Method of a first access and mobility management function (AMF) device and a first access and mobility management function (AMF) device

Abstract

This disclosure defines a registration procedure via an AMF reallocation procedure when the UE is in a CM-CONNECTED state. A method in a first Access and Mobility Management Function (AMF) device includes receiving a registration request message for a user equipment (UE) in a CM-CONNECTED state from a Radio Access Network (RAN), and directly sending the registration request message to a second AMF device.

Description

[Technical field]

[0001] The present disclosure relates to a method of a first Access and Mobility Management Function (AMF) device, a method of a user equipment (UE), a first Access and Mobility Management Function (AMF) device, and a user equipment (UE). [Background technology]

[0002] According to the registration by AMF reallocation procedure defined in Non-Patent Document 3, an initial UE message from the UE is forwarded from the initial AMF to the target AMF directly or via the RAN. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications". V17.0.0 (2020-07) [Non-Patent Document 2] 3GPP TS 23.501: "System architecture for the 5G System (5GS)". V17.0.0 (2021-03) [Non-Patent Document 3] 3GPP TS 23.502: "Procedures for the 5G System (5GS)". V17.0.0 (2021-03) [Non-Patent Document 4] 3GPP TS 38.413: "NG-RAN; NG Application Protocol (NGAP)". V16.5.0 (2021-04) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the current 3GPP specifications, it is not clear how non-initial UE messages can be transferred from the initial AMF to the target AMF when the initial AMF decides to reallocate an AMF to the UE.

[0005] That is, there is no 3GPP specification that defines how a non-initial UE message can be transferred from the initial AMF to the target AMF when the initial AMF decides to reallocate the AMF to the UE. Due to the lack of procedures defined in the 3GPP specification, some registration management procedures do not work, leading to degradation of services for mobile users. [Means for solving the problem]

[0006] In an aspect of the present disclosure, a method of a first Access and Mobility Management Function (AMF) device includes receiving a registration request message of a user equipment (UE) in a CM-CONNECTED state from a radio access network (RAN), and the method includes directly sending the registration request message to a second AMF device.

[0007] In an aspect of the present disclosure, a method of a first Access and Mobility Management Function (AMF) device includes communicating with a second AMF device, the method including receiving a registration request message for a user equipment (UE) in a CM-CONNECTED state directly from the second AMF device.

[0008] In an aspect of the present disclosure, a method of a user equipment (UE) includes communicating with a radio access network (RAN). The method includes sending a registration request message of the UE in a CM-CONNECTED state to the RAN. The registration request message is sent by the RAN to a first Access and Mobility Management Function (AMF) device, and the registration request message is sent directly by the first AMF device to a second AMF device.

[0009] In an aspect of the present disclosure, a first Access and Mobility Management Function (AMF) device includes means for receiving a registration request message of a user equipment (UE) in a CM-CONNECTED state from a radio access network (RAN). The first AMF device includes means for directly sending the registration request message to a second AMF device.

[0010] In an aspect of the present disclosure, a first Access and Mobility Management Function (AMF) device includes means for communicating with a second AMF device. The first AMF device includes means for directly receiving a registration request message of a user equipment (UE) in a CM-CONNECTED state from the second AMF device.

[0011] In an aspect of the present disclosure, a user equipment (UE) includes means for communicating with a radio access network (RAN). The UE includes means for sending a registration request message of the UE in a CM-CONNECTED state to the RAN. The registration request message is sent by the RAN to a first Access and Mobility Management Function (AMF) device, and the registration request message is sent directly by the first AMF device to a second AMF device. [Brief description of the drawings]

[0012] [Figure 1] Figure 1 shows a registration with AMF reassignment procedure (transferred via RAN). [Diagram 2] FIG. 2 shows the structure of the reroute NAS message. [Diagram 3] Figure 3 shows registration with AMF reassignment procedure (direct transfer from S-AMF to T-AMF). [Figure 4] FIG. 4 shows an overview of the system. [Diagram 5] FIG. 5 is a block diagram of a user equipment (UE). [Figure 6] FIG. 6 is a block diagram of an (R)AN node. [Figure 7] FIG. 7 shows a system overview of an (R)AN node 5 based on the O-RAN architecture. [Figure 8] FIG. 8 is a block diagram of the radio unit (RU). [Figure 9] FIG. 9 is a block diagram of the distribution unit (DU). [Figure 10] FIG. 10 is a block diagram of the consolidation unit (CU). [Figure 11] FIG. 11 is a block diagram of the AMF. [Figure 12] FIG. 12 is a block diagram of the UDM. [Figure 13] FIG. 13 is a block diagram of the Network Slice Selection Function (NSSF). [Figure 14] FIG. 14 is a block diagram of the Network Repository Function (NRF). [Figure 15] Figure 15 shows registration via AMF reassignment procedure. [Figure 16] FIG. 16 shows a reroute NAS request. [Figure 17] FIG. 17 shows the uplink NAS transport. [Figure 18] FIG. 18 shows the structure of the uplink NAS transport message. [Figure 19] FIG. 19 shows the structure of a reroute NAS request message. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Description of the Disclosure with Reference to Aspects Each of the aspects and elements included in each aspect described below may be implemented independently or in combination with each other, and each aspect includes different novel features, and thus contributes to achieving different objectives or solving different problems and achieving different advantages.

[0014] <abbreviation> For purposes of this specification, the abbreviations given in Non-Patent Document 1 and the following apply: An abbreviation defined in this specification takes precedence over the definition of the same abbreviation in Non-Patent Document 1 if such abbreviation exists.

[0015] 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 AS Access Stratum ATSSS Access Traffic Steering, Switching, Splitting ATSSS-LL ATSSS Low-Layer AUSF Authentication Server Function AUTN Authentication token 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 GPSI Generic Public Subscription Identifier GUAMI Globally Unique AMF Identifier GUTI Globally Unique Temporary UE Identity HR Home Routed (roaming) IAB Integrated access and backhaul IMEI / TAC IMEI Type Allocation Code 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 MFBR Maximum Flow Bit Rate MICO Mobile Initiated Connection Only MITM Man In the Middle MNC Mobile Network Code MPS Multimedia Priority Service MPTCP Multi-Path TCP Protocol N3IWF Non-3GPP InterWorking Function 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 NG-RAN Next Generation Radio Access Network NID Network identifier NPN Non-Public Network NR New Radio 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 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 RG Residential Gateway RIM Remote Interference Management RQA Reflective QoS Attribute RQI Reflective QoS Indication RSN Redundancy Sequence Number SA NR Standalone New Radio SBA Service Based Architecture SBI Service Based Interface SCP Service Communication Proxy SD Slice Differentiator SEAF Security Anchor Functionality SEPP Security Edge Protection Proxy 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 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 TAI Tracking Area Identity 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 GM 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 UL Uplink UL CL Uplink Classifier UPF User Plane Function URLLC Ultra Reliable Low Latency Communication URRP-AMF UE Reachability Request Parameter for AMF URSP UE Route Selection Policy VID VLAN Identifier VLAN Virtual Local Area Network VPLMN Visited PLMN 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

[0016] <Definition> For purposes of this specification, the terms and definitions given in Non-Patent Document 1 and the following apply. Terms defined in this specification take precedence over the definition of the same term in Non-Patent Document 1 if such term appears therein.

[0017] <General remarks> Those skilled in the art will appreciate that elements in the figures may be shown in simplified form and not necessarily drawn to scale. Further, with respect to the structure of a device, one or more components of the device may be represented by conventional symbols in the figures, and the figures may show only certain details appropriate to understanding 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.

[0018] To promote an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe such principles, nevertheless it will be understood that no limitation of the scope of the disclosure is intended thereby.

[0019] Such alterations and further modifications in the depicted system, 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.

[0020] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method including a list of steps not only includes those steps, but may also include other steps that are not expressly listed or that are inherent in such process or method.

[0021] Similarly, the use of "comprising" one or more devices, entities, subsystems, elements, structures, or components does not exclude the presence of other devices, subsystems, elements, structures, components, additional devices, additional subsystems, additional elements, additional structures, or additional components without further constraints. Throughout this specification, the appearances of the phrases "in an embodiment," "in another embodiment," and similar terms may all refer to the same embodiment, but do not necessarily do so.

[0022] 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.

[0023] In the following specification and claims, reference will be made to a number of terms that are defined to have the following meanings: The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0024] Information as used herein refers to data and knowledge, since data is meaningful information and represents values ​​attributed to parameters. Moreover, knowledge refers to an understanding of an abstract or concrete concept. It should be noted that this exemplary system is simplified to facilitate the description 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 contemplated to be within the scope of the present disclosure.

[0025] In this disclosure, the first access type may be 3GPP access and the second access type may be non-3GPP access, or vice versa, respectively.

[0026] <First aspect> The first aspect solves the problem when a serving AMF (or S-AMF) reassigns a new AMF (or target AMF or T-AMF) by rerouting a NAS message (e.g., a non-initial UE message) to the new AMF via NG-RAN.

[0027] When the serving AMF receives a registration request message including a Requested NSSAI for a UE in CM-CONNECTED state, if the serving AMF does not support one or more S-NSSAIs from the Requested NSSAI, the serving AMF sends a message including the Requested NSSAI to the NSSF. The NSSF determines an AMF that can provide one or more S-NSSAIs included in the Requested NSSAI. The NSSF returns a list of Allowed NSSAIs and Rejected S-NSSAIs, as well as an address of a target AMF that can provide the S-NSSAI included in the Allowed NSSAI. In this case, the serving AMF reroutes the registration request message received from the UE to the NG-RAN in a first NGAP message (e.g., a Reroute NAS message). The serving AMF includes the target AMF address (or the address of the target AMF), the list of Allowed NSSAIs and Rejected S-NSSAIs, and the security context of the UE in an NGAP message to the NG-RAN. Upon receiving the first NGAP message, the NG-RAN sends a registration request message to the target AMF in a second NGAP message (e.g., an uplink NAS transport). Upon receiving the registration request message, the target AMF proceeds with the registration procedure.

[0028] The detailed steps of the registration procedure with AMF reassignment are given below.

[0029] 0. The UE is registered with a serving AMF (or S-AMF) for S-NSSAI1 in the first access type. 5G-GUTI1 is assigned to the UE by the S-AMF.

[0030] Since there is an active PDU session associated with S-NSSAI1, the UE is in a CM-CONNECTED state, which may be referred to as a CM-CONNECTED mode.

[0031] In one example, the UE and the S-AMF have an N1 signaling connection in which no PDU session is established, or in which a PDU session is established but no data radio bearer (DRB) is established.

[0032] 1. While the UE is in CM-CONNECTED mode in a first access type, the UE receives a trigger, e.g., from an application on the UE, to register with both S-NSSAI1 and S-NSSAI2. For example, the UE in CM-CONNECTED mode performs a registration procedure to register with both the network slice indicated by S-NSSAI1 and the network slice indicated by S-NSSAI2.

[0033] 2. The UE sends a registration request message including a request NSSAI to the S-AMF. For example, the request NSSAI includes S-NSSAI1 and S-NSSAI2.

[0034] 3. When the NG-RAN (or (R)AN, (R)AN node, or NG-RAN node) receives the registration request message piggybacked in the UL information transfer message, the NG-RAN forwards the registration request message to the S-AMF by including the registration request message in an uplink NAS transport message. For example, the NG-RAN sends an uplink NAS transport message including the registration request message to the S-AMF. The uplink NAS transport message may be referred to as a non-initial UE message.

[0035] 4a. The S-AMF sends Nnssf_NSSelection_Get to the NSSF. Nnssf_NSSelection_Get may be referred to as an Nnssf_NSSelection_Get message. For example, if the S-AMF does not support one or more S-NSSAIs included in the request NSSAI of the registration request message, the S-AMF sends Nnssf_NSSelection_Get to the NSSF.

[0036] Nnssf_NSSelection_Get includes the requested NSSAI, NSSRG information (or information indicating the NSSRG or NSSRG information), mapping of the requested NSSAI, subscribed S-NSSAI in default S-NSSAI indication, TAI, allowed NSSAI for other access types (if any), mapping of allowed NSSAI, and PLMN ID of SUPI.

[0037] If network slice selection is required (see section 5.15.5.2.1 of non-patent document 2) and, for example, the S-AMF cannot provide all S-NSSAIs from the requested NSSAI that are allowed by the subscription information, the S-AMF performs an Nnssf_NSSelection_Get service operation from the NSSF by including the requested NSSAI, NSSRG information, optionally the mapping of the requested NSSAI, the subscribed S-NSSAI in the default S-NSSAI indication, the allowed NSSAIs for other access types (if any), the mapping of the allowed NSSAI, the PLMN ID of the SUPI, and the TAI of the UE.

[0038] The S-AMF may also include Network Slice Simultaneous Registration Group (NSSRG) membership information for each S-NSSAI from the NSSAI requested by the UE. The NSSRG membership information may be referred to as NSSRG information. The S-AMF may store the NSSRG information in the UE context received from the old AMF (or another AMF) when the UE is requesting mobility registration, or the S-AMF may obtain the NSSRG information from the UDM when the UE is requesting initial registration.

[0039] If one or more S-NSSAIs from the UE's Requested NSSAI are under the control of NSAC (Network Slice Admission Control) and there is no available allocation for the S-NSSAI (i.e., the number of registered UEs on the S-NSSAI has reached the maximum allowed value), the S-AMF may derive the S-NSSAI from the Requested NSSAI in the Nnssf_NSSelection_Get message and the S-AMF shall treat the S-NSSAI as a Rejected S-NSSAI.

[0040] If the S-NSSAI is under the control of an NSSAA and the NSSAA is revoked or the NSSAA status is failed in the S-AMF, the S-AMF removes the S-NSSAI from the requesting NSSAI in the Nnssf_NSSelection_Get message, i.e., the S-AMF does not send this S-NSSAI in the requesting NSSAI.

[0041] 4b. The NSSF sends a response to the Nnssf_NSSelection_Get to the S-AMF. The response may be called Nnssf_NSSelection_Get_Response. The response includes an AMF set or list of AMF addresses, allowed NSSAIs for the first access type, mapping of allowed NSSAIs, allowed NSSAIs for the second access type, mapping of allowed NSSAIs, NSI ID, NRF, list of rejected S-NSSAIs, rejection cause value, configured NSSAIs for the serving PLMN, mapping of configured NSSAIs. The AMF set may be a target AMF (T-AMF) set. The list of AMF addresses may be a list of T-AMF addresses.

[0042] The NSSF performs the steps specified in point (B) in clause 5.15.5.2.1 of 3GPP TS 2010-010116. The NSSF returns (or transmits) to the serving AMF (i.e., S-AMF) the authorized NSSAI for the first access type, optionally the mapping of the authorized NSSAI, the authorized NSSAI for the second access type (if any), optionally the mapping of the authorized NSSAI, and the target AMF (T-AMF) set, or a list of candidate AMFs based on the configuration (e.g., a list of T-AMFs). The NSSF may return (or transmit) to the serving AMF (i.e., S-AMF) the NSI ID associated with the network slice instance corresponding to the particular S-NSSAI. The NSSF may return (or transmit) to the serving AMF (i.e., S-AMF) the NSI ID used to select an NF / service in the selected network slice instance. The NSSF may also return (or send) information regarding the rejection cause for the S-NSSAI that is not included in the allowed NSSAI to the serving AMF (i.e., S-AMF). The NSSF may return (or send) the configured NSSAI for the serving PLMN, and possibly the associated mapping of the configured NSSAI, to the serving AMF (i.e., S-AMF).

[0043] If the S-AMF includes the NSSRG affiliation information for the S-NSSAI from the requesting NSSAI in the Nnssf_NSSelection_Get, the NSSF may take into account the provided NSSRG information when selecting a T-AMF (or a target AMF) or a T-AMF set for AMF reassignment. For example, the S-AMF may select a T-AMF based on the NSSRG information.

[0044] 5a. If the S-AMF does not locally store the target AMF (or T-AMF) address and if the S-AMF intends to use direct reroute to the target AMF (or T-AMF) or if the reroute via an (R)AN message needs to include the AMF address, the S-AMF performs an Nnrf_NFDiscovery_Request service operation from the NRF to find a suitable target AMF (or T-AMF) that has the NF functions required to serve the UE.

[0045] The NF type is set to AMF. The AMF set is included in the Nnrf_NFDiscovery_Request. For example, the S-AMF sends a Nnrf_NFDiscovery_Request message to the NRF.

[0046] 5b. The NRF responds with a list of potential T-AMFs. For example, the NRF sends an Nnrf_NFDiscovery_Response message to the S-AMF containing a list of potential T-AMFs. The NRF may also provide details of the services offered by the candidate AMFs, if available, along with notification endpoints for each type of notification service that the selected AMF has registered with the NRF. For example, the NRF sends an Nnrf_NFDiscovery_Response message to the S-AMF containing details of the services offered by the candidate AMFs, along with notification endpoints for each type of notification service that the selected AMF has registered with the NRF. Alternatively, the NRF provides a list of potential T-AMFs and the capabilities of the T-AMFs, and optionally additional selection rules.

[0047] For example, the NRF sends an Nnrf_NFDiscovery_Response message to the S-AMF that contains a list of possible T-AMFs and their capabilities, and optionally additional selection rules. Based on information about registered NFs and required capabilities, the T-AMF is selected by the S-AMF.

[0048] 6. The S-AMF sends a Reroute NAS message to the (R)AN (or an (R)AN node, an NG-RAN, or an NG-RAN node). The Reroute NAS message may be referred to as a Re-Route NAS message. The Reroute NAS message includes at least information about the T-AMF, an authorized NSSAI for the first access type, an authorized NSSAI for the second access type, NSSRG information, a Rejected NSSAI, NAS security information for both the first access type and the second access type, and an uplink NAS transport message including a registration request message from the UE. The information about the T-AMF, the authorized NSSAI, and the Rejected NSSAI may be obtained in step 4b from the NSSF. The information about the T-AMF may include at least one of an AMF set, a target AMF (T-AMF) set, a list of AMF addresses, and a list of T-AMF addresses. The authorized NSSAI included in the Reroute NAS message may include the S-NSSAI2. The reject NSSAI included in the reroute NAS message may include S-NSSAI1.

[0049] In one example, the AMF changes the uplink NAS transport message to a new message including the information elements sent in an existing NGAP message, such as an initial UE message, or an uplink NAS transport message, and sends it to the NG-RAN in a reroute NAS message. The registration request message in the uplink NAS transport message may be the one sent from the UE or the registration request message decrypted by the S-AMF.

[0050] The NSSRG information is about the NSSRG affiliation of the S-NSSAI in the Authorized NSSAI.

[0051] This NSSRG information is also forwarded to the T-AMF so that the T-AMF may take the NSSRG information into account when determining a new or updated authorized NSSAI for the UE at the T-AMF.

[0052] Since some (R)ANs may not have the capability to forward uplink NAS transport messages to the T-AMF, the (R)AN may inform the S-AMF about the (R)AN's capability to forward uplink NAS transport messages by a new capability indication set in the NG SETUP REQUEST message, the RAN CONFIGURATION UPDATE message, and the AMF CONFIGURATION UPDATE ACKNOWLEDGE message. For example, if the S-AMF receives a capability from the (R)AN indicating that the (R)AN supports forwarding (or sending) uplink NAS transport messages to the T-AMF, the S-AMF may send a reroute NAS message to the (R)AN.

[0053] 2 shows an example of the structure of a reroute NAS message. In one example, the reroute NAS message can be an existing NGAP message or a new NGAP message. The reroute NAS message can be called a REROUTE NAS REQUEST message.

[0054] 7. The (R)AN sends an uplink NAS transport message to the T-AMF. For example, when the (R)AN receives a reroute NAS message from the S-AMF, the (R)AN determines the T-AMF based on information about the T-AMF (e.g., the address of the T-AMF) and sends an uplink NAS transport message to the T-AMF. The uplink NAS transport message includes at least one information element sent in the reroute NAS message, e.g., the registration request message, and optionally the NAS security information of the first access type or the second access type, and an indication that the registration request message from the UE is rerouted due to the request NSSAI being changed by the UE. For example, the uplink NAS transport message includes NSSRG information.

[0055] If the registration request message received in step 6 from the S-AMF was decrypted by the S-AMF, the (R)AN includes the registration request message received in step 2 from the UE in the uplink NAS transport message instead of the one received from the S-AMF. The (R)AN may detect by comparison that the registration request message received from the S-AMF is not the same as the one received in step 2.

[0056] In one example, the uplink NAS transport message is an existing NGAP message or a new NGAP message.

[0057] 8. In the T-AMF corresponding to the new AMF, the T-AMF continues the registration procedure from step 4 of chapter 4.2.2.2.2 in non-patent document 3.

[0058] <Second aspect> The second aspect solves the problem when the serving AMF reassigns a new AMF by directly forwarding a NAS message (e.g., a non-initial UE message) to the target AMF.

[0059] When the serving AMF receives a registration request message including a request NSSAI for a UE in CM-CONNECTED state, if the serving AMF does not support one or more S-NSSAIs from the request NSSAI, the serving AMF sends a message including the request NSSAI to the NSSF. The NSSF determines an AMF that can provide one or more S-NSSAIs included in the request NSSAI. The NSSF returns a list of allowed NSSAIs and rejected S-NSSAIs, as well as the address of a target AMF that can provide the S-NSSAI included in the allowed NSSAI. In this case, the serving AMF reroutes the registration request message received from the UE directly to the target AMF. Upon receiving the registration request message, the target AMF proceeds with the registration procedure.

[0060] The detailed steps of the registration procedure with AMF reassignment are given below.

[0061] Steps 0 to 5b in FIG. 3 are the same as steps 0 to 5b in FIG.

[0062] 6. If the S-AMF decides to forward a NAS message (e.g., a registration request message received from the UE) directly to the target AMF (T-AMF) based on local policy and subscription information, the S-AMF executes Namf_Communication_N1MessageNotify to the T-AMF to convey the rerouted NAS message (e.g., a registration request message received from the UE).

[0063] For example, the S-AMF determines the T-AMF based on information about the T-AMF (e.g., the address of the T-AMF) and executes Namf_Communication_N1MessageNotify to the T-AMF. For example, the S-AMF sends Namf_Communication_N1MessageNotify to the T-AMF.

[0064] The Namf_Communication_N1MessageNotify service operation (or Namf_Communication_N1MessageNotify) includes information that enables the (R)AN to identify the N2 termination point, if available, the full registration request message (e.g., the registration request message received from the UE), and the UE's SUPI and MM context. If the initial AMF (i.e., S-AMF) has obtained information from the NSSF as described in step 4b, the information, except for the AMF set or the list of AMF addresses, is included in Namf_Communication_N1MessageNotify. Namf_Communication_N1MessageNotify may be referred to as a Namf_Communication_N1MessageNotify message.

[0065] In addition, the Namf_Communication_N1MessageNotify may include an authorized NSSAI for the first access type, an authorized NSSAI for the second access type, NSSRG information, a denied NSSAI, and NAS security information for both the first access type and the second access type.

[0066] The NSSRG information is about the NSSRG affiliation of the S-NSSAI in the Authorized NSSAI.

[0067] This NSSRG information is also forwarded to the T-AMF so that the T-AMF may take the NSSRG information into account when determining a new or updated authorized NSSAI for the UE at the T-AMF.

[0068] The target AMF (T-AMF) then updates the (R)AN with the new updated N2 termination point for the UE in a first message from the target AMF (T-AMF) to the (R)AN in step 8.

[0069] 7.T-AMF sends a Namf_Communication_N1MessageNotify response message to S-AMF.

[0070] For example, when T-AMF receives a Namf_Communication_N1MessageNotify message, T-AMF sends a Namf_Communication_N1MessageNotify response message to S-AMF.

[0071] Step 8 in FIG. 3 is the same as step 8 in FIG.

[0072] <System Overview> FIG. 4 illustrates diagrammatically a mobile (cellular or wireless) telecommunications system 1 to which the above aspects are applicable.

[0073] The telecommunication system 1 represents a system overview capable of end-to-end communication, e.g., UEs 3 (or user equipment, "mobile devices" 3) communicating with other UEs 3 or service servers in a data network 20 via respective (R)AN nodes 5 and a core network 7.

[0074] The (R)AN node 5 supports any radio access, including 5G radio access technologies (RATs), E-UTRA radio access technologies, Beyond 5G RATs, 6G RATs, and non-3GPP RATs, including wireless local area network (WLAN) technologies as defined by the Institute of Electrical and Electronics Engineers (IEEE).

[0075] The (R)AN node 5 may be separated into a radio unit (RU), a distributed unit (DU), and a centralized unit (CU). In some aspects, the units may be connected to each other to build the (R)AN node 5 by adopting an architecture as defined by the Open RAN (O-RAN) Alliance, and the units are referred to as O-RU, O-DU, and O-CU, respectively.

[0076] The (R)AN node 5 may be separated into a control plane function and a user plane function. 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 in each user plane function being aggregated at both the UE 3 and the (R)AN node 5. This separated architecture may be referred to as "dual connectivity" or "multi-connectivity."

[0077] The (R)AN node 5 may also support communications using satellite access. In some aspects, the (R)AN node 5 may support satellite and terrestrial access.

[0078] In addition, the (R)AN node 5 may also be referred to as an access node for non-wireless access, including fixed access as defined by the Broadband Forum (BBF) and optical access as defined by the Innovative Optical and Wireless Network (IOWN).

[0079] The core network 7 may include logical nodes (or "functions") that support communications in the telecommunications system 1. For example, the core network 7 may be a 5G Core Network (5GC) that includes control plane functions and user plane functions, among other functions. Each function in 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).

[0080] By adapting network virtualization technologies such as those defined by the 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 providing several execution instances at each location.

[0081] 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).

[0082] As is known, when the UE 3 is moving around the geographic area covered by the telecommunication system 1, the UE 3 may move in and out of areas (i.e., radio cells) served by the (R)AN nodes 5. To keep track of the UE 3 and facilitate movement between the various (R)AN nodes 5, the core network 7 comprises at least one Access and Mobility Management Function (AMF) 70. The AMF 70 communicates with the (R)AN nodes 5 connected to the core network 7. In some core networks, a mobility management entity (MME) or mobility management node for Beyond 5G or a mobility management node for 6G may be used instead of the AMF 70.

[0083] The core network 7 also includes, among others, a Session Management Function (SMF) 71, a User Plane Function (UPF) 72, a Policy Control Function (PCF) 73, a Network Exposure Function (NEF) 74, a Unified Data Management (UDM) 75, a Network Data Analytics Function (NWDAF) 76, a Network Slice Selection Function (NSSF) 77, and a Network Repository Function (NRF) 78. When a UE 3 roams into a visited Public Land Mobile Network (VPLMN), the home Public Land Mobile Network (HPLMN) of the UE 3 provides the UDM 75 and at least some of the functionality of the SMF 71, UPF 72, and PCF 73 to the roaming-out UE 3.

[0084] The UE 3 and the respective serving (R)AN node 5 are connected via an appropriate air interface (e.g., the so-called "Uu" interface and / or the like). Neighboring (R)AN nodes 5 are connected to each other via appropriate (R)AN node 5 to (R)AN node interfaces (such as the so-called "Xn" interface and / or the like). Each (R)AN node 5 is also connected to nodes in the core network 7 (such as the so-called core network nodes) via appropriate interfaces (such as the so-called "N2" / "N3" interfaces and / or the like). From the core network 7, a connection is also provided to a data network 20. The data network 20 may be the Internet, a public network, an external network, a private network, or an internal network of the PLMN. If the data network 20 is provided by a PLMN operator or a Mobile Virtual Network Operator (MVNO), IP Multimedia Subsystem (IMS) services may be provided by the data network 20. The UE 3 may be connected to the data network 20 using IPv4, IPv6, IPv4v6, Ethernet, or unstructured data types.

[0085] The "Uu" interface may include a control plane of the Uu interface and a user plane of the Uu interface.

[0086] 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 hierarchical structure with SDAP, PDCP, RLC, and MAC sublayers over physical connections. 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 physical connections.

[0087] For example, the following messages are communicated at the RRC layer to support AS signaling:

[0088] - 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. ue-Identity may have the value of ng-5G-S-TMSI-Part1 or randomValue.

[0089] - 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

[0090] - 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

[0091] The UE 3 and the AMF 70 are connected via a suitable interface (e.g., a so-called N1 interface and / or the like). 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 in 3GPP access and non-3GPP access. For example, the following messages are communicated in the N1 interface:

[0092] - Registration 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 included together in the Registration Request message: --5GS registration type, ngKSI, 5GS mobile identity, non-current native NAS key set identifier, 5GMM capabilities, UE security capabilities, requested NSSAI, last visited registration TAI, S1 UE network capabilities, uplink data state, PDU session state, MICO indication, UE state, additional GUTI, granted PDU session state, 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 state, requested extended DRX parameters, T3324 value, UE radio capability ID, requested mapping NSSAI, additional requested information, requested WUS assistance information, N5GC indication, and requested NB-N1 mode DRX parameters.

[0093] - 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 state, PDU session restart result, PDU session restart 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 state, negotiated extended DRX parameters, T3447 value, T3448 value, T3324 value, UE radio capability ID, UE radio capability ID removal indication, pending NSSAI, ciphering key data, CAG information list, simplified 5G-S-TMSI configuration, negotiated WUS support information, negotiated NB-N1 mode DRX parameters, and extended rejected NSSAI.

[0094] - Registration 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 included together in the registration complete message: --SOR transparent container.

[0095] -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.

[0096] -Authentication Response 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 present together in the authentication response message: --authentication response message identification information, authentication response parameters, and EAP message.

[0097] -Authentication Result Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by the aspects of the present disclosure, the following parameters may be present together in the Authentication Result message: --ngKSI, EAP Messages, and ABBA.

[0098] -Authentication Failure 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 present together in the Authentication Failure Message: --Authentication failure message identification information, 5GMM cause, and authentication failure parameters.

[0099] -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 present together in the Authentication Rejection message: --EAP messages.

[0100] -Service 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 present together in the Service Request message: --ngKSI, Service Type, 5G-S-TMSI, Uplink Data State, PDU Session State, Granted PDU Session State, NAS Message Container.

[0101] -Service Authorization Message: This message is sent from the AMF 70 to the UE 3. In addition to the parameters disclosed by the aspects of the present disclosure, the following parameters may be present together in the Service Authorization Message: --PDU session state, PDU session restart result, PDU session restart result error cause, EAP message, and T3448 value.

[0102] - 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 present together in the Service Rejection message: --5GMM cause, PDU session state, T3346 value, EAP message, T3448 value, and CAG information list.

[0103] -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 present together in the Configuration Update Command message: --Configuration update indication, 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 indication, network slicing indication, configured NSSAI, rejected NSSAI, operator defined access category definition, SMS indication, T3447 value, CAG information list, UE radio capability ID, UE radio capability ID deletion indication, 5GS registration result, simplified 5G-S-TMSI configuration, additional configuration indication, and extended rejected NSSAI.

[0104] -Configuration Update 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 present together in the configuration update complete message: --Configuration update complete message identification information.

[0105] <User Equipment (UE)> 5 is a block diagram illustrating the main components of a UE 3 (mobile device 3). As shown, the UE 3 includes a transceiver circuit 31 operable to transmit signals to and receive signals from a connection node via one or more antennas 32. In addition, the UE 3 may include a user interface 34 for inputting information from the outside or outputting information to 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 appropriate.

[0106] For example, the software may be pre-installed in the memory and / or downloaded over a telecommunications network or from a removable data storage device (RMD). The controller 33 controls the operation of the UE 3 according to the 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 a transceiver control module 3621. The communication control module 362 (using its transceiver control module 3621) controls communication between the UE 3, the (R)AN node 5 and the AMF 70 The controller 33 is responsible for processing (generating / sending / receiving) signaling and uplink / downlink data packets between the UE 3 and other nodes such as the UE 4 and the UE 5. 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 controller 33 interacts with one or more Universal Subscriber Identity Modules (USIMs) 35. In case of multiple USIMs 35, the controller 33 may activate only one USIM 35 or may activate multiple USIMs 35 simultaneously.

[0107] The UE 3 may, for example, support a non-public network (NPN), which may be a standalone non-public network (SNPN) or a public network integrated NPN (PNI-NPN).

[0108] UE3 may be, for example, an item of production or manufacturing equipment and / or an item of energy-related machinery (e.g., equipment or machines such as boilers, engines, turbines, solar panels, wind turbines, hydroelectric generators, thermal generators, nuclear generators, batteries, nuclear systems and / or related equipment, heavy electrical machinery, pumps including vacuum pumps, compressors, fans, blowers, hydraulic equipment, pneumatic equipment, metal processing machines, manipulators, robots and / or application systems thereof, tools, moulds or dies, rolls, conveying equipment, lifting equipment, material handling equipment, textile machinery, sewing machines, printing machines and / or related machines, paper converting machines, chemical machinery, mining machinery and / or construction machinery and / or related equipment, agricultural, forestry and / or fishing machinery and / or implements, safety and / or environmental protection equipment, tractors, precision bearings, chains, gears, power transmission equipment, lubrication equipment, valves, fittings, and / or application systems for any of the foregoing equipment or machines).

[0109] UE 3 may be, for example, an item of transportation equipment (e.g., vehicles, automobiles, motorbikes, bicycles, trains, buses, carts, rickshaws, ships and other watercraft, aircraft, rockets, satellites, drones, balloons, etc.).

[0110] UE 3 may be, for example, an item of information and communications equipment (eg, information and communications equipment such as electronic computers and related equipment, communications and related equipment, electronic components, etc.).

[0111] The UE3 may be, for example, a refrigeration machine, a refrigeration machine application product, an item of commercial and / or service industry equipment, a vending machine, an automated service machine, an office machine or equipment, consumer electronic devices and appliances (e.g., consumer electronic appliances such as audio equipment, video equipment, loudspeakers, radios, televisions, microwave ovens, rice cookers, coffee machines, dishwashers, washing machines, dryers, electronic fans or related appliances, vacuum cleaners, etc.).

[0112] The UE 3 may be, for example, an electrical application system or device (eg, an electrical application system or device such as an x-ray system, a particle accelerator, a radioisotope device, a sonic device, an electromagnetic application device, a power application device, etc.).

[0113] UE3 may be, for example, an electronic lamp, a lighting fixture, a measuring instrument, an analyzer, a tester, or a surveying or detecting device (e.g., a smoke alarm, a occupancy alarm sensor, a motion sensor, a radio tag, or other surveying or detecting device), a watch or clock, laboratory equipment, optical equipment, medical equipment and / or systems, a weapon, an item of cutlery, a hand tool, or the like.

[0114] UE 3 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 (eg, a personal computer, electrical measurement machine)).

[0115] The UE3 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 with respect to the "Internet of Things (IoT)". Internet of Things devices (or "Things") may be equipped with appropriate electronics, software, sensors, network connectivity, and / or the like, allowing these devices to collect and exchange data with each other and with 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 stopped for long periods of time. IoT devices may be implemented as part of a (generally) stationary device. IoT devices may also be incorporated into non-stationary devices (e.g., vehicles) or attached to animals or people being monitored / tracked.

[0116] It will be understood that IoT technology may be implemented on any communication device that can connect to a communication network to transmit / receive data, regardless of whether such communication device is controlled by human input or software instructions stored in memory.

[0117] It will be appreciated that an IoT device is sometimes referred to as a Machine Type Communication (MTC) device or a Machine-to-Machine (M2M) communication device, or a Narrowband IoT UE (NB-IoT UE). It will be appreciated that a UE 3 may support one or more IoT or MTC applications.

[0118] 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).

[0119] The UE3 may be a car, a connected car, an autonomous vehicle, a vehicle device, a motorcycle, or a V2X (Vehicle-to-Everything) communication module (e.g., a vehicle-to-vehicle communication module, a vehicle-to-infrastructure communication module, a vehicle-to-person communication module, and a vehicle-to-network communication module).

[0120] <(R)AN node> FIG. 6 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, base station for Beyond 5G, base station for 6G). As shown, the (R)AN node 5 includes a transceiver circuit 51 operable to transmit signals to and receive signals from an attached UE 3 via one or more antennas 52, and to transmit signals to and receive signals from other network nodes via a network interface 53 (directly or indirectly). A controller 54 controls the operation of the (R)AN node 5 according to software stored in a memory 55. For example, the software may be pre-installed in the memory and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 551 and a communication control module 552 having at least a transceiver control module 5521.

[0121] The communication control module 552 (using its transceiver control sub-module) is responsible for processing (generating / sending / receiving) signaling between the (R)AN node 5 and other nodes such as the UE 3, another (R)AN node 5, the AMF 70, and the UPF 72, either directly or indirectly. The signaling may include, for example, properly formatted signaling messages regarding the radio connection and connection to the core network 7 for a particular UE 3, especially those related to connection establishment and maintenance, such as RRC connection establishment and other RRC messages, NG application protocol (NGAP) messages (i.e., messages at the N2 reference point), Xn application protocol (XnAP) messages (i.e., messages at the Xn reference point), etc. Such signaling may also include, in the case of transmission, for example, broadcast information (such as master information and system information).

[0122] When implemented, the controller 54 is also configured (either by software or hardware) to process related tasks such as UE mobility estimation and / or movement trajectory estimation.

[0123] (R)AN node 5 may support a non-public network (NPN). The NPN may be a stand-alone non-public network (SNPN) or a public network integrated NPN (PNI-NPN).

[0124] <System Overview of (R)AN Node 5 Based on the O-RAN Architecture> Figure 7 schematically shows (R)AN node 5 based on the O-RAN architecture to which the (R)AN node 5 aspect is applicable.

[0125] The (R)AN node 5 based on the O-RAN architecture represents a system overview in which the (R)AN node is separated into a radio unit (RU) 60, a distribution unit (DU) 61, and a aggregation unit (CU) 62. In some aspects, each unit may be combined. For example, the RU 60 may be combined / combined with the DU 61 as a combined / combined unit, and the DU 61 may be combined / combined with the CU 62 as another combined / combined unit. Any functionality in the description of a unit (e.g., one of the RU 60, DU 61, and CU 62) may be implemented in the combined / combined unit above. 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 has a control plane function in the (R)AN node 5. The CU UP has a user plane function in the (R)AN node 5.

[0126] Each CU CP is connected to a CU UP via a suitable interface (such as a so-called "E1" interface and / or the like).

[0127] The UE 3 and the respective serving RU 60 are connected via a suitable air interface (e.g., a so-called "Uu" interface and / or the like). Each RU 60 is connected to a DU 61 via a suitable interface (such as a so-called "fronthaul", "open fronthaul", "F1" interface and / or the like). Each DU 61 is connected to a CU 62 via a suitable interface (such as a so-called "midhaul", "open midhaul", "E2" interface and / or the like). Each CU 62 is also connected to a node in the core network 7 (such as a so-called core network node) via a suitable interface (such as a so-called "backhaul", "open backhaul", "N2" / "N3" interface and / or the like). In addition, the user plane part of the DU 61 may also be connected to the core network node 7 via a suitable interface (such as a so-called "N3" interface and / or the like).

[0128] Depending on the functionality divided between the RU 60, the DU 61, and the CU 62, each unit provides a part 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 layer and the RLC layer, and the CU 62 may provide functionality for supporting the PDCP layer, the SDAP layer, and the RRC layer.

[0129] <Radio section (RU)> FIG. 8 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, base station for Beyond 5G, base station for 6G). As shown, the RU 60 includes a transceiver circuit 601 operable to transmit signals to and receive signals from an attached UE 3 via one or more antennas 602, and to transmit and receive signals to and from other network nodes or parts via a network interface 603 (directly or indirectly). A controller 604 controls the operation of the RU 60 according to software stored in a memory 605. For example, the software may be pre-installed in the memory and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6051 and a communication control module 6052 having at least a transceiver control module 60521.

[0130] The communication control module 6052 (using its transceiver control sub-module) is responsible for handling (generating / sending / receiving) signaling between (e.g., directly or indirectly) the RU 60 and other nodes or parts, such as the UE 3, another RU 60, and the DU 61. The signaling may include, for example, appropriately formatted signaling messages related to the radio connection and connectivity with the RU 60 (for a particular UE 3), in particular the MAC and RLC layers.

[0131] When implemented, the controller 604 is also configured (by software or hardware) to handle related tasks such as UE mobility estimation and / or motion trajectory estimation.

[0132] The RU 60 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).

[0133] As described above, the RU 60 may be integrated / combined with the DU 61 as an integrated / combined unit. Any function described for the RU 60 may be implemented in the integrated / combined unit.

[0134] <Distributed unit (DU)> FIG. 9 is a block diagram illustrating the main components of an exemplary DU 61, e.g., the DU portion of a base station ("eNB" in LTE, "gNB" in 5G, base station for Beyond 5G, base station for 6G).

[0135] 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 according to software stored in a memory 614.

[0136] For example, the software may be pre-installed in the memory 614 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6141 and a communication 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, such as the RU 60 and other nodes and units.

[0137] The DU 61 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).

[0138] As mentioned above, the RU 60 may be integrated / combined with the DU 61 or the CU 62 as an integrated / combined unit. Any functionality in the description of the DU 61 may be implemented in one of the integrated / combined units.

[0139] <Consolidation Unit (CU)> FIG. 10 is a block diagram showing the main components of an exemplary CU 62, e.g., the CU portion of a base station (eNB in ​​LTE, gNB in ​​5G, base station for Beyond 5G, base station for 6G).

[0140] 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 according to software stored in a memory 624.

[0141] For example, the software may be pre-installed in the memory 624 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 6241 and a communication 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, such as the DU 61 and other nodes and units.

[0142] The CU 62 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).

[0143] As described above, the CU 62 may be integrated / combined with the DU 61 as an integrated / combined unit. Any functionality in the description of the CU 62 may be implemented in the integrated / combined unit.

[0144] <amf> 11 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) via a network interface 702. A controller 703 controls the operation of the AMF 70 according to software stored in a memory 704. For example, the software may be pre-installed in the memory 704 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7041 and a communication control module 7042 having at least a transceiver control module 70421.

[0145] The communications control module 7042 (using its transceiver control module 70421) is responsible for handling (generating / sending / receiving) signaling between the AMF 70 and the UE 3 (e.g., via (R)AN node 5) and other nodes, such as 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) relating to access and mobility management procedures (for the UE 3).

[0146] 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).

[0147] <udm> 12 is a block diagram illustrating the main 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 according to software stored in a memory 754. For example, the software may be pre-installed in the memory 754 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7541 and a communication 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 out). Such signaling may include, for example, appropriately formatted signaling messages (e.g., HTTP RESTful methods based on service-based interfaces) relating to mobility management procedures (for the UE 3).

[0148] The UDM 75 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).

[0149] <nssf> 13 is a block diagram illustrating the main components of the NSSF 77. As shown, the device includes a transceiver circuit 771 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 772. A controller 773 controls the operation of the NSSF 77 according to software stored in a memory 774. For example, the software may be pre-installed in the memory 774 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7741 and a communication control module 7742 having at least a transceiver control module 77421. The communications control module 7742 (using its transceiver control module 77421) is responsible for handling (generating / sending / receiving) signaling between the NSSF 77 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) relating to network data analysis function procedures (for the UE 3).

[0150] The NSSF 77 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).

[0151] <nrf> 14 is a block diagram illustrating the main components of the NRF 78. As shown, the device includes a transceiver circuit 781 operable to transmit signals to and receive signals from other nodes (including the AMF 70) via a network interface 782. A controller 783 controls the operation of the NRF 78 according to software stored in a memory 784. For example, the software may be pre-installed in the memory 784 and / or downloaded via a telecommunications network or from a removable data storage device (RMD). The software includes, among other things, an operating system 7841 and a communication control module 7842 having at least a transceiver control module 78421. The communications control module 7842 (using its transceiver control module 78421) is responsible for handling (generating / sending / receiving) signaling between the NRF 78 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) relating to network data analysis function procedures (for the UE 3).

[0152] The NRF 78 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).

[0153] <Modifications and Replacements> Detailed embodiments have been described above. Still, those skilled in the art will appreciate that numerous modifications and alternatives may be made to the above embodiments while having the benefit of the disclosure embodied herein. Merely by way of example, numerous such alternatives and modifications are now described.

[0154] In the above description, the UE 3 and network devices are described for ease of understanding as having a number of separate modules (such as a communications control module). These modules may be provided in this manner, for example for certain applications where an existing system is modified to implement the present disclosure, and in other applications, for example in systems designed with the inventive features in mind from the beginning, but these modules may not be recognizable as separate entities because they may be built into an overall operating system or code. These modules may also be implemented in software, hardware, firmware, or a mixture of these.

[0155] Each controller may include any suitable form of processing circuitry, including, but not limited to, 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, communications buses (e.g., control buses, data buses, and / or address buses), direct memory access (DMA) facilities, hardware or software implemented counters, pointers and / or timers, and / or the like.

[0156] In the above embodiment, a number of software modules have been described. Those skilled in the art will appreciate that the software modules may be provided in compiled or uncompiled form and may be provided to the UE 3 and the network device as a signal in 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 to update the functions of the UE 3 and the network device is preferred because the software modules facilitate the updating of the UE 3 and the network device.

[0157] In the above embodiment, 3GPP wireless communication (radio access) technology is used. However, any other wireless communication technology (e.g., WLAN, Wi-Fi, WiMAX, Bluetooth, etc.) and other fixed line communication technology (e.g., BBF access, cable access, optical access, etc.) can also be used according to the above embodiment.

[0158] Items of user equipment may include, for example, communication devices such as mobile phones, smartphones, user equipment, personal digital assistants, laptop / tablet computers, web browsers, e-book readers, and / or the like. Such mobile (and even generally fixed) devices are typically operated by a user, although so-called "Internet of Things" (IoT) devices and similar machine type communication (MTC) devices may also be connected to the network. For simplicity, the present application refers to mobile devices (or UEs) in the description, but it will be understood that the described techniques may be implemented on any (mobile and / or generally fixed) communication device that may connect to a communication network to transmit / receive data, regardless of whether such communication device is controlled by human input or by software instructions stored in memory.

[0159] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0160] Although the present disclosure has been shown and described in detail with reference to exemplary embodiments thereof, the present disclosure is not limited to such 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 the embodiments are applicable to communication systems other than 5GS.

[0161] According to the present disclosure, the present disclosure defines a registration procedure via an AMF reallocation procedure when the UE is in a CM-CONNECTED state.

[0162] For example, the present disclosure can solve the problem that in current 3GPP specifications, it is not clear how a non-initial UE message (e.g., an uplink NAS transport message, or an uplink NAS transport message including a registration request message) can be forwarded from the initial AMF to the target AMF when the initial AMF decides to reallocate an AMF to a UE.

[0163] For example, the present disclosure defines how to forward non-initial UE messages from the initial AMF to the target AMF when the initial AMF decides to reassign the AMF to the UE. For example, the present disclosure can solve the problem that some registration management procedures do not work, leading to degradation of services for mobile users.

[0164] All or part of the aspects of the above disclosure may be described as follows, but are not limited to the following.

[0165] <4.2.2.2.3 Registration via AMF Reassignment> For example, when the AMF receives a registration request, if the initial AMF is not a suitable AMF to serve the UE, the AMF may need to reroute the registration request to another AMF. The registration by AMF reassignment procedure described in Figure 4.2.2.2.3-1 is used to reroute the UE's NAS messages to the target AMF during the registration procedure. This procedure can be triggered both when the UE is in CM-IDLE or CM-CONNECTED state.

[0166] Figure 4.2.2.2.3-1: Registration with AMF reassignment procedure (see Figure 15 of this application).

[0167] The initial AMF and the target AMF register the functions of the initial AMF and the target AMF in the NRF.

[0168] 1. Steps 1 and 2 in Figure 4.2.2.2.2-1 occur, and the (R)AN sends a registration request message in an initial UE message to the initial AMF if the UE is in CM-IDLE state. The (R)AN sends a registration request message in an UPLINK NAS TRANSPORT message to the initial AMF if the UE is in CM-CONNECTED state.

[0169] 2. If the AMF requires SUPI and / or UE subscription information to decide whether to reroute the registration request, or if the registration request was not sent in an integrity protected state or integrity protection is indicated as failed, the AMF performs steps 4 to 9a or 9b of Figure 4.2.2.2.2-1.

[0170] 3a. [Conditional] If the initial AMF requires the UE's subscription information to decide whether to reroute the registration request and the UE's slice selection subscription information was not provided by the old AMF, the AMF shall select a UDM as described in TS 23.501 [2], clause 6.3.8.

[0171] 3b. Initial AMF to UDM: Nudm_SDM_Get(SUPI, slice selection subscription data).

[0172] The initial AMF requests the slice selection subscription data of the UE from the UDM by executing the Nudm_SDM_Get (see clause 5.2.3.3.1) service operation. The UDM may obtain this information from the UDR by Nudr_DM_Query(SUPI, slice selection subscription data).

[0173] 3c. UDM to initial AMF: Response to Nudm_SDM_Get. The AMF obtains slice selection subscription data including the subscription S-NSSAI.

[0174] The UDM responds to the initial AMF with slice selection data.

[0175] 4a. [Conditional] From Initial AMF to NSSF: Nnssf_NSSelection_Get(Requested NSSAI, [Mapping of Requested NSSAI], Subscribed S-NSSAI with default S-NSSAI indication, TAI, Allowed NSSAI for other access types (if any), [Mapping of Allowed NSSAI], PLMN ID of SUPI).

[0176] If slice selection is required (see clause 5.15.5.2.1 of TS 23.501 [2]) and, for example, the initial AMF cannot provide all S-NSSAIs from the requested NSSAI that are allowed by the subscription information, the initial AMF performs an Nnssf_NSSelection_Get service operation from the NSSF by including the requested NSSAI, optionally the mapping of the requested NSSAI, the subscribed S-NSSAI with default S-NSSAI indication, the allowed NSSAIs for other access types (if any), the mapping of the allowed NSSAI, the PLMN ID of the SUPI, and the TAI of the UE.

[0177] 4b. [Conditional] NSSF to Initial AMF: Response to Nnssf_NSSelection_Get (List of AMF set or AMF addresses, Allowed NSSAI for first access type, [Mapping of Allowed NSSAI], [Allowed NSSAI for second access type], [Mapping of Allowed NSSAI], [NSI ID], [NRF], [List of Rejection (S-NSSAI, cause value)], [Configured NSSAI for Serving PLMN], [Configured NSSAI Mapping]).

[0178] The NSSF performs the steps specified in point (B) in clause 5.15.5.2.1 of TS 23.501 [2]. The NSSF returns to the initial AMF the authorized NSSAI for the first access type, optionally the mapping of the authorized NSSAI, the authorized NSSAI for the second access type (if any), optionally the mapping of the authorized NSSAI, and the target AMF set, or a list of candidate AMFs based on the configuration. The NSSF may return the NSI ID associated with the network slice instance corresponding to the specific S-NSSAI. The NSSF may return the NRF used to select the NF / service in the selected network slice instance. The NSSF may also return information about the rejection cause for the S-NSSAI that is not included in the authorized NSSAI. The NSSF may return the configured NSSAI for the serving PLMN, and possibly the associated mapping of the configured NSSAI.

[0179] NOTE 1: The NRF returned by the NSSF, if any, belongs to any level of NRF (see clause 6.2.6 of TS 23.501 [2]) depending on the operator's deployment decision.

[0180] 5. [Conditional] From initial AMF to old AMF: Namf_Communication_RegistrationStatusUpdate (cause of failure).

[0181] If another AMF is selected, the initial AMF sends a rejection indication to the old AMF to inform it that the UE registration procedure was not fully completed in the initial AMF. The old AMF continues as if it had not received Namf_Communication_UEContextTransfer.

[0182] 6a. [Conditional] From Initial AMF to NRF: Nnrf_NFDiscovery_Request(NF Type, AMF Set).

[0183] If the initial AMF does not locally store the target AMF address, and if the initial AMF intends to use direct reroute to the target AMF or the reroute via (NG-R)AN message needs to include the AMF address, the initial AMF executes a Nnrf_NFDiscovery_Request service operation from the NRF to find a suitable target AMF that has the necessary NF capabilities to serve the UE. The NF type is set to AMF. The AMF set is included in the Nnrf_NFDiscovery_Request.

[0184] 6b. [Conditional] NRF to AMF: Response to Nnrf_NFDiscovery_Request ((AMF pointer, AMF address, plus additional selection rules and list of NF capabilities)).

[0185] The NRF responds with a list of possible target AMFs. The NRF may also provide details of the services offered by the candidate AMFs, together with notification endpoints for each type of notification service that the selected AMF has registered with the NRF, if available. Alternatively, the NRF provides a list of possible target AMFs and their capabilities, and optionally additional selection rules.

[0186] Based on information about the registered NFs and the required functions, the target AMF is selected by the initial AMF.

[0187] If a security association is established between the UE and the initial AMF to avoid registration failure, the initial AMF forwards the NAS message to the target AMF by performing step 7(A).

[0188] Note 2: When the initial AMF forwards a NAS message to the target AMF via the (R)AN, the security context in the initial AMF is not forwarded to the target AMF. In this case, the security context in the UE and the target AMF is not synchronized, so the UE rejects the NAS message sent from the target AMF.

[0189] NOTE 3: When AMF reallocation is performed by step 7(A), network slice isolation cannot be completely maintained.

[0190] If the initial AMF is not part of the target AMF set and cannot obtain a list of candidate AMFs by querying an NRF that has the target AMF set (e.g., an NRF pre-configured locally on the AMF does not provide the required information and a query to an appropriate NRF provided by the NSSF is not successful, or the initial AMF has knowledge that the initial AMF is not authorized as a serving AMF), the initial AMF performs step 7 (B) to forward the NAS message to the target AMF via the (R)AN, unless a security association has been established between the UE and the initial AMF, and the authorized NSSAI and AMF set are included to enable the (R)AN to select the target AMF as described in TS 23.501 [2] clause 6.3.5.

[0191] 7(A). Based on the local policy and subscription information, if the initial AMF decides to forward the NAS message directly to the target AMF, the initial AMF executes Namf_Communication_N1MessageNotify to the target AMF to convey the rerouted NAS message. The Namf_Communication_N1MessageNotify service operation includes information that enables the (R)AN to identify the N2 termination point, if available, the registration request message received from the UE, and the SUPI and MM context of the UE. If the initial AMF obtained the information from the NSSF as described in step 4b, the information is included except for the AMF set or the list of AMF addresses. The target AMF then updates the (R)AN with the new updated N2 termination point for the UE in the first message from the target AMF to the RAN in step 8.

[0192] 7(B). If, based on the local policy and subscription information, the initial AMF decides to forward the NAS message to the target AMF via the (R)AN, unless the target AMF is identified by the list of candidate AMFs returned from the NSSF, the initial AMF sends a reroute NAS message to the (R)AN (step 7a). The reroute NAS message includes information about the target AMF, an authorized NSSAI for the first access type, an authorized NSSAI for the second source type, AMF information reroute from source to target, the NAS security context, and the registration request message received from the UE. If the initial AMF has obtained information as described in step 4b, the information is included. The (R)AN sends an initial UE message or an uplink NAS transport message to the target AMF (step 7b) to indicate reroute by slicing including the information from step 4b provided by the NSSF. The uplink NAS transport message includes an authorization NSSAI for the first access type, an authorization NSSAI for the second source type, information reroute from the source to the target, a NAS security context for the first access type, and a NAS security context for the second access type.

[0193] 8. After receiving the registration request message sent in step 7(A)a or step 7(B)b, the target AMF continues the registration procedure from steps 4 to 22 in Figure 4.2.2.2.2-1 (at the target AMF corresponding to the new AMF) including the UE context obtained from the old AMF. If a 5G security context is obtained from the initial AMF, the target AMF continues to use that 5G security context instead of the 5G security context obtained from the old AMF. If the initial AMF decides to forward a NAS message to the target AMF (step 7(A), the first message (initial context setup request or downlink NAS transport) from the target AMF to the (R)AN includes the AMF name of the initial AMF and the target AMF UE NGAP ID.

[0194] <8.6.5 Reroute NAS Request> <8.6.5.1 General remarks> The purpose of the reroute NAS request procedure is to allow an AMF to request that an INITIAL UE MESSAGE message or an UPLINK NAS TRANSPORT message be rerouted to another AMF.

[0195] <8.6.5.2 Success Action> Figure 8.6.5.2-1: Reroute NAS Request (See Figure 16 of this application.)

[0196] The AMF initiates the procedure by sending a REROUTE NAS REQUEST message to the NG-RAN node, which, if supported, reroutes the INITIAL UE MESSAGE message or the UPLINK NAS TRANSPORT message to the AMF indicated by the AMF Set-ID IE as described in TS 23.501 [9].

[0197] If the Allowed NSSAI IE is included in the REROUTE NAS REQUEST message, the NG-RAN node shall convey it in the rerouted INITIAL UE MESSAGE message or UPLINK NAS TRANSPORT message as specified in TS 23.502

[10] .

[0198] If the source to target AMF information reroute IE is included in the REROUTE NAS REQUEST message or the UPLINK NAS TRANSPORT message, the NG-RAN node conveys it in the rerouted INITIAL UE MESSAGE message as specified in TS 23.502

[10] .

[0199] <8.6.3 Uplink NAS Transport> <8.6.3.1 General remarks> The uplink NAS transport procedure is used when an NG-RAN node receives a NAS message from the radio interface to be forwarded to an AMF for which a UE associated logical NG connection exists for the UE, or when a UE associated logical NG connection exists for the UE with respect to the serving AMF but the UPLINK NAS TRANSPORT message is rerouted to the target AMF during AMF reassignment, in which case the serving AMF is rerouting the UPLINK NAS TRANSPORT message to the target AMF.

[0200] <8.6.3.2 Success Action> Figure 8.6.3.2-1: Uplink NAS Transport (See Figure 17 of this application.)

[0201] The NG-RAN node initiates the procedure by sending an UPLINK NAS TRANSPORT message to the AMF.

[0202] The NAS-PDU IE is forwarded without being interpreted by the NG-RAN node. UE-AMF Contains the message.

[0203] If the Allowed NSSAI IE is included in the REROUTE NAS REQUEST message, the NG-RAN node shall convey it in the rerouted INITIAL UE MESSAGE message or UPLINK NAS TRANSPORT message as specified in TS 23.502

[10] .

[0204] If the source to target AMF information reroute IE is included in the REROUTE NAS REQUEST message, the NG-RAN node conveys it in the rerouted INITIAL UE MESSAGE or UPLINK NAS TRANSPORT message as defined in TS 23.502

[10] .

[0205] If the NAS Security Context IE is included in the REROUTE NAS REQUEST message, the NG-RAN conveys it in the UPLINK NAS TRANSPORT message.

[0206] <9.2.5.3 UPLINK NAS TRANSPORT> This message is sent by NG-RAN nodes and is used to convey NAS information on the NG interface (see Figure 18 of this application).

[0207] <9.2.5.5 REROUTE NAS REQUEST> This message is sent by an AMF to request that the INITIAL UE MESSAGE message be rerouted to another AMF (see Figure 19 of this application).

[0208] All or a part of the exemplary aspects of the above disclosure may be described as, but are not limited to, the following supplementary notes.

[0209] <First Addendum> Appendix 1. A method of a first Access and Mobility Management Function (AMF) device, comprising: receiving a registration request message from a user equipment (UE) in CM-CONNECTED mode; Sending a registration request message to a second AMF device via a Radio Access Network (RAN) node; A method comprising:

[0210] Appendix 2. The method according to claim 1, wherein the registration request message received from the UE is included in an uplink non-access stratum (NAS) transport message.

[0211] Appendix 3. The method according to claim 1 or 2, wherein the registration request message sent to the second AMF device is included in a reroute NAS message.

[0212] Appendix 4. 1. A method of a Radio Access Network (RAN) node, comprising: receiving a registration request message from a user equipment (UE) in CM-CONNECTED mode; sending a first uplink Non-Access Stratum (NAS) transport message to a first Access and Mobility Management Function (AMF) device; the first uplink NAS transport message includes a registration request message received from the UE; and receiving a reroute NAS message from a first AMF device, the reroute NAS message includes a registration request message received from the UE; Sending a second uplink NAS transport message to a second AMF device, the second uplink NAS transport message includes a registration request message received from the UE; and A method comprising:

[0213] Appendix 5. A method of a first Access and Mobility Management Function (AMF) device, comprising: receiving a registration request message from a user equipment (UE) in CM-CONNECTED mode; Sending a registration request message to a second AMF device; A method comprising:

[0214] Appendix 6. The method of claim 5, wherein the registration request message received from the UE is included in an uplink non-access stratum (NAS) transport message.

[0215] Appendix 7. A method as described in Appendix 5 or 6, wherein the registration request message sent to the second AMF device is included in Namf_Communication_N1MessageNotify.

[0216] Appendix 8. A method of a first Access and Mobility Management Function (AMF) device, comprising: communicating with a second AMF device; Receiving a registration request message from a second AMF device for a user equipment (UE) in a CM-CONNECTED mode; A method comprising:

[0217] Appendix 9. Means for receiving a registration request message from a user equipment (UE) in a CM-CONNECTED mode; Means for sending a registration request message to a second AMF device via a Radio Access Network (RAN) node; A first Access and Mobility Management Function (AMF) device comprising:

[0218] Appendix 10. The first AMF device of Supplementary Note 9, wherein the registration request message received from the UE is included in an uplink non-access stratum (NAS) transport message.

[0219] Appendix 11. A first AMF device as described in Appendix 9 or 10, wherein the registration request message sent to the second AMF device is included in a reroute NAS message.

[0220] Appendix 12. Means for receiving a registration request message from a user equipment (UE) in a CM-CONNECTED mode; A means for transmitting a first uplink Non-Access Stratum (NAS) transport message to a first Access and Mobility Management Function (AMF) device, the means comprising: The first uplink NAS transport message includes a registration request message received from the UE; A means for receiving a reroute NAS message from a first AMF device, The reroute NAS message includes a registration request message received from the UE; A means for sending a second uplink NAS transport message to a second AMF device, The second uplink NAS transport message includes a registration request message received from the UE; and A radio access network (RAN) node comprising:

[0221] Appendix 13. Means for receiving a registration request message from a user equipment (UE) in a CM-CONNECTED mode; Means for sending a registration request message to a second AMF device; A first Access and Mobility Management Function (AMF) device comprising:

[0222] Appendix 14. The first AMF of Supplementary Note 13, wherein the registration request message received from the UE is included in an uplink non-access stratum (NAS) transport message.

[0223] Appendix 15. The registration request message sent to the second AMF device is the first AMF described in Appendix 13 or 14, which is included in Namf_Communication_N1MessageNotify.

[0224] Appendix 16. means for communicating with a second AMF device; Means for receiving a registration request message for a user equipment (UE) in a CM-CONNECTED mode from a second AMF device; A first Access and Mobility Management Function (AMF) device comprising:

[0225] <Second Note> Appendix 1. A method of a first Access and Mobility Management Function (AMF) device, comprising: receiving a registration request message for a user equipment (UE) in a CM-CONNECTED state from a radio access network (RAN); Sending a registration request message directly to a second AMF device; A method comprising:

[0226] Appendix 2. The method of claim 1, wherein the registration request message received from the RAN is included in an uplink non-access stratum (NAS) transport message.

[0227] Appendix 3. A method as described in Appendix 1 or 2, wherein the registration request message sent to the second AMF device is included in Namf_Communication_N1MessageNotify.

[0228] Appendix 4. 4. The method of claim 1, wherein the registration request message is sent by the UE to the RAN.

[0229] Appendix 5. The method according to any one of Supplementary Notes 1 to 4, wherein the registration procedure is continued by the second AMF device after receiving the registration request message.

[0230] Appendix 6. The method of claim 5, wherein the registration approval message is sent to the UE by the second AMF device in the registration procedure.

[0231] Appendix 7. The method according to any one of Supplementary Notes 1 to 6, wherein the registration request message sent to the second AMF device is in clear text.

[0232] Appendix 8. A method of a first Access and Mobility Management Function (AMF) device, comprising: communicating with a second AMF device; Receiving a registration request message of a user equipment (UE) in a CM-CONNECTED state directly from a second AMF device; A method comprising:

[0233] Appendix 9. The method described in Appendix 8, wherein the registration request message received from the second AMF device is included in Namf_Communication_N1MessageNotify.

[0234] Appendix 10. The method of claim 8 or 9, wherein the registration request is sent by a radio access network (RAN) to the second AMF device.

[0235] Appendix 11. The method of claim 10, wherein the registration request message sent by the RAN to the second AMF device is included in an uplink non-access stratum (NAS) transport message.

[0236] Appendix 12. 12. The method of claim 10 or 11, wherein the registration request message is sent by the UE to the RAN.

[0237] Appendix 13. 13. The method of any one of claims 8 to 12, further comprising continuing the registration procedure after receiving the registration request message.

[0238] Appendix 14. 14. The method of claim 13, further comprising sending a registration acknowledgement message to the UE in a registration procedure.

[0239] Appendix 15. A method according to any one of Supplementary Notes 8 to 14, wherein the registration request message received from the second AMF device is in clear text.

[0240] Appendix 16. 1. A method for a user equipment (UE), comprising: communicating with a radio access network (RAN); sending a registration request message of the UE in a CM-CONNECTED state to the RAN; Including, A method in which a registration request message is sent by a RAN to a first Access and Mobility Management Function (AMF) device, and the registration request message is sent directly by the first AMF device to a second AMF device.

[0241] Appendix 17. The method of claim 16, further comprising receiving a registration approval message from the second AMF device, the registration approval message including a 5G-GUTI and an authorized NSSAI.

[0242] Appendix 18. The method according to claim 16 or 17, wherein the registration request message sent by the RAN to the first AMF device is included in an uplink non-access stratum (NAS) transport message.

[0243] Appendix 19. A method according to any one of appendices 16 to 18, wherein the registration request message sent by the first AMF device to the second AMF device is included in Namf_Communication_N1MessageNotify.

[0244] Appendix 20. The method according to any one of Supplementary Notes 16 to 19, wherein the registration procedure is continued by the second AMF device after receiving the registration request message.

[0245] Appendix 21. The method of claim 20, further comprising receiving a registration approval message from the second AMF device in a registration procedure.

[0246] Appendix 22. A method according to any one of appendixes 16 to 21, wherein the registration request message sent by the first AMF device to the second AMF device is in clear text.

[0247] Appendix 23. A means for receiving a registration request message for a user equipment (UE) in a CM-CONNECTED state from a radio access network (RAN); A means for directly sending a registration request message to a second AMF device; A first Access and Mobility Management Function (AMF) device comprising:

[0248] Appendix 24. The first AMF device of Supplementary Note 23, wherein the registration request message received from the RAN is included in an uplink non-access stratum (NAS) transport message.

[0249] Appendix 25. A first AMF device as described in Appendix 23 or 24, wherein the registration request message sent to the second AMF device is included in Namf_Communication_N1MessageNotify.

[0250] Appendix 26. 26. The first AMF device of any one of Supplementary Notes 23 to 25, wherein the registration request message is sent by the UE to the RAN.

[0251] Appendix 27. A first AMF device described in any one of Supplementary Notes 23 to 26, wherein the registration procedure is continued by the second AMF device after receiving a registration request message.

[0252] Appendix 28. A first AMF device as described in Supplementary Note 27, wherein a registration approval message is sent by the second AMF device to the UE in a registration procedure.

[0253] Appendix 29. A first AMF device described in any one of Appendix 23 to 28, wherein the registration request message sent to the second AMF device is in clear text.

[0254] Appendix 30. means for communicating with a second AMF device; A means for directly receiving a registration request message of a user equipment (UE) in a CM-CONNECTED state from a second AMF device; A first Access and Mobility Management Function (AMF) device comprising:

[0255] Appendix 31. A first AMF device as described in Appendix 30, wherein the registration request message received from the second AMF device is included in Namf_Communication_N1MessageNotify.

[0256] Appendix 32. A first AMF device as described in Supplementary Note 30 or 31, wherein the registration request is sent to the second AMF device by a radio access network (RAN).

[0257] Appendix 33. The first AMF device of Supplementary Note 32, wherein the registration request message sent by the RAN to the second AMF device is included in an uplink non-access stratum (NAS) transport message.

[0258] Appendix 34. The first AMF device according to Supplementary Note 32 or 33, wherein the registration request message is sent by the UE to the RAN.

[0259] Appendix 35. The first AMF device of any one of Supplementary Notes 30 to 34, further comprising means for continuing a registration procedure after receiving a registration request message.

[0260] Appendix 36. The first AMF device as described in Supplementary Note 35, further comprising: means for sending a registration acknowledgement message to the UE in a registration procedure.

[0261] Appendix 37. A first AMF device described in any one of Supplementary Notes 30 to 36, wherein the registration request message received from the second AMF device is in clear text.

[0262] Appendix 38. A user equipment (UE), means for communicating with a Radio Access Network (RAN); A means for sending a registration request message of the UE in a CM-CONNECTED state to the RAN; Equipped with A registration request message is sent by the RAN to a first Access and Mobility Management Function (AMF) device, and the registration request message is sent directly by the first AMF device to a second AMF device, a user equipment (UE).

[0263] Appendix 39. The UE of claim 38, further comprising means for receiving a registration approval message including a 5G-GUTI and an authorized NSSAI from the second AMF device.

[0264] Appendix 40. 39. The UE of claim 38, wherein the registration request message sent by the RAN to the first AMF device is included in an uplink non-access stratum (NAS) transport message.

[0265] Appendix 41. A UE described in any one of Addendums 38 to 40, wherein the registration request message sent by the first AMF device to the second AMF device is included in Namf_Communication_N1MessageNotify.

[0266] Appendix 42. 42. A UE as described in any one of Supplementary Notes 38 to 41, wherein the registration procedure is continued by the second AMF device after receiving the registration request message.

[0267] Appendix 43 The UE of claim 42, further comprising means for receiving a registration acknowledgement message from a second AMF device in a registration procedure.

[0268] Appendix 44. A UE as described in any one of Supplementary Notes 38 to 43, wherein the registration request message sent by the first AMF device to the second AMF device is in clear text.

[0269] Although the present invention has been described above with reference to the embodiments (and examples), the present invention is not limited to the above-mentioned embodiments (and examples). Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0270] This application claims priority to Indian Provisional Patent Application No. 202111028660, filed on June 25, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0271] 1. Telecommunications Systems 3. UE 5 (R)AN Nodes 7 Core Network 20 Data Network 31 Transceiver Circuit 32 Antenna 33 Controller 34 User Interface 35 USIM 36 Memory 51 Transceiver Circuit 52 Antenna 53 Network Interface 54 Controller 55 Memory 60RU 61DU 62 CU 70 AMF 71 SMF 72 UPF 73 PCF 74 NEF 75 UDM 76 NWDAF 77 NSSF 78 NRF 361 Operating Systems 362 Communication Control Module 551 Operating Systems 552 Communication Control Module 601 Transceiver Circuit 602 Antenna 603 Network Interface 604 Controller 605 Memory 611 Transceiver Circuit 612 Network Interface 613 Controller 614 Memory 621 Transceiver Circuit 622 Network Interface 623 Controller 624 Memory 701 Transceiver Circuit 702 Network Interface 703 Controller 704 Memory 751 Transceiver Circuit 752 Network Interface 753 Controller 754 Memory 771 Transceiver Circuit 772 Network Interface 773 Controller 774 Memory 781 Transceiver Circuit 782 Network Interface 783 Controller 784 Memory 3621 Transceiver Control Module 5521 Transceiver Control Module 6051 Operating System 6052 Communication Control Module 6141 Operating Systems 6142 Communication Control Module 6241 Operating Systems 6242 Communication Control Module 7041 Operating Systems 7042 Communication Control Module 7541 Operating Systems 7542 Communication Control Module 7741 Operating Systems 7742 Communication Control Module 7841 Operating Systems 7842 Communication Control Module 60521 Transceiver Control Module 61421 Transceiver Control Module 62421 Transceiver Control Module 70421 Transceiver Control Module 75421 Transceiver Control Module 77421 Transceiver Control Module 78421 Transceiver Control Module< / nrf> < / nssf> < / udm> < / amf>

Claims

1. A method performed by a first Access and Mobility Management Function (AMF) device, comprising: receiving a first confidentiality protected registration request message from a User Equipment (UE) via a Radio Access Network (RAN); the first registration request message includes a Requested NSSAI; the first registration request message is included in an uplink Non-Access Stratum (NAS) transport message; When the first AMF device cannot provide an S-NSSAI included in the Requested NSSAI, sending an Nnssf_NSSelection_Get including the Requested NSSAI to a Network Slice Selection Function (NSSF) device; receiving an Nnssf_NSSelection_Get response from the NSSF device, the NSSFA response including information of one or more AMF devices that can provide the S-NSSAI; Sending a Nnrf_NFDiscovery_Request to a Network Repository Function (NRF) device, the NRF device including information of the one or more AMF devices; receiving an Nnrf_NFDiscovery_Request response from the NRF device that includes information regarding the capabilities of the one or more AMF devices; selecting a second AMF device from the one or more AMF devices based on information regarding the capabilities of the one or more AMF devices; obtaining a second registration request message, the second registration request message being non-confidentiality protected, based on the first registration request message; Sending the second registration request message directly to a second AMF device; The first AMF device method.

2. A method of the first AMF device described in claim 1, wherein the second registration request message is included in Namf_Communication_N1MessageNotify.

3. The method of claim 2 , wherein a registration procedure is continued by the second AMF device after receiving the second registration request message.

4. The method of claim 3, wherein a registration approval message is sent by the second AMF device to the UE in the registration procedure.

5. A method for receiving a confidentiality-protected first registration request message from a user equipment (UE) via a radio access network (RAN), the first registration request message being included in an uplink non-access stratum (NAS) transport message and including a Requested NSSAI; means for transmitting an Nnssf_NSSelection_Get including the Requested NSSAI to a Network Slice Selection Function (NSSF) device when an S-NSSAI included in the Requested NSSAI cannot be provided; means for receiving an Nnssf_NSSelection_Get response from the NSSF device, the Nssf_NSSelection_Get response including information of one or more AMF devices that can provide the S-NSSAI; means for sending a Nnrf_NFDiscovery_Request to a Network Repository Function (NRF) device, the NRF request including information of the one or more AMF devices; means for receiving an Nnrf_NFDiscovery_Request response from the NRF device, the NRF response including information regarding the capabilities of the one or more AMF devices; means for selecting a second AMF device from the one or more AMF devices based on information regarding capabilities of the one or more AMF devices; means for obtaining a second registration request message, the second registration request message being non-confidentiality protected, based on the first registration request message; means for directly sending the second registration request message to a second AMF device; A first Access and Mobility Management Function (AMF) device comprising:

6. The first AMF device described in claim 5, wherein the second registration request message is included in Namf_Communication_N1MessageNotify.

7. The first AMF device of claim 6 , wherein a registration procedure is continued by the second AMF device after receiving the second registration request message.

8. The first AMF device of claim 7, wherein a registration approval message is sent by the second AMF device to the UE in the registration procedure.

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