMF (re)selection function based on segment information" may mean that the XXX can perform the process related to the selection of the AMF 7002 of the PLMN 2 in the present disclosure.

[0083] Step 2. Upon receiving the registration request message in step 1, the AMF 7001 sends a Nudm_UECM_Registration Request message to the UDM 75 in PLMN 1. In one example, the AMF 7001 may include a segment support indication in the Nudm_UECM_Registration Request message if at least one of the UE 3, the NG-RAN 5, and the AMF 7001 supports the AMF (re)selection function based on segment information. The PLMN 1 may be the HPLMN of the UE 3. For example, if AMF7001 determines that at least one of UE3, NG-RAN5, and AMF7001 supports an AMF (re)selection function based on segment information, AMF7001 may include a segment support indication in a Nudm_UECM_Registration Request message and send the Nudm_UECM_Registration Request message.

[0084] For example, in step 1, if AMF7001 receives a segment support indication from UE3, AMF7001 may send a Nudm_UECM_Registration Request message including the segment support indication. The segment support indication included in the Nudm_UECM_Registration Request message may indicate that at least one of the UE 3, the NG-RAN 5, and the AMF 7001 supports the AMF (re)selection function based on segment information. The AMF 7001 supporting the AMF (re)selection function based on segment information may mean that the AMF 7001 can send a segment support indication.

[0085] For example, based on the segment support indication from UE3 in step 1, AMF7001 may determine (or learn or understand or understand) that UE3 supports the AMF (re)selection function based on segment information. For example, if AMF7001 receives a segment support indication from UE3, AMF7001 may determine that UE3 supports the AMF (re)selection function based on segment information.

[0086] For how the AMF 7001 determines (or learns, or knows, or understands) whether the NG-RAN 5 supports the AMF (re)selection function based on segment information, reference may be made to the third example of the first aspect. For example, based on the processing in the third example of the first aspect, the AMF 7001 may determine that the NG-RAN 5 supports the AMF (re)selection function based on segment information.

[0087] For example, AMF7001 may determine that AMF7001 itself supports the AMF (re)selection function based on segment information based on configuration information, an operator's policy, or any other information in AMF7001. For example, AMF7001 may determine that AMF7001 itself supports the AMF (re)selection function if configuration information, an operator's policy, or any other information in AMF7001 indicates that AMF7001 itself supports the AMF (re)selection function. For example, AMF7001 may be configured to support the AMF (re)selection function.

[0088] Step 3. Upon receiving the Nudm_UECM_Registration Request message in step 2, the UDM 75 sends a Nudm_UECM_Registration Response message to the AMF 7001.

[0089] Step 4. If at least one of the UE 3, the NG-RAN 5, and the AMF 7001 supports the AMF (re)selection function based on segment information, the AMF 7001 sends a Nudm_SDM_Get Request message including a segment support indication to the UDM 75 in the PLMN 1. For example, the AMF 7001 may send a Nudm_SDM_Get Request message including a segment support indication to the UDM 75.

[0090] For example, if AMF7001 determines that at least one of UE3, NG-RAN5 and AMF7001 supports an AMF (re)selection function based on segment information, AMF7001 may send a Nudm_SDM_Get Request message to UDM75 including a segment support indication.

[0091] For example, if AMF7001 receives at least one of a segment support indication from UE3 and segment support information from NG-RAN5, AMF7001 may send a Nudm_SDM_Get Request message including a segment support indication to UDM75 in PLMN1.

[0092] For example, AMF7001 may send a Nudm_SDM_Get Request message when AMF7001 receives a Nudm_UECM_Registration Response message. The segment support indication included in the Nudm_SDM_Get Request message may indicate that at least one of the UE 3, NG-RAN 5 and AMF 7001 supports the AMF (re)selection function based on segment information.

[0093] Step 5. Upon receiving the Nudm_SDM_Get Request message of step 4, the UDM 75 sends a Nudm_SDM_Get Response message including subscriber data to the AMF 7001. The subscriber data in the Nudm_SDM_Get Response message may include segment information and / or a target PLMN identifier. The subscriber data in the Nudm_SDM_Get Response message may include segment information of the UE 3 and / or a target PLMN identifier of the UE 3.

[0094] If a segment support indication is indicated in the Nudm_SDM_Get Request message of step 4 and UDM 75 holds information in the subscriber data of UE 3 indicating that UE 3 supports an AMF (re)selection function based on segment information, the subscriber data in the Nudm_SDM_Get Response message may include the segment information and / or the target PLMN identifier. For example, if a segment support indication is indicated in the Nudm_SDM_Get Request message of step 4, the subscriber data in the Nudm_SDM_Get Response message may include the segment information and / or the target PLMN identifier.

[0095] For example, the segment information may be information about a segment. The segment information may be expressed using numbers or letters that can distinguish PLMNs associated with the segment within a PLMN. The segment information may be expressed differently. For example, the segment information may include or be a segment identifier in FQDN format, a PLMN identifier including MCC and MNC, both a PLMN identifier and a segment identifier, etc. For example, the segment information may indicate that UE3 is within the specific IMSI range. For example, the segment information may indicate that UE3 is a UE within the specific IMSI range. For example, the segment information may indicate that UE3 is within a segment. For example, the segment information may indicate that UE3 is a UE within the segment. For example, the segment information may indicate that UE3 is included in or belongs to an area where the unique service(s) are provided. For example, the segment information may indicate that UE3 is eligible to have the unique service(s). For example, the segment information may indicate that UE3 is included in the group of subscriber(s).

[0096] The target PLMN identifier may be a PLMN identifier including an MCC and an MNC. The target PLMN identifier may be information identifying a PLMN or may include information identifying a PLMN. The target PLMN identifier may indicate a PLMN where the UE 3 needs to perform a registration or registration procedure. The target PLMN identifier may indicate a PLMN where the UE 3 needs to camp. The target PLMN identifier may be information identifying a PLMN where the UE 3 needs to perform a registration or registration procedure or may include such information. The target PLMN identifier may be information identifying a PLMN where the UE 3 needs to camp or may include such information. The target PLMN identifier may be information identifying a PLMN related to RVAS or may include such information. The target PLMN identifier may indicate a PLMN where the UE 3 needs to perform a registration or registration procedure for RVAS. The target PLMN identifier may indicate a PLMN where the UE 3 needs to camp for RVAS. The target PLMN identifier may be information identifying a PLMN where the UE 3 needs to perform a registration or registration procedure for RVAS or may include such information. The target PLMN identifier may be or may include information that identifies the PLMN in which the UE 3 needs to camp for RVAS.

[0097] If the PLMN indicated by the target PLMN identifier can have multiple segments, the target PLMN identifier may be managed in the UDM 75 together with segment information. The segment information may be used to route any NAS messages between UE3 and node(s) (e.g., AMF(s) in different PLMNs, AMF(s) in PLMN2). The segment information may be used to route any Hypertext Transfer Protocol (HTTP) messages over the SBI between signaling control node(s) (e.g., AMF, PCF, SMF, NEF, NWDAF, etc.) across PLMNs (e.g., including PLMN2). The target PLMN identifier may be used to route any signaling messages (NAS message(s) and / or HTTP message(s) over any SBI) to signaling control node(s) (e.g., AMF, PCF, SMF, NEF, NWDAF, etc.) within the PLMN (e.g., PLMN2) associated with the segment information or indicated by the target PLMN identifier. The combination of segment information and target PLMN identifier may be used to route any signaling message (e.g., NAS message(s) and HTTP message(s) via any SBI) to the associated signaling control node(s) (e.g., AMF, PCF, SMF, NEF, NWDAF, etc.) to a segment (e.g., "X") within the associated PLMN (e.g., PLMN2).

[0098] In Figure 1, as an example, segment information set to "X" is shown as segment = X, and the target PLMN identifier set to PLMN2 is shown as PLMN identifier = PLMN2. For example, "segment = X" may be expressed as a segment set to "X", segment information set to "X", segment "X", etc. For example, the segment information may be set to "X" and the target PLMN identifier may be set to PLMN2. Segment information set to "X" may indicate a group of subscriber(s) (e.g., the group is named "X") that are entitled to have a unique service(s) provided by PLMN2, or may indicate that the user or UE3 indicated by the user ID is included in group "X". Segment information set to "X" may indicate an area (e.g., an area named "X") in which a unique service(s) is provided, or may indicate that the user or UE3 indicated by the user ID is included in area "X." Segment information set to "X" may indicate an area (e.g., an area named "X") in which a unique service(s) is provided, or may indicate that the user or UE3 indicated by the user ID is a user (or UE) within area "X". The segment information set to "X" may indicate the above-mentioned specific IMSI range (for example, the name of the IMSI range is "X"), or may indicate that the user or UE3 indicated by the user ID is included in the IMSI range "X". Segment information set to "X" may indicate a group of subscribers at a particular priority level or a particular security level that may steer subscribers to another PLMN (e.g., PLMN2) if the current PLMN is congested. Segment information set to "X" may indicate a group of subscribers with subscriptions to a particular network slice or multiple network slices that are eligible for service from another PLMN, e.g., PLMN2.

[0099] A target PLMN identifier set to PLMN2 may indicate that the target PLMN for UE 3 is PLMN 2. A target PLMN identifier set to PLMN2 may indicate that UE 3 needs to register on PLMN 2. A target PLMN identifier set to PLMN2 may indicate that UE 3 needs to register on PLMN 2 (e.g., for RVAS). The target PLMN identifier set to PLMN2 may indicate that UE3 needs to perform a registration procedure for PLMN2 (eg, for RVAS). The target PLMN identifier set to PLMN2 may indicate that UE3 needs to camp on PLMN2 (eg, for RVAS).

[0100] The segment information may indicate that the UE 3 belongs to or is included in the segment. The segment support indication included in the Nudm_SDM_Get Request message may indicate that the AMF 7001 supports receiving segment information and / or a target PLMN identifier from the UDM 75. The segment support indication included in the Nudm_SDM_Get Request message may indicate that the AMF 7001 supports receiving a Nudm_SDM_Get Response message including segment information and / or a target PLMN identifier from the UDM 75. For example, if AMF7001 receives at least one of a segment support indication from UE3 and segment support information from NG-RAN5, and AMF7001 supports receiving segment information and / or a target PLMN identifier from UDM75, AMF7001 may send a Nudm_SDM_Get Request message to UDM75 in PLMN1, including a segment support indication.

[0101] For example, if AMF7001 receives at least one of a segment support indication from UE3 and segment support information from NG-RAN5, and AMF7001 supports receiving a Nudm_SDM_Get Response message including segment information and / or a target PLMN identifier from UDM75, AMF7001 may send a Nudm_SDM_Get Request message including a segment support indication to UDM75 in PLMN1.

[0102] Step 6. Upon receiving the Nudm_SDM_Get Response message of step 5, the AMF 7001 sends a registration reject message to the UE 3, including the re-registration request indication, segment information, and / or target PLMN identifier received from the UDM 75. The re-registration request indication indicates to the UE 3 that the UE 3 is requested to initiate a new registration procedure taking into account the received segment information and / or target PLMN identifier. The re-registration request indication may indicate to the UE 3 that the UE 3 is requested to initiate a new registration procedure. The segment support indication included in the Nudm_SDM_Get Request message may indicate that the AMF 7001 supports sending at least one of a re-registration request indication, segment information, and target PLMN identifier to the UE 3.

[0103] Steps 7-9. Upon receiving the registration reject message in step 6, the UE 3 knows that a new registration procedure needs to be initiated. For example, if UE3 receives the registration reject message of step 6, it may know that it needs to initiate a new registration procedure towards PLMN2. The UE 3 establishes an RRC connection to transmit a NAS message. For example, the UE 3 establishes an RRC connection to transmit a NAS message to the AMF 7002.

[0104] For example, to establish an RRC connection, in step 7, the UE 3 may send an RRC setup request message to the NG-RAN 5 to establish an RRC connection. For example, in step 8, the NG-RAN 5 may send an RRC setup message to the UE 3. For example, in step 8, the NG-RAN 5 may send an RRC setup message to the UE 3 if the NG-RAN 5 receives an RRC setup request message from the UE 3. For example, in step 9, UE 3 may send an RRC setup complete message to NG-RAN 5. For example, in step 9, UE 3 may send an RRC setup complete message to NG-RAN 5 if UE 3 receives an RRC setup message from NG-RAN 5.

[0105] For example, the RRC Setup Complete message of step 9 includes a nas-Container that includes the Registration Request message, SelectedPLMN-Identity set to PLMN2, and / or segment information set to "X". In one example, SelectedPLMN-Identity is set by UE3 to the value received in step 6 in the Registration Reject message (e.g., PLMN2). In one example, segment information is set by UE3 to the value received in step 6 in the Registration Reject message (e.g., "X").

[0106] In one example, the SelectedPLMN-Identity in the RRC Setup Complete message may be set to only PLMN2, which forces NG-RAN5 to select only one AMF in PLMN2 if the cell to which UE3 is connected supports multiple SelectedPLMN-Identities.

[0107] For example, UE3 may perform step 7 of Figure 1 if UE3 receives a registration rejection message in step 6. For example, UE3 may perform step 7 of Figure 1 if UE3 receives a registration rejection message in step 6 even if UE3 does not send a segment support indication in step 1. For example, UE3 may not send a segment support indication in step 1. For example, the segment support indication in step 1 may indicate that UE3 supports receiving a registration rejection message in step 6. For example, the segment support indication in step 1 may indicate that UE3 can understand at least one of the re-registration request indication, segment information, and target PLMN identifier in the registration rejection message in step 6. For example, the segment support indication in step 1 may indicate that UE3 can understand at least one of the re-registration request indication, segment information, and target PLMN identifier in the registration reject message in step 6 and can send an RRC setup request message.

[0108] For example, the segment support indication in step 1 may indicate that UE3 can understand at least one of the re-registration request indication, segment information, and target PLMN identifier in the registration reject message of step 6, and can send an RRC setup complete message including a nas-Container that includes at least one of the registration request message, SelectedPLMN-Identity, and segment information. Segment information set to "X" may indicate the segment is set to "X." Segment information set to "X" may indicate that the segment is "X."

[0109] Step 10. When the NG-RAN 5 receives the RRC Setup Complete message from the UE 3, it performs AMF selection based on the received Selected PLMN-Identity and / or segment information. The NG-RAN 5 may consider congestion on each candidate AMF to select an AMF during AMF selection. This AMF selection may be expressed as a segment information-based AMF (re)selection function, segment information-based AMF (re)selection, etc. The NG-RAN 5 supporting the AMF (re)selection function based on segment information may mean that the NG-RAN 5 can perform AMF selection based on the received SelectedPLMN-Identity and / or segment information.

[0110] For example, the NG-RAN 5 may store information indicating the relationship between the PLMN(s) and the AMF(s). For example, the NG-RAN 5 may store information indicating the relationship between the segment and the AMF(s). For example, the NG-RAN 5 may store information indicating a relationship between PLMN(s), AMF(s), and segments. For example, the NG-RAN 5 may store information indicating AMF(s) available for a segment (e.g., segment "X"). For example, the NG-RAN 5 may store information indicating AMF(s) available in PLMN2. For example, the NG-RAN 5 may store information indicating AMF(s) available for a segment (e.g., segment "X") in PLMN2. For example, the NG-RAN 5 may store information indicating AMF(s) associated with a segment (e.g., segment "X"). For example, the NG-RAN 5 may store information indicating AMF(s) associated with PLMN2. For example, the NG-RAN 5 may store information indicating AMF(s) associated with a segment (e.g., segment "X") and PLMN2.

[0111] For example, assume that NG-RAN 5 may store information indicating that PLMN2 is associated with AMF 7002 (or indicating that AMF 7002 is available in PLMN2). In this case, NG-RAN 5 may select or discover AMF 7002 associated with PLMN2 indicated by the received SelectedPLMN-Identity.

[0112] For example, the NG-RAN 5 may store information indicating that the AMF 7002 is associated with or available to a segment set to "X." The segment set to "X" may mean segment information set to "X," or may mean that the name of the segment is "X." In this case, the NG-RAN 5 may select or discover the AMF 7002 associated with the received segment information set to "X." For example, the NG-RAN 5 may use the segment information set to "X" to determine that the UE 3 is associated with the segment set to "X," or may select the AMF 7002 associated with the segment set to "X." The segment information set to "X" may indicate a group of subscriber(s) eligible to have unique service(s) provided by the PLMN 2, and may indicate that the name of the group is "X." The segment information set to "X" may indicate an area in which the unique service(s) are provided, and may indicate that the area name is "X."

[0113] For example, assume that the NG-RAN 5 may store information indicating that the AMF 7002 is associated with or available for the above-mentioned particular IMSI range "X." In this case, the NG-RAN 5 may select or discover the AMF 7002 associated with the received segment information set to "X" (or associated with the IMSI range "X"). The received segment information set to "X" may indicate the IMSI range "X." For example, assume that NG-RAN 5 may store information indicating that a segment set to "X" in PLMN2 is associated with AMF 7002 (or indicating that AMF 7002 is available for a segment set to "X" in PLMN2). In this case, NG-RAN 5 may select or discover AMF 7002 associated with the segment set to "X" in PLMN2 indicated by the received SelectedPLMN-Identity and the received segment information set to "X". In this case, the segment set to "X" may indicate a group of subscriber(s) eligible to have (one or more) unique service(s) in PLMN2, and may indicate that the name of the group is "X". In this case, the segment set to "X" may indicate an area in PLMN2 in which the unique service(s) are provided, and may indicate that the area name is "X". AMF7002 may be included in PLMN2.

[0114] Step 11. Once NG-RAN 5 discovers (or selects) the AMF 7002 in PLMN 2 with which UE 3 needs to associate, NG-RAN 5 sends a UE Initial Message (or Initial UE Message) to AMF 7002 containing a nas-Container containing the Registration Request message and the User ID among other information elements.

[0115] Step 12. The registration procedure continues with step 4 of section 4.2.2.2.2 of 3GPP TS 23.502 [4]. For example, the AMF 7002 may perform the registration procedure for the UE 3.

[0116] In this example, there may be some other examples not shown in FIG. 1. First, NG-RAN 5 may provide PLMN1 and PLMN2 on the BCCH (e.g., in SIB1). PLMN1 may be provided in the first entry of a PLMN list and PLMN2 may be provided in the second entry of the same PLMN list, or vice versa. For example, NG-RAN 5 may provide a PLMN list via the BCCH, with the first entry of the list configured for PLMN1 and the second entry of the list configured for PLMN2. Alternatively, NG-RAN 5 may provide PLMN1 and PLMN2 in separate PLMN lists on the BCCH (e.g., in SIB1). The same may apply to other examples referring to FIG. 1. Second, upon receiving the registration reject message in step 6, the NAS layer of UE 3 notifies (or sends) to the AS layer of UE 3 the selected PLMN identifier information configured for PLMN2 and the segment information configured for PLMN2. The AS layer (e.g., the RRC layer) then initiates the RRC connection setup procedure as described above with respect to step 7. For example, if UE3 receives SIB1 including PLMN1 and PLMN2 (e.g., in the PLMN list or separate PLMN lists) and UE3 receives a registration reject message including a re-registration request indication, segment information, and / or a target PLMN identifier set to PLMN2 (e.g., UE3 consults the PLMN list(s) on the BCCH and recognizes that PLMN2 indicated by the target PLMN identifier is available in UE3's serving area), UE3 may perform the processing of step 7.

[0117] Variation 1 of the first example of the first aspect: If the Nudm_UECM_Registration Request message in step 2 includes a segment support indication, the Nudm_SDM_Get Request message in step 4 may not include a segment support indication. The UDM 75 may consider that the UE 3, the NG-RAN 5 and the AMF 7001 support the AMF (re)selection function based on segment information as long as the UDM 75 receives a segment support indication via the Nudm_UECM_Registration Request message and / or the Nudm_SDM_Get Request message.

[0118] Variation 2 of the first example of the first aspect: If the AMF 7001 receives a Nudm_SDM_Get Response message including only segment information in step 5, the AMF 7001 may convert the received segment information into a target PLMN identifier. For example, the AMF 7001 may store information for performing this conversion (e.g., the AMF 7001 may store information indicating that the segment information set to "X" is associated with PLMN2. In this case, the AMF 7001 may obtain the target PLMN identifier set to PLMN2 based on the segment information). Then, the AMF 7001 may send a registration rejection message including a re-registration request indication, the segment information, and / or the target PLMN identifier to the UE 3 in step 6.

[0119] Variation 3 of the first example of the first aspect: In another example, in step 5 of Figure 1, the AMF 7001 stores the segment information of UE 3 retrieved from the UDM 75, and the AMF 7001 may store the segment information in the UE context of UE 3 within the AMF 7001. Then, upon final UE 3 mobility within PLMN 1, the AMF 7001 may transfer the segment information of UE 3 to the target AMF in PLMN 1 as part of the context of UE 3 via a Namf_Communication_UEContextTransfer service operation in mobility re-registration or a Namf_Communication_N1N2MessageTransfer service operation in N2 handover. The target AMF in PLMN 1 may use the so-transferred segment information for UE 3 to further steer UE 3 according to steps 6 to 12 of Figure 1.

[0120] Variation 4 of the first example of the first aspect: In one example, instead of sending a registration rejection message, AMF 7001 may send a registration accept message including the same content as the registration rejection message of step 6. After UE 3 receives the registration accept message including the re-registration request indication, segment information, and / or target PLMN identifier, UE 3 may send a registration complete message to AMF 7001. After sending the registration complete message, UE 3 may select a cell of PLMN 2 and perform a registration procedure to PLMN 2. For example, UE 3 may perform the process of step 7 for PLMN 2 when UE 3 sends the registration complete message.

[0121] Variation 5 of the first example of the first aspect: In one example, in step 2 or 4, or in any message sent from the AMF to the UDM during the registration procedure, the AMF 7001 may indicate a capability that the AMF 7001 supports for sending a re-registration request indication and / or segment information to the UE 3, and / or for processing procedures related thereto. The UDM 75 may include the target PLMN identifier and / or segment information only for the AMF (e.g., AMF 7001) that indicated the capability in step 4. The capability may be the segment support indication for the AMF 7001 described above.

[0122] Second example of the first aspect: This aspect includes a mechanism for (re)selecting AMF7002 based on UE3 subscription data updates in UDM75. AMF (re)selection is performed by the NG-RAN 5 based on segment information and / or PLMN identifier. Figure 2: UE configuration update procedure with subscription renewal The detailed process of the second example of the first embodiment is described below with reference to FIG.

[0123] Step 0. As an example, UE3 is registered with AMF7001 in PLMN1.

[0124] Step 1. For example, segment information indicating or set to segment "X" is added or modified for UE 3 in UDM 75. In addition, a target PLMN identifier, for example, indicating or set to PLMN 2, is added or modified for UE 3 in UDM 75. For example, the UDM 75 may update the subscription data of the UE 3 by adding or changing the segment information and / or target PLMN identifier of the UE 3 . For example, UDM 75 may add segment information set to "X" to the subscription data of UE 3.

[0125] For example, UDM 75 may change the old segment information in the subscription data of UE 3 to new segment information set to "X." For example, UDM 75 may add a target PLMN identifier set to PLMN2 to the subscription data of UE 3. For example, UDM 75 may change the old target PLMN identifier in the subscription data of UE3 to a new target PLMN identifier set to PLMN2. The definition of the segment information in the first example of the first aspect may be applied to the second example of the first aspect. The definition of the target PLMN identifier in the first example of the first aspect may be applied to the second example of the first aspect.

[0126] Step 2. The UDM 75 sends a Nudm_SDM_Notification message containing subscriber data to the AMF 7001. The subscriber data in the Nudm_SDM_Notification message includes segment information and / or target PLMN identifier. The segment information and / or target PLMN identifier are newly added in step 1 or updated or changed in step 1. For example, UDM75 may send a Nudm_SDM_Notification message to AMF7001 if UDM75 adds, updates, or changes segment information and / or target PLMN identifier in step 1. For details of the segment information and / or the target PLMN identifier, reference may be made to the first example of the first aspect.

[0127] Step 3. Upon receiving the Nudm_SDM_Notification message of step 2, the AMF 7001 sends a UE Configuration Update Command message to the UE 3, including the re-registration request indication, segment information and / or target PLMN identifier received from the UDM 75. For details of the re-registration request instruction, please refer to the first example of the first aspect.

[0128] Step 4. When UE3 receives the UE configuration update command message from AMF7001, it sends a UE configuration update complete message to AMF7001.

[0129] Step 5. Steps 7 to 12 in FIG. 1 of the first example of the first embodiment are performed after step 4.

[0130] Variation 1 of the second example of the first aspect: When the AMF 7001 receives a Nudm_SDM_Notification message including the segment information and / or the target PLMN identifier, the AMF 7001 may verify whether the AMF 7001 itself is considered an AMF suitable for providing the unique service(s), for example, a Roaming Value Added Service (RVAS), associated with the received segment information and / or the target PLMN identifier. If so (e.g., when the AMF 7001 verifies that the AMF 7001 is considered an appropriate AMF for providing the unique service(s)), the AMF 7001 may not send a UE Configuration Update Command message to the UE 3 in step 3. That is, the AMF 7001 may terminate this procedure.

[0131] For example, the AMF 7001 may store information to determine whether the AMF 7001 itself is considered an AMF suitable for providing a unique service(s). For example, AMF 7001 may store information indicating that AMF 7001 is available for PLMN 2. If AMF 7001 receives a target PLMN identifier configured for PLMN 2 from UDM 75, AMF 7001 may consider itself to be a suitable AMF for providing the unique service(s) based on the stored information.

[0132] For example, AMF 7001 may store information indicating that AMF 7001 is included in or available for a segment set to "X." If AMF 7001 receives segment information set to "X" from UDM 75, AMF 7001 may consider itself to be a suitable AMF for providing unique service(s) based on the stored information.

[0133] Variation 2 of the second example of the first aspect: In one example, in step 2 of Figure 2, UE3 may be in idle mode, i.e., there is no signaling connection available between AMF7001 and UE3. In this case, AMF7001 may page UE3, and after establishing a signaling connection with UE3, AMF7001 may send a UE Configuration Update Command message in step 3, and the procedure continues according to steps 4 and 5 of Figure 2.

[0134] Alternatively, AMF7001 may first wait for UE3 to connect back to the network (e.g., to access a service), and then, while there is a signaling connection between UE3 and AMF7001, AMF7001 may send a UE configuration update command message to UE3, and the procedure continues according to steps 4 and 5 of Figure 2.

[0135] Third example of the first aspect: This example involves capability negotiation between NG-RAN5 and AMF7001. Figure 3: Capability negotiation between NG-RAN and AMF The detailed process of the third example of the first embodiment is described below with reference to FIG.

[0136] Steps 1a and 2a illustrate the NG-RAN initiated interface management procedure, and these steps may be independent from steps 1b and 2b.

[0137] Step 1a. The NG-RAN 5 sends an NG SETUP REQUEST message including a segment support indication to the AMF 7001. The segment support indication indicates to the AMF 7001 that the NG-RAN 5 supports the AMF (re)selection function based on segment information. The segment support indication from the NG-RAN 5 may be used by the AMF 7001 when the AMF 7001 performs the registration procedure, as disclosed in the first example of the first aspect and the second example of the first aspect in this disclosure. For example, if the AMF 7001 receives a segment support indication from the NG-RAN 5, the AMF 7001 may determine that the NG-RAN 5 supports the AMF (re)selection function based on segment information.

[0138] The segment support indication included in the NG SETUP REQUEST message may indicate that the NG-RAN 5 supports receiving segment information and / or the target PLMN identity (or the SelectedPLMN-Identity set to PLMN 2) from the UE 3. The segment support indication included in the NG SETUP REQUEST message may indicate that the NG-RAN 5 supports receiving an RRC SETUP COMPLETE message from the UE 3 including segment information and / or a target PLMN identifier (or a SelectedPLMN-Identity set to PLMN 2).

[0139] The segment support indication included in the NG SETUP REQUEST message may indicate that NG-RAN5 supports selecting an AMF (e.g., an AMF (e.g., AMF7002) in a PLMN (e.g., PLMN2) other than the PLMN of NG-RAN5 (e.g., PLMN1)) based on segment information (e.g., segment information set to "X") and / or a target PLMN identifier (or SelectedPLMN-Identity set to PLMN2). The SelectedPLMN-Identity set to PLMN2 may mean that the SelectedPLMN-Identity is set to a PLMN other than the PLMN of NG-RAN5. For example, the segment support indication in the NG SETUP REQUEST message may indicate that NG-RAN5 can understand at least one of the SelectedPLMN-Identity and segment information configured for PLMN2.

[0140] For example, the segment support indication in the NG SETUP REQUEST message may indicate that NG-RAN5 can understand at least one of the SelectedPLMN-Identity and segment information configured for PLMN2 and can select an AMF based on at least one of the SelectedPLMN-Identity and segment information configured for PLMN2.

[0141] For example, the segment support indication in the NG SETUP REQUEST message may indicate that NG-RAN5 can understand at least one of the SelectedPLMN-Identity and segment information configured for PLMN2, can select an AMF based on at least one of the SelectedPLMN-Identity and segment information configured for PLMN2, and can send an initial UE message to the selected AMF. The segment support indication included in the NG SETUP REQUEST message may indicate that the NG-RAN 5 supports or is capable of performing at least one of steps 9 to 11 in FIG.

[0142] Step 2a. When AMF7001 receives the NG SETUP REQUEST message in step 1a, it stores the segment support indication received in step 1a as the capability of NG-RAN5 and sends an NG SETUP RESPONSE message to NG-RAN5.

[0143] For example, steps 1a and 2a may be performed before the process of Figure 1. For example, steps 1a and 2a may be performed before steps 1, 2 or 4 of Figure 1.

[0144] Steps 1b and 2b illustrate an AMF initiated interface management procedure, and these steps may be independent from steps 1a and 2a.

[0145] Step 1b. AMF7001 sends an AMF CONFIGURATION UPDATE message to NG-RAN5.

[0146] Step 2b. The NG-RAN 5 sends an AMF CONFIGURATION UPDATE message including a segment support indication to the AMF 7001. For details of the segment support indication, see step 2a.

[0147] For example, if AMF7001 receives a segment support indication from NG-RAN5, AMF7001 may determine that NG-RAN5 supports the AMF (re)selection function based on segment information.

[0148] For example, steps 1b and 2b may be performed before the process of Figure 1. For example, steps 1b and 2b may be performed before steps 1, 2 or 4 of Figure 1.

[0149] Variation 1 of the third example of the first aspect: Step 1a can be replaced by a RAN CONFIGURATION UPDATE message. Similarly, step 2a can be replaced by a RAN CONFIGURATION UPDATE ACKNOWLEDGE message.

[0150] Variation 2 of the third example of the first aspect: In one example, the AMF 7001 may provide its segment support capability indication (e.g., segment support indication for the AMF 7001) to the NG-RAN 5 within the CN assistance information parameter in the N2 message.

[0151] Fourth example of the first aspect: Figure 4 includes an example of AMF (re)selection by AMF 7001 based on segment and / or PLMN identifier. Figure 4: AMF (re)selection by AMF based on segment and / or PLMN identifier The detailed process of the fourth example of the first embodiment is described below with reference to FIG.

[0152] Step 1. The registration procedure of steps 1 to 5 in FIG. 1 for the first example of the first aspect may be performed.

[0153] Step 2. When AMF 7001 receives a Nudm_SDM_Get Response message including segment information and / or target PLMN identifier from UDM 75, it performs AMF selection based on the received segment information and / or target PLMN identifier.

[0154] For example, in step 1, if AMF 7001 receives a registration request message from NG-RAN 5, AMF 7001 may send a Nudm_UECM_Registration Request message to UDM 75 in the same manner as step 2 of Figure 1. Then, upon receiving the Nudm_UECM_Registration Request message, UDM 75 may send a Nudm_UECM_Registration Response message to AMF 7001 in the same manner as step 3 of Figure 1. Then, AMF 7001 may send a Nudm_SDM_Get Request message to UDM 75 in the same manner as step 4 of Figure 1. Upon receiving the Nudm_SDM_Get Request message, UDM 75 may send a Nudm_SDM_Get Response message in the same manner as step 5 of Figure 1. When AMF7001 receives a Nudm_SDM_Get Response message including segment information and / or target PLMN identifier from UDM75, it performs AMF selection based on the received segment information and / or target PLMN identifier. For example, AMF 7001 may perform AMF selection in the same manner as the AMF selection by NG-RAN 5 in step 10 of Figure 1. For example, AMF 7001 may store information for performing AMF selection in the same manner as NG-RAN 5. For example, AMF 7001 may select or choose AMF 7002 in AMF selection.

[0155] Step 3. When AMF7001 selects AMF7002 (e.g., AMF7001 selects AMF7002 as the target AMF for AMF relocation), AMF7001 sends a Namf_Communication_NewService message to AMF7002 including a SUPI (e.g., SUPI of UE3) and a 5G-GUTI request. The 5G-GUTI request may indicate that AMF7001 requests AMF7002 to issue or allocate a 5G-GUTI for UE3. The 5G-GUTI request may indicate that AMF7001 requests AMF7002 to issue or allocate a 5G-GUTI for UE3 as indicated in the SUPI.

[0156] Step 4. When AMF7002 receives the Namf_Communication_NewService message from AMF7001, it allocates a 5G-GUTI to UE3. For example, AMF7002 allocates a 5G-GUTI to UE3 as indicated by the SUPI. AMF7002 sends a Namf_Communication_NewService response message to AMF7001 including the allocated 5G-GUTI (for example, the 5G-GUTI allocated by AMF7002).

[0157] Step 5. When the AMF 7001 receives the Namf_Communication_NewService response message from the AMF 7002, the AMF 7001 sends a registration accept message to the UE 3 including the 5G-GUTI set to the allocated 5G-GUTI and a re-registration request instruction. The re-registration request instruction indicates to the UE 3 that the UE 3 is requested to start a new registration procedure using the received 5G-GUTI. For example, the AMF 7001 may send a registration accept message including the allocated 5G-GUTI and a re-registration request instruction.

[0158] Step 6. The UE 3 initiates a registration procedure as described in 3GPP TS 23.502 [4] using the received 5G-GUTI. Because the 5G-GUTI is assigned by the AMF 7002, the registration procedure may be performed using the AMF 7002. For example, if the UE 3 receives a re-registration request instruction, the UE 3 may initiate the registration procedure using the received 5G-GUTI. For example, if the UE 3 receives a re-registration request instruction, the UE 3 may determine that a new registration procedure using the received 5G-GUTI is requested. The UE 3 may then initiate a new registration procedure using the received 5G-GUTI. For example, if the UE 3 initiates a new registration procedure using the received 5G-GUTI, the UE 3 may send a registration request message to the AMF 7002 via the NG-RAN in NG-RAN5 or PLMN2.

[0159] Variant 1 of the fourth example of the first aspect: Step 3 can be replaced with a UEContextTransfer message, a CreateUEContext message, a RelocateUEContext message, or an existing or new AMF service message. Similarly, step 4 can be replaced with a UEContextTransfer response message, a CreateUEContext response message, a RelocateUEContext response message, or an existing or new AMF service response message.

[0160] Variation 2 of the fourth example of the first aspect: Step 5 can be replaced with a registration reject message, a DL NAS transfer message, or any existing or new NAS message.

[0161] Variant 3 of the fourth example of the first aspect: In step 2, the AMF 7001 may query the NSSF, PCF, or OAM system to discover the target AMF (e.g., AMF 7002). In this case, the AMF 7001 may send a message including segment information and / or a target PLMN identifier and a user ID to the NSSF, PCF, or OAM system. In response, the NSSF, PCF, or OAM system may send a response message including information indicating the target AMF (e.g., AMF 7002). For example, at least one of the NSSF, the PCF, and the OAM system may be configured to discover the target AMF. For example, at least one of the NSSF, the PCF, and the OAM system may store information indicating AMF(s) corresponding to at least one of the segment information, the target PLMN identifier, and the user ID. Based on the stored information, at least one of the NSSF, the PCF, and the OAM system may discover the target AMF. For example, at least one of the NSSF, the PCF, and the OAM system may discover or select the target AMF in the same manner as the NG-RAN 5 in step 10 of FIG. 1.

[0162] Variant 4 of the fourth example of the first aspect: In one example, in step 3, AMF 7001 may include the requested NSSAI received from UE 3 in the registration request message in a Namf_communication_Newservice message. Upon receiving the Namf_communication_Newservice message, AMF 7002 may discover a third AMF that can handle the requested NSSAI. For example, AMF 7002 may store information for discovering the third AMF (e.g., information indicating that the requested NSSAI (e.g., S-NSSAI(s) in the requested NSSAI) can be handled by the third AMF) and may discover the third AMF based on the stored information. For example, AMF 7002 may discover the third AMF when AMF 7002 itself cannot handle the requested NSSAI (e.g., S-NSSAI(s) in the requested NSSAI). Then, in step 4, AMF7002 may pass the GUAMI of the third AMF to AMF7001. AMF7001 may include the received GUAMI in a registration accept message. For example, AMF7001 may set the received GUAMI of step 4 to the GUAMI of 5G-GUTI to be sent to UE3, and may send a registration accept message including 5G-GUTI including the received GUAMI of step 4. The third AMF may be included in PLMN2.

[0163] Upon receiving the registration accept message, the UE 3 may select a PLMN (e.g., PLMN2) using the MCC and MNC set in the received GUAMI. Furthermore, the UE 3 may include the GUAMI in an RRC setup complete message when performing the registration procedure to PLMN2. The NG-RAN 5 uses this GUAMI to select a third AMF. The registration procedure with the third AMF may then continue.

[0164] Fifth example of the first aspect: 5 includes an example of AMF (re)selection by the AMF 7001 based on segment information and / or PLMN identifier. This example can work with either UE(s) 3 that are compliant with 3GPP Release 18 or older releases. Figure 5: AMF (re)selection by AMF based on segment and / or PLMN identifier The detailed process of the fifth example of the first embodiment is described below with reference to FIG.

[0165] Step 1: The registration procedure of steps 1 to 4 in FIG. 4 of the fourth example of the first aspect is performed.

[0166] Step 2. Upon receiving the Namf_Communication_NewService response message from AMF7002, AMF7001 sends a registration accept message including 5G-GUTI to UE3.

[0167] For example, if AMF7001 receives a 5G-GUTI (e.g., a 5G-GUTI set to an assigned 5G-GUTI) from AMF7002, AMF7001 may send a registration accept message including the 5G-GUTI to UE3.

[0168] Step 3. Immediately after (or after) AMF7001 sends the registration accept message to UE3 in step 2, AMF7001 sends a deregistration request message to UE3, including a deregistration type set in the re-registration request. The deregistration type set in the re-registration request may indicate to UE3 that UE3 is requested to start a new registration procedure using the received 5G-GUTI (e.g., the 5G-GUTI sent to UE3 in step 2).

[0169] Step 4. UE3 sends a deregistration acceptance message to AMF7001. Step 5. Step 6 of FIG. 4 of the fourth example of the first embodiment is performed. For example, if UE3 receives a deregistration request message with the deregistration type set to re-registration request, UE3 may initiate the registration procedure using the received 5G-GUTI.

[0170] For example, if the UE 3 receives a deregistration request message with the deregistration type set to re-registration request, the UE 3 may determine that a new registration procedure using the received 5G-GUTI is requested, and the UE 3 may initiate a new registration procedure using the received 5G-GUTI. For example, UE 3 may use the received 5G-GUTI to perform a new registration procedure for PLMN 2. For example, UE 3 may use the received 5G-GUTI to perform a new registration procedure with AMF 7002.

[0171] Sixth Example of the First Aspect: 6 includes an example of AMF (re)selection by the AMF 7001 based on segment information and / or PLMN identifier. This example can work with either UE(s) 3 that comply with 3GPP Release 18 or older releases. Figure 6: AMF (re)selection by AMF based on segment and / or PLMN identifier The detailed process of the sixth example of the first embodiment is described below with reference to FIG.

[0172] Step 1: The registration procedure of steps 1 and 2 in FIG. 4 of the fourth example of the first aspect is performed.

[0173] Step 2. When AMF7001 selects AMF7002 (e.g., AMF7001 selects AMF7002 as the target AMF to be reassigned), AMF7001 sends a Namf_Communication_N1MessageNotify message including the NAS message received from UE3. For example, AMF7001 may instruct AMF7002 to perform a registration procedure for UE3 by sending a Namf_Communication_N1MessageNotify message. The Namf_Communication_N1MessageNotify message may include information necessary to perform the registration procedure.

[0174] Step 3. The registration procedure continues from step 4 of the registration procedure described in section 4.2.2.2.2 of 3GPP TS 23.502 [4] using AMF 7002. The registration procedure may be performed via NG-RAN 5 or an NG-RAN within PLMN 2. For example, AMF7002 may perform a registration procedure for UE3 when AMF7002 receives a Namf_Communication_N1MessageNotify message.

[0175] For example, AMF7002 may perform a registration procedure for UE3 when AMF7002 receives a Namf_Communication_N1MessageNotify message to perform a registration procedure.

[0176] Seventh example of the first aspect: 7 includes an example of SMF selection by the AMF 7001 based on segment information and / or PLMN identifier associated with the UE 3. In this example, a unique service, e.g., a Roaming Value Added Service (RVAS) associated with the received segment information and / or PLMN identifier, is provided by a PDU session established between the UE 3 and the PLMN 2. This example can work with either UE(s) 3 that are compliant with 3GPP Release 18 or older releases. Figure 7: PDU session establishment procedure with PLMN2 The detailed process of the seventh example of the first embodiment is described below with reference to FIG.

[0177] Step 1. The registration procedure of steps 1 to 5 in FIG. 1 relating to the first example of the first aspect is performed.

[0178] Step 2. When AMF7001 receives a Nudm_SDM_Get Response message including segment information and / or target PLMN identifier from UDM75, it stores the received segment information and / or target PLMN identifier in the UE context for UE3 in AMF7001.

[0179] Step 3. The AMF 7001 sends a registration acceptance message to the UE 3.

[0180] Step 4. After successfully registering with AMF 7001 in PLMN 1, UE 3 sends an UL NAS TRANSPORT message to AMF 7001, including an N1 SM container containing a PDU SESSION ESTABLISHMENT REQUEST (e.g., a PDU session establishment request message). The UL NAS TRANSPORT message may include a request type. For example, UE 3 may send the UL NAS TRANSPORT message to establish a PDU session. The UL NAS TRANSPORT message may include a PDU session establishment request message.

[0181] The request type can be set to initial request, existing PDU session, initial emergency request, existing emergency PDU session, modification request, or MA PDU request. The PDU session establishment request message is sent by the UE 3 when the UE 3 requests a Roaming Value Added Service (RVAS) associated with the target PLMN identifier and / or segment information provided by the PDU session established between the UE 3 and the PLMN 2.

[0182] The request type may be set to PDU SESSION ESTABLISHMENT REQUEST. The request type set in the PDU SESSION ESTABLISHMENT REQUEST may indicate that the AMF 7001 is requested to perform SMF selection as described in step 5 below.

[0183] The request type set to PDU SESSION ESTABLISHMENT REQUEST may indicate to AMF 7001 that SMF selection is required, as described below in step 5. The request type set to PDU SESSION ESTABLISHMENT REQUEST may indicate that UE 3 requests the establishment of a PDU session. For example, if the UE 3 sent a segment support indication in step 1, the UE 3 may send a UL NAS TRANSPORT message with the request type set to PDU SESSION ESTABLISHMENT REQUEST.

[0184] Step 5. If AMF7001 receives a UL NAS TRANSPORT message or a UL NAS TRANSPORT message with the request type set to PDU SESSION ESTABLISHMENT REQUEST, it selects SMF7102 based on the segment information and / or target PLMN identifier stored in the UE context of UE3. For example, the AMF 7001 may store information indicating the relationship between the PLMN(s) and the SMF(s).

[0185] For example, the AMF 7001 may store information indicating a relationship between a segment and an SMF(s). For example, the AMF 7001 may store information indicating a relationship between a PLMN(s), an SMF(s), and a segment. For example, the AMF 7001 may store information indicating available SMF(s) for a segment (e.g., segment "X"). For example, the AMF 7001 may store information indicating available SMF(s) in PLMN2. For example, the AMF 7001 may store information indicating SMF(s) associated with a segment (e.g., segment "X"). For example, the AMF 7001 may store information indicating SMF(s) associated with PLMN2. For example, assume that the AMF 7001 may store information indicating that PLMN2 is associated with SMF 7102 (or indicating that SMF 7102 is available in PLMN2). In this case, the AMF7001 may select or discover the SMF7102 associated with the PLMN2 indicated by the stored target PLMN identifier.

[0186] For example, assume that the AMF 7001 may store information indicating that the SMF 7102 is associated with or available for a segment set to "X". The segment set to "X" may mean segment information set to "X", or may mean that the name of the segment is "X", etc. In this case, the AMF 7001 may select or find the SMF 7102 associated with the stored segment information set to "X". For example, the AMF 7001 may use the stored segment information set to "X" to determine that the UE 3 is associated with the segment set to "X", or may select the SMF 7102 associated with the segment set to "X". The segment information set to "X" may indicate a group of subscriber(s) eligible to have a unique service(s) provided by the PLMN 2, and may indicate that the name of the group is "X". The segment set to "X" may indicate an area in which the unique service(s) are provided, and may indicate that the area name is "X". For example, it is assumed that the AMF 7001 may store information indicating that the SMF 7102 is associated with or available for use with the above-mentioned specific IMSI range "X". In this case, the AMF 7001 may select or discover the SMF 7102 associated with the stored segment information set to "X" (or associated with the IMSI range "X"). The stored segment information set to "X" may indicate the IMSI range "X". For example, it is assumed that the AMF 7001 may store information indicating that the segment set to "X" in PLMN2 is associated with the SMF 7102 (or indicating that the SMF 7102 is available for the segment set to "X" in PLMN2). In this case, the AMF 7001 may select or discover the SMF 7102 associated with the segment set to "X" in PLMN2 indicated by the stored target PLMN identifier and the stored segment information set to "X". In this case, a segment set to "X" may indicate a group of subscriber(s) who are eligible to have the unique service(s) in PLMN2, and indicate that the name of the group is "X." In this case, a segment set to "X" may indicate an area in PLMN2 in which the unique service(s) are provided, and indicate that the area name is "X." SMF7102 may be included in PLMN2. For example, AMF7001 may perform the above SMF selection for UE3 when AMF7001 receives an UL NAS TRANSPORT message from UE3. For example, when AMF7001 receives an UL NAS TRANSPORT message from UE3, AMF7001 may check the segment information and / or target PLMN identifier in the UE context for UE3 in AMF7001. Then, AMF7001 may find an appropriate SMF (e.g., SMF7102) for UE3 based on the segment information and / or target PLMN identifier in the UE context for UE3. For example, the UL NAS TRANSPORT message may include information identifying UE3. For example, when AMF7001 receives information identifying UE3, AMF7001 may check the segment information and / or target PLMN identifier in the UE context for UE3 in AMF7001.

[0187] Step 6. Once SMF 7102 is selected, AMF 7001 sends an Nsmf_PDUSession_CreateSMContext Request message to SMF 7102 in PLMN 2. For example, AMF 7001 may send an Nsmf_PDUSession_CreateSMContext Request message to establish a PDU session.

[0188] Step 7. The PDU session establishment procedure continues with step 4 of section 4.3.2.2.1 of 3GPP TS 23.502 [4] using SMF 7102 in PLMN2. For example, if SMF 7102 receives the Nsmf_PDUSession_CreateSMContext Request message, SMF 7102 may perform the PDU session establishment procedure and establish a PDU session for UE 3.

[0189] Variant 1 of the seventh example of the first aspect: If the UE 3 sends a service request message after step 3, the AMF 7001 may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF 7102. The service request procedure then continues to step 5b of section 4.2.3.2 of 3GPP TS 23.502 [4]. For example, in the same manner as step 5 of Figure 7, if AMF7001 receives a service request message from UE3 and AMF7001 selects SMF7102, AMF7001 may send an Nsmf_PDUSession_UpdateSMContext Request message to SMF7102.

[0190] Variant 2 of the seventh example of the first aspect: When UE3 is removed from segment "X", UDM75 sends an update message (e.g., a Nudm_SDM_Notification message) to AMF7001 to notify AMF7001 of the change(s) in the user profile (e.g., subscriber data for UE3). The update message may also include additional instructions for updating the user profile, such as a time lag of X seconds / minutes (e.g., "X" may be a number greater than 0). When AMF7001 receives an update message indicating removal from segment "X" (e.g., an update message indicating that UE3 has been removed from segment "X") from UDM75, if PDU session(s) associated with segment "X" are established, AMF7001 may initiate a PDU session release procedure as described in 3GPP TS 23.502 [4] for all established PDU session(s) associated with segment "X". Alternatively, UDM75 may send an update message (e.g., a Nudm_SDM_Notification message) to SMF7101 that may trigger SMF7101 to modify all PDU sessions associated with segment "X" according to the procedures described in 3GPP TS 23.502 [4].

[0191] Eighth example of the first aspect: Figure 8 includes an example of AMF addition by AMF7001 based on segment information and / or PLMN identifier for UE3. In this example, a unique service associated with the received segment information and / or PLMN identifier, such as a Roaming Value Added Service (RVAS), is provided by the PDU session established between UE3 and PLMN2. This example can work with either UE(s) 3 that are compliant with 3GPP Release 18 or older releases. Figure 8: PDU session establishment procedure with PLMN2 using AMF in PLMN1 and PLMN2 The detailed process of the eighth example of the first embodiment is described below with reference to FIG.

[0192] Step 1. Steps 1 to 4 of FIG. 7 relating to the seventh example of the first embodiment are performed.

[0193] Step 2. When AMF7001 receives a UL NAS TRANSPORT message or a UL NAS TRANSPORT message with the request type set to PDU SESSION ESTABLISHMENT REQUEST, it selects AMF7002 based on the segment information and / or target PLMN identifier stored in the UE context of UE3. For example, AMF 7001 may perform AMF selection in the same manner as step 2 of Figure 4. For example, AMF7001 may select AMF7002 in the same manner as step 2 of FIG.

[0194] Step 3. The AMF 7001 sends a Namf_Communication_N1MessageNotify message including AS information and a generic NAS message container to the selected AMF 7002. The generic NAS message container encapsulates the NAS message received from the UE 3. For example, the generic NAS message container may encapsulate the NAS message received from the UE 3 in at least one of step 1 of Figure 1 and step 4 of Figure 7.

[0195] For example, the generic NAS message container may contain at least one content or information of a NAS message received from UE 3 in at least one of step 1 of FIG. 1 and step 4 of FIG.

[0196] The NAS message in step 1 of Fig. 1 may be a registration request message. The NAS message in step 4 of Fig. 7 may be a UL NAS TRANSPORT message. The Namf_Communication_N1MessageNotify message may include information or message(s) related to the PDU session (e.g., a PDU session establishment request message). The generic NAS message container may include information or message(s) related to the PDU session (e.g., a PDU session establishment request message). For example, AMF7001 may send a Namf_Communication_N1MessageNotify message to establish a PDU session.

[0197] Step 4. Upon receiving the Namf_Communication_N1MessageNotify message from AMF 7001, AMF 7002 sends an Nsmf_PDUSession_CreateSMContext Request message to SMF 7102 in PLMN 2. For example, AMF 7002 may send an Nsmf_PDUSession_CreateSMContext Request message in the same manner as step 6 in Figure 7.

[0198] Step 5. The PDU session establishment procedure continues with step 4 of section 4.3.2.2.1 of 3GPP TS 23.502 [4] using the SMF 7102 in PLMN2. For example, the AMF 7002 may perform the PDU session establishment procedure in the same manner as step 7 in Figure 7. For example, in step 5, the following step 5a may be performed.

[0199] Step 5a includes the process of how AMF7001 in PLMN1 and AMF7002 in PLMN2 communicate during the PDU session establishment procedure. -When AMF7001 receives a NAS message related to a PDU session from UE3 (for example, when AMF7001 receives a NAS message related to a PDU session from UE3 (for example, the NAS message mentioned in step 3), or when AMF7001 receives a NAS message mentioned in at least one of step 1 of Figure 1 and step 4 of Figure 7 from UE3), AMF7001 sends a Namf_Communication_N1MessageNotify message including AS information and a generic NAS message container to AMF7002. The generic NAS message container sent by AMF7001 encapsulates the NAS message received from UE3. -When AMF7002 receives any Nsmf service message or Namf service message from SMF7102 including an N1 SM container intended to be sent to UE3, AMF7002 sends a Namf_Communication_N1MessageNotify message including AS information and a generic NAS message container to AMF7001. The generic NAS message container sent by AMF7002 includes the N1 SM container received from SMF7102.

[0200] Variant 1 of the eighth example of the first aspect: When UE3 sends a service request message after step 5, the receiving NAS message handling and receiving N1 SM container handling between AMF7001 and AMF7002 are the same as the message handling described in step 5a.

[0201] According to at least one of the first aspect and the variant of the first aspect, it is possible to solve the above-mentioned problem. For example, according to the latest 3GPP mobility management function, at least one of the first aspect and the variant of the first aspect can solve the problem that an AMF in an HPLMN of a UE cannot be relocated to another AMF from a PLMN different from the HPLMN of the UE. For example, according to at least one of the first aspect and the variant of the first aspect, it is possible to solve the problem that the latest 3GPP specification(s) may not satisfy new service requirements. For example, according to at least one of the first aspect and the variant of the first aspect, NG-RAN 5 in PLMN 1 or AMF 7001 in PLMN 1 can select AMF 7002 in PLMN 2 different from AMF 7001 in PLMN 1 (e.g., HPLMN of UE 3) based on segment information and / or a target PLMN identifier. That is, AMF 7001 in PLMN 1 (corresponding to an AMF in the HPLMN) can be relocated to AMF 7002 in PLMN 2 (corresponding to another AMF from a PLMN different from the HPLMN). Also, for example, UE 3 can perform a registration procedure with AMF 7002. Therefore, the above problem can be solved.

[0202] For example, according to at least one of the first aspect and the modified example of the first aspect, the AMF 7001 in the PLMN 1 can select the AMF 7002 in the PLMN 2 or the SMF 7102 in the PLMN 2, and can communicate with the AMF 7002 or the SMF 7102 to establish a PDU session(s) (e.g., a PDU session(s) for RVAS). Thus, the above-mentioned problem can be solved.

[0203] Second Aspect For example, this disclosure focuses on the following limitations as operational issues in the latest 3GPP mobility management functionality: Due to these limitations, for example, the latest 3GPP specification(s) may not meet new service requirements. For example, a UE may not be able to continue camping on a PLMN that is different from the UE's HPLMN. Therefore, there is a need to improve the latest 3GPP mobility management functionality. Operational Issues: According to the latest 3GPP mobility management functionality, a UE must stay in a cell that broadcasts the PLMN identifier of the HPLMN as long as the UE has access to that cell. That is, (1) the UE must stay in a cell that broadcasts the PLMN identifier of the HPLMN, and (2) when the UE is in a cell that does not broadcast the PLMN identifier of the HPLMN, the UE must return to a cell that broadcasts the PLMN identifier of the HPLMN. This aspect includes a mechanism for UE3 to stay in a cell of a PLMN other than UE3's HPLMN while UE3 can listen to broadcast messages from other cell(s) that broadcast the PLMN identifier of UE3's HPLMN.

[0204] For example, this aspect includes a mechanism that can solve the above-mentioned problems.

[0205] First example of the second aspect: Figure 9 includes an example of UE behavior for staying in a cell(s) that broadcasts a PLMN identifier other than the PLMN identifier of UE3's HPLMN based on a target PLMN identifier from AMF7001 associated with UE3. Figure 9: The UE retains a cell in PLMN2 by stopping timer T

[0206] A detailed process of a first example of the second aspect is described below with reference to Figure 9. For example, the NG-RAN 501 in PLMN1 may be the same as the NG-RAN 5 in Figure 1 and may have the same function(s).

[0207] Step 1. Steps 1 to 5 of Fig. 1 for the first example of the first aspect may be performed. For example, processing may be performed for UE 3, NG-RAN 502 in PLMN 2, AMF 7002 in PLMN 2, and UDM 75 in PLMN 1 (or UDM in PLMN 2) in the same manner as steps 1 to 5 of Fig. 1 for the first example of the first aspect.

[0208] For example, UE 3 may send a registration request message to AMF 7002 in the same manner as in step 1 of Figure 1. The content of the registration request message sent to AMF 7002 may be the same as the content of the registration request message in step 1 of Figure 1.

[0209] For example, when the AMF 7002 receives a registration request message from the UE 3, it may send a Nudm_UECM_Registration Request message to the UDM 75 in the same manner as step 2 of FIG.

[0210] For example, when AMF 7002 receives a registration request message from UE 3, it may send a Nudm_UECM_Registration Request message to a UDM in PLMN 2 in the same manner as in step 2 of Figure 1. The content of the Nudm_UECM_Registration Request message sent to UDM 75 or a UDM in PLMN 2 may be the same as the content of the Nudm_UECM_Registration Request message in step 2 of Figure 1. For example, UDM 75 may store not only information about PLMN 1 (e.g., subscriber data for UE(s) in PLMN 1) but also information about PLMN 2 (e.g., subscriber data for UE(s) in PLMN 2). AMF 7002 may send a Nudm_UECM_Registration Request message to UDM 75 if UDM 75 stores not only information about PLMN 1 (e.g., subscriber data for UE(s) in PLMN 1) but also information about PLMN 2 (e.g., subscriber data for UE(s) in PLMN 2). For example, UDM 75 may be commonly used by both node(s) in PLMN 1 and node(s) in PLMN 2. For example, UDM 75 may store at least one of information about PLMN 1 (e.g., subscriber data for UE(s) in PLMN 1) and information about PLMN 2 (e.g., subscriber data for UE(s) in PLMN 2). For example, the UDM in PLMN2 may store at least one of information about PLMN1 (e.g., subscriber data for UE(s) in PLMN1) and information about PLMN2 (e.g., subscriber data for UE(s) in PLMN2). For example, upon receiving the Nudm_UECM_Registration Request message, UDM75 or the UDM in PLMN2 may send a Nudm_UECM_Registration Response message to AMF7002 in the same manner as in step 3 of Figure 1. For example, AMF7002 may send a Nudm_SDM_Get Request message including a segment support indication to UDM75 or the UDM in PLMN2 if at least one of UE3, NG-RAN502, and AMF7002 supports the AMF (re)selection function based on segment information in the same manner as in step 4 of Figure 1. The content of the Nudm_SDM_Get Request message sent to UDM 75 or a UDM in PLMN 2 may be the same as the content of the Nudm_SDM_Get Request message in step 4 of FIG. The segment support indication included in the Nudm_SDM_Get Request message may indicate that at least one of the UE 3, the NG-RAN 502, and the AMF 7002 supports the AMF (re)selection function based on segment information. For example, the AMF 7002 may determine that the UE 3 supports the AMF (re)selection function based on segment information in the same manner as in the first aspect. For example, the AMF 7002 may determine whether the NG-RAN 502 supports the AMF (re)selection function based on segment information in the same manner as in the first aspect. For example, the AMF 7002 may determine that the AMF 7002 itself supports the AMF (re)selection function based on segment information in the same manner as in the first aspect.

[0211] For example, upon receiving the Nudm_SDM_Get Request message, UDM 75 or a UDM in PLMN 2 may send a Nudm_SDM_Get Response message to AMF 7002 in the same manner as in step 5 of Figure 1. The content of the Nudm_SDM_Get Response message sent to AMF 7002 may be the same as the content of the Nudm_SDM_Get Response message in step 5 of Figure 1.

[0212] The processes performed by AMF7001 in steps 1 to 5 of FIG. 1 may be replaced with the processes performed by AMF7002 in the second embodiment, respectively. The processes performed by UDM 75 in steps 2 to 5 of FIG. 1 may be replaced with the processes performed by UDM 75 in the second embodiment or the UDM in PLMN 2, respectively.

[0213] Information about the AMF 7001 communicated between the AMF 7001 and the UDM 75 in steps 2 to 5 of Fig. 1 may be replaced with information about the AMF 7002 in the second aspect. Information about the AMF 7002 may be communicated between the AMF 7002 and the UDM 75 (or a UDM in PLMN2). Information about the message(s) and node (e.g., AMF(s), NG-RAN(s), UDM(s), UE(s)) in the first aspect may be replaced with information about the message(s) and node (e.g., AMF(s), NG-RAN(s), UDM(s), UE(s)) in the second aspect.

[0214] Step 2. The AMF 7002 sends a registration accept message to the UE 3, including a timer T stop instruction, segment information, and / or a target PLMN identifier. The timer T stop instruction indicates to the UE 3 that the UE 3 can stop timer T as long as the UE 3 is within the PLMN indicated by the target PLMN identifier. Timer T is defined in section 4.4.3.3.1.1 of 3GPP TS 23.122 [7]. For example, the segment information may be set to "X" and the target PLMN identifier may be set to PLMN2. For example, if timer T expires, the UE 3 may attempt to select a HPLMN (e.g., PLMN1) or may attempt to return to the HPLMN (e.g., PLMN1). For example, if timer T expires, the UE 3 may attempt to acquire service(s) on the HPLMN (e.g., PLMN1).

[0215] For example, if AMF7002 receives a Nudm_SDM_Get Response message, AMF7002 may send a registration acceptance message. The segment information in the second aspect may be the same as the segment information in the first aspect. The definition of the segment information in the first aspect may be applied to the second aspect.

[0216] The target PLMN identifier in the second aspect may be the same as the target PLMN identifier in the first aspect. The definition of the target PLMN identifier in the first aspect may also be applied to the second aspect. For example, the target PLMN identifier may be set to PLMN2. For example, the timer T stop indication may indicate to the UE 3 that the timer T is forced to be stopped as long as the UE 3 is in the PLMN 2 indicated by the target PLMN identifier. For example, if the registration accept message includes a target PLMN identifier set to PLMN2 and a timer T stop instruction, the timer T stop instruction may indicate to UE3 that UE3 should be forced to stop timer T as long as UE3 is in PLMN2 indicated by the target PLMN identifier.

[0217] Step 3a. Cell(s) connected to NG-RAN 501 broadcast their PLMN identifiers configured for PLMN1. Note that the broadcasting message in step 3a may always be broadcast by cell(s) connected to NG-RAN 501. The PLMN identifiers may be broadcast via BCCH (e.g., SIB1). For example, the PLMN identifier configured for PLMN1 may be included in SIB1. For example, NG-RAN 501 may broadcast SIB1. For example, NG-RAN 501 may broadcast SIB1 on cell(s) connected to NG-RAN 501. For example, if UE3 receives or scans the PLMN identifier configured for PLMN1, UE3 may determine or consider that UE3 is camped on PLMN1 (or that UE3 is camped on a cell(s) of PLMN1).

[0218] Step 3b. Cell(s) connected to NG-RAN 502 broadcast their PLMN identifiers configured for PLMN2. Note that the broadcasting message in step 3b may be constantly broadcast by cell(s) connected to NG-RAN 502. For example, the PLMN identifier configured for PLMN2 may be included in SIB1. For example, NG-RAN 502 may broadcast SIB1. For example, NG-RAN 502 may broadcast SIB1 on cell(s) connected to NG-RAN 502. For example, if UE3 receives or scans for a PLMN identifier configured for PLMN2, UE3 may determine or consider that UE3 is camped on PLMN2 (or that UE3 is camped on a cell(s) of PLMN2).

[0219] Step 4. UE3 stops timer T as long as UE3 is camped in the cell(s) of PLMN2. Stopping timer T prevents UE3 from moving to other cell(s) of other PLMNs, including the cell(s) for PLMN1, so that UE3 can stay in the cell(s) for PLMN2.

[0220] Stopping timer T can be interpreted as one of the following: The UE 3 stops the timer T. For example, if the timer T is running, the UE 3 may stop the timer T and stay in the PLMN 2. The UE 3 ignores the expiration of the timer T. For example, the UE 3 may ignore the expiration of the timer T and may stay in the PLMN 2 even if the timer T expires. The UE 3 overrides the timer T of the UE 3's SIM (or USIM) without periodic attempts. For example, the UE 3 may stop the timer T or may disable the function of the timer T. The UE 3 may also configure the function of the timer T so that the UE 3 does not periodically attempt to return to the HPLMN (e.g., PLMN1).

[0221] For example, the timer T stop instruction may instruct or indicate to the UE 3 to at least one of stop the timer T, ignore the expiration of the timer T, and override the timer T.

[0222] For example, the timer T stop instruction may instruct or indicate to UE3 to stay in PLMN2 (e.g., a cell(s) within PLMN2) by at least one of stopping timer T, ignoring the expiration of timer T, and overriding timer T. For example, the timer T stop indication may instruct or indicate to UE 3 to camp on PLMN2 (eg, cell(s) within PLMN2).

[0223] For example, the timer T stop indication may instruct or indicate to UE 3 to camp on the PLMN indicated by the target PLMN identifier (eg, PLMN 2). For example, the timer T stop indication may instruct or indicate to UE3 to camp on a cell(s) of the PLMN indicated by the target PLMN identifier (eg, a cell(s) in PLMN2). For example, if UE3 stops timer T, ignores the expiration of timer T, and / or overrides timer T, UE3 may stay in a cell(s) of PLMN2 (or UE3 may stay in a cell(s) of PLMN2, or UE3 may continue to stay in a cell(s) of PLMN2). The cell(s) for PLMN1 may be represented as the cell(s) connected to NG-RAN501. The cell(s) for PLMN2 may be referred to as the cell(s) connected to NG-RAN 502. For example, if UE3 receives (or listens to) a broadcast PLMN identifier configured for PLMN1, UE3 may determine that UE3 is camped in a cell(s) of PLMN1. For example, if UE3 receives (or listens to) a broadcast PLMN identifier configured for PLMN2, UE3 may determine that UE3 is camped in a cell(s) of PLMN2. For example, if UE3 receives (or listens to) both a broadcast PLMN identifier configured for PLMN1 and a broadcast PLMN identifier configured for PLMN2, UE3 may determine that UE3 is camped in both a cell(s) of PLMN1 and a cell(s) of PLMN2. For example, if UE3 receives a broadcast PLMN identifier configured for PLMN2, UE3 may camp in a cell(s) for PLMN2 (or UE3 can camp in a cell(s) for PLMN2, or UE3 may continue to camp in a cell(s) for PLMN2).

[0224] For example, if UE3 receives a registration accept message including a target PLMN identifier set to PLMN2 and a timer T stop indication, and UE3 receives a broadcasted PLMN identifier set to PLMN2, then UE3 may camp on the cell(s) for PLMN2 (or UE3 may camp on the cell(s) for PLMN2, or UE3 may continue to camp on the cell(s) for PLMN2).

[0225] For example, if UE3 receives a registration accept message including a target PLMN identifier set to PLMN2 and a timer T stop instruction, and UE3 receives a broadcasted PLMN identifier set to PLMN2, UE3 may stop timer T (or ignore the expiration of timer T or override timer T) and may camp on the cell(s) for PLMN2 (or UE3 may camp on the cell(s) for PLMN2, or UE3 may continue to camp on the cell(s) for PLMN2).

[0226] For example, if UE3 receives a registration accept message including a target PLMN identifier set to PLMN2 and a timer T stop instruction, and UE3 receives a broadcasted PLMN identifier set to PLMN2, then even if UE3 receives (or listens to) the broadcasted PLMN identifier set to PLMN1, it may stop timer T (or ignore the expiration (or revocation) of timer T or override timer T) and may camp on the cell(s) for PLMN2 (or UE3 may camp on the cell(s) for PLMN2, or UE3 may continue camping on the cell(s) for PLMN2). If UE3 cannot find a cell broadcasting the PLMN identifier configured for PLMN2 (e.g., UE3 cannot find a cell broadcasting the PLMN identifier configured for the target PLMN identifier received in the registration accept message of step 2, or UE3 cannot receive the PLMN identifier configured for the target PLMN identifier received in the registration accept message of step 2), UE3 removes (or deletes) the timer T stop indication and uses the value of timer T in the SIM (or USIM). UE3 may then start timer T set to that value.

[0227] If UE3 tunes to a cell that does not broadcast the PLMN identifier configured in PLMN2 (e.g., the PLMN identifier configured in the target PLMN identifier received in the registration accept message in step 2), UE3 may remove the timer T stop indication and use the value of timer T in the SIM (or USIM). UE3 may then start timer T set to that value.

[0228] For example, if UE3 receives a target PLMN identifier set to PLMN2, even if UE3 is also located in PLMN1 (e.g., even if UE3 is able to receive a PLMN identifier set to PLMN1), UE3 may determine that UE3 continues to reside in PLMN2.

[0229] Variation 1 of the first example of the second aspect: In step 2, the timer T stop indication can be replaced with another value. For example, timer T may be set in one-day increments ranging from 1 day to 40 days. Longer periodic network selection attempts may reconfirm the network configuration by UE 3 while UE 3 is in PLMN 2, i.e., outside the HPLMN.

[0230] Second example of the second aspect: FIG. 10 includes an example of UE behavior for camping in a cell(s) that broadcasts a PLMN identifier other than the PLMN identifier of UE3's HPLMN based on the RVAS PLMN list. Figure 10: UE holds cells in PLMN2 with RVAS PLMN list A detailed process of the second example of the second embodiment is described below with reference to FIG.

[0231] Step 1. Steps 1 to 4 in Fig. 1 for the first example of the first aspect may be performed. For example, UE 3 may send a registration request message to AMF 7002 in PLMN 2 in the same manner as in step 1 in Fig. 1. The content of the registration request message sent to AMF 7002 may be the same as the content of the registration request message in step 1 in Fig. 1.

[0232] For example, when AMF 7002 receives a registration request message from UE 3, it may send a Nudm_UECM_Registration Request message to UDM 75 in the same manner as in step 2 of Figure 1. For example, when AMF 7002 receives a registration request message from UE 3, it may send a Nudm_UECM_Registration Request message to UDM 75 in the same manner as in step 2 of Figure 1. The content of the Nudm_UECM_Registration Request message sent to UDM 75 or a UDM in PLMN2 may be the same as the content of the Nudm_UECM_Registration Request message in step 2 of Figure 1. For example, UDM 75 may store not only information about PLMN1 (e.g., subscriber data for UE(s) in PLMN1) but also information about PLMN2 (e.g., subscriber data for UE(s) in PLMN2). AMF 7002 may send the Nudm_UECM_Registration Request message to UDM 75 if UDM 75 stores not only information about PLMN1 (e.g., subscriber data for UE(s) in PLMN1) but also information about PLMN2 (e.g., subscriber data for UE(s) in PLMN2). For example, UDM 75 may be commonly used by both node(s) in PLMN1 and node(s) in PLMN2. For example, UDM75 may store at least one of information about PLMN1 (e.g., subscriber data for UE(s) in PLMN1) and information about PLMN2 (e.g., subscriber data for UE(s) in PLMN2). For example, the UDM in PLMN2 may store at least one of information about PLMN1 (e.g., subscriber data for UE(s) in PLMN1) and information about PLMN2 (e.g., subscriber data for UE(s) in PLMN2).

[0233] For example, upon receiving the Nudm_UECM_Registration Request message, UDM75 or a UDM in PLMN2 may send a Nudm_UECM_Registration Response message to AMF7002 in the same manner as step 3 of FIG.

[0234] For example, in the same manner as step 4 of Figure 1, AMF7002 may send a Nudm_SDM_Get Request message including a segment support indication to UDM75 or a UDM in PLMN2 if at least one of UE3, NG-RAN502 and AMF7002 supports an AMF (re)selection function based on segment information.

[0235] The content of the Nudm_SDM_Get Request message sent to UDM 75 or a UDM in PLMN 2 may be the same as the content of the Nudm_SDM_Get Request message in step 4 of FIG.

[0236] The segment support indication included in the Nudm_SDM_Get Request message may indicate that at least one of the UE3, NG-RAN502 and AMF7002 supports the AMF (re)selection function based on segment information.

[0237] For example, AMF7002 may determine that UE3 supports the AMF (re)selection function based on segment information in the same manner as in the first aspect.

[0238] For example, the AMF 7002 may determine whether the NG-RAN 502 supports the AMF (re)selection function based on segment information in the same manner as the first aspect. For example, the AMF 7002 may determine that the AMF 7002 itself supports the AMF (re)selection function based on segment information in the same manner as the first aspect. For example, step 1 of the first example of the second aspect may be performed without transmitting a Nudm_SDM_Get Response message.

[0239] Step 2. The UDM 75 sends a Nudm_SDM_Get Response message including subscriber data. The subscriber data in the Nudm_SDM_Get Response message includes an RVAS PLMN list, segment information, and / or a target PLMN identifier. The segment information may be the same as in the first aspect. The target PLMN identifier may be the same as in the first aspect. The RVAS PLMN list indicates a preferred PLMN list for the UE 3 taking RVAS into consideration. The RVAS PLMN list may indicate preferred PLMN(s) for the UE 3 taking RVAS into consideration. The RVAS PLMN list may include PLMN(s) selected by the UE 3 taking RVAS into consideration. The RVAS PLMN list may include PLMN(s) associated with the RVAS. For example, the RVAS PLMN list may include PLMN2. When the UE 3 receives the RVAS PLMN list, the UE 3 may take one of the following actions: The RVAS PLMN list takes priority over the HPLMN list, the EHPLMN list, the preferred PLMN list, the forbidden PLMN list, and the network slice-based PLMN list. For example, the UE 3 may use the RVAS PLMN list in priority to at least one of the EHPLMN list, the preferred PLMN list, the forbidden PLMN list, and the network slice-based PLMN list. The RVAS PLMN list takes priority over the preferred PLMN list, the forbidden PLMN list, and the network slice-based PLMN list. For example, the UE 3 may use the RVAS PLMN list in priority over at least one of the preferred PLMN list, the forbidden PLMN list, and the network slice-based PLMN list. The RVAS PLMN list takes priority over the preferred PLMN list and the network slice-based PLMN list. For example, the UE 3 may use the RVAS PLMN list in priority over at least one of the preferred PLMN list and the network slice-based PLMN list. The RVAS PLMN list takes priority over the preferred PLMN list and the forbidden PLMN list. For example, the UE 3 may use the RVAS PLMN list in priority over at least one of the preferred PLMN list and the forbidden PLMN list. For details of the segment information and target PLMN identifier, see step 5 of FIG.

[0240] 10, as an example, segment information set to "X" is shown as segment=X, and the target PLMN identifier set to PLMN2 is shown as PLMN identifier=PLMN2. For example, the segment information may be set to "X", and the target PLMN identifier may be set to PLMN2.

[0241] Step 3. The AMF 7002 sends a registration accept message including the RVAS PLMN list to the UE 3. How the UE 3 uses the RVAS PLMN list may refer to step 2. The registration accept message may include segment information and / or a target PLMN identifier.

[0242] Step 4a. Cell(s) connected to NG-RAN 501 broadcast their PLMN identifier set to PLMN1. For example, NG-RAN 501 may broadcast or transmit the PLMN identifier set to PLMN1. Note that a broadcasting message such as shown in step 3a may always be broadcast by cell(s) connected to NG-RAN 501.

[0243] Step 4b. The cell connected to NG-RAN 502 broadcasts its configured PLMN identifier to PLMN2. For example, NG-RAN 502 may broadcast or transmit the configured PLMN identifier to PLMN2. Note that the broadcasting message as shown in step 3b may be constantly broadcast by the cell(s) connected to NG-RAN 502.

[0244] Step 5. The NAS unit of UE3 forwards the received RVAS PLMN list to the AS unit of UE3. UE3 camps on a cell(s) of PLMN2 if, according to the RVAS PLMN list, PLMN2 is listed as the highest priority or a higher priority than any PLMN that UE3 can scan. For example, if PLMN2 is listed in the RVAS PLMN list, UE3 may camp on a cell(s) of PLMN2. For example, UE3 may camp on a cell(s) of PLMN2 if PLMN2 is listed in the RVAS PLMN list and / or if UE3 receives a PLMN identifier configured for PLMN2 even if UE3 is in PLMN1 (e.g., even if UE3 receives a PLMN identifier configured for PLMN1 and / or even if PLMN1 is listed in the above PLMN list other than the RVAS PLMN list).

[0245] Third example of the second aspect: FIG. 11 includes an example of UE behavior for camping in a cell(s) that broadcasts a PLMN identifier other than the PLMN identifier of UE3's HPLMN by scanning only the frequency band(s) indicated by the RRC message. Figure 11: UE reserves cells in PLMN2 with limited ARFCN scanning

[0246] The detailed process of the third example of the second embodiment is described below with reference to FIG.

[0247] Step 1. Steps 1 to 4 in Fig. 1 for the first example of the first embodiment may be performed. Alternatively, step 1 in Fig. 10 for the second example of the second embodiment may be performed.

[0248] Step 2. UDM 75 (or a UDM in PLMN 2) sends a Nudm_SDM_Get Response message with subscriber data. The subscriber data in the Nudm_SDM_Get Response message includes segment information and an RFSP index. The RFSP index is used for a specific RRM strategy, taking into account any available information in the RAN(s) related to the segment information. The RFSP index is mapped to a configuration defined locally by the RAN(s) to derive UE-specific cell reselection priorities for controlling idle mode camping and deciding to redirect active mode UE(s) to a different frequency layer or RAT(s). The RFSP index may be associated with segment information. The RFSP index may be associated with an ARFCN. For details about segment information, see step 5 of Figure 1.

[0249] 11, as an example, segment information set to "X" is shown as segment=X. For example, the segment information may be set to "X".

[0250] Step 3. The AMF 7002 sends an INITIAL CONTEXT SETUP REQUEST message to the NG-RAN 502, including a NAS PDU and target segment information. The NAS PDU includes a registration accept message. The registration accept message includes segment information set to "X". The target segment information includes a combination of the segment information set to "X" and an RFSP index. In one example, the segment information may be associated with multiple RFSP indices.

[0251] Step 4. NG-RAN 502 sends a DLInformationTransfer message to UE 3, including a dedicatedNAS-Message and a CarrierInfo segment. The dedicatedNAS-Message includes a registration accept message. The registration accept message includes segment information set to "X". The CarrierInfo segment includes a combination of segment information set to "X" and an ARFCN. In one example, the segment information may be associated with multiple ARFCNs.

[0252] For example, the NG-RAN 502 may convert the received RFSP index to an ARFCN. For example, the NG-RAN 502 may store information for performing this conversion. For example, the NG-RAN 502 may store information indicating a mapping between the RFSP index and the ARFCN. For example, based on the stored information, the NG-RAN 502 may convert the received RFSP index to an ARFCN.

[0253] For example, the CarrierInfo segment may contain only the ARFCN(s), in which case the UE 3 can associate the CarrierInfo segment received in an RRC message (e.g., a DLInformationTransfer message) with the segment information received separately in a NAS message (e.g., a Registration Accept message).

[0254] Step 5. When UE3 receives the CarrierInfo segment containing the segment information and ARFCN, it scans or background scans only the frequency band(s) indicated by the ARFCN in the RRC message (e.g., DLInformationTransfer message) as long as UE3 is subscribed to segment=X (e.g., segment set to "X"). For example, the UE 3 may only scan or background scan the frequency band(s) indicated by the ARFCN.

[0255] For example, UE3 may determine that UE3 is subscribed to the segment set to "X" based on information in the SIM (or USIM) of UE3. For example, the SIM (or USIM) may include information indicating that UE3 is subscribed to a segment. For example, if UE3 determines that there is information in the SIM (or USIM) indicating that UE3 is subscribed to a segment, UE3 may determine that UE3 is subscribed to the segment set to "X".

[0256] For example, if UE3 receives segment information set to "X" from NG-RAN 502, UE3 may determine that UE3 is subscribed to the segment set to "X." For example, if UE3 receives a DLInformationTransfer message including segment information set to "X," UE3 may determine that UE3 is subscribed to the segment set to "X." For example, if UE3 receives a registration accept message including segment information set to "X" and a DLInformationTransfer message including at least one CarrierInfo segment including segment information set to "X", UE3 may determine that UE3 is subscribed to the segment set to "X".

[0257] For example, if UE3 is subscribed to a segment set to "X", UE3 may only scan or background scan the frequency band(s) indicated by the ARFCN in the RRC message (e.g., DLInformationTransfer message).

[0258] For example, if UE3 determines that UE3 is subscribed to a segment set to "X", UE3 may scan or background scan only the frequency band(s) indicated by the ARFCN in the RRC message (e.g., DLInformationTransfer message). For example, UE3 may scan only the frequency band(s) indicated by the ARFCN, thus reducing the power consumption of UE3.

[0259] If UE3 receives (or listens to) a broadcasted PLMN identifier configured for PLMN2 in the frequency band(s) indicated by ARFCN, UE3 may determine that UE3 is present in a cell(s) of PLMN2, may stay in a cell(s) of PLMN2, and may stop timer T, in the same manner as in the first example of the second aspect. This mechanism may also be applied to the second example of the second aspect. For example, in the second example of the second aspect, UE3 may receive (or listen to) a broadcasted PLMN identifier configured for PLMN2 on the frequency band(s) indicated by ARFCN.

[0260] Variation 1 of the third example of the second aspect: In step 4, the DLInformationTransfer message can be replaced with an RRC Setup message, an RRCReject message, an RRCRelease message, an RRCResume message, an RRCReconfiguration message, an RRCReestablishment message, or any existing or new RRC message.

[0261] Fourth example of the second aspect: FIG. 12 includes an example of UE behavior for camping in a cell(s) that broadcasts a PLMN identifier other than the PLMN identifier of UE3's HPLMN based on segment information or PLMN identifier and associated frequency band information broadcast by the cell(s). Figure 12: UE reserves cells in PLMN2 with limited ARFCN scanning The detailed process of the fourth example of the second embodiment is described below with reference to FIG.

[0262] Step 1. Steps 1 to 5 of Fig. 1 for the first example of the first embodiment may be performed. Alternatively, step 1 of Fig. 9 for the first example of the second embodiment may be performed.

[0263] Step 2. The AMF 7002 sends a registration accept message to the UE 3, including segment information and / or a target PLMN identifier. For details of the segment information and the target PLMN identifier, see step 5 of FIG. 1. For example, the target PLMN identifier may indicate a PLMN on which the UE 3 needs to camp. For example, a target PLMN identifier set to PLMN2 may indicate that the UE 3 needs to camp on PLMN2. For example, the target PLMN identifier may indicate that the UE 3 needs to camp on a cell(s) in the PLMN indicated by the target PLMN identifier. For example, a target PLMN identifier set to PLMN2 may indicate that the UE 3 needs to camp on a cell(s) of PLMN2.

[0264] Step 3a. The cell(s) connected to NG-RAN 501 broadcast their PLMN identifier set to PLMN1, as well as a list of segment information (e.g., segment "X"), target PLMN identifier, and ARFCN combinations (e.g., a list including segment information set to "X", target PLMN identifier, and ARFCN combination(s)).

[0265] The list may be a list of combinations of segment information and ARFCN (e.g., a list including combination(s) of segment information and ARFCN set to "X") The list may be a list of combination(s) of target PLMN identifier and ARFCN (e.g., a list including combination(s) of target PLMN identifier and ARFCN).

[0266] It should be noted that the broadcasting message in step 3a may be continuously broadcast by a cell(s) connected to the NG-RAN 501. At least one of the PLMN identifier and the list may be broadcast via the BCCH (e.g., SIB1). For example, at least one of the PLMN identifier and the list configured for the PLMN1 may be included in the SIB1. For example, the NG-RAN 501 may broadcast the SIB1. For example, the NG-RAN 501 may broadcast the SIB1 on a cell(s) connected to the NG-RAN 501.

[0267] For example, the AMF 7001 may transmit the segment information and the RFSP index to the NG-RAN 501 in the same manner as in step 3 of FIG. 11. The AMF 7001 may also transmit the target PLMN identifier received from the UDM 75 to the NG-RAN 501. For example, the NG-RAN 501 may convert the received RFSP index to an ARFCN in the same manner as in step 4 of FIG. 11. The NG-RAN 501 may then create a list based on the received segment information, target PLMN identifier, and ARFCN. For example, the NG-RAN 501 may associate and combine the segment information set to "X," the target PLMN identifier, and the ARFCN, and include the combination in the list. For example, if the NG-RAN 501 receives the segment information, the target PLMN identifier, and the RFSP index in one message (e.g., an INITIAL CONTEXT SETUP REQUEST message), the NG-RAN 501 may determine that these received parameters are associated with each other. The NG-RAN 501 may then convert the RFSP index to an ARFCN and create a combination of the received segment information, the received target PLMN identifier, and the ARFCN converted from the received RFSP index.

[0268] For example, when the AMF 7001 transmits segment information, a target PLMN identifier, and an RFSP index to the NG-RAN 501, the NG-RAN 501 may transmit a list including the combination(s) of the segment information, the target PLMN identifier, and the ARFCN. In this case, the NG-RAN 501 may convert the RFSP index in the received list to an ARFCN and create a list including the combination(s) of the segment information, the target PLMN identifier, and the ARFCN.

[0269] Step 3b. The cell(s) connected to NG-RAN 502 broadcast their PLMN identifier set to PLMN2 and a list of segment information (e.g., segment "X"), target PLMN identifier, and ARFCN combinations (e.g., a list including segment information set to "X", target PLMN identifier, and ARFCN combination(s)). The list may be a list of combinations of segment "X" and ARFCN (e.g., a list including combination(s) of segment information set to "X" and ARFCN). The list may be a list of combinations of target PLMN identifiers and ARFCN (e.g., a list including combination(s) of target PLMN identifiers and ARFCN). It should be noted that the broadcasting message in step 3b may always be broadcast by cell(s) connected to NG-RAN 502. At least one of the PLMN identifier and the list may be broadcast via BCCH (e.g., SIB1). For example, SIB1 may include at least one of the PLMN identifier and the list configured for PLMN2. For example, NG-RAN 502 may broadcast SIB1. For example, NG-RAN 502 may broadcast SIB1 on a cell(s) connected to NG-RAN 502.

[0270] In the same manner as NG-RAN 501, NG-RAN 502 may create the list based on parameters received from AMF 7002 (e.g., segment information, target PLMN identifier, and RFSP index).

[0271] Step 4. UE 3 reads the list of combinations of segment information (e.g., segment "X"), target PLMN identifier, and ARFCN broadcast on the BCCH (e.g., in SIB1) by NG-RAN 501 and NG-RAN 502. UE 3 then finds the combination(s) including segment information, target PLMN identifier, and ARFCN that correspond to the segment information and / or target PLMN identifier in the registration accept message in step 2.

[0272] For example, assume that the list includes a combination (or entry) of segment "X", PLMN2, and ARFCN1, and assume that UE3 receives a registration accept message that includes segment "X" and PLMN2. In this case, UE3 may discover or identify ARFCN1.

[0273] If UE3 finds one or several matches (e.g., if UE3 finds matching ARFCN(s)), as long as UE3 is subscribed to the segment set to "X", UE3 scans or background scans only the frequency band(s) that match or correspond to the ARFCN(s) discovered by UE3. For example, UE3 may scan only the frequency band(s) that match or correspond to the ARFCN, thereby reducing the power consumption of UE3. For example, UE3 may determine that UE3 is subscribed to the segment set to "X" in the same manner as step 5 of FIG. 11. If UE3 receives (or listens to) a broadcasted PLMN identifier that is set to PLMN2 in the frequency band(s) indicated by the ARFCN (e.g., ARFCN1 above), UE3 may determine that UE3 is camped on the cell(s) for PLMN2 in the same manner as the first example of the second aspect, may camp on the cell(s) for PLMN2, and may stop timer T.

[0274] This mechanism may also be applied to the second example of the second aspect. For example, in the second example of the second aspect, UE3 may receive (or listen to) a broadcasted PLMN identifier configured for PLMN2 on the frequency band(s) indicated by ARFCN.

[0275] At least one of the second aspect and the variant of the second aspect can solve the above problem. For example, at least one of the second aspect and the variant of the second aspect can solve a problem that, according to the latest 3GPP mobility management function, the UE must stay in a cell that broadcasts the PLMN identifier of the HPLMN as long as the UE can access the cell. For example, at least one of the second aspect and the variant of the second aspect can solve the problem that, according to the latest 3GPP mobility management function, (1) the UE must stay in a cell that broadcasts the PLMN identifier of the HPLMN, and (2) when the UE is in a cell that does not broadcast the PLMN identifier of the HPLMN, the UE must return to the cell that broadcasts the PLMN identifier of the HPLMN. For example, at least one of the second aspect and the variant of the second aspect can solve a problem that the latest 3GPP specification(s) may not satisfy new service requirements. For example, according to at least one of the second aspect and the modified example of the second aspect, the UE 3 can stay in a PLMN 2 different from the PLMN 1 (e.g., the HPLMN of the UE 3) by using, for example, a timer T stop instruction, an RVAS PLMN list, etc. Therefore, the above-mentioned problem can be solved.

[0276] For example, according to at least one of the second aspect and the modified example of the second aspect, the UE 3 can discover the PLMN 2 (e.g., the cell(s) of the PLMN 2) by scanning only the frequency band(s) instructed by the network, and can stay in the PLMN 2 that is different from the PLMN 1 (e.g., the HPLMN of the UE 3). Therefore, the above-mentioned problem can be solved by reducing the power consumption of the UE 3.

[0277] System Overview FIG. 13 illustrates schematically a mobile (cellular or wireless) telecommunications system 1 to which the above aspects are applicable. The telecommunications system 1 represents an overview of a system in which end-to-end communication is possible, for example, UEs 3 (or user equipment, "mobile devices" 3) communicate with other UEs 3 or service servers in a data network 20 via respective (R)AN nodes 5 and a core network 7.

[0278] The (R)AN node 5 supports any radio access technology, including 5G radio access technology (RAT), E-UTRA radio access technology, beyond 5G RAT, 6G RAT, and non-3GPP RAT, including wireless local area network (WLAN) technology defined by the Institute of Electrical and Electronics Engineers (IEEE).

[0279] The (R)AN node 5 may be divided into a Radio Unit (RU), a Distributed Unit (DU), and a Centralized Unit (CU). In some aspects, each of the units may be connected to each other to construct the (R)AN node 5 by adopting an architecture defined by the Open RAN (O-RAN) Alliance, where the above units are referred to as an O-RU, an O-DU, and an O-CU, respectively.

[0280] The (R)AN node 5 may be divided into control plane functions and user plane functions. Furthermore, multiple user plane functions may be allocated to support communications. In some aspects, user traffic may be distributed across multiple user plane functions, with user traffic on each user plane function being aggregated at both the UE 3 and the (R)AN node 5. This divided architecture is sometimes referred to as "dual connectivity" or "multi-connectivity."

[0281] The (R)AN node 5 may also support communications using satellite access. In some aspects, the (R)AN node 5 may support satellite access and terrestrial access. The (R)AN node 5 may also be referred to as an access node for non-wireless access, including fixed line access as defined by the Broadband Forum (BBF) and optical access as defined by the Innovative Optical and Wireless Network (IOWN).

[0282] The core network 7 may include logical nodes (or "functions") for supporting communications in the telecommunications system 1. For example, the core network 7 may be a 5G Core Network (5GC) that includes, among other functions, control plane functions and user plane functions. Each function within a logical node may be considered a network function. A network function may be provided to another node by adapting a Service Based Architecture (SBA).

[0283] By adapting network virtualization technology defined as European Telecommunications Standards Institute, Network Functions Virtualization (ETSI NFV), network functions can be deployed as distributed, redundant, stateless, and scalable, providing services from several locations and several running instances of each location. The core network 7 may support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN).

[0284] As is known, a UE 3 may move in and out of an area (i.e., a radio cell) served by an (R)AN node 5 as the UE 3 moves within the geographic area covered by the telecommunications system 1. To track the UE 3 and facilitate movement between different (R)AN nodes 5, the core network 7 includes at least one access and mobility management function (AMF) 70. The AMF 70 communicates with the (R)AN nodes 5 coupled to the core network 7. In some core networks, a mobility management entity (MME), a mobility management node for Beyond 5G, or a mobility management node for 6G may be used instead of the AMF 70.

[0285] The core network 7 also includes, among other things, a Session Management Function (SMF) 71, a User Plane Function (UPF) 72, a Policy Control Function (PCF) 73, an Authentication Server Function (AUSF) 74, a Unified Data Management (UDM) 75, and a Network Slice Selection Function (NSSF) 76. When a UE 3 is roaming in a visited Public Land Mobile Network (VPLMN), the home Public Land Mobile Network (HPLMN) of the UE 3 provides the roaming-out UE 3 with the UDM 75 and at least some of the functionality of the SMF 71, UPF 72, and PCF 73.

[0286] The UE 3 and each serving (R)AN node 5 are connected via an appropriate air interface (e.g., a so-called "Uu" interface, etc.). Adjacent (R)AN nodes 5 are connected to each other via appropriate (R)AN node 5-to-(R)AN node interfaces (e.g., a so-called "Xn" interface, etc.). Each (R)AN node 5 is also connected to nodes in the core network 7 (e.g., so-called core network nodes) via appropriate interfaces (e.g., so-called "N2" / "N3" interface(s)). The core network 7 also provides connectivity to a data network 20. The data network 20 can be the Internet, a public network, an external network, a private network, or an internal network of a PLMN. If the data network 20 is provided by a PLMN operator or a Mobile Virtual Network Operator (MVNO), IP Multimedia Subsystem (IMS) services can be provided by the data network 20. The UE 3 can be connected to the data network 20 using IPv4, IPv6, IPv4v6, Ethernet, or an unstructured data type. The data network can include a CSCF 201.

[0287] The "Uu" interface may include a control plane of the Uu interface and a user plane of the Uu interface. The user plane of the Uu interface is responsible for carrying user traffic between the UE 3 and the serving (R)AN node 5. The user plane of the Uu interface may have a layered structure with SDAP, PDCP, RLC, and MAC sublayers over the physical connection.

[0288] The control plane of the Uu interface is responsible for establishing, modifying, and releasing the connection between the UE 3 and the serving (R)AN node 5. The control plane of the Uu interface may have a hierarchical structure with RRC, PDCP, RLC, and MAC sublayers over the physical connection. For example, the following messages are communicated over the RRC layer to support AS signaling: RRC Setup Request Message: This message is sent from the UE 3 to the (R)AN node 5. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be included together in the RRC Setup Request message: -establishmentCause and ue-Identity, where ue-Identity can take the value of ng-5G-S-TMSI-Part1 or a random value. RRC Setup Message: This message is sent from the (R)AN node 5 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be included together in the RRC Setup message: -masterCellGroup and radioBearerConfig RRC Setup Complete message: This message is sent from the UE 3 to the (R)AN node 5. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be included together in the RRC Setup Complete message: -guami-Type, iab-NodeIndication, idleMeasAvailable, mobilityState, ng-5G-S-TMSI-Part2, registeredAMF, selectedPLMN-Identity

[0289] The UE 3 and the AMF 70 are connected via an appropriate interface (such as the so-called N1 interface). The N1 interface is responsible for providing communication between the UE 3 and the AMF 70 to support NAS signaling. The N1 interface can be established via 3GPP access and non-3GPP access. For example, the following messages are communicated via the N1 interface: Registration Request Message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by the aspects of the present disclosure, the following parameters may be included together in the Registration Request message: -5GS registration type, ngKSI, 5GS mobile identity, non-current native NAS key set identifier, 5GMM capability, UE security capability, requested NSSAI, last visited registration TAI, S1 UE network capability, uplink data status, PDU session status, MICO indication, UE status, additional GUTI, allowed PDU session status, UE usage configuration, requested DRX parameters, EPS NAS message container, LADN indication, payload container type, payload container, network slicing indication, 5GS update type, mobile station class mark 2, supported codecs, NAS message container, EPS bearer context status, requested extended DRX parameters, T3324 value, UE radio capability ID, requested mapping NSSAI, requested additional information, requested WUS support information, N5GC indication, and requested NB-N1 mode DRX parameters. Registration Accept Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be included together in the registration accept message: -5GS Registration Result, 5G-GUTI, Equivalent PLMN, TAI List, Allowed NSSAI, Rejected NSSAI, Configured NSSAI, 5GS Network Capability Support, PDU Session Status, PDU Session Reactivation Result, PDU Session Reactivation Result Error Cause, LADN Information, MICO Indication, Network Slicing Indication, Service Area List, T3512 Value, Non-3GPP Deregistration Timer Value, T3502 Value, Emergency Number List, Extended Emergency Number List, SOR Transparent Container, EAP Message, NSSAI Inclusion Mode, Operator Defined Access Category Definition, Negotiated DRX Parameters, Non-3GPP NW policy, EPS bearer context status, negotiated extended DRX parameters, T3447 value, T3448 value, T3324 value, UE radio capability ID, UE radio capability ID removal instruction, pending NSSAI, ciphering key data, CAG information list, aborted 5G-S-TMSI configuration, negotiated WUS assistance information, negotiated NB-N1 mode DRX parameters, and extended rejected NSSAI. Registration Complete Message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by the aspects of the present disclosure, the following parameters may be included together in the registration complete message: -SOR transparent container. -Authentication Request Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be included together in the Authentication Request message: -ngKSI, ABBA, authentication parameter RAND (5G authentication challenge), authentication parameter AUTN (5G authentication challenge), and EAP message. Authentication Response Message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the authentication response message: -Authentication response message identification information, authentication response parameters, and EAP message. -Authentication Result Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Authentication Result Message: -ngKSI, EAP Message, and ABBA. Authentication Failure Message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Authentication Failure Message: -Authentication failure message identification information, 5GMM cause, and authentication failure parameters. -Authentication Rejection Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the authentication rejection message: -EAP message. - Service Request Message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Service Request message: -ngKSI, Service Type, 5G-S-TMSI, Uplink Data Status, PDU Session Status, Allowed PDU Session Status, NAS Message Container. -Service Acceptance Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Service Acceptance Message: -PDU session status, PDU session reactivation result, PDU session reactivation result error cause, EAP message and T3448 value. Service Rejection Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Service Rejection Message: -5GMM cause, PDU session status, T3346 value, EAP message, T3448 value, and CAG information list. Configuration Update Command Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the Configuration Update Command message: -Configuration update instruction, 5G-GUTI, TAI list, Allowed NSSAI, Service area list, Network full name, Network short name, Local time zone, Universal time and local time zone, Network daylight saving time, LADN information, MICO instruction, Network slicing instruction, Configuration NSSAI, Rejected NSSAI, Operator defined access category definition, SMS instruction, T3447 value, CAG information list, UE radio capability ID, UE radio capability ID deletion instruction, 5GS registration result, Abort 5G-S-TMSI configuration, Additional configuration instruction and Extended Rejected NSSAI. Configuration Update Complete message: This message is sent from the UE 3 to the AMF 70. In addition to the parameters disclosed by aspects of the present disclosure, the following parameters may be taken together in the configuration update complete message: Configuration update complete message identification information. Figure 13: System overview

[0290] User equipment (UE) FIG. 14 is a block diagram illustrating the main components of a mobile device 3 (UE 3). As illustrated, the UE 3 includes a transceiver circuit 31 operable to transmit signals to and receive signals from connected node(s) via one or more antennas 32. The UE 3 may also include a user interface 34 for inputting or outputting information from the outside. Although not necessarily shown in the figure, the UE 3 may have all the usual functions of a conventional mobile device, which may be provided by any one or any combination of hardware, software, and firmware, as needed. The software may be pre-installed in memory and / or downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The controller 33 controls the operation of the UE 3 in accordance with software stored in the memory 36. The software includes, among other things, an operating system 361 and a communication control module 362 having at least one transceiver control module 3621. The communication control module 362 (using its transceiver control module 3621) is responsible for processing (generating / sending / receiving) signaling and uplink / downlink data packets between the UE 3 and other nodes, such as the (R)AN node 5 and the AMF 70. Such signaling may include, for example, appropriately formatted signaling messages related to access and mobility management procedures (for the UE 3) (e.g., registration request messages and associated response messages). The controller 33 interacts with one or more Universal Subscriber Identity Modules (USIMs) 35. If multiple USIMs 35 are installed, the controller 33 may activate only one USIM 35 or multiple USIMs 35 simultaneously.

[0291] The UE 3 may support, for example, a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). UE3 may be, for example, an item of equipment and / or energy-related machinery for production or manufacturing (e.g., equipment or machinery such as boilers; engines; turbines; solar panels; wind turbines; hydroelectric generators; thermal power plants; nuclear generators; batteries; nuclear systems and / or related equipment; heavy electrical equipment; pumps including vacuum pumps; compressors; fans; blowers; hydraulic equipment; pneumatic equipment; metalworking machinery; manipulators; robots and / or their application systems; tools; molds or dies; rolls; material handling equipment; textile machinery; sewing machines; printing and / or related machinery; paper converting machinery; chemical machinery; mining and / or construction machinery and / or related equipment; machinery and / or implements for agriculture, forestry and / or fisheries; safety and / or environmental protection equipment; tractors; precision bearings; chains; gears; power transmission equipment; lubrication equipment; valves; pipe fittings; and / or application systems for any of the aforementioned equipment or machines). The UE 3 may be, for example, an item of transportation equipment (e.g., a rail car; a car; a motorcycle; a bicycle; a train; a bus; a cart; a rickshaw; a ship or other watercraft; an aircraft; a rocket; a satellite; a drone; a balloon, etc.).

[0292] The UE 3 may be, for example, an information and communication equipment item (e.g., information and communication equipment such as electronic computers and related equipment; communication and related equipment; electronic components, etc.). The UE 3 may be, for example, a refrigerator, a refrigerator application product, a goods and / or service industry equipment item, a vending machine, an automatic service machine, an office machine, a consumer electronic device and an electronic appliance (e.g., audio equipment; video equipment; speakers; radios; televisions; microwave ovens; rice cookers; coffee machines; dishwashers; washing machines; dryers; electronic fans or related appliances; consumer electrical appliances such as vacuum cleaners, etc.).

[0293] The UE 3 may be, for example, an electrical application system or equipment (e.g., an electrical application system or equipment such as an X-ray system; a particle accelerator; a radioisotope equipment; a sound wave equipment; an electromagnetic application equipment; a power application equipment, etc.). The UE 3 may be, for example, an electronic lamp, a lighting fixture, a measuring instrument, an analyzer, a tester, or a surveying or sensing equipment (e.g., a smoke detector; a motion sensor; a radio tag, etc.), a wristwatch or watch, an inspection equipment, an optical device, a medical device and / or system, a weapon, a cutlery product, a hand tool, etc.

[0294] UE3 may be, for example, a wireless-equipped personal digital assistant or related equipment (such as a wireless card or module designed to be attached to or inserted into another electronic device (e.g., a personal computer, electrical measuring instrument)). The UE 3 may be part of a device or system that uses various wired and / or wireless communication technologies to provide the applications, services, and solutions described below in relation to the "internet of things (IoT)."

[0295] Internet of Things devices (or "Things") may be equipped with appropriate electronics, software, sensors, network connections, etc. that enable these devices to collect and exchange data with each other and other communicating devices. IoT devices may comprise automated machines that follow software instructions stored in internal memory. IoT devices may operate without the need for human supervision or interaction. IoT devices may also remain stationary and / or inactive for extended periods of time. IoT devices may be implemented as part of (typically) stationary equipment. IoT devices may also be incorporated into non-stationary equipment (e.g., vehicles) or attached to animals or people being monitored / tracked.

[0296] It will be appreciated that IoT technologies may be implemented on any communication device that can connect to a communication network to send / receive data, whether such communication device is controlled by human input or by software instructions stored in memory.

[0297] It will be appreciated that an IoT device may also be referred to as a Machine-Type Communication (MTC) device, a Machine-to-Machine (M2M) communication device, or a Narrow Band-IoT UE (NB-IoT UE). It will be appreciated that a UE 3 may support one or more IoT or MTC applications.

[0298] The UE 3 may be a smartphone or a wearable device (e.g., smart glasses, a smart watch, a smart ring, or a hearable device). The UE 3 may be an automobile, a connected automobile, an autonomous automobile, a vehicle device, a motorcycle, or a Vehicle to Everything (V2X) communication module (e.g., a vehicle-to-vehicle communication module, a vehicle-to-infrastructure communication module, a vehicle-to-pedestrian communication module, and a vehicle-to-network communication module). Figure 14: User equipment (UE)

[0299] (R)AN Node FIG. 15 is a block diagram illustrating the main components of an exemplary (R)AN node 5, e.g., a base station (eNB in ​​LTE, gNB in ​​5G, later 5G base station, 6G base station). As shown, the (R)AN node 5 includes transceiver circuitry 51 operable to transmit signals to and receive signals from connected UE(s) 3 via one or more antennas 52, and to transmit signals to and receive signals from other network nodes (directly or indirectly) via a network interface 53. A controller 54 controls operation of the (R)AN node 5 in accordance with software stored in memory 55. The software may be pre-installed in memory and / or may be downloaded, for example, over a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 551 and a communications control module 552 having at least a transceiver control module 5521.

[0300] The communications control module 552 (using its transceiver control sub-module) is responsible for handling (generating / sending / receiving) signaling between (e.g., directly or indirectly) the (R)AN node 5 and other nodes, such as a UE 3, another (R)AN node 5, an AMF 70, or a UPF 72. The signaling may include, for example, appropriately formatted signaling messages related to the radio connection and connectivity with the core network 7 (for a particular UE 3), in particular connection establishment and maintenance (e.g., RRC connection establishment and other RRC messages), NG Application Protocol (NGAP) messages (i.e., messages over the N2 reference point) and Xn application protocol (XnAP) messages (i.e., messages over the Xn reference point), etc. Such signaling may also include, for example, broadcast information (e.g., master information and system information) in the transmit case.

[0301] The control unit 54, when implemented, is also configured (by software or hardware) to handle related tasks such as UE mobility estimation and / or movement trajectory estimation.

[0302] The (R)AN node 5 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN).

[0303] The NG-RAN 5, NG-RAN 501, and NG-RAN 502 may have the same components as the (R)AN node 5. The (R)AN node 5 may also be referred to as a RAN node, a RAN, an (R)AN, etc. Figure 15: (R)AN node

[0304] System overview of (R)AN Node 5 based on O-RAN architecture FIG. 16 illustrates schematically an (R)AN node 5 based on an O-RAN architecture to which aspects of the (R)AN node 5 are applicable. The (R)AN node 5 based on the O-RAN architecture represents a system overview in which the (R)AN node is divided into a Radio Unit (RU) 60, a Distributed Unit (DU) 61, and a Centralized Unit (CU) 62. In some aspects, each unit may be combined. For example, the RU 60 may be combined with the DU 61 as a combined / combined unit, and the DU 61 may be combined with the CU 62 as another combined / combined unit. Any functionality described for a unit (e.g., one of the RU 60, DU 61, and CU 62) may be implemented in the combined / combined unit. Furthermore, the CU 62 may be separated into two functional units, such as a CU Control plane (CP) and a CU User plane (UP). The CU CP performs the control plane function in the (R)AN node 5. The CU UP performs the user plane function in the (R)AN node 5. Each CU CP is connected to the CU UP via an appropriate interface (such as a so-called "E1" interface).

[0305] The UE 3 and each serving RU 60 are connected via an appropriate air interface (e.g., the so-called "Uu" interface, etc.). Each RU 60 is connected to a DU 61 via an appropriate interface (e.g., the so-called "fronthaul," "open fronthaul," "F1" interface, etc.). Each DU 61 is connected to a CU 62 via an appropriate interface (e.g., the so-called "midhaul," "open midhaul," "E2" interface, etc.). Each CU 62 is also connected to a node in the core network 7 (e.g., a so-called core network node) via an appropriate interface (e.g., the so-called "backhaul," "open backhaul," "N2" / "N3" interface(s)), etc. The user plane part of the DU 61 can also be connected to the core network node 7 via an appropriate interface (e.g., the so-called "N3" interface(s)). Depending on the functionality divided between the RU 60, DU 61, and CU 62, each unit provides a portion of the functionality provided by the (R)AN node 5. For example, the RU 60 may provide functionality for communicating with the UE 3 over the air interface, the DU 61 may provide functionality for supporting the MAC and RLC layers, and the CU 62 may provide functionality for supporting the PDCP, SDAP, and RRC layers. Figure 16: System overview of (R)AN node 5 based on O-RAN architecture

[0306] Radio Unit (RU) FIG. 17 is a block diagram illustrating the main components of an exemplary RU 60, e.g., the RU portion of a base station (eNB in ​​LTE, gNB in ​​5G, later 5G base station, 6G base station). As shown, the RU 60 includes a transceiver circuit 601 operable to transmit signals to and receive signals from connected UE(s) 3 via one or more antennas 602 and to transmit and receive signals to and from other network nodes or units (directly or indirectly) via a network interface 603. A controller 604 controls the operation of the RU 60 according to software stored in memory 605. The software may be pre-installed in the memory and / or downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6051 and a communications control module 6052 having at least a transceiver control module 60521.

[0307] The communications control module 6052 (using its transceiver control sub-module) is responsible for handling (generating / sending / receiving) signaling between the RU 60 (e.g., directly or indirectly) and other nodes or units, such as a UE 3, another RU 60, or a DU 61. The signaling may include, for example, appropriately formatted signaling messages related to the radio connection and connection with the RU 60 (for a particular UE 3), in particular related to the MAC and RLC layers.

[0308] The controller 604, when implemented, is also configured (by software or hardware) to handle related tasks such as UE mobility estimation and / or motion trajectory estimation. The RU 60 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN).

[0309] As mentioned above, the RU 60 can be integrated / combined with the DU 61 as an integrated / combined unit. Any function described for the RU 60 can be implemented in the integrated / combined unit. Figure 17: Radio Unit (RU)

[0310] Distributed Unit (DU) FIG. 18 is a block diagram illustrating the main components of an exemplary DU 61, e.g., a DU section of a base station (e.g., an eNB in ​​LTE, a gNB in ​​5G, a later 5G base station, or a 6G base station). As shown, the device includes a transceiver circuit 611 operable to transmit signals to and receive signals from other nodes or units (including the RU 60) via a network interface 612. A controller 613 controls the operation of the DU 61 in accordance with software stored in memory 614. The software may be pre-installed in memory 614 and / or downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6141 and a communications control module 6142 having at least a transceiver control module 61421. The communication control module 6142 (using its transceiver control module 61421) is responsible for handling (generating / sending / receiving) signaling between the DU 61 and other nodes or units, for example, between the RU 60 and other nodes and units.

[0311] The DU 61 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). As described above, the RU 60 can be integrated / combined with the DU 61 or the CU 62 as an integration / combination unit. Any function described for the DU 61 can be implemented in the above integration / combination unit. Figure 18: Distributed Unit (DU)

[0312] Centralized Unit (CU) FIG. 19 is a block diagram illustrating the main components of an exemplary CU 62, e.g., the CU portion of a base station (e.g., an eNB in ​​LTE, a gNB in ​​5G, a later 5G base station, or a 6G base station). As shown, the device includes a transceiver circuit 621 operable to transmit signals to and receive signals from other nodes or units (including the DU 61) via a network interface 622. A controller 623 controls the operation of the CU 62 in accordance with software stored in memory 624. The software may be pre-installed in memory 624 and / or downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6241 and a communications control module 6242 having at least a transceiver control module 62421. The communication control module 6242 (using its transceiver control module 62421) is responsible for handling (generating / sending / receiving) signaling between the CU 62 and other nodes or units, for example, between the DU 61 and other nodes and units.

[0313] The CU 62 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). As described above, the CU 62 can be integrated / combined with the DU 61 as an integration / combination unit. Any of the functions described for the CU 62 can be implemented in the integration / combination unit. Figure 19: Centralized Unit (CU)

[0314] AMF 20 is a block diagram illustrating the main components of the AMF 70. As shown, the device includes a transceiver circuit 701 operable to transmit signals to and receive signals from other nodes (including UE 3, NSSF 76) via a network interface 702. A controller 703 controls the operation of the AMF 70 in accordance with software stored in memory 704. The software may be pre-installed in memory 704 and / or may be downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7041 and a communications control module 7042 having at least a transceiver control module 70421. The communications control module 7042 (using its transceiver control module 70421) is responsible for processing (generating / sending / receiving) signaling between the AMF 70 and other nodes, such as the UE 3 (e.g., via the (R)AN node 5) and other core network nodes (including core network nodes in the UE 3's HPLMN when the UE 3 is roaming in). Such signaling may include, for example, appropriately formatted signaling messages (e.g., registration request messages and associated response messages) related to access and mobility management procedures (for the UE 3). The AMF 70 may support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). The AMF 7001 and AMF 7002 may have the same components as the AMF 70. Figure 20: AMF

[0315] SMF 21 is a block diagram illustrating the major components of the SMF 71. As shown, the device includes a transceiver circuit 711 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 712. A controller 713 controls the operation of the SMF 71 in accordance with software stored in memory 714. The software may be pre-installed in the memory 714 and / or downloaded over a telecommunications network or from a removable memory device (RMD), for example. This software includes, among other things, an operating system 7141 and a communications control module 7142 having at least one transceiver control module 71421. The communications control module 7142 (using its transceiver control module 71421) is responsible for handling (generating / sending / receiving) signaling between the SMF 71 and other nodes, such as the UPF 72 and other core network nodes (including core network nodes in the UE 3's HPLMN when the UE 3 is roaming). Such signaling may include, for example, appropriately formatted signaling messages (e.g., Hypertext Transfer Protocol (HTTP) restful methods based on service-based interfaces) related to session management procedures (for the UE 3). The SMF 71 can support a Non-Public Network (NPN), which can be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). SMF7101 and SMF7102 may have the same components as SMF71. Figure 21: SMF

[0316] PCF FIG. 22 is a block diagram illustrating the main components of the PCF 73. As shown, the device includes a transceiver circuit 731 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 732. A controller 733 controls the operation of the PCF 73 in accordance with software stored in a memory 734. The software may be pre-installed in the memory 734 and / or downloaded, for example, via a telecommunications network or from a removable storage device (e.g., a removable memory device (RMD)). The software includes, among other things, an operating system 7341 and a communications control module 7342 having at least a transceiver control module 73421. The communications control module 7342 (using its transceiver control module 73421) is responsible for processing (generating / sending / receiving) signaling between the PCF 73 and other nodes, such as the AMF 70 and other core network nodes (including core network nodes in the UE 3's HPLMN when the UE 3 is roaming in). Such signaling may include, for example, appropriately formatted signaling messages (e.g., HTTP restful methods based on service-based interfaces) related to policy management procedures (for UE 3). The PCF 73 may support Non-Public Networks (NPNs), which may be Stand-alone Non-Public Networks (SNPNs) or Public Network Integrated NPNs (PNI-NPNs). Figure 22: PCF

[0317] AUSF FIG. 23 is a block diagram illustrating the main components of the AUSF 74. As shown, the device includes a transceiver circuit 741 operable to transmit signals to and receive signals from other nodes (including the UDM 75) via a network interface 742. A controller 743 controls the operation of the AUSF 74 according to software stored in a memory 744. The software may be pre-installed in the memory 744 and / or downloaded, for example, via a telecommunications network or from a removable storage device (e.g., a removable memory device (RMD)). The software includes, among other things, an operating system 7441 and a communications control module 7442 having at least a transceiver control module 74421. The communications control module 7442 (using its transceiver control module 74421) is responsible for processing (generating / sending / receiving) signaling between the AUSF 74 and other nodes, such as the AMF 70 and other core network nodes (including core network nodes in the UE 3's HPLMN when the UE 3 is roaming). Such signaling may include, for example, appropriately formatted signaling messages (e.g., HTTP restful methods based on service-based interfaces) related to policy management procedures (for UE3).

[0318] The AUSF74 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). Figure 23: AUSF

[0319] UDM 24 is a block diagram illustrating the major components of the UDM 75. As shown, the device includes a transceiver circuit 751 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 752. A controller 753 controls the operation of the UDM 75 in accordance with software stored in memory 754. The software may be pre-installed in memory 754 and / or may be downloaded, for example, over a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7541 and a communications control module 7542 having at least a transceiver control module 75421. The communications control module 7542 (using its transceiver control module 75421) is responsible for handling (generating / sending / receiving) signaling between the UDM 75 and other nodes, such as the AMF 70 and other core network nodes (including core network nodes in the UE 3's VPLMN when the UE 3 is roaming). Such signaling may include, for example, appropriately formatted signaling messages (e.g., HTTP restful methods based on service-based interfaces) related to mobility management procedures (for the UE 3).

[0320] The UDM 75 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). The UDM in PLMN2 may have the same components as UDM75. Figure 24: UDM

[0321] NSSF FIG. 25 is a block diagram illustrating the main components of the NSSF 76. As shown, the device includes a transceiver circuit 761 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 762. A controller 763 controls the operation of the NSSF 76 in accordance with software stored in a memory 764. The software may be pre-installed in the memory 764 and / or downloaded, for example, via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7641 and a communications control module 7642 having at least a transceiver control module 76421. The communications control module 7642 (using its transceiver control module 76421) is responsible for processing (generating / sending / receiving) signaling between the NSSF 76 and other nodes, such as the AMF 70 and other core network nodes (including core network nodes in the UE 3's VPLMN when the UE 3 is roaming out). Such signaling may include, for example, appropriately formatted signaling messages (for UE 3) related to mobility management procedures (e.g., HTTP restful methods based on service-based interfaces).

[0322] The NSSF 76 can support a Non-Public Network (NPN), which may be a Stand-alone Non-Public Network (SNPN) or a Public Network Integrated NPN (PNI-NPN). Figure 25: NSSF

[0323] The exemplary embodiments disclosed above can be described in whole or in part as follows, without limitation.

[0324] Modifications and Substitutions Having described detailed embodiments above, those skilled in the art will appreciate that several modifications and alternatives can be made to the above embodiments while still benefiting from the disclosure embodied in the above embodiments. By way of example only, some of these alternatives and modifications are now described.

[0325] In the above description, for ease of understanding, the UE 3 and network devices have been described as having several separate modules (such as a communications control module). These modules may be provided in this manner in certain applications, for example, where an existing system is modified to implement the present disclosure, but in other applications, for example, in systems designed from the beginning with the features of the present invention in mind, these modules may be incorporated into an overall operating system or code, and therefore may not be identified as separate entities. These modules may also be implemented as software, hardware, firmware, or a mixture of these. Each control unit may comprise any suitable form of processing circuitry, including (but not limited to), for example, one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuitry, internal memory / cache (program and / or data), processing registers, communication buses (e.g., control buses, data buses, and / or address buses), direct memory access (DMA) functions, hardware or software-implemented counters, pointers, and / or timers, etc.

[0326] In the above embodiments, several software modules have been described. As will be appreciated by those skilled in the art, the software modules may be provided in compiled or uncompiled form and may be provided to the UE 3 and network devices as signals over a computer network or on a recording medium. Furthermore, the functions performed by some or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates updating the UE 3 and network devices to update their functionality.

[0327] In the above embodiments, 3GPP wireless communication (radio access) technologies are used. However, any other wireless communication technologies (e.g., WLAN, Wi-Fi, WiMAX, Bluetooth, etc.) and other fixed-line communication technologies (e.g., BBF access, cable access, optical access, etc.) can also be used in accordance with the above embodiments. Items of user equipment can include communication devices such as mobile phones, smartphones, user equipment, personal digital assistants, laptop / tablet computers, web browsers, e-book readers, etc. Such mobile (or more generally, fixed) devices are typically operated by users, although so-called "Internet of Things" (IoT) devices and similar machine-type communication (MTC) devices can also be connected to the network. For simplicity, this application refers to mobile devices (or UE) in the description, but it will be understood that the described techniques can be implemented on any communication device (mobile and / or generally fixed) that can connect to a communication network to transmit and receive data, regardless of whether such communication device is controlled by human input or software instructions stored in memory. Various other modifications will be apparent to those skilled in the art and will not be described in further detail herein.

[0328] As will be appreciated by those skilled in the art, the present disclosure may be embodied as a method and a system, and thus may take the form of an entirely hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects.

[0329] It will be understood that each block of the block diagrams may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to create a machine such that the instructions, when executed by the processor of the computer or other programmable data processing apparatus, cause the processor to implement the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., multiple microprocessors, one or more microprocessors, or any other such configuration.

[0330] The methods or algorithms described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. The storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC.

[0331] The previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure.

[0332] Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0333] Although the present disclosure has been shown and described in detail with reference to exemplary embodiments thereof, the present disclosure is not limited to these embodiments. It will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as defined herein. For example, the above embodiments are not limited to 5GS, and these embodiments are also applicable to communication systems other than 5GS (e.g., 6G systems, 5G Beyond systems).

[0334] Additional notes The exemplary aspects disclosed above may be explained in whole or in part as follows, but are not limited to the following: (Appendix 1) A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; The third information indicates a second PLMN with which the UE needs to perform a registration procedure; and sending a second message, the second message includes a registration request message and at least one of the second information and the third information. (Appendix 2) and transmitting fourth information indicating that the UE supports receiving the first message. The method described in Appendix 1. (Appendix 3) The first message is a registration rejection message, The second message is a Radio Resource Control (RRC) Setup Complete message. 3. The method according to claim 1 or 2. (Appendix 4) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a user equipment (UE); the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device, the second message comprising a registration request message. (Appendix 5) transmitting third information indicating that the first communication device supports the selection of the second communication device; receiving the first message includes receiving the first message when transmitting the third information; The method described in Appendix 4. (Appendix 6) The first message is a Radio Resource Control (RRC) Setup Complete message; The second message is an initial UE message. 6. The method according to claim 4 or 5. (Appendix 7) the first communication device is an NG-RAN node; The second communication device is an Access and Mobility Management Function (AMF); The method according to any one of appendices 4 to 6. (Appendix 8) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a second communication device; the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and sending a second message to the UE; the second message includes third information indicating that a registration procedure is required and at least one of the first information and the second information. (Appendix 9) transmitting fourth information indicating that the first communication device supports receiving the first message; receiving the first message includes receiving the first message when transmitting fourth information; The method described in Appendix 8. (Appendix 10) receiving fifth information indicating that the UE supports receiving the second message; transmitting the second message includes transmitting the second message if the fifth information is received; 10. The method according to claim 8 or 9. (Appendix 11) The first message is a Nudm_SDM_Get Response message, The second message is a registration rejection message. The method according to any one of appendices 8 to 10. (Appendix 12) the first communication device is an Access and Mobility Management Function (AMF); The second communication device is a Unified Data Management (UDM). The method according to any one of appendices 8 to 11. (Appendix 13) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: communicating with a second communication device; and sending a message to the second communication device; the message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The method, wherein the second information indicates a second PLMN with which the UE needs to perform a registration procedure. (Appendix 14) receiving fourth information indicating that the second communication device is responsive to receive the message; transmitting the message includes transmitting the message when the fourth information is received; The method described in Appendix 13. (Appendix 15) The message is a Nudm_SDM_Get Response message. 15. The method according to claim 13 or 14. (Appendix 16) The first communication device is a Unified Data Management (UDM), The second communication device is an Access and Mobility Management Function (AMF); The method according to any one of appendices 13 to 15. (Appendix 17) sending another message to the second communication device when at least one of the first information and the second information is updated; the other message includes at least one of the updated first information and the updated second information; The method according to any one of appendices 13 to 16. (Appendix 18) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving 5G-GUTI; and transmitting to the UE a 5G-GUTI and fourth information indicating that a registration procedure is required. (Appendix 19) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 18. The method described in Appendix 18. (Appendix 20) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message from a second communication device in a second PLMN; The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and and transmitting a 5G-GUTI. (Appendix 21) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 21. The method described in Appendix 20. (Appendix 22) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; sending a second message to a second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving 5G-GUTI; Transmitting 5G-GUTI; and sending, to the UE, fourth information indicating that a registration procedure is required. (Appendix 23) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 23. The method described in Appendix 22. (Appendix 24) A method for a User Equipment (UE), the method comprising: receiving a message from a communication device in a first Public Land Mobile Network (PLMN); The message includes information indicating that a registration procedure is required and a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and and performing a registration procedure based on 5G-GUTI. (Appendix 25) 25. The method of claim 24, wherein the message is a registration acceptance message. (Appendix 26) A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and receiving a second message, the second message includes information indicating that a registration procedure is required; and and performing a registration procedure based on 5G-GUTI. (Appendix 27) 27. The method of claim 26, wherein the first message is a registration acceptance message and the second message is a deregistration request message. (Appendix 28) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in a second PLMN based on the first information and the second information; and sending a second message to the second communication device to instruct the second communication device to perform a registration procedure for the UE. (Appendix 29) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 29. The method described in Appendix 28. (Appendix 30) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a second communication device in a second PLMN for performing a registration procedure for the user equipment; performing a registration procedure. (Appendix 31) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 31. The method described in Appendix 30. (Appendix 32) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure; and receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE; selecting a second communication device in a second PLMN based on the first information and the second information; and sending a third message to the second communication device to establish the PDU session. (Appendix 33) The first message is a Nudm_SDM_Get Response message, and the second message is a UL NAS TRANSPORT message; The third message is the Nsmf_PDUSession_CreateSMContext Request message. 32. The method described in Appendix 32. (Appendix 34) the first communication device is an Access and Mobility Management Function (AMF); the second communication device is a Session Management Function (SMF); 34. The method of claim 32 or 33. (Appendix 35) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. The method according to any one of appendices 32 to 34. (Appendix 36) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and performing a procedure for establishing a PDU session. (Appendix 37) The method described in Supplementary Note 36, wherein the message is an Nsmf_PDUSession_CreateSMContext Request message. (Appendix 38) the first communication device is a Session Management Function (SMF); The second communication device is an Access and Mobility Management Function (AMF); 38. The method according to claim 36 or 37. (Appendix 39) 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and transmitting a second message to a third communication device in the first PLMN to establish a PDU session. (Appendix 40) The first message is a Namf_Communication_N1MessageNotify message, The second message is the Nsmf_PDUSession_CreateSMContext Request message. 39. The method described in Appendix 39. (Appendix 41) the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; The third communication device is a Session Management Function (SMF); 41. The method according to claim 39 or 40. (Appendix 42) A method for a user equipment (UE), comprising: communicating with a communication device; and when the UE is camped on a first Public Land Mobile Network (PLMN) and a second PLMN, stopping the timer, or ignoring expiration of the timer, or overriding the timer, thereby continuing to camp on the first PLMN; the timer is configured to return the UE to the second PLMN if the timer expires; The method, wherein the second PLMN is a Home Public Land Mobile Network (HPLMN) of the UE. (Appendix 43) The stopping is performed by the information to stop the timer. 42. The method described in Appendix 42. (Appendix 44) determining whether the UE is in the first PLMN by scanning a PLMN identifier configured for the first PLMN; 44. The method according to claim 42 or 43. (Appendix 45) receiving information indicative of a frequency band; Scanning for PLMN identifiers configured for the first PLMN includes scanning for PLMN identifiers configured for the first PLMN over a frequency band. The method described in Appendix 44. (Appendix 46) A method for a user equipment (UE), comprising: communicating with a communication device; When the UE is camped on a first Public Land Mobile Network (PLMN) and a second PLMN, using a PLMN list for Roaming Value Added Service (RVAS) to continue camping on the first PLMN; the first PLMN is included in the PLMN list; the PLMN list indicates that a first PLMN is to be selected for RVAS in preference to a second PLMN; The method, wherein the second PLMN is a Home Public Land Mobile Network (HPLMN) of the UE. (Appendix 47) determining whether the UE is in the first PLMN by scanning a PLMN identifier configured for the first PLMN; The method described in Appendix 46. (Appendix 48) receiving information indicative of a frequency band; Scanning for PLMN identifiers configured for the first PLMN includes scanning for PLMN identifiers configured for the first PLMN over a frequency band. The method described in Appendix 47. (Appendix 49) A user equipment (UE), means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; the third information indicating a second PLMN with which the UE needs to perform a registration procedure; a means for transmitting a second message, the means comprising: The UE comprises means for receiving the second message including a registration request message and at least one of the second information and the third information. (Appendix 50) and means for transmitting fourth information indicating that the UE supports receiving the first message. UE as described in Appendix 49. (Appendix 51) The first message is a registration rejection message, The second message is a Radio Resource Control (RRC) Setup Complete message. 51. The UE of claim 49 or 50. (Appendix 52) A first communication device in a first Public Land Mobile Network (PLMN), comprising: A means for receiving a first message from a user equipment (UE), the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; A segment indicates a group of subscribers or an area in which a UE is included or in which service is provided for a UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; and means for transmitting a second message to the second communication device, the second message including a registration request message. (Appendix 53) means for transmitting third information indicating that the first communication device supports selection of the second communication device; and means for receiving the first message when the third information is transmitted. 53. The first communications device of claim 52. (Appendix 54) The first message is a Radio Resource Control (RRC) Setup Complete message; The second message is an initial UE message. 54. The first communication device of claim 52 or 53. (Appendix 55) the first communication device is an NG-RAN node; The second communication device is an Access and Mobility Management Function (AMF); 55. The first communication device according to any one of Supplementary notes 52 to 54. (Appendix 56) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message from a second communication device, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; A means for transmitting a second message to the UE, and means for the second message to include third information indicating that a registration procedure is required and at least one of the first information and the second information. (Appendix 57) means for transmitting fourth information indicating that the first communication device supports receiving the first message; and means for receiving the first message when the fourth information is transmitted. 57. The first communications device of claim 56. (Appendix 58) means for receiving fifth information indicating that the UE supports receiving the second message; means for transmitting a second message when the fifth information is received; 58. The first communication device of claim 56 or 57. (Appendix 59) The first message is a Nudm_SDM_Get Response message and the second message is a Registration Reject message. 59. The first communication device according to any one of Supplementary notes 56 to 58. (Appendix 60) the first communication device is an Access and Mobility Management Function (AMF); The second communication device is a Unified Data Management (UDM). 60. The first communication device according to any one of appendices 56 to 59. (Appendix 61) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for communicating with a second communication device; means for sending a message to a second communication device; the message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates a second PLMN with which the UE needs to perform a registration procedure, the first communication device. (Appendix 62) means for receiving fourth information indicating that the second communication device supports receiving the message; means for transmitting a message when the fourth information is received; 62. The first communications device of claim 61. (Appendix 63) The message is a Nudm_SDM_Get Response message. 63. The first communication device according to claim 61 or 62. (Appendix 64) The first communication device is a Unified Data Management (UDM), The second communication device is an Access and Mobility Management Function (AMF); 64. The first communication device according to any one of Supplementary notes 61 to 63. (Appendix 65) means for transmitting another message to the second communication device when at least one of the first information and the second information is updated; the other message includes at least one of the updated first information and the updated second information; 65. The first communication device according to any one of appendices 61 to 64. (Appendix 66) A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; means for transmitting a second message to a second communication device, the second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); a means for receiving 5G-GUTI; and means for transmitting to the UE a 5G-GUTI and fourth information indicating that a registration procedure is required. (Appendix 67) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 67. The first communications device of claim 66. (Appendix 68) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a message from a second communication device in a second PLMN, the means comprising: The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); A first communication device comprising: a means for transmitting a 5G-GUTI. (Appendix 69) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 69. The first communications device of claim 68. (Appendix 70) A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers or an area in which a user equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; means for transmitting a second message to a second communication device, the second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); a means for receiving 5G-GUTI; a means for transmitting 5G-GUTI; and means for transmitting fourth information to the UE indicating that a registration procedure is required. (Appendix 71) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 71. The first communications device of claim 70. (Appendix 72) A user equipment (UE), means for receiving a message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: The message includes information indicating that a registration procedure is required and a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and and means for performing a registration procedure based on 5G-GUTI. (Appendix 73) 73. The UE of claim 72, wherein the message is a registration accept message. (Appendix 74) A user equipment (UE), means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in the second PLMN; and means for receiving a second message, the second message includes information indicating that a registration procedure is required; and means for performing a registration procedure based on 5G-GUTI. (Appendix 75) 75. The UE of claim 74, wherein the first message is a registration accept message and the second message is a deregistration request message. (Appendix 76) A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in a second PLMN based on the first information and the second information; and means for sending a second message to the second communication device to instruct the second communication device to perform a registration procedure for the UE. (Appendix 77) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 77. The first communications device of claim 76. (Appendix 78) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message from a second communication device in a second PLMN for performing a registration procedure for the user equipment; and means for performing a registration procedure. (Appendix 79) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 79. The first communications device of claim 78. (Appendix 80) A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding the segment and second information regarding a second PLMN other than the first PLMN; A segment indicates a group of subscribers, or a user equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating a second PLMN with which the UE needs to perform a registration procedure; means for receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE; means for selecting a second communication device in a second PLMN based on the first information and the second information; The first communication device comprises means for transmitting a third message to the second communication device to establish a PDU session. (Appendix 81) The first message is a Nudm_SDM_Get Response message, the second message is a UL NAS TRANSPORT message, and the third message is a Nsmf_PDUSession_CreateSMContext Request message; 81. The first communications device of claim 80. (Appendix 82) the first communication device is an Access and Mobility Management Function (AMF); 82. The first communication device of claim 80 or 81, wherein the second communication device is a Session Management Function (SMF). (Appendix 83) the first communication device is a first Access and Mobility Management Function (AMF); The second communication device is a second AMF. 83. The first communication device according to any one of appendices 80 to 82. (Appendix 84) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a Protocol Data Unit (PDU) session establishment message from a second communication device in a second PLMN; and means for performing a procedure for establishing a PDU session. (Appendix 85) The message is a Nsmf_PDUSession_CreateSMContext Request message. 85. The first communications device of claim 84. (Appendix 86) the first communication device is a Session Management Function (SMF); The second communication device is an Access and Mobility Management Function (AMF); 86. The first communication device of claim 84 or 85. (Appendix 87) A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and means for transmitting a second message to a third communication device in the first PLMN to establish a PDU session. (Appendix 88) The first message is a Namf_Communication_N1MessageNotify message, The second message is the Nsmf_PDUSession_CreateSMContext Request message. 88. The first communications device of claim 87. (Appendix 89) the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; The third communication device is a Session Management Function (SMF); 89. The first communication device of claim 87 or 88. (Appendix 90) A user equipment (UE), means for communicating with a communication device; means for, when the UE is in a first Public Land Mobile Network (PLMN) and a second PLMN, continuing to stay in the first PLMN by stopping a timer, or by ignoring expiration of the timer, or by overriding the timer; The timer is configured to cause the UE to return to the second PLMN if the timer expires, the second PLMN being a Home Public Land Mobile Network (HPLMN) of the UE. (Appendix 91) The stopping is performed by the information to stop the timer. UE as described in Appendix 90. (Appendix 92) and means for determining whether the UE is in the first PLMN by scanning a PLMN identifier configured in the first PLMN. 92. The UE of claim 90 or 91. (Appendix 93) means for receiving information indicating a frequency band; means for scanning a PLMN identifier configured for the first PLMN on the frequency band; UE as described in Appendix 92. (Appendix 94) means for communicating with a communication device; means for, when visiting a first Public Land Mobile Network (PLMN) and a second PLMN, continuing to stay in the first PLMN using a PLMN list related to a Roaming Value Added Service (RVAS); The first PLMN is included in a PLMN list, the PLMN list indicates that the first PLMN is selected for RVAS in preference to a second PLMN, and the second PLMN is a Home Public Land Mobile Network (HPLMN) of the UE, user equipment (UE). (Appendix 95) and means for determining whether the UE is in the first PLMN by scanning a PLMN identifier configured in the first PLMN. UE as described in Appendix 94. (Appendix 96) means for receiving information indicating a frequency band; means for scanning a PLMN identifier configured for the first PLMN on the frequency band; UE as described in Appendix 95. (Appendix 97) 1. A method of a communication device in a first Public Land Mobile Network (PLMN), comprising: Communicating with a User Equipment (UE); transmitting information to the UE indicating to stop the timer, or to ignore the expiration of the timer, or to override the timer; the timer is configured to cause the UE to return to the second PLMN if the timer expires; The method, wherein the second PLMN is a Home Public Land Mobile Network (HPLMN) of the UE. (Appendix 98) and transmitting information to the UE indicating frequency bands to be scanned by the UE. 97. The method described in Appendix 97. (Appendix 99) A communication device in a first Public Land Mobile Network (PLMN), comprising: means for communicating with a User Equipment (UE); means for stopping the timer, or means for ignoring the expiration of the timer, or means for transmitting information to the UE indicating an override of the timer; the timer is configured to return the UE to the second PLMN if the timer expires; The second PLMN is the Home Public Land Mobile Network (HPLMN) of the UE, the communications device. (Appendix 100) means for transmitting, to the UE, information indicating frequency bands to be scanned by the UE; 99. The communication device of claim 99. (Appendix 101) 1. A method of a communication device in a first Public Land Mobile Network (PLMN), comprising: Communicating with a User Equipment (UE); transmitting a PLMN list for Roaming Value Added Service (RVAS) to cause the UE to camp on the first PLMN; the first PLMN is included in the PLMN list; the PLMN list indicates that a first PLMN is to be selected for RVAS in preference to a second PLMN; The method, wherein the second PLMN is a Home Public Land Mobile Network (HPLMN) of the UE. (Appendix 102) and transmitting information to the UE indicating frequency bands to be scanned by the UE. 102. The method of claim 101. (Appendix 103) A communication device in a first Public Land Mobile Network (PLMN), comprising: means for communicating with a User Equipment (UE); means for transmitting a PLMN list for Roaming Value Added Service (RVAS) to cause the UE to camp on a first PLMN; the first PLMN is included in the PLMN list; the PLMN list indicates that a first PLMN is to be selected for RVAS in preference to a second PLMN; The second PLMN is the Home Public Land Mobile Network (HPLMN) of the UE, the communications device. (Appendix 104) means for transmitting, to the UE, information indicating frequency bands to be scanned by the UE; 104. The communications device of claim 103. (Appendix 105) 1. A method of a communication device in a first Public Land Mobile Network (PLMN), comprising: Communicating with a User Equipment (UE); transmitting first information related to a second PLMN other than the first PLMN and second information related to a frequency band; The first information indicates a second PLMN in which the UE needs to camp; The second information indicates frequency bands that the UE should scan. (Appendix 106) A communication device in a first Public Land Mobile Network (PLMN), comprising: means for communicating with a User Equipment (UE); means for transmitting first information regarding a second PLMN other than the first PLMN and second information regarding a frequency band; The first information indicates a second PLMN in which the UE needs to camp; The second information indicates frequency bands that the UE should scan.

[0335] This application claims priority from Indian Patent Application No. 202311015787, filed on March 9, 2023, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0336] 3UE 5 NG-RAN 7 Core Network 20 Data Network 33 Control Unit 35 USIM 36 memory 71 Session Management Function (SMF) 72 User Plane Function(UPF) 73 Policy Control Function(PCF) 74 Authentication Server Function(AUSF) 75 Unified Data Management(UDM) 76 Network Slice Selection Function(NSSF) 7001 AMF 7002 AMF 7101 SMF 7102 SMF

Claims

1. 1. A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which the UE is included or a service is provided for the UE; the third information indicates the second PLMN in which the UE needs to perform the registration procedure; and sending a second message, the second message includes a registration request message and at least one of the second information and the third information.

2. transmitting fourth information indicating that the UE supports receiving the first message. The method of claim 1.

3. the first message is a registration rejection message; the second message is a Radio Resource Control (RRC) Setup Complete message; 3. The method according to claim 1 or 2.

4. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a user equipment (UE), the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; The segment indicates a group of subscribers or an area in which the UE is included or a service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in the second PLMN based on the first information and the second information; sending a second message to the second communication device, the second message comprising the registration request message.

5. transmitting third information indicating that the first communication device supports selection of the second communication device; receiving the first message includes receiving the first message when transmitting the third information; The method of claim 4.

6. the first message is a Radio Resource Control (RRC) Setup Complete message; the second message is an initial UE message.

6. The method according to claim 4 or 5.

7. the first communication device is an NG-RAN node; the second communication device is an Access and Mobility Management Function (AMF); The method according to any one of claims 4 to 6.

8. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a second communication device; the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and sending a second message to the UE; the second message includes third information indicating that the registration procedure is required and at least one of the first information and the second information.

9. transmitting fourth information indicating that the first communication device supports receiving the first message; receiving the first message includes receiving the first message when transmitting the fourth information; The method of claim 8.

10. receiving fifth information indicating that the UE supports reception of the second message; transmitting the second message includes transmitting the second message when the fifth information is received.

10. The method according to claim 8 or 9.

11. The first message is a Nudm_SDM_Get Response message, and the second message is a registration rejection message. The method according to any one of claims 8 to 10.

12. the first communication device is an Access and Mobility Management Function (AMF); the second communication device is a Unified Data Management (UDM); The method according to any one of claims 8 to 11.

13. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: communicating with a second communication device; and sending a message to the second communication device; the message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure.

14. receiving fourth information indicating that the second communication device is enabled to receive the message; the transmitting the message includes transmitting the message when the fourth information is received. The method of claim 13.

15. The message is a Nudm_SDM_Get Response message.

15. The method of claim 13 or 14.

16. the first communication device is a Unified Data Management (UDM); the second communication device is an Access and Mobility Management Function (AMF); The method according to any one of claims 13 to 15.

17. sending another message to the second communication device when the at least one of the first information and the second information is updated; the other message includes at least one of the updated first information and the updated second information; The method according to any one of claims 13 to 16.

18. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in the second PLMN based on the first information and the second information; sending a second message to the second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving the 5G-GUTI; and transmitting the 5G-GUTI and fourth information indicating that the registration procedure is required to the UE.

19. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 20. The method of claim 18.

20. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message from a second communication device in a second PLMN; The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and and transmitting the 5G-GUTI.

21. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 21. The method of claim 20.

22. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in the second PLMN based on the first information and the second information; sending a second message to the second communication device; The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); and Receiving the 5G-GUTI; Transmitting the 5G-GUTI; and sending fourth information to the UE indicating that the registration procedure is required.

23. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 23. The method of claim 22.

24. 1. A method for a User Equipment (UE), the method comprising: receiving a message from a communication device in a first Public Land Mobile Network (PLMN); The message includes information indicating that a registration procedure is required and a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in a second PLMN; and and performing the registration procedure based on the 5G-GUTI.

25. the message is a registration acceptance message.

25. The method of claim 24.

26. 1. A method for a User Equipment (UE), the method comprising: receiving a first message from a communication device in a first Public Land Mobile Network (PLMN); the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is allocated in a second PLMN; and receiving a second message, the second message includes information indicating that a registration procedure is required; and and performing the registration procedure based on the 5G-GUTI.

27. the first message is a registration acceptance message and the second message is a deregistration request message; 27. The method of claim 26.

28. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and selecting a second communication device in the second PLMN based on the first information and the second information; sending a second message to the second communication device to instruct the second communication device to perform the registration procedure for the UE.

29. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 29. The method of claim 28.

30. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message from a second communication device in a second PLMN to perform a registration procedure for the user equipment; performing said registration procedure.

31. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 31. The method of claim 30.

32. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area in which service is provided for the UE; The second information indicates the second PLMN with which the UE needs to perform a registration procedure; and receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE; selecting a second communication device in the second PLMN based on the first information and the second information; and sending a third message to the second communication device to establish the PDU session.

33. the first message is a Nudm_SDM_Get Response message, and the second message is a UL NAS TRANSPORT message; The third message is an Nsmf_PDUSession_CreateSMContext Request message.

33. The method of claim 32.

34. the first communication device is an Access and Mobility Management Function (AMF); the second communication device is a Session Management Function (SMF); 34. The method of claim 32 or 33.

35. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 35. The method of any one of claims 32 to 34.

36. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and performing a procedure for establishing the PDU session.

37. The message is an Nsmf_PDUSession_CreateSMContext Request message.

37. The method of claim 36.

38. the first communication device is a Session Management Function (SMF); the second communication device is an Access and Mobility Management Function (AMF); 38. The method of claim 36 or 37.

39. 1. A method of a first communication device in a first Public Land Mobile Network (PLMN), the method comprising: receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; and sending a second message to a third communication device in the first PLMN to establish the PDU session.

40. the first message is a Namf_Communication_N1MessageNotify message; the second message is an Nsmf_PDUSession_CreateSMContext Request message; 40. The method of claim 39.

41. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; the third communication device is a Session Management Function (SMF); 41. The method of claim 39 or 40.

42. A user equipment (UE), means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes first information indicating that a registration procedure is required, and at least one of second information regarding a segment and third information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which the UE is included or a service is provided for the UE; the third information indicating the second PLMN in which the UE needs to perform the registration procedure; and a means for transmitting a second message, the second message includes a registration request message and at least one of the second information and the third information.

43. means for transmitting fourth information indicating that the UE supports receiving the first message.

43. The UE of claim 42.

44. the first message is a registration rejection message; the second message is a Radio Resource Control (RRC) Setup Complete message; 44. The UE of claim 42 or 43.

45. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message from a user equipment (UE), the means comprising: the first message includes a registration request message and at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN of the first communication device; The segment indicates a group of subscribers or an area in which the UE is included or a service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in the second PLMN based on the first information and the second information; means for transmitting a second message to the second communication device, the second message including the registration request message.

46. means for transmitting third information indicating that the first communication device supports selection of the second communication device; means for receiving the first message when the third information is transmitted; 46. ​​The first communication device of claim 45.

47. the first message is a Radio Resource Control (RRC) Setup Complete message; the second message is an initial UE message.

47. A first communication device according to claim 45 or 46.

48. the first communication device is an NG-RAN node; the second communication device is an Access and Mobility Management Function (AMF); A first communication device according to any one of claims 45 to 47.

49. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message from a second communication device, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; a means for transmitting a second message to the UE, means for receiving the second message including third information indicating that the registration procedure is required and at least one of the first information and the second information.

50. means for transmitting fourth information indicating that the first communication device supports receiving the first message; means for receiving the first message when the fourth information has been transmitted; 50. The first communications device of claim 49.

51. means for receiving fifth information indicating that the UE supports receiving the second message; means for transmitting the second message when the fifth information is received; 51. A first communication device according to claim 49 or 50.

52. the first message is a Nudm_SDM_Get Response message; the second message is a registration rejection message; A first communication device according to any one of claims 49 to 51.

53. the first communication device is an Access and Mobility Management Function (AMF); the second communication device is a Unified Data Management (UDM); A first communication device according to any one of claims 49 to 52.

54. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for communicating with a second communication device; means for sending a message to the second communication device; the message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; The first communication device, wherein the second information indicates the second PLMN with which the UE needs to perform a registration procedure.

55. means for receiving fourth information indicating that the second communication device supports receiving the message; means for transmitting the message when the fourth information is received; 55. The first communications device of claim 54.

56. The message is a Nudm_SDM_Get Response message.

56. A first communication device according to claim 54 or 55.

57. the first communication device is a Unified Data Management (UDM); the second communication device is an Access and Mobility Management Function (AMF); A first communication device according to any one of claims 54 to 56.

58. means for transmitting another message to the second communication device when the at least one of the first information and the second information is updated; the other message includes at least one of the updated first information and the updated second information. A first communication device according to any one of claims 54 to 57.

59. A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in the second PLMN based on the first information and the second information; means for transmitting a second message to the second communication device, The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); A means for receiving the 5G-GUTI; A first communication device including: means for transmitting the 5G-GUTI and fourth information indicating that the registration procedure is required to the UE.

60. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 60. The first communications device of claim 59.

61. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a message from a second communication device in a second PLMN, the means comprising: The message includes information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); A first communication device comprising: a means for transmitting the 5G-GUTI.

62. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 62. The first communications device of claim 61.

63. A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers or an area in which a User Equipment (UE) is included in the group or in which service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in the second PLMN based on the first information and the second information; means for transmitting a second message to the second communication device, The second message includes third information requesting allocation of a 5G Globally Unique Temporary Identifier (5G-GUTI); A means for receiving the 5G-GUTI; A means for transmitting the 5G-GUTI; means for transmitting fourth information to the UE indicating that the registration procedure is required.

64. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 64. The first communications device of claim 63.

65. A user equipment (UE), means for receiving a message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: The message includes information indicating that a registration procedure is required and a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is assigned in a second PLMN; and and means for performing the registration procedure based on the 5G-GUTI.

66. the message is a registration acceptance message.

66. The UE of claim 65.

67. A user equipment (UE), means for receiving a first message from a communication device in a first Public Land Mobile Network (PLMN), the means comprising: the first message includes a 5G Globally Unique Temporary Identifier (5G-GUTI); The 5G-GUTI is assigned in a second PLMN; and a means for receiving a second message, the second message includes information indicating that a registration procedure is required; and and means for performing the registration procedure based on the 5G-GUTI.

68. the first message is a registration acceptance message; the second message is a deregistration request message.

68. The UE of claim 67.

69. A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; means for selecting a second communication device in the second PLMN based on the first information and the second information; means for transmitting a second message to the second communication device to instruct the second communication device to perform the registration procedure for the UE.

70. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 70. The first communications device of claim 69.

71. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message from a second communication device in a second PLMN for performing a registration procedure for the user equipment; and means for performing the registration procedure.

72. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; 72. The first communications device of claim 71.

73. A first communication device in a first Public Land Mobile Network (PLMN), comprising: a means for receiving a first message, the first message includes at least one of first information regarding a segment and second information regarding a second PLMN other than the first PLMN; The segment indicates a group of subscribers, or a User Equipment (UE) included in the group, or an area in which service is provided for the UE; the second information indicating the second PLMN with which the UE needs to perform a registration procedure; means for receiving a second message for establishing a Protocol Data Unit (PDU) session from the UE; means for selecting a second communication device in the second PLMN based on the first information and the second information; A first communication device comprising: means for transmitting a third message to the second communication device for establishing the PDU session.

74. the first message is a Nudm_SDM_Get Response message; the second message is a UL NAS TRANSPORT message; The third message is an Nsmf_PDUSession_CreateSMContext Request message.

74. The first communications device of claim 73.

75. the first communication device is an Access and Mobility Management Function (AMF); the second communication device is a Session Management Function (SMF); 75. A first communication device according to claim 73 or 74.

76. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; A first communication device according to any one of claims 73 to 75.

77. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; A first communication device comprising: means for performing a procedure for establishing the PDU session.

78. The message is an Nsmf_PDUSession_CreateSMContext Request message.

78. The first communications device of claim 77.

79. the first communication device is a Session Management Function (SMF); the second communication device is an Access and Mobility Management Function (AMF); 79. A first communication device according to claim 77 or 78.

80. A first communication device in a first Public Land Mobile Network (PLMN), comprising: means for receiving a first message for establishing a Protocol Data Unit (PDU) session from a second communication device in a second PLMN; means for transmitting a second message to a third communication device in the first PLMN to establish the PDU session.

81. the first message is a Namf_Communication_N1MessageNotify message; the second message is an Nsmf_PDUSession_CreateSMContext Request message; 81. The first communications device of claim 80.

82. the first communication device is a first Access and Mobility Management Function (AMF); the second communication device is a second AMF; the third communication device is a Session Management Function (SMF); 82. A first communication device according to claim 80 or 81.

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