Registration in same AMF for different ues

Abstract

Example embodiments of the present disclosure provide solutions for registration in a same AMF for different UEs. In an example method, a first UE transmits, to a base station, information identifying a serving AMF of a second UE during an RRC setup procedure with the base station for the first UE. The first UE further performs registration for the first UE with the serving AMF of the second UE.

Description

REGISTRATION IN SAME AMF FOR DIFFERENT UESFIELD

[0001] Example embodiments of the present disclosure generally relate to the field of communication, and in particular, to terminal devices, a user equipment (UE), a base station, network devices, methods, apparatuses, and computer readable media for registration in a same Access and Mobility Function (AMF) for different UEs (in the same device).BACKGROUND

[0002] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. Such communication networks operate in accordance with standards, such as those promulgated by 3 GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of such standards include the so-called 5G (5th Generation) standard or other standards promulgated by 3GPP.

[0003] In communication network, when a UE wants to connect to the network, it first performs registration with an Access and Mobility Function (AMF). This process involves the UE sending a Registration Request to the AMF, which then authenticates and authorizes the UE, and sets up necessary contexts for mobility and session management. This ensures that the UE can access network services securely and efficiently.SUMMARY

[0004] In general, embodiments of the present disclosure provide solutions for registration in a same AMF for different UEs (in the same device).

[0005] In a first aspect, there is provided a first user equipment (UE) comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first UE at least to: transmit, to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and perform registration for the first UE with the serving AMF of the second UE.

[0006] In a second aspect, there is provided a base station comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the base station at least to: receive, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and select, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0007] In a third aspect, there is provided a network device comprising a first Access and Mobility management Function (AMF), the network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: receive, from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirect the registration for the first UE to the second AMF serving the second UE.

[0008] In a fourth aspect, there is provided a network device comprising Unified Data Management (UDM), the network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a first Access and Mobility management Function (AMF), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to a first UE.

[0009] In a fifth aspect, there is provided a method comprising: transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and performing registration for the first UE with the serving AMF of the second UE.

[0010] In a sixth aspect, there is provided a method comprising: receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0011] In a seventh aspect, there is provided a method comprising: receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management(UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirecting the registration for the first UE to the second AMF serving the second UE.

[0012] In an eighth aspect, there is provided a method comprising: transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

[0013] In an ninth aspect, there is provided an a apparatus comprising: means for transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and means for performing registration for the first UE with the serving AMF of the second UE.

[0014] In a tenth aspect, there is provided an apparatus comprising: means for receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and means for selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0015] In a eleventh aspect, there is provided an apparatus comprising: means for receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and means for redirecting the registration for the first UE to the second AMF serving the second UE.

[0016] In a twelfth aspect, there is provided an apparatus comprising: means for transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

[0017] In a thirteenth aspect, there is provided a computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a RadioResource Control (RRC) setup procedure with the base station for the first UE; and performing registration for the first UE with the serving AMF of the second UE.

[0018] In a fourteenth aspect, there is provided a computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0019] In a fifteenth aspect, there is provided a computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirecting the registration for the first UE to the second AMF serving the second UE.

[0020] In a sixteenth aspect, there is provided a computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

[0021] In a seventeenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and performing registration for the first UE with the serving AMF of the second UE.

[0022] In an eighteenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedurewith the base station for the first UE; and selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0023] In a nineteenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirecting the registration for the first UE to the second AMF serving the second UE.

[0024] In a twentieth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

[0025] In a twenty-first aspect, there is provided a first UE. The UE comprises: a transmitting circuitry configured to transmit, to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and registering circuitry configured to perform registration for the first UE with the serving AMF of the second UE.

[0026] In a twenty-second aspect, there is provided a base station. The base station comprises: a receiving circuitry configured to receive, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and selecting circuitry configured to select, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0027] In a twenty-third aspect, there is provided a network device comprising a first Access and Mobility management Function (AMF). The network device comprises: a receiving circuitry configured to receive, from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and a redirecting circuitry configured to redirect the registration for the first UE to the second AMF serving the second UE.

[0028] In a twenty-fourth aspect, there is provided a network device comprising Unified Data Management (UDM). The network device comprises a transmitting circuitry configured to transmit, to a first Access and Mobility management Function (AMF), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to a first UE.

[0029] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Some embodiments will now be described with reference to the accompanying drawings, in which:

[0031] FIG. 1 illustrates an example network environment in which some embodiments of the present disclosure can be implemented;

[0032] FIG. 2 illustrates an example of a process flow for selecting the same AMF based on information identifying the AMF in accordance with some embodiments of the present disclosure;

[0033] FIG. 3 illustrates an example of a detailed process flow for selecting the same AMF based on information identifying the AMF in accordance with some embodiments of the present disclosure;

[0034] FIG. 4 illustrates an example of a process flow for selecting the same AMF based on registration redirection in accordance with some embodiments of the present disclosure;

[0035] FIG. 5 illustrates an example of another process flow for selecting the same AMF based on registration redirection in accordance with some embodiments of the present disclosure;

[0036] FIG. 6 illustrates an example flowchart of a method implemented at a UE according to embodiments of the present disclosure;

[0037] FIG. 7 illustrates an example flowchart of a method implemented at a base station according to embodiments of the present disclosure;

[0038] FIG. 8 illustrates an example flowchart of a method implemented at a terminal device according to embodiments of the present disclosure;

[0039] FIG. 9 illustrates an example flowchart of a method implemented at a terminal device according to embodiments of the present disclosure;

[0040] FIG. 10 illustrates an example flowchart of a method implemented at a network device comprising an AMF according to embodiments of the present disclosure;

[0041] FIG. 11 illustrates an example flowchart of a method implemented at a network device comprising UDM according to embodiments of the present disclosure;

[0042] FIG. 12 illustrates an example simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure; and

[0043] FIG. 13 illustrates an example block diagram of an example computer readable medium in accordance with some embodiments of the present disclosure.

[0044] Throughout the drawings, the same or similar reference numerals represent the same or similar elements.DETAILED DESCRIPTION

[0045] Principles of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

[0046] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0047] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0048] It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0050] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor s), that requires software (for example, firmware) for operation, but the software may not be present when it is not needed for operation.

[0051] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0052] As used herein, the term “network”, “communication network” or “data network” refers to a network following any suitable communication standards, such as long term evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), wireless fidelity (Wi-Fi), narrow band Internet of things (NB-IoT), satellite, enhanced machine-type communication (eMTC), nonterrestrial communication, terrestrial communication, and so on. Furthermore, the communications between a terminal device and a network device / element in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G), 4.5G, the fifth generation (5G), the sixth generation (6G), new radio (NR), IEEE 802.11 communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0053] As used herein, the term “network device” may refer to a device comprising or performing a core network function. Note that the device comprising or performing the core network function may mean that such device is configured to or is able to perform at least part of functionalities provided by the core network function. For instance, a network device may refer to a device comprising or performing network functions, including but not limitedto, Access and Mobility Management Function (AMF), Session Management Function (SMF), Application Function (AF), Network Exposure Function (NEF), Policy Control Function (PCF), Unified Data Management / Repository (UDM / UDR), Traffic Steering Function (TSF), among others things.

[0054] It is understood that references in the above to various network functions (e.g., to an AMF, an SMF, TNF etc.) may be implemented by apparatus (e.g., network apparatus) that performs at least some of the functionalities associated with those network functions. Further, an apparatus configured to implement a network function may further be configured to implement a virtual network function instance of that network function.

[0055] In some embodiments, the apparatus may be or comprise a network function, such as an AMF, NEF, UDM / UDR, etc. In the present disclosure, an apparatus being / comprising a network function refers to an apparatus / device configured to provide / perform at least part of functionalities of that network function.

[0056] The term “network device” may refer also to a network node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) or a transmission and reception point (TRP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a WiFi (Wireless Fidelity) device, a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. In the following description, the terms “network device”, “AP device”, “AP” and “access point” may be used interchangeably.

[0057] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), a station (STA) or station device, or an access terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mountedequipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (for example, remote surgery), an industrial device and applications (for example, a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may be a Dual Steer (DS) device which could comprise of two logical UEs or one UE with 2 Universal Subscriber Identity Modules (USIMs).

[0058] The term “transceiver” may refer to any device that may be coupled to one or more antennas or antenna ports to wirelessly transmit and / or receive communication signals. The antennas or antenna ports may be the same or different types. The antennas or antenna ports may be located in different positions of an apparatus. One or more transceivers allow the apparatus to communicate with other devices that may be wired and / or wireless. The one or more transceivers may include processors, controllers, radios, sockets, plugs, buffers, or the like circuits to form one or more communication channels to one or more radio frequency units. The one or more transceivers may be integrated in an apparatus or a system, for example a cellular communication apparatus or system, a satellite communication apparatus or system, a WLAN system, or a short ranging system for example Bluetooth system.

[0059] A Dual Steer (DS) device may comprise of two logical UEs or one UE with 2 USIMs. Application traffic could be steered to the device via one or two UE(s) both on the uplink (UL) direction and on the downlink (DL) direction. In some embodiments, the DS device may support traffic steering and switching of user data (for different services) across two networks (e.g., 3 GPP access networks); it can be a single UE, in case of nonsimultaneous data transmission over the two networks, or two separate UEs in case of simultaneous data transmission over the two networks.

[0060] The following requirements cover scenarios and functionalities for supporting enhanced traffic steering and switching of user data (for different services) of a DS device across two networks (e.g., 3GPP access networks), assuming the ability to differentiate the two connections for the same device and minimize impacts to core network (CN), Operation and Maintenance (O&M) or IT systems.

[0061] Target scenarios cover two (3GPP access) networks belonging to the same Public Land Mobile Network (PLMN), or between two different PLMNs, or between one PLMN and one PLMN-integrated Non-Public Network (NPN), over same or different Radio Access Technologies (RATs), which can use terrestrial and / or satellite access (including the case of two different satellite orbits). Scenarios may also include traffic steering and / or switching across Evolved Universal Terrestrial Radio Access and Evolved Packet Core (E-UTRA / EPC) and NR / 5GC, with anchoring in 5GC. Traffic policies are intended to be in full control of the home network operator. The requirements below can apply to different Dual Steer device types, e.g., smartphones, loT (Internet of Things), UAV (Unmanned Aerial Vehicle), VSAT (Very Small Aperture Terminal) devices. For a DS device, a subscriber may have two subscriptions or Subscriber Permanent Identifiers (SUPIs), sharing one subscription profile from the same operator.

[0062] For simultaneous transmission over two networks, the DS device is assumed to include two separate UEs. In order for the application traffic to be aggregated and / or steered from the User Plane Function (UPF) towards the two UEs, the same UPF must be serving the corresponding Protocol Data Unit (PDU) sessions. There are different solutions being proposed to correlate the session management requests however the UEs may still be served by different AMFs, which has the following side impacts. First, mobile terminated transactions are duplicated via the air interface and / or within the 5GC; second, paging replicated consumes significant energy and signaling load. Hence it is crucial to find solutions to ensure that the two UEs are served by the same AMF in order to overcome the issues mentioned above. Aspects of the present disclosure will be described with reference to FIGS. 1 to 13.

[0063] FIG. 1 illustrates an example network environment in which some embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 may include a terminal device 110, aBS 120 (e.g., a gNB, which can be interchangeably used in this disclosure), and a core network including various Network Functions (NFs), including but not limited to AMFs 130 and 140, Unified Data Management (UDM) 150, and others. The core network may include other NFs such as Session Management Function (SMF), Network Exposure Function (NEF), Policy Control Function (PCF), which are not shown for brevity. The NFs may communicate with each other inside the core network.

[0064] As illustrated, the terminal device 110 may comprise more than one UEs, including UE-1 112 and UE-2 114. Each UE 112 or 114 may be associated with a unique identity, for example, Subscriber Permanent Identifier (SUPI). In some embodiments, the terminal device 110 may be a Dual Steer Device as mentioned above, where each UE 112 or 114 may communicate with the BS 120 and the core network separately. In some embodiments, the terminal device 110 may include a proxy which proxies the UE-1 112 and UE-2 114 and communicates with the network on behalf of the UEs. In some embodiments, the UE-1 112 and the UE-2 114 may communicate with each other via an internal interface, namely, a dual steer layer.

[0065] When the terminal device 110 is within coverage of the BS 120, it can communicate with the BS 120 over Uu interface. In some embodiments, to register with the network, the UE 112 or 114 of the terminal device 110 may firstly perform an RRC (Radio Resource Control) setup procedure via the Uu interface to establish a communication channel between the UE(s) and the BS 130. The RRC setup procedure may include the following steps: the UE112 / 114 sends an RRC Setup Request message to the BS 120, the BS 120 responds with an RRC Setup response, which can include configuration details for the UE 112 / 114, and the UE 112 / 114 acknowledges the setup by sending an RRC Setup Complete message to the BS 120.

[0066] During UE registration, the BS 120 may select a serving AMF for UE registration. After the UE registration, the UE 112 or 114 can be assigned with a temporary identity for use in the network, for example, a 5G-GUTI (Globally Unique Temporary UE Identity), or a 5G S-TMSI (Service Temporary Mobile Subscriber Identity) which can be derived from the 5G-GUTI.

[0067] As illustrated, the terminal device 110 (or UEs 112 and 114) may bidirectionally communicate with the core network, e.g., with the AMFs 130 or 140 over N1 interface, a logical interface between the terminal device 110 and the AMF 130 or 140. The N1 interface may carry, using a NAS (Non-Access Stratum) container, NAS messages (e.g., registration request and accept messages) between the terminal device 110 and the AMF 130 or 140. Additionally or alternatively, the terminal device 110 may bidirectionally communicates with the core network via the BS 120 over Uu interface and N2 interface.

[0068] It is to be understood that the numbers of terminal devices, UEs, BSs or core network entities shown in FIG. 1 are only for ease of illustration. The communication network 100 may include any suitable numbers of devices.

[0069] In a nutshell, the present disclosure provides two exemplified options to register the two UEs 112 and 114 of the terminal device 110 with a same AMF. Note that, throughout the present disclosure, it is assumed that the UE-2 (also referred as a second UE) has been registered with AMF-2 (e.g., the AMF-2 130 in FIG. 1), and the UE-1 is to be registered with the same AMF using the proposed solutions.

[0070] In the first option, the UE-1 signals to the NG-RAN (e.g., the BS 130) using RRC signaling, during its registration, the linked 5G S-TMSI of UE-2 (i.e., 5G S-TMSI derived from the 5G-GUTI of UE-2 obtained during the earlier registration performed by UE-2), or <AMF Set ID><AMF Pointer> of the linked 5G S-TMSI of UE-2, to identify the AMF-2 of UE-2. Using this information identifying the AMF-2, the NG-RAN can select the serving AMF-2 of UE-2 for the registration of UE-1. The first option will be discussed in detail with reference to FIGS. 2 and 3.

[0071] In the second option, during the registration of UE-1, the AMF-1 of UE-1, selected by the NG-RAN, retrieves from the UDM information identifying the serving AMF-2 to allow the forwarding over N14 (inter AMF interface,) or the redirection over N2 (RAN-Core interface) of the registration of UE-1 towards the AMF-2 serving the UE-2. The AMF-1 may determine to redirect the NAS registration of UE-1 to another AMF of the same PLMN, for a Dual Steer Device already registered in a different AMF of the same PLMN. The second option will be discussed in detail with reference to FIGS. 4 and 5.

[0072] Further, both options may take place at initial registration or at mobility registration with AMF change. In case of Hand-Over (with AMF change), it is up to the source AMF being aware that the 2 registrations are linked to ensure that the same target AMF is selected for the Hand-Over related with the second registration.

[0073] FIG. 2 illustrates an example of a process flow 200 for selecting the same AMF based on information identifying the AMF in accordance with some embodiments of the present disclosure. For ease of understanding, the process flow 200 will be described with reference to FIG. l, It would be appreciated that although the process flow 200 has been described referring to the communication network 100 of FIG. 1, the process flow 200 may be likewise applied to other similar communication scenarios.

[0074] The process flow 200 involves a terminal device 110 including UE-1 112 and UE- 2 114, a BS 120, an AMF-2 130, and a UDM 150. As shown in FIG. 2, at step 201, the UE- 2 is registered and RRC connected through the AMF-2 130, i.e., the AMF-2 130 is the serving AMF of UE-2. Based on the registration of the UE-2 114, the terminal device 112 can obtain a temporary ID of the UE-2 114 for use in the network, for example, 5G-GUTI or 5G-S-TMSI.

[0075] At step 202, the UE-1 112 transmits information 203 identifying a serving AMF-2 130 of the UE-2 114 to the BS 120. Correspondingly, at 204, the BS 120 receives the information 203 identifying the serving AMF-2 130 of the UE-2 114. In some embodiments, the terminal device 110 may detect a trigger to register the UE-2 114 with the network, and cause the UE-2 114 to initiate an RRC setup procedure with the BS 120.

[0076] During the RRC setup procedure, the UE-2 114 may include the information 203 identifying the serving AMF of the UE-2 114 into an RRC Setup Request message and / or an RRC Setup Complete message. In some embodiments, the information 203 may be split into two parts, one part is transmitted in the RRC Setup Request message, and the other part in the RRC Setup Complete message.

[0077] The information 203 identifying the AMF-2 130 may include at least a part of an AMF identifier of the AMF-2 130. The AMF identifier includes an AMF Region ID, an AMF Set ID and AMF Pointer. In some embodiments, the information 203 may include the AMF pointer of the AMF-2 130. In some embodiments, the information 203 may further include the AMF Set ID of the AMF-2 130.

[0078] The terminal device 110 or the UE-1 112 may extract the information on the AMF- 2 130 based on the registration result of the UE-2 114, e.g., the 5G-GUTI or the 5G-S-TMSI. The format of the 5G-GUTI is the following:<5G-GUTI> = <GUAMI><5G-TMSI>, where <GUAMI> = <MCC><MNC><AMF Identified, and<AMF Identified = <AMF Region ID><AMF Set ID><AMF Pointed.Here, GUAMI stands for Globally Unique AMF Identifier, MCC stands for Mobile Country Code, and MNC stands for Mobile Network Code. Note that the 5G-S-TMSI is constructed from the AMF Set ID, the AMF Pointer and the 5G-TMSI as below:<5G-S-TMSI> = <AMF Set ID><AMF Pointer><5G-TMSI>

[0079] At 205, the BS 120 selects, based on the information 203 identifying the AMF-2 130 of the UE-2 114, the same serving AMF-2 130 for the UE-1 112. Under such conditions, when / if receiving a NAS message of / from the UE-1 112, the BS 120 would transmit / convey / forward / transfer this NAS message to the serving AMF-2 130. For instance, the BS 120 may forward a registration request contained in a NAS container (e.g., piggybacked on an RRC message from the UE-1 112) to the selected AMF, i.e., the same serving AMF as UE-2 114.

[0080] At 206, the UE-1 112 performs registration (procedure) with the AMF-2 130 serving the UE-2 114. For example, the UE-1 112 may perform authentication or security check with AMF-2 130, and the AMF-2 130 may perform UDM selection and UE context management registration with the UDM 150. After the registration is complete, the AMF-2 130 may transmit a Registration Accept message including a 5G-GUTI assigned to the UE-1 112 for use in the network. Note that, the transmission of the registration request in the NAS container which is comprised in or piggybacked on an RRC message (e.g., RRC Setup Complete) may be considered as a part of the registration (procedure).

[0081] FIG. 3 illustrates an example of a detailed process flow 300 for selecting the same AMF based on information identifying the AMF accordance with some embodiments of the present disclosure. For ease of understanding, the process flow 300 will be described with reference to FIG. l, It would be appreciated that although the process flow 300 has been described referring to the communication network 100 of FIG. 1, the process flow 300 may be likewise applied to other similar communication scenarios.

[0082] The process flow 300 involves a terminal device 110 including UE-1 112 and UE-2 114, a BS 120, an AMF-2 130, and a UDM 150. The terminal device 110 may be a dual steer device with each UE 112 or 114 being associated with a corresponding SUPI.

[0083] As shown in FIG. 3, at step 301, the UE-2 114 is registered and RRC connected through the AMF-2 130, i.e., the AMF-2 130 is the serving AMF of the UE-2 114. Based on the registration of the UE-2 114, the terminal device 112 can obtain a temporary ID of the UE-2 114 for use in the network, for example, 5G-GUTI or 5G-S-TMSI.

[0084] At 302, the UE-1 112 may receive the information identifying the serving AMF-2 130 of the UE-2 114. In some embodiments, the UE-1 112 may receive the information over an internal interface between the UE-1 112 and the UE-2 114. The internal interface may bea dual steer layer. In some embodiments, if the UEs 112 and 114 cannot communication with each other directly, step 302 may be omitted.

[0085] In some embodiments, the information identifying the serving AMF-2 130 may be the full or a part of the temporary ID of the UE-2 114, such as 5G-S-TMSI or 5G-GUTI, to include at least a part of the AMF identifier. Alternatively, it may comprise full or a part of the GUAMI of AMF-2 130, which can be derived from the 5G-GUTI. In particular, the information identifying the serving AMF-2 130 may include the AMF pointer of the serving AMF-2 130, and in some cases, further include the AMF Set ID.

[0086] At 303, the UE-1 112 may store the information identifying the serving AMF-2 130 at the UE-1 112. Alternatively, if the UEs 112 and 114 cannot communication with each other directly, the terminal device 110 or the UE-2 114 may store the information identifying the serving AMF-2 130 into a cache accessible to the UE-1 112.

[0087] When / If the terminal device 110 detects a trigger to register the UE-1 112 with the network, the UE-1 112 may initiate an RRC setup procedure with the BS 120. At 304, the UE-1 112 transmits an RRC Setup Request message including at least part of the information on the serving AMF-2 130 of the UE-2 114.

[0088] At 305, the UE-1 112 receives an RRC Setup Response message including the RRC configuration and other parameters to establish an RRC connection with the BS 120.

[0089] At 306, the UE-1 112 transmits an RRC Setup Complete message to the BS 120. The RRC Setup Complete message may also include at least part of the information on the serving AMF-2 130 of the UE-2 114. In some embodiments, the parts transmitted in the RRC Setup Request message and the RRC Setup Complete message may be combined to form the full information on the AMF-2 130. Alternatively, the information on the AMF-2 130 may be transmitted in any of the RRC Setup Request message and the RRC Setup Complete message.

[0090] In some embodiments, the RRC Setup Complete message may include a NAS container (transparent to the BS 120) encapsulating a registration request for the UE-1 112. The registration request may include identity information of the UE-1 112 (e.g., Subscription Concealed Identifier, SUCI), the registration type, security parameters that are required to register the UE with the network.

[0091] At 307, the BS 120 selects the same AMF-2 130 for the UE-1 112 based on the information identifying the serving AMF-2 130 of the UE-2 114 (received during the RRC setup procedure).

[0092] At 308, the BS 120 may transmit a NGAP (Next Generation Application Protocol) Initial UE message to the AMF-2 130 based on the selection at 307 to forward the NAS container. The NGAP Initial UE message relays the registration request included in the NAS container from the BS 120 to the AMF-2 130. The NAS registration request is therefore contained in the RRC Setup Complete message at 306 and the NGAP Initial UE message at 308, as illustrated in FIG. 3.

[0093] Upon reception of the registration request, the AMF-2 130 may proceed with registering the UE-1 112. At 309, the AMF-2 130 may transmit a NAS Registration Response message the UE-1 112, which may include a 5G-GUTI of the UE-1 112 for use in the network.

[0094] FIG. 4 illustrates an example of a process flow 400 for selecting the same AMF based on registration redirection in accordance with some embodiments of the present disclosure. For ease of understanding, the process flow 400 will be described with reference to FIG. l, It would be appreciated that although the process flow 400 has been described referring to the communication network 100 of FIG. 1, the process flow 400 may be likewise applied to other similar communication scenarios.

[0095] As shown in FIG. 4, at step 401, the UE-2 114 is registered and RRC connected through the AMF-2 130, i.e., the AMF-2 130 is the serving AMF of UE-2. Based on the registration of the UE-2 114, the UDM 150 stores subscriber-related data, including user profiles, subscription information, and authentication credentials.

[0096] In some embodiments, the registration request from the terminal device 110 (e.g. for both UEs 112 and 114) may include an indication that the registration request is for a dual steer device. Besides the identity information of the UE-1 112, the registration request may include an identifier of the UE-2 114, for example, a SUCI. After the registration of the UE-2 114, the UDM 150 may store identity information of the UEs 112 and 114 in a linked manner. For example, the UDM 150 may store the SUPIs of the UEs in the linked manner, after decryption of the SUCIs.

[0097] When / If the terminal device 110 detects a trigger to register the UE-1 112 with the network, the UE-1 112 initiates an RRC setup procedure with the BS 120. At 402, the UE-1 112 transmits an RRC Setup Request message to the BS 120.

[0098] At 403, the UE-1 112 receives an RRC Setup Response message including the RRC configuration and other parameters to establish an RRC connection with the BS 120.

[0099] At 404, the UE-1 112 transmits an RRC Setup Complete message to the BS 120. The RRC Setup Complete message may include a NAS container including a registration request for the UE-1 112. If a 5G-S-TMSI or GUAMI is not included or the 5G-S-TMSI or GUAMI does not indicate a valid AMF, the baste station 120 may select an AMF based on requested NSSAI (Network Slice Selection Assistance Information). In this embodiment, the BS 120 selects the AMF-1 140 for the UE-1 112, which is different from the AMF-2 130 of the UE-2 114.

[0100] At 405, the BS 120 transmits an NGAP Initial message to relay the NAS registration request for the UE-1 112 to the AMF-1 140. The NAS registration request may include an indication that the registration request is for a dual steer device and / or an identifier of the UE-2 114. Then, the AMF-1 140 performs registration for the UE-1 112.

[0101] During the registration, at 406, the AMF-1 140 may transmit a UE Context Management (UECM) message for registration for the UE-1 112 to the UDM 150. Upon reception of the UECM message, the UDM 150 may determine that the UE-1 112 is linked to the UE-2 114, e.g., because / since their identity information (e.g., SUPIs) have been stored in a linked manner in the UDM 150. The UDM 150 has the knowledge that both the UE-1 112 and the UE-2 114 belong to a same device.

[0102] At 407, the UDM 150 may transmit a UECM response message including information on the UE-2 114 to the AMF-1 140. In some embodiments, the UDM 150 may send the information identifying the AMF-2 130 of the linked UE-2 114 to the AMF-1 140. Similar to the embodiments described with reference to FIGs. 2 and 3, the information may include an AMF pointer of the AMF-2 130, and in some embodiments, an AMF Set ID of the second AMF.

[0103] At 408, the AMF-1 140 then determines, based on the information retrieved from the UDM 150, to redirect the registration of the UE-1 112 to the AMF-2 130 (e.g., redirect the registration request of / for the UE-1 112 to the AMF-2 130), and at 409, forwards the registration request for the UE-1 112 to the AMF-2 130. After the forwarding / redirection issuccessful, at 410, the AMF-2 130 replies to the UE-1 112 with a NAS Registration Accept message. Therefore, the UE-1 112 is successfully registered with same AMF as the UE-2 114.

[0104] FIG. 5 illustrates an example of another process flow 500 for selecting the same AMF based on registration redirection in accordance with some embodiments of the present disclosure.

[0105] In FIG. 5, the steps 501 to 507 are similar as the steps 401 to 407 described in FIG. 4. At 508, the AMF-2 determines to redirect the NAS registration to AMF-2 130 of the same PLMN. In comparison with the embodiment in FIG. 4, the redirection of the registration towards the AMF-2 serving the UE-2 in FIG. 5 is performed via the RAN, i.e., over N2 interface. Specifically, at 509, the AMF-1 140 forwards the registration request for the UE- 1 112 to the BS 120 serving the UE-1 112. At 510, the BS 120 may transmit an NGAP Initial UE message including the registration request to the AMF-2 130. Then, the UE-1 112 performs the registration with same AMF-2 130 of the UE-2 114.

[0106] Embodiments of the present disclosure can ensure that the same AMF is selected also after idle mode mobility and / or connected mode Handover (HO). It is also ensured that the same AMF is selected also at inter AMF mobility (in CONNECTED mode).

[0107] At the time of inter AMF change for a SUPI (e.g. SUPH) the source AMF may store in the context of the other SUPI (SUPI2), the target AMF selected for SUPH and use this stored target AMF when it is triggered at HO of that other SUPI.

[0108] In a case that SUPI 1 is moved to a third AMF before the SUPI2 is subject to an inter AMF change, the second option (i.e., the redirecting scheme) can be applied. For example, at the inter-AMF handover for SUPI 2, the source AMF 1 can include the SUPI 1 to target AMF2, then target AMF 2 can check if SUPI 1 was further handed over to target AMF3 and redirect the UE to target AMF3.

[0109] In IDLE mode mobility the UEs make their own decision on cell reselection (change of the serving cell), but they should move to CONNECTED mode (establish a connection) when move to a new registration area. As when an AMF change is needed the registration area also changes, the UEs should move to CONNECTED mode at that point, and from this point the basic registration procedure is performed and the selection of the same AMF can be ensured as described above.

[0110] Selecting the same AMF as proposed can achieve the following benefits. This allows to stick to the existing principle of having a single AMF per PLMN for a given UE, and so e.g. S-AMF moving all the PDU session contexts to the target AMF instead of having to move different PDU session contexts of the same dual steer UE to different AMFs based on the specific SUPI / Regi strati on ID associated with each PDU session. By doing so, impacts to the 5GS are limited.

[0111] Selecting the same AMF for a dual steer UE (for registrations in the same PLMN) will also help reduce signaling, including DM initiated signaling to AMF, such as request to serving AMF for T-ADS (Terminating- Access Domain Selection) determination, request for user location subscription data modification, and deregistration of 3GPP access, and MT (Mobile Terminated) signaling, such as MT SMS and LCS request (also enabling the use of the same LMF).

[0112] Assume there is a Dual Steer device (including SUPI1 and SUPI2) and an established Dual Steer PDU session with inactive User Plane (Dual Steer PDU session has a common SMF and UPF). When the common SMF receives a DDN from the UPF (due to the reception of a MT PDU in a PDU session with inactive UP) the SMF would have to determine what is the best AMF to use to trigger PDU session resource establishment with possibly paging). This would be optimized with a common AMF.

[0113] FIG. 6 illustrates a flowchart of an example method 600 implemented at a first UE in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 600 will be described from the perspective of the UE-1 112 with reference to FIGS. 2 and 3.

[0114] At block 610, the first UE transmits, to a base station, information identifying a serving AMF of a second UE during a RRC setup procedure with the base station for the first UE. At block 620, the first UE performs registration for the first UE with the serving AMF of the second UE.

[0115] In some embodiments, to transmit, to the base station, the information identifying the serving AMF of the second UE, the first UE may transmit, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or transmit, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0116] In some embodiments, to perform registration for the first UE with the serving AMF of the second UE, the first UE may transmit an RRC Setup Complete message including a registration request message for the first UE.

[0117] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0118] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0119] In some embodiments, the information identifying the serving AMF includes at least a part of: a GUAMI of the serving AMF of the second UE; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0120] In some embodiments, the first and second UEs are included in a same device.

[0121] In some embodiments, the same device is a dual steer device.

[0122] In some embodiments, the first UE may receive, from the second UE, the information identifying the AMF of the second UE.

[0123] In some embodiments, the first UE may store the information identifying the AMF of the second UE.

[0124] FIG. 7 illustrates a flowchart of an example method 700 implemented at a base station in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 700 will be described from the perspective of the BS 120 with reference to FIGS. 2 and 3.

[0125] At block 710, the base station receives, from a first UE, information identifying a serving AMF of a second UE during an RRC setup procedure with the base station for the first UE. At block 720, the base station selects, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0126] In some embodiments, to receive, from the first UE, the information identifying the serving AMF of the second UE, the base station may receive, from the first UE, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or receive, from the first UE, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0127] In some embodiments, the base station may receive an RRC Setup Completemessage including a registration request message for the first UE; and forward the registration request message for the first UE to the serving AMF of the second UE.

[0128] In some embodiments, the information identifying the serving AMF at least comprises an AMF pointer of the serving AMF.

[0129] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0130] In some embodiments, the information identifying the serving AMF includes at least a part of: a GUAMI of the server AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0131] FIG. 8 illustrates a flowchart of an example method 800 implemented at a terminal device in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 800 will be described from the perspective of the terminal device 110 with reference to FIGS. 2 and 3.

[0132] At block 810, the terminal device registers the second UE with a network. At block 820, the terminal device receives, from the network, identity information of the second UE for use in the network, wherein the identity information includes information identifying a serving AMF of the second UE. At block 830, the terminal device transmits, to a base station, information identifying the serving AMF of the second UE during an RRC setup procedure with the base station for the first UE. At block 840, the terminal device performs registration for the first UE with the serving AMF of the second UE.

[0133] In some embodiments, to transmit, to the base station, the information identifying the serving AMF of the second UE, the terminal device may transmit, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or transmit, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0134] In some embodiments, to perform registration for the first UE with the serving AMF of the second UE, the terminal device may transmit an RRC Setup Complete message including a registration request message for the first UE.

[0135] In some embodiments, the terminal device may further store the identity information of the second UE in the first UE.

[0136] In some embodiments, the identity information comprises a 5G-GUTI of the second UE.

[0137] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0138] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0139] In some embodiments, the terminal device comprises a dual steer device.

[0140] FIG. 9 illustrates a flowchart of an example method 900 implemented at a terminal device in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 900 will be described from the perspective of the terminal device 110 with reference to FIGS. 2 and 3.

[0141] At block 910, the terminal device registers the second UE with a network. At block 920, the terminal device receives, at the second UE and from the network, identity information of the second UE for use in the network. At block 930, the terminal device forwards, from the second UE to the first UE, at least a part of the identity information of the second UE including information identifying a serving Access and Mobility Function (AMF) of the second UE. At block 940, the terminal device transmits, from the first UE and to a base station, the information identifying the serving AMF of the second UE during an RRC setup procedure with the base station for the first UE. At block 950, the terminal device performs registration for the first UE with the serving AMF of the second UE.

[0142] In some embodiments, to transmit, to the base station, the information identifying the serving AMF of the second UE, the terminal device may transmit, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or transmit, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0143] In some embodiments, to perform registration for the first UE with the serving AMF of the second UE, the terminal device may transmit an RRC Setup Complete message including a registration request message for the first UE.

[0144] In some embodiments, the terminal device comprises a dual steer device.

[0145] In some embodiments, at least the part of the identity information of the second UEis forwarded over a dual steer layer between the first UE and the second UE.

[0146] In some embodiments, the terminal device may store at least the part of the identity information of the second UE in the first UE.

[0147] In some embodiments, the identity information comprises a 5G-GUTI of the second UE.

[0148] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0149] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0150] FIG. 10 illustrates a flowchart of an example method 1000 implemented at a network device comprising a first AMF in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 1000 will be described from the perspective of the AMF-1 140 with reference to FIGS. 4 and 5.

[0151] At block 1010, the network device receives, from a UDM, information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE. At block 1020, the network device redirects the registration for the first UE to the second AMF serving the second UE.

[0152] In some embodiments, the network device may receive, from the first UE, a registration request including at least one of an indication that the registration request is for a dual steer device or an identifier of the second UE.

[0153] In some embodiments, the information identifying the second AMF at least comprises an AMF pointer of the second AMF.

[0154] In some embodiments, the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

[0155] In some embodiments, the information identifying the second AMF includes at least a part of: a GUAMI of the second AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0156] In some embodiments, to redirect the registration for the first UE to the second AMF, the network device may forward the registration request received from the first UE to the second AMF.

[0157] In some embodiments, to redirect the registration for the first UE to the second AMF, the network device may forward a registration request received from the first UE to a serving base station of the first UE for forwarding to the second AMF.

[0158] In some embodiments, the linking between the first and the second UEs comprises linking SUPIs of the first and second UEs.

[0159] FIG. 11 illustrates a flowchart of an example method 1100 implemented at a network device comprising a UDM in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 1100 will be described from the perspective of the UDM 150 with reference to FIGS. 4 and 5.

[0160] At block 1110, the network device transmits, to a first AMF, information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to a first UE.

[0161] In some embodiments, the network device may receive a UECM message for registration for the first UE; and obtain, based on the UECM message, the information identifying the second AMF that serves the second UE linked to the first UE.

[0162] In some embodiments, the network device may store identity information of the first UE and the second UE in a linked manner after registration for the second UE after registration for the second UE.

[0163] In some embodiments, the identity information is SUPI.

[0164] In some embodiments, the information identifying the second AMF at least comprises an AMF pointer of the second AMF.

[0165] In some embodiments, the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

[0166] In some embodiments, the information identifying the second AMF includes at least a part of: a GUAMI of the second AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0167] In some embodiments, an apparatus capable of performing the method 600 (for example, at a UE) may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0168] In some embodiments, the apparatus comprises: means for means for transmitting, from a first UE and to a base station, information identifying a serving AMF of a second UE during an RRC setup procedure with the base station for the first UE; and means for performing registration for the first UE with the serving AMF of the second UE.

[0169] In some embodiments, means for transmitting, to the base station, the information identifying the serving AMF of the second UE may comprise means for transmitting, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or means for transmitting, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0170] In some embodiments, means for performing registration for the first UE with the serving AMF of the second UE may comprise means for transmitting an RRC Setup Complete message including a registration request message for the first UE.

[0171] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0172] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0173] In some embodiments, the information identifying the serving AMF includes at least a part of: a GUAMI of the serving AMF of the second UE; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0174] In some embodiments, the first and second UEs are included in a same device.

[0175] In some embodiments, the same device is a dual steer device.

[0176] In some embodiments, the apparatus may further comprise means for receiving, from the second UE, the information identifying the AMF of the second UE.

[0177] In some embodiments, the apparatus may further comprise means for storing the information identifying the AMF of the second UE.

[0178] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 600. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, causethe performance of the apparatus.

[0179] In some embodiments, an apparatus capable of performing the method 700 (for example, at a base station) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0180] In some embodiments, the apparatus comprises: means for receiving, from a first UE, information identifying a serving AMF of a second UE during an RRC setup procedure with the base station for the first UE; and means for selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

[0181] In some embodiments, means for receiving, from the first UE, the information identifying the serving AMF of the second UE may comprise means for receiving, from the first UE, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or means for receiving, from the first UE, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0182] In some embodiments, the apparatus may comprise means for receiving an RRC Setup Complete message including a registration request message for the first UE; and means for forwarding the registration request message for the first UE to the serving AMF of the second UE.

[0183] In some embodiments, the information identifying the serving AMF at least comprises an AMF pointer of the serving AMF.

[0184] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0185] In some embodiments, the information identifying the serving AMF includes at least a part of: a GUAMI of the server AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0186] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 700. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, causethe performance of the apparatus.

[0187] In some embodiments, an apparatus capable of performing the method 800 (for example, at a terminal device including a first UE and a second UE) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0188] In some embodiments, the apparatus comprises: means for registering the second UE of the terminal device with a network; means for receiving, from the network, identity information of the second UE for use in the network, wherein the identity information includes information identifying a serving AMF of the second UE; means for transmitting, to a base station, information identifying the serving AMF of the second UE during an RRC) setup procedure with the base station for the first UE; and means for performing registration for the first UE with the serving AMF of the second UE.

[0189] In some embodiments, means for transmitting, to the base station, the information identifying the serving AMF of the second UE may comprise means for transmitting, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or means for transmitting, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0190] In some embodiments, means for performing registration for the first UE with the serving AMF of the second UE may comprise means for transmitting an RRC Setup Complete message including a registration request message for the first UE.

[0191] In some embodiments, the apparatus may comprise means for storing the identity information of the second UE in the first UE.

[0192] In some embodiments, the identity information comprises a 5G-GUTI of the second UE.

[0193] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0194] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0195] In some embodiments, the apparatus may comprise a dual steer device.

[0196] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 800. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0197] In some embodiments, an apparatus capable of performing the method 900 (for example, at a terminal device including a first UE and a second UE) may comprise means for performing the respective steps of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0198] In some embodiments, the apparatus comprises: means for registering the second UE of the terminal device with a network; means for receiving, at the second UE and from the network, identity information of the second UE for use in the network, means for forwarding, from the second UE to the first UE of the terminal device, at least a part of the identity information of the second UE including information identifying the serving AMF of the second UE; means for transmitting, from the first UE and to a base station, the information identifying the serving AMF of the second UE during an RRC setup procedure with the base station for the first UE; and means for performing registration for the first UE with the serving AMF of the second UE.

[0199] In some embodiments, means for transmitting, to the base station, the information identifying the serving AMF of the second UE may comprise means for transmitting, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; and / or means for transmitting, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

[0200] In some embodiments, means for performing registration for the first UE with the serving AMF of the second UE may comprise means for transmitting an RRC Setup Complete message including a registration request message for the first UE.

[0201] In some embodiments, the apparatus may comprise a dual steer device.

[0202] In some embodiments, at least the part of the identity information of the second UE is forwarded over a dual steer layer between the first UE and the second UE.

[0203] In some embodiments, the apparatus may comprise means for storing at least the part of the identity information of the second UE in the first UE.

[0204] In some embodiments, the identity information comprises a 5G-GUTI of the second UE.

[0205] In some embodiments, the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

[0206] In some embodiments, the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

[0207] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 900. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0208] In some embodiments, an apparatus capable of performing the method 1000 (for example, at a network device comprising a first AMF) may comprise means for performing the respective steps of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0209] In some embodiments, the apparatus comprises: means for receiving, at a first AMF and from a UDM, information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and means for redirecting the registration for the first UE to the second AMF serving the second UE.

[0210] In some embodiments, the apparatus may comprise means for receiving, from the first UE, a registration request including at least one of an indication that the registration request is for a dual steer device or an identifier of the second UE.

[0211] In some embodiments, the information identifying the second AMF at least comprises an AMF pointer of the second AMF.

[0212] In some embodiments, the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

[0213] In some embodiments, the information identifying the second AMF includes at least a part of: a GUAMI of the second AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI ofthe second UE.

[0214] In some embodiments, means for redirecting the registration for the first UE to the second AMF may comprise means for forwarding the registration request received from the first UE to the second AMF.

[0215] In some embodiments, means for redirecting the registration for the first UE to the second AMF may comprise means for forwarding a registration request received from the first UE to a serving base station of first UE for forwarding to the second AMF.

[0216] In some embodiments, the linking between the first and the second UEs comprises linking SUPIs of the first and second UEs.

[0217] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 1000. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0218] In some embodiments, an apparatus capable of performing the method 1100 (for example, at a network device comprising a UDM) may comprise means for performing the respective steps of the method 1100. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0219] In some embodiments, the apparatus comprises means for transmitting, to a first AMF information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

[0220] In some embodiments, the apparatus may comprise means for receiving a UECM message for registration for the first UE; and means for obtaining, based on the UECM message, the information identifying the second AMF that serves the second UE linked to the first UE.

[0221] In some embodiments, the apparatus may comprise means for storing identity information of the first UE and the second UE in a linked manner after registration for the second UE after registration for the second UE.

[0222] In some embodiments, the identity information is SUPI.

[0223] In some embodiments, the information identifying the second AMF at leastcomprises an AMF pointer of the second AMF.

[0224] In some embodiments, the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

[0225] In some embodiments, the information identifying the second AMF includes at least a part of: a GUAMI of the second AMF; a 5G-GUTI of the second UE; or a 5G-S-TMSI of the second UE.

[0226] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 1100. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0227] FIG. 12 illustrates a simplified block diagram of a device 1200 that is suitable for implementing some embodiments of the present disclosure. The device 1200 may be provided to implement a communication device, for example, UEs, the network devices, base stations, or the terminal devices as shown in FIGS. 1 to 5. As shown, the device 1200 includes one or more processors 1210, one or more memories 1220 coupled to the processor 1210, and one or more communication modules 1240 coupled to the processor 1210.

[0228] The communication module 1240 is for bidirectional communications. The communication module 1240 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

[0229] The processor 1210 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1200 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0230] The memory 1220 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1224, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD),and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1222 and other volatile memories that will not last in the power-down duration.

[0231] A computer program 1230 includes computer executable instructions that are executed by the associated processor 1210. The program 1230 may be stored in the ROM 1224. The processor 1210 may perform any suitable actions and processing by loading the program 1230 into the RAM 1222.

[0232] The embodiments of the present disclosure may be implemented by means of the program 1230 so that the device 1200 may perform any process of the disclosure as discussed with reference to FIGS. 6 to 11. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0233] In some embodiments, the program 1230 may be tangibly contained in a computer- readable medium which may be included in the device 1200 (such as in the memory 1220) or other storage devices that are accessible by the device 1200. The device 1200 may load the program 1230 from the computer-readable medium to the RAM 1222 for execution. The computer-readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

[0234] FIG. 13 illustrates a block diagram of an example of a computer-readable medium 1300 in accordance with some embodiments of the present disclosure. The computer- readable medium 1300 has the program 1230 stored thereon. It is noted that although the computer-readable medium 1300 is depicted in form of CD or DVD in FIG. 13, the computer-readable medium 1300 may be in any other form suitable for carry or hold the program 1230.

[0235] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or othercomputing devices, or some combination thereof.

[0236] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or methods 600 to 1100 as described above with reference to FIGS. 6 to 11. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0237] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0238] In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer-readable medium, and the like.

[0239] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0240] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0241] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A first user equipment (UE) comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first UE at least to: transmit, to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and perform registration for the first UE with the serving AMF of the second UE.

2. The first UE of claim 1, wherein, to transmit, to the base station, the information identifying the serving AMF of the second UE, the first UE is caused to at least one of: transmit, to the base station, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; or transmit, to the base station, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

3. The first UE of claim 1 or 2, wherein, to perform registration for the first UE with the serving AMF of the second UE, the first UE is caused to: transmit an RRC Setup Complete message including a registration request message for the first UE.

4. The first UE of any of claims 1 to 3, wherein the information identifying the serving AMF comprises an AMF pointer of the serving AMF.

5. The first UE of claim 4, wherein the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

6. The first UE of claim 4 or 5, wherein the information identifying the serving AMF includes at least a part of: a Globally Unique AMF Identifier (GUAMI) of the serving AMF of the second UE; a 5G-Globally Unique Temporary UE Identity (5G-GUTI) of the second UE; or37a 5G-service-Temporary Mobile Subscriber Identity (5G-S-TMSI) of the second UE.

7. The first UE of any of claims 1 to 6, wherein the first and second UEs are included in a same device.

8. The first UE of claim 7, wherein the same device is a dual steer device.

9. The first UE of any of claims 1 to 8, wherein the first UE is further caused to: receive, from the second UE, the information identifying the AMF of the second UE.

10. The first UE of any of claims 1 to 9, wherein the first UE is further caused to: store the information identifying the AMF of the second UE.

11. A base station comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the base station at least to: receive, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and select, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

12. The base station of claim 11, wherein, to receive, from the first UE, the information identifying the serving AMF of the second UE, the base station is caused to at least one of: receive, from the first UE, an RRC Setup Request message including at least part of the information identifying the serving AMF of the second UE; or receive, from the first UE, an RRC Setup Complete message including at least part of the information identifying the serving AMF of the second UE.

13. The base station of claim 11 or 12, wherein the base station is further caused to:38receive an RRC Setup Complete message including a registration request message for the first UE; and forward the registration request message for the first UE to the serving AMF of the second UE.

14. The base station of any of claims 11 to 13, wherein the information identifying the serving AMF at least comprises an AMF pointer of the serving AMF.

15. The base station of claim 14, wherein the information identifying the serving AMF further comprises an AMF Set ID of the serving AMF.

16. The base station of claim 14 or 15, wherein the information identifying the serving AMF includes at least a part of: a Globally Unique AMF Identifier (GUAMI) of the server AMF; a 5G-Globally Unique Temporary UE Identity (5G-GUTI) of the second UE; or a 5G-service-Temporary Mobile Subscriber Identity (5G-S-TMSI) of the second UE.

17. A network device comprising a first Access and Mobility management Function (AMF), the network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: receive, from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirect the registration for the first UE to the second AMF serving the second UE.

18. The network device of claim 17, wherein network device is further caused to: receive, from the first UE, a registration request including at least one of an indication that the registration request is for a dual steer device or an identifier of the second UE.

19. The network device of claim 17 or 18, wherein the information identifying the second AMF at least comprises an AMF pointer of the second AMF.

20. The network device of claim 19, wherein the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

21. The network device of claim 19 or 20, wherein the information identifying the second AMF includes at least a part of: a Globally Unique AMF Identifier (GUAMI) of the second AMF; a 5G-Globally Unique Temporary UE Identity (5G-GUTI) of the second UE; or a 5G-service-Temporary Mobile Subscriber Identity (5G-S-TMSI) of the second UE.

22. The network device of any of claims 17 to 21, wherein, to redirect the registration for the first UE to the second AMF, the network device is caused to: forward the registration request received from the first UE to the second AMF.

23. The network device of any of claims 17 to 21, wherein, to redirect the registration for the first UE to the second AMF, the network device is caused to: forward a registration request received from the first UE to a serving base station of the first UE for forwarding to the second AMF.

24. The network device of any claims 17 to 23, wherein the linking between the first and the second UEs comprises linking Subscription Permanent Identifiers (SUPIs) of the first and second UEs.

25. A network device comprising Unified Data Management (UDM), the network device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a first Access and Mobility management Function (AMF), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to a first UE.

26. The network device of claim 25, wherein the network device is further caused to: receive a UE Context Management (UECM) message for registration for the first UE; and obtain, based on the UECM message, the information identifying the second AMF that serves the second UE linked to the first UE.

27. The network device of claim 25 or 26, wherein the network device is further caused to: after registration for the second UE, store identity information of the first UE and the second UE in a linked manner.

28. The network device of claim 27 wherein the identity information is Subscription Permanent Identifier (SUPI).

29. The network device of any of claims 25 to 28, wherein the information identifying the second AMF at least comprises an AMF pointer of the second AMF.

30. The network device of claim 29, wherein the information identifying the second AMF further comprises an AMF Set ID of the second AMF.

31. The network device of claim 29 or 30, wherein the information identifying the second AMF includes at least a part of: a Globally Unique AMF Identifier (GUAMI) of the second AMF; a 5G-Globally Unique Temporary UE Identity (5G-GUTI) of the second UE; or a 5G-service-Temporary Mobile Subscriber Identity (5G-S-TMSI) of the second UE.

32. A method comprising: transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and performing registration for the first UE with the serving AMF of the second UE.

33. A method comprising: receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

34. A method comprising: receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirecting the registration for the first UE to the second AMF serving the second UE.

35. A method comprising: transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

36. An apparatus comprising: means for transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and means for performing registration for the first UE with the serving AMF of the second UE.

37. An apparatus comprising: means for receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and means for selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.4238. An apparatus comprising: means for receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and means for redirecting the registration for the first UE to the second AMF serving the second UE.

39. An apparatus comprising: means for transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.

40. A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: transmitting, from a first user equipment (UE) and to a base station, information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and performing registration for the first UE with the serving AMF of the second UE.

41. A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving, from a first user equipment (UE), information identifying a serving Access and Mobility Function (AMF) of a second UE during a Radio Resource Control (RRC) setup procedure with the base station for the first UE; and selecting, based on the information identifying the serving AMF of the second UE, the serving AMF of the second UE for the first UE.

42. A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving, at a first Access and Mobility management Function (AMF) and from a Unified Data Management (UDM), information identifying a second AMF duringregistration for a first UE, wherein the second AMF serves a second UE linked to the first UE; and redirecting the registration for the first UE to the second AMF serving the second UE.

43. A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: transmitting, to a first Access and Mobility management Function (AMF) information identifying a second AMF during registration for a first UE, wherein the second AMF serves a second UE linked to the first UE.44

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