WO2021030946A1

WO2021030946A1 - A method of registration with access and mobility management function re-allocation

Info

Publication number: WO2021030946A1
Application number: PCT/CN2019/101046
Authority: WO
Inventors: Shilin You; Jiyan Cai; Shuang Liang; Jinguo Zhu; Fei Lu; Jin Peng; Wantao Yu; Zhaoji Lin
Original assignee: Zte Corporation
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-02-25
Also published as: CN114175770A; CN114175770B

Abstract

A system and method of terminating any pending listen-before-talk (LBT) attempts after they have been submitted to the physical layer of a system interconnection model if one or more of the LBT attempts succeed. The system and method include receiving, by an initial access and mobility management function (AMF) from a wireless communication device via a radio access network (RAN), a first registration request comprising a first device identifier associated with the wireless communication device. The system and method include allocating, by the initial AMF responsive to receiving the registration request, a second device identifier associated with the wireless communication device. The system and method include generating, by the initial AMF, a second registration request comprising the second device identifier.

Description

A METHOD OF REGISTRATION WITH ACCESS AND MOBILITY MANAGEMENT FUNCTION RE-ALLOCATION

TECHNICAL FIELD

The disclosure relates generally to wireless communications and, more particularly, to systems and methods for registration with access and mobility management function re-allocation.

BACKGROUND

The standardization organization Third Generation Partnership Project (3GPP) is currently in the process of specifying a new Radio Interface called 5G New Radio (5G NR) as well as a Next Generation Packet Core Network (NG-CN or NGC) . The 5G NR will have three main components: a 5G Access Network (5G-AN) , a 5G Core Network (5GC) , and a User Equipment (UE) . In order to facilitate the enablement of different data services and requirements, the elements of the 5GC, also called Network Functions, have been simplified with most of them being software based so that they could be adapted according to need.

SUMMARY

The example embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, example systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and are not limiting, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of this disclosure.

In one embodiment, a method includes receiving, by an initial access and mobility management function (AMF) from a wireless communication device via a radio access network (RAN) , a first registration request comprising a first device identifier associated with the wireless communication device. In some embodiments, the method includes allocating, by the initial AMF responsive to receiving the registration request, a second device identifier associated with the wireless communication device. In some embodiments, the method includes generating, by the initial AMF, a second registration request comprising the second device identifier.

In another embodiment, a method includes receiving, by a target access and mobility management function (AMF) from an initial AMF via a radio access network (RAN) , a protected registration request comprising a second device identifier, the protected registration request generated by the initial AMF responsive to receiving a registration request comprising a first device identifier associated with a wireless communication device and integrity protected by the initial AMF using a security context. In some embodiments, the method includes fetching, by the target AMF responsive to receiving the protected registration request, the security context from the initial AMF. In some embodiments, the method includes registering, by the target AMF, the wireless communication device with the target AMF using the security context.

The above and other aspects and their embodiments are described in greater detail in the drawings, the descriptions, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various example embodiments of the present solution are described in detail below with reference to the following figures or drawings. The drawings are provided for purposes of illustration only and merely depict example embodiments of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be considered limiting of the breadth, scope, or applicability of the present solution. It should be noted that for clarity and ease of illustration, these drawings are not necessarily drawn to scale.

FIG. 1 illustrates an example cellular communication network in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure.

FIG. 2 illustrates block diagrams of an example base station and a user equipment device, in accordance with some embodiments of the present disclosure.

FIG. 3 illustrates a block diagram of an example architecture of a 5G system, in accordance with some embodiments of the present disclosure.

FIG. 4 illustrates a flow diagram of an example environment of a 5G system with AMF re-allocation, in accordance with some embodiments of the present disclosure.

FIG. 5 is a flow diagram depicting a method for registration with access and mobility management function re-allocation from the perspective of an initial AMF, in accordance with some embodiments of the present disclosure.

FIG. 6 is a flow diagram depicting a method for registration with access and mobility management function re-allocation from the perspective of a target AMF, in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various example embodiments of the present solution are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the present solution. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the present solution. Thus, the present solution is not limited to the example embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely example approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present solution. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the present solution is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

The following acronyms are used throughout the present disclosure:

3GPP 3rd Generation Partnership Project

5G 5th Generation Mobile Networks

5G-AN 5G Access Network

5G gNB Next Generation NodeB

5G-GUTI 5G-Globally Unique Temporary UE Identify

AF Application Function

AMF Access and Mobility Management function

AN Access Network

ANDSP Access Network Discovery and Selection Function

AUSF Authentication Server Function

CM Connected Mode

DL Down Link

DNN Data Network Name

DRX Discontinuous Reception

ETSI European Telecommunications Standards Institute

H-PCF Home Policy Control Function

HPLMN Home Public Land Mobile Network

GUAMI Globally Unique AMF Identifier

LADN Local Area Data Network

MICO mode preference Mobile Initiated Connection Only

MPS Multimedia Priority Service

MCS Modulation and Coding Scheme

N3IWF Non-3GPP InterWorking Function

NAS Non-Access Stratum

NF Network Function

NG-RAN Next Generation Node Radio Access Node

NGAP NG Application Protocol

NR Next Generation RAN

NSSAI Network Slice Selection Assistance Information

NSSF Network Slice Selection Function

OFDM Orthogonal Frequency-Division Multiplexing

OFDMA Orthogonal Frequency-Division Multiple Access

PLMN Public Land Mobile Network

PSI Public Service Identifier

PCF Policy Control Function

PDU Packet Data Unit.

PEI Permanent Equipment Identifier

RAN Radio Access Network

RAN CP Radio Access Network Control Plane

RAT Radio Access Technology

S-NSSAI Single-Network Slice Selection Assistance Information

SM NAS Session Management Non Access Stratum

SMF Session Management Function

SUCI Subscription Concealed Identifier

SUPI Subscription Permanent Identifier

TAI Tracking Area Identity

UDM Unified Data Management

UDSF Unstructured Data Storage Function

UDR Unified Data Repository

UE User Equipment

UE MM User Equipment Mobile Management

UE-TNLA User Equipment Transport Network Layer Association

UPF User Plane Function

V-PCF Visited Policy Control Function

Clause 4.2.2.2.2 and 4.2.2.2.3 in ETSI 123.502, which is hereby incorporated by reference in its entirety, defines the registration procedure with AMF reallocation. The registration procedure, however, has security flaws that could lead to a registration failure of UEs. That is, in the idle mobility registration procedure with AMF reallocation, the registration could fail when (1) the initial AMF and the UE have established a new NAS security context that is different from the old NAS security context established between the old AMF and the UE, and (2) the target AMF fetched the old NAS security context of the UE from the old AMF and the target AMF has decided to use it. In this case, the NAS security context, including the K _AMF (e.g., a mobility management key) used by the UE, is different (e.g., not matching) from that used by the target AMF. As such, the integrity check of the NAS message will fail, which in turn, causes a registration failure.

Accordingly, the system and method discussed herein modifies a registration request that an AMF (e.g., an initial AMF) receives from a UE to ensure that the UE passes the registration procedure during a handover to another AMF (e.g., a target AMF) . In general, and discussed in greater detail below, when a UE sends a registration request (also referred to herein as, a Registration Request or RR message) including a device identifier (also referred to herein as, UE ID) to an initial AMF (e.g., initial AMF 406 in FIG. 4) , the UE (e.g., UE 402 in FIG. 4) and the initial AMF establish a security association. In response to receiving the registration request from the UE, the initial AMF allocates (e.g., generates, reserves, etc. ) a new device identifier (e.g., a 5G-GUTI) and uses the new device identifier instead of the UE ID contained in the Registration Request message. The initial AMF invokes (e.g., performs, executes, etc. ) integrity protection on the Registration Request using a 5G NAS security context and sends a message including (or paired with) the Registration Request to a target AMF (e.g., target AMF 410 in FIG. 4) . In response to receiving the message, the target AMF fetches the security context from the initial AMF by sending a context transfer request to the initial AMF. The context transfer request causes the initial AMF to validate the integrity protection of the protected registration request and/or send to the target AMF the UE context including the UE security context. The target AMF then completes the remaining steps of the registration process.

Mobile Communication Technology and Environment

FIG. 1 illustrates an example wireless communication network, and/or system, 100 in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. In the following discussion, the wireless communication network 100 may be any wireless network, such as a cellular network or a narrowband Internet of things (NB-IoT) network, and is herein referred to as “network 100. ” Such an example network 100 includes a base station 102 (hereinafter “BS 102” ; also referred to as wireless communication node) and a user equipment device 104 (hereinafter “UE 104” ; also referred to as wireless communication device) that can communicate with each other via a communication link 110 (e.g., a wireless communication channel) , and a cluster of

cells

126, 130, 132, 134, 136, 138 and 140 overlaying a geographical area 101. In Figure 1, the BS 102 and UE 104 are contained within a respective geographic boundary of cell 126. Each of the

other cells

130, 132, 134, 136, 138 and 140 may include at least one base station operating at its allocated bandwidth to provide adequate radio coverage to its intended users.

For example, the BS 102 may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE 104. The BS 102 and the UE 104 may communicate via a downlink radio frame 118, and an uplink radio frame 124 respectively. Each radio frame 118/124 may be further divided into sub-frames 120/127 which may include data symbols 122/128. In the present disclosure, the BS 102 and UE 104 are described herein as non-limiting examples of “communication nodes, ” generally, which can practice the methods disclosed herein. Such communication nodes may be capable of wireless and/or wired communications, in accordance with various embodiments of the present solution.

FIG. 2 illustrates a block diagram of an example wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM/OFDMA signals) in accordance with some embodiments of the present solution. The system 200 may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one illustrative embodiment, system 200 can be used to communicate (e.g., transmit and receive) data symbols in a wireless communication environment such as the wireless communication environment 100 of Figure 1, as described above.

System 200 generally includes a base station 202 (hereinafter “BS 202” ) and a user equipment device 204 (hereinafter “UE 204” ) . The BS 202 includes a BS (base station) transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each module being coupled and interconnected with one another as necessary via a data communication bus 220. The UE 204 includes a UE (user equipment) transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each module being coupled and interconnected with one another as necessary via a data communication bus 240. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium suitable for transmission of data as described herein.

As would be understood by persons of ordinary skill in the art, system 200 may further include any number of modules other than the modules shown in Figure 2. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software can depend upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present disclosure

In accordance with some embodiments, the UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 that includes a radio frequency (RF) transmitter and a RF receiver each comprising circuitry that is coupled to the antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210 that includes a RF transmitter and a RF receiver each comprising circuity that is coupled to the antenna 212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to the downlink antenna 212 in time duplex fashion. The operations of the two transceiver modules 210 and 230 may be coordinated in time such that the uplink receiver circuitry is coupled to the uplink antenna 232 for reception of transmissions over the wireless transmission link 250 at the same time that the downlink transmitter is coupled to the downlink antenna 212. Conversely, the operations of the two transceivers 210 and 230 may be coordinated in time such that the downlink receiver is coupled to the downlink antenna 212 for reception of transmissions over the wireless transmission link 250 at the same time that the uplink transmitter is coupled to the uplink antenna 232. In some embodiments, there is close time synchronization with a minimal guard time between changes in duplex direction.

The UE transceiver 230 and the base station transceiver 210 are configured to communicate via the wireless data communication link 250, and cooperate with a suitably configured RF antenna arrangement 212/232 that can support a particular wireless communication protocol and modulation scheme. In some illustrative embodiments, the UE transceiver 210 and the base station transceiver 210 are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G standards, and the like. It is understood, however, that the present disclosure is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

In accordance with various embodiments, the BS 202 may be an evolved node B (eNB) , a serving eNB, a target eNB, a femto station, or a pico station, for example. In some embodiments, the UE 204 may be embodied in various types of user devices such as a mobile phone, a smart phone, a personal digital assistant (PDA) , tablet, laptop computer, wearable computing device, etc. The

processor modules

214 and 236 may be implemented, or realized, with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by

processor modules

214 and 236, respectively, or in any practical combination thereof. The

memory modules

216 and 234 may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard,

memory modules

216 and 234 may be coupled to the processor modules 210 and 230, respectively, such that the processors modules 210 and 230 can read information from, and write information to,

memory modules

216 and 234, respectively. The

memory modules

216 and 234 may also be integrated into their respective processor modules 210 and 230. In some embodiments, the

memory modules

216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by processor modules 210 and 230, respectively.

Memory modules

216 and 234 may also each include non-volatile memory for storing instructions to be executed by the processor modules 210 and 230, respectively.

The network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 202 that enable bi- directional communication between base station transceiver 210 and other network components and communication nodes configured to communication with the base station 202. For example, network communication module 218 may be configured to support internet or WiMAX traffic. In a typical deployment, without limitation, network communication module 218 provides an 802.3 Ethernet interface such that base station transceiver 210 can communicate with a conventional Ethernet based computer network. In this manner, the network communication module 218 may include a physical interface for connection to the computer network (e.g., Mobile Switching Center (MSC) ) . The terms “configured for, ” “configured to” and conjugations thereof, as used herein with respect to a specified operation or function, refer to a device, component, circuit, structure, machine, signal, etc., that is physically constructed, programmed, formatted and/or arranged to perform the specified operation or function.

The Open Systems Interconnection (OSI) Model (referred to herein as, “open system interconnection model” ) is a conceptual and logical layout that defines network communication used by systems (e.g., wireless communication device, wireless communication node) open to interconnection and communication with other systems. The model is broken into seven subcomponents, or layers, each of which represents a conceptual collection of services provided to the layers above and below it. The OSI Model also defines a logical network and effectively describes computer packet transfer by using different layer protocols. The OSI Model may also be referred to as the seven-layer OSI Model or the seven-layer model. In some embodiments, a first layer may be a physical layer. In some embodiments, a second layer may be a Medium Access Control (MAC) layer. In some embodiments, a third layer may be a Radio Link Control (RLC) layer. In some embodiments, a fourth layer may be a Packet Data Convergence Protocol (PDCP) layer. In some embodiments, a fifth layer may be a Radio Resource Control (RRC) layer. In some embodiments, a sixth layer may be a Non Access Stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer being the other layer.

Access and Mobility Management Function (AMF) Re-Allocation

FIG. 3 illustrates a block diagram of an example architecture of a 5G system, in accordance with some embodiments of the present disclosure. The 5G system 300 includes various components, such as a UE 302 (e.g., UE 104 in FIG. 1) , a 5G-AN 304, an AMF 306, a UDM 308, a PCF 310, an SMF 312, an AF 314, a UPF 318, and a data network 316. The AMF 306 includes one or more functionalities, such as UE mobility management, reachability management, connection management. Although shown with only one component of each type, the environment 300 may include any number of components (e.g., a plurality of UEs 302, a plurality of 5G-ANs 304, a plurality of AMFs 306, etc. ) interconnected in any arrangement to facilitate the operations of the 5G system, as described herein.

The AMF 306 terminates the RAN CP interface (depicted in FIG. 3 as, N2) and NAS (depicted in FIG. 3 as, N1) , NAS ciphering and integrity protection. The AMF 306 distributes the SM NAS to the proper SMFs 312 via the N11 interface. The SMF 312 includes a UE IP address allocation & management, selection and control of UPF 318, and PDU connection management.

The UPF 318 is the anchor point for Intra-/Inter-RAT mobility and the external PDU session point of interconnect to data network 316. The UPF 318 also routes and forwards the data packet as the indication from the SMF 312. The UPF 318 also buffer the DL data when the UE 302 is in idle mode. The UDM 308 stores the subscription profile for the UEs 302.

The PCF 310 generates the police to govern network behavior based on the subscription and indication from AF 314. The PCF 310 also provides policy rules to control plane functions (e.g., AMF 306 and SMF 312) to enforce them.

FIG. 4 illustrates a flow diagram of an example environment of a 5G system with AMF re-allocation, in accordance with some embodiments of the present disclosure. The example environment 400 includes a UE 402, a RAN 404 (also referred to herein as, (R) AN) , an initial AMF 406, an old AMF 408, and a target AMF 410. In some embodiments, the UE 402 may be UE 104 in FIG. 1. In some embodiments, any of initial AMF 406, old AMF 408, and target AMF 410 may be AMF 306 in FIG. 3 or any other AMF (not shown in FIG. 3) that includes some or all of the functionality of AMF 306.

At step 1 (labeled in FIG. 4 as, Registration Request) , the UE 402 sends (e.g., transmits, delivers) an AN message to a RAN 404 (e.g., a 5G gNB or BS 102 in FIG. 1) . In some embodiments, the AN message may include AN parameters, a Registration Request (also referred to herein as, RR message) , and/or UE Policy Container. In some embodiments, the Registration Request may include a Registration type, SUCI or 5G-GUTI (e.g., a device identifier associated with UE 402) or PEI, last visited TAI (if available) , Security parameters, Requested NSSAI, [Mapping Of Requested NSSAI] , Default Configured NSSAI Indication, UE Radio Capability Update, UE MM Core Network Capability, PDU Session status, List Of PDU Sessions To Be Activated, Follow-on request, MICO mode preference, Requested DRX parameters, [LADN DNN (s) or Indicator Of Requesting LADN Information] , and/or [NAS message container] . In some embodiments, may include the list of PSIs and/or an indication of UE support for ANDSP and the operating system identifier.

In some embodiments, the UE Policy Container and its usage is be defined by 3GPP TS 23.503.

In the case of NG-RAN, the AN parameters may include 5G-S-TMSI or GUAMI, the Selected PLMN ID and Requested NSSAI, the AN parameters also include Establishment cause. The Establishment cause provides the reason for requesting the establishment of an RRC connection. Whether and how the UE includes the Requested NSSAI as part of the AN parameters is dependent on the value of the Access Stratum Connection Establishment NSSAI Inclusion Mode parameter, as specified in clause 5.15.9 of 3GPP TS 23.501, which is hereby incorporated by reference in its entirety.

The Registration type indicates if UE 402 wants to perform an Initial Registration (i.e. the UE 402 is in RM-DEREGISTERED state) , a Mobility Registration Update (i.e. the UE 402 is in RM-REGISTERED state and initiates a Registration procedure due to mobility or due to the UE 402 needs to update its capabilities or protocol parameters, or to request a change of the set of network slices it is allowed to use) , a Periodic Registration Update (i.e., the UE 402 is in RM-REGISTERED state and initiates a Registration procedure due to the Periodic Registration Update timer expiry, see clause 4.2.2.2.1 of 3GPP TS 23.502, which is hereby incorporated by reference in its entirety) or an Emergency Registration (i.e., the UE 402 is in limited service state) .

When the UE 402 is performing an Initial Registration the UE 402 indicates its UE identity in the Registration Request message as follows, listed in decreasing order of preference:

a) a native 5G-GUTI assigned by the which the UE 402 is attempting to register, if available;

b) a native 5G-GUTI assigned by an equivalent PLMN to the PLMN to which the UE is attempting to register, if available; and

c) a native 5G-GUTI assigned by any other PLMN, if available.

In some embodiments, this can also be a 5G-GUTI assigned via another access type. In some embodiments, the UE 402 may include its SUCI in the Registration Request, as defined in 3GPP TS 33.501, which is hereby incorporated by reference in its entirety.

The NAS message container may be included if the UE 402 is sending a Registration Request message as an Initial NAS message and the UE 402 has a valid 5G NAS security context and the UE 402 needs to send non-cleartext IEs, see clause 4.4.6 in 3GPP TS 24.501. If the UE does not need to send non-cleartext IEs, the UE 402 may send a Registration Request message without including the NAS message container.

If the UE 402 does not have a valid 5G NAS security context, the UE 402 may send the Registration Request message without including the NAS message container. The UE 402 may include the entire Registration Request message (i.e., containing cleartext IEs and non-cleartext IEs) in the NAS message container that is sent as part of the Security Mode Complete message in step 9b in FIG. 4.

When the UE 402 is performing an Initial Registration (i.e., the UE 402 is in RM-DEREGISTERED state) with a native 5G-GUTI then the UE 402 may indicate the related GUAMI information in the AN parameters. When the UE 402 is performing an Initial Registration with its SUCI, the UE 402 may not indicate any GUAMI information in the AN parameters.

For an Emergency Registration, the SUCI may be included if the UE 402 does not have a valid 5G-GUTI available; the PEI may be included when the UE 402 has no SUPI and no valid 5G-GUTI. In some embodiments, the 5G-GUTI is included and it indicates the last serving AMF.

The UE 402 may provide the UE's 402 usage setting based on its configuration as defined in clause 5.16.3.7 of 3GPP TS 23.501, which is hereby incorporated by reference in its entirety. The UE 402 provides Requested NSSAI as described in 3GPP TS 23.501 clause 5.15.5.2.1, and in the case of Initial Registration or Mobility Registration Update, the UE 402 includes the Mapping Of Requested NSSAI (if available) , which is the mapping of each S-NSSAI of the Requested NSSAI to the HPLMN S-NSSAIs, to ensure that the network is able to verify whether the S-NSSAI (s) in the Requested NSSAI are permitted based on the Subscribed S-NSSAIs.

The UE 402 includes the Default Configured NSSAI Indication if the UE 402 is using a Default Configured NSSAI, as defined in 3GPP TS 23.501.

In the case of Mobility Registration Update, the UE 402 includes in the List Of PDU Sessions To Be Activated the PDU Sessions for which there are pending uplink data. When the UE 402 includes the List Of PDU Sessions To Be Activated, the UE 402 indicates PDU Sessions only associated with the access the Registration Request is related to. As defined in 3GPP TS 24.501, the UE 402 may include always-on PDU Sessions which are accepted by the network in the List Of PDU Sessions To Be Activated even if there are no pending uplink data for those PDU Sessions.

In some embodiments, a PDU Session corresponding to a LADN is not included in the List Of PDU Sessions To Be Activated when the UE 402 is outside the area of availability of the LADN.

The UE MM Core Network Capability is provided by the UE 402 and handled by AMF, as defined in TS 23.501 [2] clause 5.4.4a. The UE 402 includes in the UE MM Core Network Capability an indication if it supports Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 5.17.2.3.1 of 3GPP TS 23.501.

The UE 402 may provide either the LADN DNN (s) or an Indication Of Requesting LADN Information, as described in 3GPP TS 23.501 clause 5.6.5.

If available, the last visited TAI may be included in order to help the AMF produce Registration Area for the UE 402.

The Security parameters are used for Authentication and integrity protection, see TS 33.501 [15] . Requested NSSAI indicates the Network Slice Selection Assistance Information (as defined in clause 5.15 of 3GPP TS 23.501) . The PDU Session status indicates the previously established PDU Sessions in the UE 402. When the UE 402 is connected to the two AMFs belonging to different PLMN via 3GPP access and non-3GPP access then the PDU Session status indicates the established PDU Session of the current PLMN in the UE 402.

The Follow-on request is included when the UE 402 has pending uplink signaling and the UE does not include List Of PDU Sessions To Be Activated, or the Registration type indicates the UE 402 wants to perform an Emergency Registration. In Initial Registration and Mobility Registration Update, the UE 402 provides the UE Requested DRX parameters, as defined in clause 5.4.5 of 3GPP TS 23.501.

The UE 402 provides UE Radio Capability Update indication as described in 3GPP TS 23.501.

At step 2 (labeled in FIG. 4 as, AMF selection) , if a 5G-S-TMSI or GUAMI is not included or the 5G-S-TMSI or GUAMI does not indicate a valid AMF the RAN 404, based on (R)AT and Requested NSSAI, if available, selects an AMF.

The RAN 404 selects an AMF as described in 3GPP TS 23.501, clause 6.3.5. If the UE 402 is in CM-CONNECTED state, the RAN 404 can forward the Registration Request message to the AMF based on the N2 connection of the UE 402.

If the RAN 404 cannot select an appropriate AMF, it forwards the Registration Request to an AMF which has been configured, in the RAN 404, to perform AMF selection.

At step 3 (labeled in FIG. 4 as, Registration Request) , the RAN 404 sends (i.e., transmits, delivers) an N2 message and a UE Policy Container to the initial AMF 406. In some embodiments, the N2 message includes N2 parameters and/or a Registration Request (as described in step 1 in FIG. 4) .

When NG-RAN is used, the N2 parameters include the Selected PLMN ID, Location Information and Cell Identity related to the cell in which the UE 402 is camping, UE Context Request which indicates that a UE context including security information needs to be setup at the NG-RAN.

When NG-RAN is used, the N2 parameters also include the Establishment cause.

The Mapping Of Requested NSSAI is provided only if available.

If the Registration type indicated by the UE 402 is Periodic Registration Update, then steps 4 to 19 may be omitted.

When the Establishment cause is associated with priority services (e.g., MPS, MCS) , the AMF includes a Message Priority header to indicate priority information. Other NFs relay the priority information by including the Message Priority header in service-based interfaces, as specified in 3GPP TS 29.500, which is hereby incorporated by reference in its entirety.

At step 4 (labeled in FIG. 4 as, Namf_Communication_UEContextTransfer) , the initial AMF 406 sends to the old AMF 408 a Namf_Communication_UEContextTransfer (complete Registration Request) and/or the initial AMF 406 sends to the UDSF (not shown in FIG. 4) a Nudsf_Unstructured Data Management_Query () .

In the case with UDSF Deployment, if the UE's 402 5G-GUTI was included in the Registration Request and the serving AMF has changed since last Registration procedure, the initial AMF 406 and old AMF 408 are in the same AMF Set and UDSF is deployed, the initial AMF 406 retrieves the stored UE's 402 SUPI and UE context directly from the UDSF using Nudsf_UnstructuredDataManagement_Query service operation or they can share stored UE context via implementation specific means if UDSF is not deployed. This includes also event subscription information by each NF consumer for the given UE. In this case, the initial AMF 406 uses integrity protected complete Registration request NAS message to perform and verify integrity protection.

In the case without UDSF Deployment, if the UE's 402 5G-GUTI was included in the Registration Request and the serving AMF has changed since last Registration procedure, the initial AMF 406 may invoke the Namf_Communication_UEContextTransfer service operation on the old AMF 408 including the complete Registration Request NAS message, which may be integrity protected, as well as the Access Type, to request the UE's SUPI and UE Context (see clause 5.2.2.2.2 of 3GPP TS 23.502 for details of this service operation. ) In this case, the old AMF 408 uses either 5G-GUTI and the integrity protected complete Registration request NAS message, or the SUPI and an indication that the UE 402 is validated from the initial AMF 406, to verify integrity protection if the context transfer service operation invocation corresponds to the UE requested. The old AMF 408 also transfers the event subscriptions information by each NF consumer, for the UE 402, to the initial AMF 406.

If the old AMF 408 has PDU Sessions for another access type (e.g., different from the Access Type indicated in this step) and if the old AMF 408 determines that there is no possibility for relocating the N2 interface to the initial AMF 406, the old AMF 408 returns UE's SUPI and indicates that the Registration Request has been validated for integrity protection, but does not include the rest of the UE context.

In some embodiments, the initial AMF 406 sets the indication that the UE 402 is validated according to step 9a in FIG. 4, in case the initial AMF 406 has performed successful UE authentication after previous integrity check failure in the old AMF 408.

In some embodiments, the NF consumers does not need to subscribe for the events once again with the initial AMF 406 after the UE 402 is successfully registered with the initial AMF 406.

If the initial AMF 406 has already received UE contexts from the old AMF 408 during handover procedure, then steps 4, 5, and 10 in FIG. 4 may be skipped.

For an Emergency Registration, if the UE 402 identifies itself with a 5G-GUTI that is not known to the AMF, steps 4 and 5 in FIG. 4 may be skipped and the AMF immediately requests the SUPI from the UE 402. If the UE 402 identifies itself with PEI, the SUPI request may be skipped. Allowing Emergency Registration without a user identity may be dependent on local regulations.

At step 5 (labeled in FIG. 4 as, Namf_Communication_UEContextTransfer response) the old AMF 408 sends to the initial AMF 406 a response to the Namf_Communication_UEContextTransfer and/or the UDSF (not shown in FIG. 4) sends to the initial AMF 406 a Nudsf_Unstructured Data Management_Query () . In some embodiments, the Namf_Communication_UEContextTransfer may include a SUPI and/or UE Context in AMF (as per Table 5.2.2.2.2-1 of 3GPP TS 23.502) . The old AMF 408 may start an implementation specific (guard) timer for the UE context.

If the UDSF was queried in step 4 in FIG. 4, the UDSF responds to the initial AMF 406 for the Nudsf_Unstructured Data Management_Query invocation with the related contexts including established PDU Sessions, the old AMF 408 includes SMF information DNN, S-NSSAI (s) and PDU Session ID, active NGAP UE-TNLA bindings to N3IWF, the old AMF includes information about the NGAP UE-TNLA bindings. If the old AMF 408 was queried in step 4 in FIG. 4, old AMF 408 responds to the initial AMF 406 for the Namf_Communication_UEContextTransfer invocation by including the UE's SUPI and UE Context.

If the old AMF 408 holds information about established PDU Session (s) , the old AMF 408 includes SMF information, DNN (s) , S-NSSAI (s) and PDU Session ID (s) .

If the old AMF 408 holds UE context established via N3IWF, the old AMF 408 includes the CM state for UE 402 connected via N3IWF. If the UE 402 is in CM-CONNECTED state via N3IWF, the old AMF 408 includes information about the NGAP UE-TNLA bindings.

If the old AMF 408 fails the integrity check of the Registration Request NAS message, the old AMF 408 may indicate the integrity check failure.

If the old AMF 408 holds information about AM Policy Association and the information about UE Policy Association (i.e. the Policy Control Request Trigger for updating UE Policy as defined in 3GPP TS 23.503, which is hereby incorporated by reference in its entirety) , the old AMF 408 includes the information about the AM Policy Association, the UE Policy Association and PCF ID. In the roaming case, V-PCF ID and H-PCF ID are included.

In some embodiments, when initial AMF 406 uses UDSF for context retrieval, interactions between the old AMF 408, the initial AMF 406, and the UDSF due to UE signaling on the old AMF 408 at the same time is implementation issue.

At step 6 (labeled in FIG. 4 as, Identify Request/Response) the initial AMF 406 sends to the UE 402 an Identity Request () . If the SUCI is not provided by the UE 402 nor retrieved from the old AMF 408 the Identity Request procedure is initiated by AMF sending an Identity Request message to the UE 402 requesting the SUCI.

At step 7 (not shown in FIG. 4) the UE 402 sends to the initial AMF 406 an Identity Response () . In some embodiments, the UE 402 responds with an Identity Response message including the SUCI. The UE 402 derives (e.g., calculates, generates) the SUCI by using the provisioned public key of the HPLMN, as specified in 3GPP TS 33.501.

At step 8 (labeled in FIG. 4 as, AUSF selection) , the initial AMF 406 may decide to initiate UE authentication by invoking an AUSF 412. In that case, the AMF selects an AUSF 412 based on SUPI or SUCI, as described in 3GPP TS 23.501, clause 6.3.4.

If the initial AMF 406 is configured to support Emergency Registration for unauthenticated SUPIs and the UE 402 indicated Registration type Emergency Registration, the initial AMF 406 skips the authentication or the initial AMF 406 accepts that the authentication may fail and continues the Registration procedure.

At step 9 (labeled in FIG. 4 as, Authentication/Security) , if authentication is required, the initial AMF 406 requests it from the AUSF 412; if Tracing Requirements about the UE 402 are available at the initial AMF 406, the initial AMF 406 provides Tracing Requirements in its request to AUSF 412. Upon request from the initial AMF 406, the AUSF 412 may execute authentication of the UE 402. The authentication is performed as described in 3GPP TS 33.501. The AUSF 412 selects a UDM (e.g., UDM 418) as described in 3GPP TS 23.501, clause 6.3.8 and gets (e.g., fetches, retrieves, queries) the authentication data from UDM (e.g., UDM 418) .

Once the UE 402 has been authenticated the AUSF 412 provides relevant security related information to the initial AMF 406. In case the initial AMF 406 provided a SUCI to AUSF 412, the AUSF 412 may return the SUPI to the initial AMF 406 only after the authentication is successful.

After successful authentication in initial AMF 406, which is triggered by the integrity check failure in old AMF 408 at step 5 in FIG. 4, the initial AMF 406 invokes step 4 in FIG. 4 again and indicates that the UE 402 is validated (i.e., through the reason parameter as specified in clause 5.2.2.2.2 of 3GPP TS 23.502) .

At step 9b, if NAS security context does not exist, the NAS security initiation is performed as described in 3GPP TS 33.501. If the UE 402 had no NAS security context in step 1 in FIG. 4, the UE 402 includes the full Registration Request message as defined in 3GPP TS 24.501.

At step 9c, the initial AMF 406 initiates NGAP procedure to provide the 5G-AN with security context as specified in 3GPP TS 38.413, which is hereby incorporated by reference in its entirety, if the 5G-AN had requested for UE Context. Also, if the AMF does not support N26 for EPS interworking and it received UE MM Core Network Capability including an indication that it supports Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 5.17.2.3.1 of 3GPP TS 23.501, initial AMF 406 provides an indication "Redirection for EPS fallback for voice is possible" towards 5G-AN as specified in 3GPP TS 38.413. In addition, if Tracing Requirements about the UE 402 are available at the initial AMF 406, the initial AMF 406 provides the 5G-AN with Tracing Requirements in the NGAP procedure.

At step 9d, the 5G-AN stores the security context and acknowledges to the initial AMF 406. The 5G-AN uses the security context to protect the messages exchanged with the UE 402 as described in 3GPP TS 33.501.

At step 10 (labeled in FIG. 4 as, Security Mode Command/Complete) , the Initial AMF 406 sends the NAS Security Mode Command (SMC) to the UE 402. The UE 402 replies with NAS Security Mode Complete message containing a complete Registration Request message, as specified in clause 6.4.6 of 3GPP TS 33.501.

At step 11 (labeled in FIG. 4 as, UDM Selection) , if the initial AMF 406 needs UE's subscription information to decide whether to reroute the Registration Request and UE's slice selection subscription information was not provided by the old AMF 408, the AMF selects a UDM (e.g., UDM 418) as described in 3GPP TS 23.501, clause 6.3.8.

At step 12 (labeled in FIG. 4 as, Nudm_SDM_Get/Response) , the initial AMF 406 may initiate the Nudm_SDM_Get procedure with the UDM 418.

In some embodiments, the initial AMF 406 sends to the UDM 418 a Nudm_SDM_Get. In some embodiments, the Nudm_SDM_Get may include a SUPI and/or Slice Selection Subscription data. The initial AMF 406 request UE's Slice Selection Subscription data from UDM 418 by invoking the Nudm_SDM_Get (see clause 5.2.3.3.1 of 3GPP TS 23.502) service operation. The UDM 418 may get this information from UDR by Nudr_DM_Query. In some embodiments, the Nudr_DM_Query may include SUPI and/or Subscribed S-NSSAIs.

In some embodiments, the UDM 418 may send to the initial AMF 406 a response to Nudm_SDM_Get. The AMF gets the Slice Selection Subscription data including Subscribed S-NSSAIs. The UDM 418 may provide indication that the subscription data for network slicing is updated for the UE 402.

In some embodiments, the UDM 418 responds with slice selection data to initial AMF 406.

At step 13 (labeled in FIG. 4 as, Nnssf_NSselection_Get/Response) , the initial AMF 406 may initiate the Nnssf_NSSelection_Get procedure with the NSSF 414.

In some embodiments, the initial AMF 406 may send to NSSF 414 a Nnssf_NSSelection_Get. The Nnssf_NSSelection_Get may include a Requested NSSAI, [Mapping Of Requested NSSAI] , Subscribed S-NSSAI (s) with the default S-NSSAI indication, TAI, Allowed NSSAI for the other access type (if any) , [Mapping of Allowed NSSAI] , and/or PLMN ID of the SUPI) .

In some embodiments, if there is a need for slice selection, (see clause 5.15.5.2.1 of 3GPP TS 23.501) , e.g. the initial AMF 406 cannot serve all the S-NSSAI (s) from the Requested NSSAI permitted by the subscription information, the initial AMF 406 invokes the Nnssf_NSSelection_Get service operation from the NSSF 414 by including Requested NSSAI, optionally Mapping Of Requested NSSAI, Subscribed S-NSSAIs with the default S-NSSAI indication, Allowed NSSAI for the other access type (if any) , Mapping of Allowed NSSAI, PLMN ID of the SUPI and the TAI of the UE 402.

In some embodiments, the NSSF 414 sends to the initial AMF 406 a response to Nnssf_NSSelection_Get. The Nnssf_NSSelection_Get includes AMF Set or list of AMF addresses, Allowed NSSAI for the first access type, [Mapping Of Allowed NSSAI] , [Allowed NSSAI for the second access type] , [Mapping of Allowed NSSAI] , [NSI ID (s) ] , [NRF (s) ] , [List of rejected (S-NSSAI (s) , cause value (s) ) ] , [Configured NSSAI for the Serving PLMN] , and/or [Mapping Of Configured NSSAI] ) .

In some embodiments, the NSSF 414 performs the steps specified in point (B) in clause 5.15.5.2.1 of 3GPP TS 23.501. The NSSF 414 returns to initial AMF 406 the Allowed NSSAI for the first access type, optionally the Mapping Of Allowed NSSAI, the Allowed NSSAI for the second access type (if any) , optionally the Mapping of Allowed NSSAI and the target AMF Set or, based on configuration, the list of candidate AMF (s) . The NSSF 414 may return NSI ID (s) associated to the Network Slice instance (s) corresponding to certain S-NSSAI (s) . The NSSF 414 may return the NRF (s) to be used to select NFs/services within the selected Network Slice instance (s) . It may return also information regarding rejection causes for S-NSSAI (s) not included in the Allowed NSSAI. The NSSF 414 may return Configured NSSAI for the Serving PLMN, and possibly the associated mapping of the Configured NSSAI.

At step 14 (labeled in FIG. 4 as, Nnrf_NFDiscovery_Request/Response) , the initial AMF 406 may initiate the Nnrf_NFDiscovery procedure with the NRF.

In some embodiments, the initial AMF 406 may send to the NRF 416 a Nnrf_NFDiscovery_Request. The Nnrf_NFDiscovery_Request may include an NF type, and/or an AMF Set.

In some embodiments, if the initial AMF 406 does not locally store the target AMF address, and if the initial AMF 406 intends to use direct reroute to target AMF 410 or the reroute via (NG-R) AN message needs to include AMF address, then the initial AMF 406 invokes the Nnrf_NFDiscovery_Request service operation from the NRF to find a proper target AMF (e.g., target AMF 410) which has required NF capabilities to serve the UE 402. The NF type is set to AMF. The AMF Set is included in the Nnrf_NFDiscovery_Request.

In some embodiments, the NRF 416 sends to the AMF a response to Nnrf_NFDiscovery_Request. The Nnrf_NFDiscovery_Request may include a list of AMF pointer, AMF address, and/or additional selection rules and NF capabilities.

The NRF 416 replies with the list of potential target AMF (s) . The NRF 416 may also provide the details of the services offered by the candidate AMF (s) along with the notification end-point for each type of notification service that the selected AMF had registered with the NRF 416, if available. As an alternative, it provides a list of potential target AMFs and their capabilities, and optionally, additional selection rules. Based on the information about registered NFs and required capabilities, a target AMF 410 is selected by the initial AMF 406.

If the initial AMF 406 is not part of the target AMF set, and is not able to get a list of candidate AMF (s) by querying the NRF 416 with the target AMF set (e.g. the NRF 416 locally pre-configured on AMF does not provide the requested information, the query to the appropriate NRF 416 provided by the NSSF 414 is not successful, or the initial AMF 406 has knowledge that the initial AMF 406 is not authorized as serving AMF etc. ) then the initial AMF 406 may forward the NAS message to the target AMF 410 via RAN 404executing; the Allowed NSSAI and the AMF Set are included to enable the RAN 404 to select the target AMF 410 as described in 3GPP TS 23.501 clause 6.3.5.

At step 15 (labeled in FIG. 4 as, allocates a new 5G-GUTI) , the initial AMF 406 allocates (e.g., assigns, reserves, distributes) a new device identifier (e.g., 5G-GUTI) that identifies the UE 402. For example, an initial AMF 406 may receive, from a wireless communication device via a radio access network (RAN) , a first registration request comprising a first device identifier associated with the wireless communication device. The initial AMF 406 may allocate, responsive to receiving the registration request, a second device identifier associated with the wireless communication device. The first device identifier and/or the second device identifier may include a 5th Generation Globally Unique Temporary User Equipment Identify (5G-GUTI) . The initial AMF may establish the security context associated with the wireless communication device.

At step 16 (labeled in FIG. 4 as, uses 5G-GUTI instead of UE ID (also referred to herein as, UE ID) in the full RR message) , the initial AMF 406 uses the new device identifier (e.g., 5G-GUTI) instead of the device identifier (e.g., UE ID) identifying the UE 402 that was included in the full Registration Request (RR) message in step 1 or step 6 in FIG. 4. For example, the initial AMF may generate a second registration request comprising the second device identifier. The initial AMF may generate the second registration request by replacing, by the initial AMF, the device identifier of the first registration request with the second device identifier. The first device identifier may be absent from the second registration request.

At step 17 (labeled in FIG. 4 as, integrity protect the RR message using 5G NAS security context) , the initial AMF 406 invokes (e.g., performs, executes, etc. ) integrity protection on the Registration Request using the 5G NAS security context. For example, the initial AMF may perform an integrity protection on the second registration request using a security context to generate a protected registration request.

At step 18 (labeled in FIG. 4 as, Reroute NAS message (RR (new 5G-GUTI) ) ) , if the initial AMF 406, based on local policy and subscription information, decides to forward the NAS message to the target AMF 410 via RAN 404 unless the target AMF (s) 410 are returned from the NSSF 414 and identified by a list of candidate AMF (s) , the initial AMF 406 sends a Reroute NAS message to the RAN 404. The Reroute NAS message includes the information about the target AMF 410, and the full Registration Request message. If the initial AMF 406 has obtained the information as described at step 13 in FIG. 4, that information is included.

At step 19 (labeled in FIG. 4 as, Initial UE message (RR (new 5G-GUTI) ) ) ) , the RAN 404 sends the Initial UE message to the target AMF 410 indicating reroute due to slicing including the information from step 13 in FIG. 4 that the NSSF 414 provided. For example, the initial AMF may transmit, to a target AMF via the RAN, the protected registration request causing the target AMF to fetch the UE context which includes the security context from the initial AMF using the second device identifier and register the wireless communication device with the target AMF using the security context. As another example, the initial AMF may transmit, to the RAN, a reroute message comprising the protected registration request and a function identifier associated with the target AMF. In some embodiments, the reroute message causing the RAN to transmit the protected registration request to the target AMF.

As another example, the target AMF may receive, from an initial AMF via a radio access network (RAN) , a protected registration request comprising a second device identifier. The protected registration request may be generated by the initial AMF responsive to receiving a registration request comprising a first device identifier associated with a wireless communication device and integrity protected by the initial AMF using a security context. The target AMF may fetch, responsive to receiving the protected registration request, UE context which includes the the security context from the initial AMF. The target AMF may register the wireless communication device with the target AMF using the security context.

At step 20 (labeled in FIG. 4 as, Namf_Communication_UEContextTransfer) , the target AMF 410 sends to the initial AMF 406 a Namf_Communication_UEContextTransfer. The Namf_Communication_UEContextTransfer may include a complete Registration Request.

In some embodiments, if the new 5G-GUTI (e.g., a new device identifier) was included in the Registration Request and the serving AMF has changed since last Registration procedure, the target AMF 410 may invoke the Namf_Communication_UEContextTransfer service operation on the initial AMF 406 including the complete Registration Request NAS message, which may be integrity protected, as well as the Access Type, to request the UE's 402 SUPI and UE Context. See clause 5.2.2.2.2 of 3GPP TS 23.502 for details of this service operation. In this case, the initial AMF 406 uses either new 5G-GUTI and the integrity protected complete Registration request NAS message, or the SUPI and an indication that the UE 402 is validated from the target AMF 410, to verify integrity protection if the context transfer service operation invocation corresponds to the UE requested. The initial AMF 406 also transfers the event subscriptions information by each NF consumer, for the UE 402, to the target AMF 410.

In some embodiments, if the initial AMF 406 has PDU Sessions for another access type (different from the Access Type indicated in this step) and if the initial AMF 406 determines that there is no possibility for relocating the N2 interface to the target AMF 410, the initial AMF 406 returns UE's SUPI and indicates that the Registration Request has been validated for integrity protection, but does not include the rest of the UE context.

In some embodiments, the target AMF 410 sets the indication that the UE 402 is validated according to step 22a in FIG. 4, in case the target AMF 410 has performed successful UE authentication after previous integrity check failure in the initial AMF 406.

In some embodiments, the NF consumers does not need to subscribe for the events once again with the target AMF 410 after the UE 402 is successfully registered with the target AMF 410.

At step 21 (labeled in FIG. 4 as, Namf_Communication_UEContextTransfer response) , the initial AMF 406 sends to the target AMF 410 a response to Namf_Communication_UEContextTransfer. In some embodiments, the response to Namf_Communication_UEContextTransfer may include SUPI and/or UE Context in AMF (as per Table 5.2.2.2.2-1 of 3GPP TS 23.502) . The initial AMF 406 may start an implementation specific (guard) timer for the UE context.

In some embodiments, if initial AMF 406 holds information about established PDU Session (s) , the initial AMF 406 includes SMF information, DNN (s) , S-NSSAI (s) and PDU Session ID (s) .

In some embodiments, if initial AMF 406 holds UE context established via N3IWF, the initial AMF 406 includes the CM state for the UE 402 connected via N3IWF. If the UE 402 is in CM-CONNECTED state via N3IWF, the initial AMF 406 includes information about the NGAP UE-TNLA bindings.

In some embodiments, if initial AMF 406 fails the integrity check of the Registration Request NAS message, the initial AMF 406 may indicate the integrity check failure.

In some embodiments, if initial AMF 406 holds information about AM Policy Association and the information about UE Policy Association (i.e., the Policy Control Request Trigger for updating UE Policy as defined in 3GPP TS 23.503) , the initial AMF 406 includes the information about the AM Policy Association, the UE Policy Association and PCF ID. In the roaming case, V-PCF ID and H-PCF ID are included.

For example, the initial AMF may receive a context transfer request to transmit the UE context which includes the security context to the target AMF. The initial AMF may transmit, responsive to the context transfer request, the UE context which includes the security context to the target AMF. The initial AMF may validate the integrity protection of the protected registration request using the security context. The initial AMF may validate the integrity protection of the protected registration request responsive to receiving the context transfer request from the target AMF. As another example, the target AMF may transmit, to the initial AMF, a context transfer request causing the initial AMF to transmit the UE context which includes the security context to the target AMF. The context transfer request further causes the initial AMF to validate the integrity protection of the protected registration request using the security context. The target AMF may transmit, to the initial AMF, a first message indicating that the wireless communication device is registered with the target AMF. The first message may cause the initial AMF to transmit a second message to an old AMF indicating that the wireless communication device is registered with the target AMF. The initial AMF may generate the protected registration request by replacing the first device identifier of the registration request with the second device identifier. The first device identifier may be absent from the protected registration request. The first device identifier and/or the second device identifier may include a 5th Generation Globally Unique Temporary User Equipment Identify (5G-GUTI) . The security context associated with the wireless communication device may be established by the initial AMF.

At step 22 (labeled in FIG. 4 as, Authentication/Security) , the UE 402 and the target AMF 410 negotiate information associated with authentication and/or security.

In some embodiments, if authentication is required, the target AMF 410 requests it from the AUSF 412; if Tracing Requirements about the UE 402 are available at the target AMF 410, the target AMF 410 provides Tracing Requirements in its request to AUSF 412. Upon request from the target AMF 410, the AUSF 412 may execute authentication of the UE 402. The authentication is performed as described in 3GPP TS 33.501. The AUSF 412 selects a UDM 418 as described in 3GPP TS 23.501, clause 6.3.8 and gets the authentication data from UDM 418.

Once the UE 402 has been authenticated the AUSF 412 provides relevant security related information to the target AMF 410.

After successful authentication in target AMF 410, which is triggered by the integrity check failure in initial AMF 406 at step 21 in FIG. 4, the target AMF 410 invokes step 20 in FIG. 4 again and indicates that the UE 402 is validated (i.e. through the reason parameter as specified in clause 5.2.2.2.2 of 3GPP TS 23.502) .

In some embodiments, the target AMF 410 initiates NGAP procedure to provide the 5G-AN with security context as specified in 3GPP TS 38.413 if the 5G-AN had requested for UE Context. If the target AMF 410 does not support N26 for EPS interworking and it received UE MM Core Network Capability including an indication that it supports Request Type flag "handover" for PDN connectivity request during the attach procedure as defined in clause 5.17.2.3.1 of 3GPP TS 23.501, target AMF 410 provides an indication "Redirection for EPS fallback for voice is possible" towards 5G-AN as specified in 3GPP TS 38.413. In addition, if Tracing Requirements about the UE 402 are available at the target AMF 410, the target AMF 410 provides the 5G-AN with Tracing Requirements in the NGAP procedure.

The 5G-AN stores the security context and acknowledges to the target AMF 410. The 5G-AN uses the security context to protect the messages exchanged with the UE 402 as described in 3GPP TS 33.501.

At step 23 (labeled in FIG. 4 as, Namf_Communication_RegistrationCompleteNotify) , the target AMF 410 sends to the initial AMF 406 a Namf_Communication_RegistrationCompleteNotify () .

In some embodiments, if the AMF has changed the target AMF 410 notifies the initial AMF 406 that the registration of the UE 402 in the target AMF 410 is completed by invoking the Namf_Communication_RegistrationCompleteNotify service operation.

In some embodiments, if the authentication/security procedure fails, then the Registration shall be rejected, and the target AMF 410 invokes the Namf_Communication_RegistrationCompleteNotify service operation with a reject indication reason code towards the initial AMF 406. The initial AMF 406 continues as if the UE context transfer service operation was never received.

In some embodiments, if one or more of the S-NSSAIs used in the old Registration Area cannot be served in the target Registration Area, the target AMF 410 determines which PDU Session cannot be supported in the new Registration Area. The target AMF 410 invokes the Namf_Communication_RegistrationCompleteNotify service operation including the rejected PDU Session ID and a reject cause (e.g. the S-NSSAI becomes no longer available) towards the initial AMF 406. Then the new AMF modifies the PDU Session Status correspondingly. The initial AMF 406 informs the corresponding SMF (s) to locally release the UE's SM context by invoking the Nsmf_PDUSession_ReleaseSMContext service operation (see clause 5.2.2.2.3 of 3GPP TS 23.502 for details of Namf_Communication_RegistrationCompleteNotify service operation. )

In some embodiments, if target AMF 410 received in the UE context transfer in step 20 the information about the AM Policy Association and the UE Policy Association and decides, based on local policies, not to use the PCF (s) identified by the PCF ID (s) for the AM Policy Association and the UE Policy Association, then it will inform the initial AMF 406 that the AM Policy Association and the UE Policy Association in the UE context is not used any longer and then the PCF selection is performed.

At step 24 (labeled in FIG. 4 as, Namf_Communication_RegistrationCompleteNotify) , the initial AMF 406 sends to the old AMF 408 a Namf_Communication_RegistrationCompleteNotify () .

In some embodiments, if the AMF has changed the initial AMF 406 notifies the old AMF 408 that the registration of the UE 402 in the initial AMF 406 is completed by invoking the Namf_Communication_RegistrationCompleteNotify service operation.

In some embodiments, if the authentication/security procedure fails, then the Registration shall be rejected, and the initial AMF 406 invokes the Namf_Communication_RegistrationCompleteNotify service operation with a reject indication reason code towards the old AMF 408. The old AMF 408 continues as if the UE context transfer service operation was never received.

In some embodiments, if one or more of the S-NSSAIs used in the old Registration Area cannot be served in the target Registration Area, the initial AMF determines which PDU Session cannot be supported in the new Registration Area. The initial AMF 406 invokes the Namf_Communication_RegistrationCompleteNotify service operation including the rejected PDU Session ID and a reject cause (e.g., the S-NSSAI becomes no longer available) towards the old AMF 408. Then the new AMF modifies the PDU Session Status correspondingly. The old AMF 408 informs the corresponding SMF (s) to locally release the UE's SM context by invoking the Nsmf_PDUSession_ReleaseSMContext service operation (see clause 5.2.2.2.3 of 3GPP TS 23.502 for details of Namf_Communication_RegistrationCompleteNotify service operation. )

In some embodiments, if initial AMF 406 received in the UE context transfer in step 3 in FIG. 4 the information about the AM Policy Association and the UE Policy Association and decides, based on local policies, not to use the PCF (s) identified by the PCF ID (s) for the AM Policy Association and the UE Policy Association, then it will inform the old AMF 408 that the AM Policy Association and the UE Policy Association in the UE context is not used any longer and then the PCF selection is performed.

For example, the initial AMF may receive, from the target AMF, a first message indicating that the wireless communication device is registered with the target AMF. The initial AMF may transmit, to an old AMF responsive to receiving the first message, a second message indicating that the wireless communication device is registered with the target AMF.

At step 25 (labeled in FIG. 4 as, Steps 11-22 of figure 4.2.2.2.2-1 in 3GPP TS 23.502) , after receiving the Registration Request message transmitted, if the UE context is received from the initial AMF 406, the target AMF 410 continues with the Registration procedure from step 11 until step 22 of figure 4.2.2.2.2-1 of 3GPP TS 23.502.

FIG. 5 is a flow diagram depicting a method for registration with access and mobility management function re-allocation from the perspective of an initial AMF, in accordance with some embodiments of the present disclosure. Additional, fewer, or different operations may be performed in the method depending on the particular embodiment. In some embodiments, some or all operations of method 500 may be performed by a wireless communication node, such as BS 102 in FIG. 1. In some operations, some or all operations of method 500 may be performed by a wireless communication device, such as UE 104 in FIG. 1. In some operations, some or all operations of method 500 may be performed by an AMF, such as an initial AMF 406, an old AMF 408 and/or a target AMF 410 in FIG. 4. Each operation may be re-ordered, added, removed, or repeated.

As shown, the method 500 includes the operation 502 of receiving, by an initial access and mobility management function (AMF) from a wireless communication device via a radio access network (RAN) , a first registration request comprising a first device identifier associated with the wireless communication device. The method also includes the operation 504 of allocating, by the initial AMF responsive to receiving the registration request, a second device identifier associated with the wireless communication device. The method also includes the operation 506 generating, by the initial AMF, a second registration request comprising the second device identifier.

FIG. 6 is a flow diagram depicting a method for registration with access and mobility management function re-allocation from the perspective of a target AMF, in accordance with some embodiments of the present disclosure. Additional, fewer, or different operations may be performed in the method depending on the particular embodiment. In some embodiments, some or all operations of method 600 may be performed by a wireless communication node, such as BS 102 in FIG. 1. In some operations, some or all operations of method 600 may be performed by a wireless communication device, such as UE 104 in FIG. 1. In some operations, some or all operations of method 600 may be performed by an AMF, such as an initial AMF 406, an old AMF 408 and/or a target AMF 410 in FIG. 4. Each operation may be re-ordered, added, removed, or repeated.

As shown, the method 600 includes the operation 602 of receiving, by a target access and mobility management function (AMF) from an initial AMF via a radio access network (RAN) , a protected registration request comprising a second device identifier, the protected registration request generated by the initial AMF responsive to receiving a registration request comprising a first device identifier associated with a wireless communication device and integrity protected by the initial AMF using a security context. The method 600 also includes the operation 604 of fetching, by the target AMF responsive to receiving the protected registration request, the UE context which includes the security context from the initial AMF. The method 600 also includes the operation 606 of registering, by the target AMF, the wireless communication device with the target AMF using the security context.

While various embodiments of the present solution have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand example features and functions of the present solution. Such persons would understand, however, that the solution is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described illustrative embodiments.

It is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A person of ordinary skill in the art would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, various forms of program or design code incorporating instructions (which can be referred to herein, for convenience, as "software" or a "software module) , or any combination of these techniques. To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, modules, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "module" as used herein, refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various modules are described as discrete modules; however, as would be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs the associated functions according embodiments of the present solution.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present solution. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present solution with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the present solution. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below

Claims

A method, comprising,

receiving, by an initial access and mobility management function (AMF) from a wireless communication device via a radio access network (RAN) , a first registration request comprising a first device identifier associated with the wireless communication device;

allocating, by the initial AMF responsive to receiving the registration request, a second device identifier associated with the wireless communication device; and

generating, by the initial AMF, a second registration request comprising the second device identifier.
The method of Claim 1, further comprising:

performing, by the initial AMF, an integrity protection on the second registration request using a security context to generate a protected registration request; and

transmitting, by the initial AMF to a target AMF via the RAN, the protected registration request causing the target AMF to fetch the security context from the initial AMF using the second device identifier and register the wireless communication device with the target AMF using the security context.
The method of Claim 2, wherein transmitting the protected registration request comprising:

transmitting, by the initial AMF to the RAN, a reroute message comprising the protected registration request and a function identifier associated with the target AMF, the reroute message causing the RAN to transmit the protected registration request to the target AMF.
The method of Claim 2, further comprising:

receiving, by the initial AMF, a context transfer request to transmit the security context to the target AMF; and

transmitting, by the initial AMF responsive to the context transfer request, the security context to the target AMF.
The method of Claim 4, further comprising:

validating, by the initial AMF, the integrity protection of the protected registration request using the security context.
The method of Claim 5, wherein the initial AMF validates the integrity protection of the protected registration request responsive to receiving the context transfer request from the target AMF.
The method of Claim 1, further comprising:

receiving, by the initial AMF and from the target AMF, a first message indicating that the wireless communication device is registered with the target AMF; and

transmitting, by the initial AMF to an old AMF responsive to receiving the first message, a second message indicating that the wireless communication device is registered with the target AMF.
The method of Claim 1, wherein generating the second registration request comprising:

replacing, by the initial AMF, the device identifier of the first registration request with the second device identifier.
The method of Claim 1, wherein the first device identifier is absent from the second registration request.
The method of Claim 1, wherein at least one of the first device identifier and the second device identifier comprising a 5th Generation Globally Unique Temporary User Equipment Identify (5G-GUTI) .
The method of Claim 1, further comprising:

establishing, by the initial AMF, the security context associated with the wireless communication device.
A method, comprising,

receiving, by a target access and mobility management function (AMF) from an initial AMF via a radio access network (RAN) , a protected registration request comprising a second device identifier, the protected registration request generated by the initial AMF responsive to receiving a registration request comprising a first device identifier associated with a wireless communication device and integrity protected by the initial AMF using a security context;

fetching, by the target AMF responsive to receiving the protected registration request, the security context from the initial AMF; and

registering, by the target AMF, the wireless communication device with the target AMF using the security context.
The method of Claim 12, further comprising:

transmitting, by the target AMF to the initial AMF, a context transfer request causing the initial AMF to transmit the security context to the target AMF.
The method of Claim 13, wherein the context transfer request further causes the initial AMF to validate the integrity protection of the protected registration request using the security context.
The method of Claim 12, further comprising:

transmitting, by the target AMF and to the initial AMF, a first message indicating that the wireless communication device is registered with the target AMF, the first message causing the initial AMF to transmit a second message to an old AMF indicating that the wireless communication device is registered with the target AMF.
The method of Claim 12, wherein the initial AMF generates the protected registration request by replacing the first device identifier of the registration request with the second device identifier.
The method of Claim 12, wherein the first device identifier is absent from the protected registration request.
The method of Claim 12, wherein at least one of the first device identifier and the second device identifier comprising a 5th Generation Globally Unique Temporary User Equipment Identify (5G-GUTI) .
The method of Claim 12, wherein the security context associated with the wireless communication device is established by the initial AMF.
A computer program product comprising a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a method recited in any of claims 1 to 20.