KR102029742B1 - Network triggered service request method, and user equipment triggered service request method - Google Patents

Abstract

A service request method triggered by a network performed by an AMF device, comprising: Namf_Communication_N1N2Message Transfer from an SMF device that receives a data notification message indicating that a UPF device that has not received access network tunnel information for a PDU session has received downlink data Receiving a message; And sending a paging message for a PDU session between the AMF device and a user terminal to an access network based on the PDU session ID included in the Namf_Communication_N1N2Message Transfer message, and receiving the paging message from the access network. The user terminal may be a service request method triggered by the network to start a service request procedure according to the connection management state of the user terminal.

Description

Service request method triggered by network, and service request method triggered by user terminal {NETWORK TRIGGERED SERVICE REQUEST METHOD, AND USER EQUIPMENT TRIGGERED SERVICE REQUEST METHOD}

The following embodiments relate to a service request method triggered by a network and a service request method triggered by a user terminal.

Mobile edge computing (MEC) technology has been proposed to provide low latency data services in user equipment (UE). MEC technology is used to minimize the round trip time (RTT) between the UE and the server providing the service requested by the UE. MEC technology not only reduces the number of routing hops between the UE and the server, but also relates to a technique for positioning the geopolitical location of the server close to the UE.

5G mobile communication networks require various services to be provided to the UE via 5G network technology. Accordingly, 5G mobile communication networks also support edge computing technology to provide improved quality of service than existing network methods.

According to an embodiment, it may represent a process of performing a service request procedure triggered by the network in the 5G network.

According to an embodiment, it may represent a process of performing a service request procedure triggered by a user terminal.

According to one aspect, in the service request method triggered by the network performed by the AMF device, receiving a data notification message indicating that the UPF device has received downlink data that does not include access network tunnel information for the PDU session Receiving a Namf_Communication_N1N2Message Transfer message from an SMF device; transmitting a paging message for a PDU session between the AMF device and a user terminal to an access network based on the PDU session ID included in the Namf_Communication_N1N2Message Transfer message; And the user terminal receiving the paging message from the access network may be a service request method triggered by the network to start a service request procedure according to the connection management state of the user terminal.

The user terminal, if the connection management state for the Non-3GPP access is CM-IDLE and the connection management state for the 3GPP access is CM-CONNECTED, a list of allowed PDU sessions that can be reactivated in the 3GPP access. It may be a service request method triggered by the network to start the service request procedure while transmitting to the AMF device.

The list of PDU sessions may be a service request method triggered by a network including a session allowed to be used through the 3GPP access among PDU sessions related to the Non-3GPP access.

The user terminal, if the connection management state for 3GPP access is CM-IDLE, the service request triggered by the network to start the service request procedure when receiving the paging message for the PDU session associated with the 3GPP access. It may be a method.

When the connection management state for 3GPP access and Non-3GPP access is CM-IDLE, the user terminal transmits a list of allowed PDU sessions that can be reactivated in the 3GPP access to the AMF device while requesting the service. Service request method triggered by the network initiating the procedure.

According to one aspect, a service request method triggered by a network performed by a UPF device, the method comprising: receiving downlink data for a PDU session; Transmitting a Data Notification Message to the SMF device indicating that the downlink data has been received; When receiving a data notification acknowledgment message from the SMF device that has received the data notification message, transmitting the downlink data to the SMF device, wherein the SMF device receives a Namf_Communication_N1N2Message Transfer message; One AMF device may be a service request method triggered by a network that transmits a paging message for a PDU session between the AMF device and the user terminal to an access network to initiate a service request procedure according to the connection management state of the user terminal. have.

The UPF device that receives the downlink data may be a service request method triggered by a network that buffers the downlink data when there is no access network tunnel information for the PDU session.

Transmitting a Data Notification Message to the SMF device indicating that the downlink data has been received, the additional downlink data for the QoS flow of the PDU session having the same or lower priority as the PDU session may be received. When received by the UPF device, the UPF device may be a service request method triggered by a network that buffers the additional downlink data without transmitting a new data notification message.

According to an aspect, a service request method triggered by a network performed by an SMF device, the method comprising: receiving a data notification message from a UPF device that receives downlink data for a PDU session; Receiving downlink data from the UPF device when sending a Data Notification Acknowledge Message to the UPF device indicating that the data notification message has been received; After receiving the downlink data, transmitting a Namf_Communication_N1N2Message Transfer message including a PDU session ID included in the data notification message to an AMF device, wherein the AMF device provides a service according to a connection management state of a user terminal; The service request method may be triggered by a network that transmits a paging message for a PDU session between the AMF device and the user terminal to an access network to start a request procedure.

Receiving a data notification message from the UPF device indicating that the downlink data has been received, the additional downlink data for the QoS flow of the PDU session having the same or lower priority as the PDU session may be received. When received by the UPF device, the UPF device may be a service request method triggered by a network that buffers the additional downlink data without transmitting a new data notification message.

According to an aspect, a service request method triggered by a network performed by a user terminal (UE), comprising: a PDU session ID transmitted by an SMF device receiving a data notification message from a UPF device receiving downlink data When a AMF device receives a Namf_Communication_N1N2Message Transfer message, receiving a paging message for a PDU session between the user terminal and the AMF device from an access network; Downloading downlink data from the UPF device by performing a service request procedure according to a connection management state of the user terminal, wherein the paging message is transmitted to a network transmitted according to a paging strategy managed by the AMF device. It may be a service request method triggered by.

The method of claim 11, wherein the UPF device that receives the downlink data is a service request method triggered by a network that buffers the downlink data when there is no access network tunnel information for the PDU session.

The paging strategy determines whether a paging strategy is set by a timer supervised by the AMF device, or whether the AMF device sends the paging message during high load conditions, or in a sub-area. It may be a service request method triggered by a network that determines whether to apply paging based on (sub-area).

According to one aspect, in the service request method triggered by the user terminal performed by the SMF device, receiving a location change notification message of the dormant user terminal from the AMF device, the user terminal is located outside the available area of the LADN Determining the amount of time; In accordance with the determination, determining control of the UPF device for managing the PDU session, wherein the control of the UPF device for forwarding uplink data from the user terminal to the UPF device comprises: an intermediate UPF It may be a service request method triggered by the user terminal to insert or remove the intermediate UPF.

The inserted intermediate UPF may be a service request method triggered by a user terminal receiving downlink data from a UPF operating as a PDU session anchor (PSA).

The removed intermediate UPF may be a service request method triggered by a user terminal transmitting buffered data to a UPF operating as a PDU session anchor (PSA).

According to an aspect, in a service request method triggered by a user terminal performed by an Access and Mobility Management Function (AMF) device, an N2 message including a service request message (N2) When a message is received from an access network (AN), transmitting an Nsmf_PDUSession_UpdateSMContext Request message including a PDU session ID, location information of the user terminal, and an access type to a session management function (SMF) device. ; If an Nsmf_PDUSession_UpdateSMContext Response message including N2 SM information is received from the SMF device, sending an N2 Request including N2 SM information received from the SMF device to the access network, wherein the SMF The apparatus may be a service request method triggered by the user terminal controlling the UPF apparatus to forward the uplink data from the user terminal to the UPF apparatus by determining that the user terminal is located outside an available area of the LADN. .

The AMF device receiving the N2 message from the access network, NAS authentication procedure and authentication with the user terminal when the service request message is not integrity protected (integrity protection verification failed) It may be a service request method triggered by a user terminal that initiates a server function (Authentication Server Function, AUSF) and a security procedure.

According to one aspect, in a service request method triggered by a user terminal performed by a new UPF device, when the new UPF device is selected as an intermediate UPF for the PDU session by the SMF device, N4 session from the SMF device Receiving a establishment request message; Transmitting to the SMF device an N4 session establishment response message indicating that an N4 session between the new UPF and the SMF device has been established on behalf of the existing UPF, and transmitting a position change notification message of the dormant user terminal to the AMF device. The SMF device received from the service request method may be triggered by a user terminal for selecting the new UPF device.

The new UPF device receiving the N4 session establishment request message may be a service request method triggered by a user terminal which allocates DL CN tunnel information and UL CN tunnel information for the new UPF operating as a PDU session anchor. .

1 illustrates a Registration Management (RM) state model of a user terminal according to an embodiment.
2 illustrates an RM state model of an AMF device according to an embodiment.
3 illustrates a CM state transition in a user terminal according to an embodiment.
4 illustrates a CM state transition in an AMF device according to an embodiment.
5 illustrates a user plane architecture of an uplink delimiter, according to one embodiment.
6 is a diagram illustrating a multi-homed PDU session: service continuity case according to an embodiment.
7 illustrates a multi-homed PDU session: local access to the same data network, according to an embodiment.
8 illustrates an N4 session establishment procedure according to an embodiment.
9 illustrates an N4 session modification procedure according to an embodiment.
10 illustrates an N4 session release procedure according to an embodiment.
11 illustrates a UE triggered service request procedure according to an embodiment.
12 illustrates a network triggered service request procedure according to an embodiment.
FIG. 13 is a diagram illustrating a change procedure of an SSC mode 2 PSA for a PDU session according to an embodiment. FIG.
14 is a diagram illustrating a procedure of changing an SSC mode 3 PDU session anchor having a plurality of PDU sessions according to an embodiment.
15 illustrates a network triggered service request procedure according to another embodiment.
16 is a diagram illustrating a user terminal triggered service request procedure in a CM-IDLE state according to an embodiment.
17 illustrates a UE triggered service request procedure in a CM-IDLE state according to another embodiment.
18 illustrates a UE triggered service request procedure in a CM-CONNECTED state according to another embodiment.
19 illustrates a network triggered service request according to another embodiment.

Specific structural or functional descriptions of the embodiments are disclosed for purposes of illustration only, and may be practiced in various forms. Accordingly, the embodiments are not limited to the specific disclosure, and the scope of the present specification includes changes, equivalents, or substitutes included in the technical idea.

Terms such as first or second may be used to describe various components, but such terms should be interpreted only for the purpose of distinguishing one component from another component. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

When a component is referred to as being "connected" to another component, it should be understood that there may be a direct connection or connection to that other component, but there may be other components in between.

Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but includes one or more other features or numbers, It is to be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined herein. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Definitions>

5G Access Network: An access network comprising an NG-RAN and / or non-3GPP AN that connects to a 5G core network.

5G Core Network: Connected to a 5G access network.

5G System: 3GPP system consisting of a 5G access network, a 5G core network and a user terminal.

Allowed Area: The area where the user terminal can start communication.

AMF Region: An AMF region consisting of one or more AMF sets.

Local Area Data Network: a DN that is accessible by a UE at a specific location, provides a connection to a specific DNN, and provides the availability of the UE.

NG-RAN: A radio access network supporting one or more of the following options with common characteristics connected to 5G core networks: 1) standalone new radios 2) new radios are anchors with E-UTRA extensions 3) standalone E- UTRA 4) E-UTRA is an anchor with a new wireless extension

Protocol Data Unit Session (PDU Session): An association between a user equipment and a data network providing a PDU connection service.

PDU Connectivity Service: A service that provides PDUs exchange between a user terminal and a data network.

PDU Session Type: Type of PDU session, which may be IPv4, IPv6, Ethernet or Unstructured.

Service Continuity: Uninterrupted user experience, including when IP addresses and / or anchoring points change.

Session Continuity: PDU session continuity. For a PDU session of IPv4 or IPv6 type, "session continuity" means that the IP address is preserved for the lifetime of the PDU session.

<Abbreviations>

5GC: 5G Core Network

5GS: 5G system

-5G-AN: 5G Access Network

5G-GUTI: 5G Globally Unique Temporary Identifier

AMF: Access and Mobilty Management Function

AUSF: Authentication Server Function

CP: Control Plane

DL: Downlink

DN: Data Network

DNN: Data Network Name

HR: Home Routed (roaming)

LADN: Local Area Data Network

-MICO: Mobile Initiated Connection Only

N3IWF: Non-3GPP Inter Working Function

NAI: Network Access Identifier

-NF: Network Function

NR: New Radio

NEF: Network Exposure Function

NRF: Network Repository Function

PCF: Policy Control Function

PSA: PDU Session Anchor

-(R) AN: (Wireless) Access Network ((Radio) Access Netwrok)

SSC: Session and Service Continuity

SUCI: Subscription Concealed Identifier

SUPI: Subscription Permanent Identifier

UL: Uplink

UL CL: Uplink Classifier

UPF: User Plane Function

Session Management Functions (SMFs), Access and Mobility Management Functions (AMFs), and User Plane Functions (UPFs) described below are either software functions, It may be installed or performed on each of a plurality of hardware.

Concepts

The 5G system architecture is defined to support data connectivity and services using technologies such as Network Function Virtualization (NFV) and Custom Defined Netwroking (SDN). The 5G system architecture should take advantage of service-based interactions between control plane network functions where they are identified. Some key principles and concepts of 5G system architecture include:

I) Separating the user plane (UP) function from the control plane (CP) function allows for independent scalability, evolution and flexible deployment. For example, it may be placed in a centralized location or in a distributed (remote) location. Ii) modularize the functional design; For example, it enables flexible and efficient network slicing. Iii) Where applicable, re-use may be possible by defining a procedure as a service (eg, a set of interactions between network functions). Iii) If necessary, each network function can interact directly with other NFs. The architecture does not preclude the use of intermediate functions that help route control plane messages. Iii) Minimize dependency between access network (AN) and core network (CN). The architecture is defined as a core network with a common AN-CN interface that integrates different access types. V) support an integrated authentication framework; V) Support for "stateless" NFs in which "computed" resources are separated from "storage" resources. Iii) support capability exposure. Iii) Support simultaneous access to local and centralized services. In order to support low latency services and access to the local data network, UP functions can be placed close to the access network. Iii) Visited PLMNs support both local breakout traffic and home routing traffic.

Architecture Reference Model

Describe the architecture of a 5G system. 5G architecture is defined as a service foundation, and the interaction between network functions is expressed in two ways:

I) A network function (eg AMF) within the control plane is a service-based representation that allows other authorized network functions to access the service. This service-based representation includes reference points between points as necessary. Ii) the reference point representation indicates that the interaction between NF services in the network function described by the reference point (eg, N11) between points between any two network functions (eg, AMF and SMF). Indicates that it exists.

<Service based interface>

The 5G system architecture includes the following service-based interfaces.

Iv) Namf: service-based interface exhibited by AMF ii) Nsmf: service-based interface exhibited by SMF ⅲ) Nnef: service-based interface exhibited by NEF ⅳ) Npcf: service-based exhibited by PCF Interface Nu) Nudm: service-based interface displayed by UDM ⅵ) Naf: service-based interface displayed by AF ⅶ) Nnrf: service-based interface displayed by NRF N) Nnssf: service-based interface displayed by NSSF ⅸ Nausf: service-based interface exhibited by AUSF dr) Nudr: service-based interface exhibited by UDR ⅹⅰ) Nudsf: service-based interface exhibited by UDSF

Reference Points

The 5G system architecture includes the following reference points:

1) N1: reference point between user terminal and AMF device 2) N2: reference point between access network and AMF device 3) N3: reference point between access network and UPF device 4) N4: reference point between SMF device and UPF device 5) N6: Reference Point between UPF Devices and Data Network 6) N9: Represents a reference point between UPF devices.

The following reference points represent the interactions that exist between NF services of NFs. These reference points are realized by corresponding NF service-based interfaces, and by specifying interactions as well as identified consumer and producer NF services to realize specific system procedures.

1) N5: reference point between PCF and AF 2) N7: reference point between SMF device and PCF 3) N8: reference point between UDM and AMF device 4) N10: reference point between UDM and SMF device 5) N11: with AMF device Reference point between SMF devices 6) N12: Reference point between AMF device and AUSF 7) N14: Reference point between AMF devices.

<Support for Non-3GPP>

The 5G core network supports the UE's connectivity through Non-3GPP access networks such as WLAN access. Support for Non-3GPP Access Networks (called "standalone" Non-3GPP Access) deployed outside NG-RAN is described.

The 5G core network can support untrusted Non-3GPP access. Non-3GPP access network can be connected to the 5G core network through the Non-3GPP interworking function (N3IWF). N3IWF can interface 5G core network CP and UP functions through N2 and N3 interfaces respectively.

N2 and N3 reference points may be used to connect standalone Non-3GPP access to 5G core network control plane and user plane functions, respectively.

After UE attachment, a UE accessing a 5G core network via standalone Non-3GPP access may support NAS signaling with 5G core network control plane functionality using the N1 reference point.

When a UE is connected via NG-RAN and standalone Non-3GPP access, there may be multiple N1 instances for the UE. That is, there may be one N1 instance for Non-3GPP access and NG-RAN.

If the selected N3IWF is located in the same PLMN as the 3GPP access, UEs simultaneously connected to the same 5G core network of the PLMN via 3GPP access and Non-3GPP access may be serviced by a single AMF device.

When a UE is connected to 3GPP access of a PLMN, if the UE selects N3IWF and the N3IWF is located in a PLMN that is different from the PLMN of the 3GPP access (for example, another VPLMN or HPLMN), the UE is connected by two PLMNs. Can be serviced separately. The UE is registered with two separate AMFs. PDU sessions over 3GPP access are serviced by V-SMF and other V-SMFs that service PDU sessions over Non-3GPP access.

PLMN selection for 3GPP access does not depend on N3IWF selection. If the UE is registered via Non-3GPP, the UE performs PLMN selection for 3GPP access independently of the PLMN to which the N3IWF belongs.

The UE can establish an IPSec tunnel with N3IWF to connect to the 5G core network through unreliable Non-3GPP access. The UE may be authenticated by the 5G core network and connected to the IP core 5G core network during the IPSec tunnel establishment procedure.

After all PDU sessions for the UE have been released or handed over to 3GPP access, it should be able to maintain the UE signaling connection with the AMF device via Non-3GPP access. N1 NAS signaling via standalone Non-3GPP access can be protected by the same security mechanism applied to N1 via 3GPP access.

<Registration Management>

Registration management is used to register or unregister a user terminal / user to the network and to establish user content in the network.

The user terminal / user needs to register with the network in order to receive a service requiring registration. Once registered and applicable, the user terminal 1) periodically, to be reachable (periodic registration update); Or 2) on the move (mobility registration update); Or 3) update the registration in the network to update the function or renegotiate the protocol parameters:

The initial registration procedure involves the execution of network access control functions (ie, user authentication and access authorization based on UDM's subscription profiles). As a result of the registration procedure, the identifier of the AMF device serving the UE in the UE-registered access will be registered in the UDM.

Registration management procedures are applicable to both 3GPP access and non-3GPP access. 3GPP and non-3GPP registration states are independent of each other.

The following two registration management states, which reflect the registration status of the user terminal in the selected PLMN, are used in the user terminal and the AMF device:

I) RM-DEREGISTERED ii) RM-REGISTERED

1 illustrates a Registration Management (RM) state model of a user terminal according to an embodiment. 2 illustrates an RM state model of an AMF device according to an embodiment.

1.RM-DEREGISTERED status

In the RM-DEREGISTERED state, the user terminal is not registered in the network. Because the user terminal context in the AMF device does not hold valid location or routing information for the user terminal, the user terminal is not reachable by the AMF device. However, part of the user terminal context may still be stored in the user terminal and the AMF device for the same reason as avoiding the authentication procedure during all registration procedures.

In the RM-DEREGISTERED state, the user terminal is:

Iii) If you need to receive a service that requires registration, try to register with the selected PLMN using the initial registration procedure. Ii) Upon receipt of a registration refusal at the time of initial registration, the RM-DEREGISTERED status is maintained. Iv) If the registration approval is received, the RM-REGISTERED state is entered.

If the UE RM status of the AMF device is RM-DEREGISED, then the AMF device is:

Iii) if applicable, approves the initial registration of the user terminal by sending a registration approval to the user terminal and enters the RM-REGISTERED state for the UE; Or ii) if applicable, reject the initial registration of the user terminal by sending a registration refusal to the user terminal.

2.RM-REGISTERED Status

In the RM-REGISTERED state, the user terminal is registered in the network. In the RM-REGISTERED state, the user terminal can receive a service that needs to be registered in the network.

In the RM-REGISTERED state, the user terminal is:

Iv) if there is no current TAI of the serving cell in the list of TAIs received from the network by the user terminal to maintain registration and enable the AMF device to page the user terminal, perform a mobility registration update procedure; Ii) performing a periodic registration update procedure triggered by the expiration of the periodic update timer to notify the network that the user terminal is still active. Iii) Perform the registration information update procedure to update the function information or renegotiate the protocol parameters with the network. I) Perform the deregistration procedure and enter the RM-DEREGISTERED state when the user terminal is no longer registered in the PLMN. The user terminal can determine deregistration from the network at any time. Iv) It enters the RM-DEREGISTERED state when receiving a registration rejection message or a registration release message. The operation of the user terminal depends on the 'cause value' of the registration rejection or deregistration message.

If the UE RM status of the AMF device is RM-REGISTERED, then the AMF device is:

I) Perform the deregistration procedure and enter the RM-DEREGISTERED state when the user terminal is no longer registered in the PLMN. The network may determine deregistration of the user terminal at any time; Ii) Implicit deregistration is performed at any time after the implicit deregistration timer expires. After implicit deregistration, the AMF device enters the RM-DEREGISTERED state for the user terminal. Iii) If applicable, approve or reject the registration request or service request from the user terminal.

3. Registration area management

Registration area management includes the function of assigning and reassigning a registration area to the UE. The registration area is managed for each access type (3GPP access or non-3GPP access).

When the UE registers with the network via 3GPP access, the AMF can assign the UE a set of tracking areas in the TAI List. When the AMF assigns a registration area (i.e. a set of tracking areas in the TAI list) to the UE, the UE may consider various information (eg, mobility patterns and allowed / non-licensed areas, etc.). An AMF having a full PLMN as its serving area may alternatively assign a full PLMN (“all PLMN”) as a registration area for the UE in MICO mode.

The 5G system may support assigning a TAI list through another 5G-RAT to a single TAI list.

When a UE registers with the network via Non-3GPP access, the registration area for Non-3GPP access corresponds to a unique reserved TAI value (ie, a value dedicated to Non-3GPP access). . Therefore there is a unique tracking area for Non-3GPP access to 5GC called N3GPP TAI.

When creating a TAI list, the AMF may include TAIs applicable to the access to which the TAI list is sent.

4. Support of registered UEs via 3GPP and Non-3GPP access

When a UE is serviced continuously or simultaneously by 3GPP access and Non-3GPP access (via N3IWF) of the same PLMN, there may be one RM context for the UE for each access for a given serving PLMN. The UDM can manage separate / independent UE registration procedures for each access.

If served by the same PLMN for 3GPP and non-3GPP access, the UE may be served by the same AMF except for mobility from EPS while the UE has a PDU session associated with the non-3GPP access.

The AMF can associate multiple access specific RM contexts for the UE with:

Iii) 5G-GUTI common to both 3GPP and non-3GPP access. This 5G-GUTI can represent a unique value worldwide. Ii) Registration Status by Access Type (3GPP / Non-3GPP) iii) Registration Area by Access Type: Registration area for 3GPP access and other registration area for non-3GPP access. At this time, registration areas for 3GPP access and non-3GPP access are independent. Iii) Periodic registration timer for 3GPP access. Iii) non-3GPP Implicit Deregistration Timer.

AMF cannot provide periodic registration timers to UEs through Non-3GPP access. As a result, the UE does not need to perform a periodic registration update procedure for Non-3GPP access. Instead, during the initial registration procedure and re-registration, the UE may be provided by a network having a UE Non-3GPP deregistration timer that starts when the UE enters the Non-3GPP CM-IDLE state.

5G-GUTI may be allocated or reallocated via any 3GPP and non-3GPP access. AMF assigns a UE a single 5G-GUTI used via 3GPP and non-3GPP access of the same PLMN or equivalent PLMN (assuming there is a control and user plane connection between registered PLMNs and equivalent PLMN nodes) do. . 5G-GUTI is assigned upon successful registration of the UE and is valid for both 3GPP and non-3GPP access to the same PLMN or equivalent PLMN for the UE. Performing any initial access via non-3GPP access or 3GPP access, the UE provides 5G-GUTI received at early successful registration via any access of the same PLMN or equivalent PLMN. This allows the AN to select an AMF that maintains the UE context created in the previous registration procedure and allows the AMF to correlate the UE request with the existing UE context.

If a UE performs registration via one access and wants to perform registration via another access on the same PLMN or equivalent PLMN (e.g. 3GPP access and selected N3IWF are located in the same PLMN), the UE will You may not start registration through other accesses until the registration process is completed.

If the UE successfully registers for access (3GPP access or non-3GPP access respectively) and the UE registers via another access:

Iii) If the second access is in the same PLMN or equivalent PLMN (e.g. when the UE selects N3IWF registered via 3GPP access and located in the same PLMN), then the UE is first access in the same PLMN or equivalent PLMN The 5G-GUTI provided by the UE upon previous registration with may use for registration with the PLMN associated with the new access.

Ii) if the second access is located in a different PLMN than the registered PLMN of the first access (ie, not a registered PLMN or a PLMN equivalent to the registered PLMN) (e.g., the UE is registered to 3GPP access and the 3GPP access Select a N3IWF located at a PLMN different from the PLMN of the PLMN, or if the UE registers via non-3GPP and registers for 3GPP access at a PLMN different from the N3IWF's PLMN), with 5G-GUTI previously received from the equivalent PLMN If yes, the UE may use 5G-GUTI to register with the PLMN associated with the new access. However, if the UE does not yet have 5G-GUTI from the PLMN attempting registration or equivalent PLMN, SUCI can be used for new registration.

When the UE 5G-GUTI assigned during the registration procedure via 3GPP (e.g., when a UE first registers via 3GPP access) is location-dependent, the same when the N3IWF function is selected as 3GPP access in the same PLMN. UE 5G-GUTI can be reused via non-3GPP access. If a UE 5G-GUTI is assigned during a registration procedure performed through a Non-3GPP access (e.g., a UE initially registers via a non-3GPP access), the UE 5G-GUTI may not depend on location, and thus UE 5G-GUTI may not be valid for NAS procedures over 3GPP access so that a new AMF is assigned during the registration procedure over 3GPP access.

When the UE is initially registered via 3GPP access, if the UE registers with the same PLMN via non-3GPP access, the UE can send the GUAMI obtained via 3GPP access to N3IWF. At this time, the N3IWF may select the same AMF using the received GUAMI.

The deregistration request indicates whether it applies to 3GPP access, non-3GPP access, or both.

If the UE is registered for both 3GPP and non-3GPP access, and is CM-IDLE over non-3GPP access, the UE or AMF can initiate the deregistration procedure for 3GPP access to unregister the UE over non-3GPP. Can be. In this case, all PDU sessions related to non-3GPP access may be released.

If the UE is registered with both 3GPP and non-3GPP access, and CM-IDLE through 3GPP access and CM-CONNECTED through non-3GPP access, the UE initiates the deregistration procedure through non-3GPP access to access 3GPP access. UE can be deregistered. In this case, all PDU sessions related to 3GPP access may be released.

<Connection Management>

The connection management is used to establish or release a signaling connection between the user terminal and the AMF device. The connection management includes a function of establishing and releasing a signaling connection between the user terminal and the AMF device through the N1. This signaling connection is used to enable NAS signaling exchange between the user terminal and the core network. This includes both the AN signaling connection between the user terminal and the AN (3GPP access via N3GPP access or RRC connection via UE-N3IWF connection) and the N2 connection to the user terminal between the AN and the AMF device.

The two CM states are used to reflect the NAS signaling connection of the AMF device and the user terminal:

Iii) CM-IDLE ii) CM-CONNECTED

CM states for 3GPP access and Non-3GPP access are independent of each other. That is, when one is in the CM-CONNECTED state, the other may be in the CM-IDLE state at the same time.

3 illustrates a CM state transition in a user terminal according to an embodiment. 4 illustrates a CM state transition in an AMF device according to an embodiment.

1. CM-IDLE Status

The user terminal in CM-IDLE state is a NAS established with the AMF device through N1.

It does not have a signaling connection. The user terminal performs cell selection / cell reselection and performs PLMN selection.

The user terminal in the CM-IDLE state has no AN signaling connection, N2 connection, and N3 connection.

If the user terminal is in the CM-IDLE state and the RM-REGISTERED state, the user terminal performs the following:

I) If the user terminal is not in the MICO mode, it responds to paging by performing a service request procedure. Ii) Perform a service request procedure when the user terminal has uplink signaling or user data to be transmitted. Certain conditions apply to LADN.

Whenever an AN signaling connection is established between a user terminal and AN (the UE enters an RRC connected state through 3GPP access or establishes a UE-N3IWF connection through non-3GPP access), the user terminal is in CM-CONNECTED state. Enter The transmission of the initial NAS message (Registration Request, Service Request or Deregistration Request) initiates a transition from CM-IDLE to CM-CONNECTED state.

If the user terminal status of the AMF device is CM-IDLE and RM-REGISTERED, the AMF device performs the following:

Iii) if the UE is not prevented from responding, send a paging request to the user terminal to perform a network triggered service request procedure when it has mobile-ended data or signaling to be sent to the user terminal.

Each time an N2 connection is established for the user terminal between the AN and the AMF device, the AMF device enters the CM-CONNECTED state for the user terminal. Receipt of an initial N2 message (eg, an N2 initial user terminal message) initiates the transition of the AMF device from CM-IDLE to CM-CONNECTED state.

The user terminal and the AMF device may optimize power efficiency and signaling efficiency of the user terminal when in the CM-IDLE state.

2. CM-CONNECTED Status

The user terminal in the CM-CONNECTED state has a NAS signaling connection with the AMF device through N1. The NAS signaling connection uses an RRC connection between the UE and the NG-RAN and an NGAP UE association between the AN and the AMF device for 3GPP access. The UE may be in a CM-CONNECTED state with an NGAP UE association not coupled to any TNLA between the AN and the AMF device. When the NAS signaling procedure is completed, the AMF device may decide to release the NAS signaling connection with the user terminal.

In CM-CONNECTED state, the UE does the following:

Iii) enters the CM-IDLE state whenever AN signaling connection is released (every time the RRC idle state is entered via 3GPP access or the release of UE-N3IWF connection via non-3GPP access is detected by the user terminal). .

If the UE CM status of the AMF device is CM-CONNECTED, the AMF device does the following:

Iii) Upon completion of the AN release procedure, whenever the logical NGAP signaling connection and the N3 user plane connection to the UE are released, it enters the CM-IDLE state for the UE.

Until the UE deregisters from the core network, the AMF device may maintain the UE CM state in the AMF device in the CM-CONNECTED state.

The UE in CM-CONNECTED state may be in RRC inactive state. The following applies when the UE is in an RRC inactive state:

Iii) UE reachability is managed by the RAN along with assistance information from the core network. Ii) UE paging is managed by the RAN. Iii) UE monitors paging with CN (5G S-TMSI) and RAN identifier of UE.

<UE mobility limit>

Mobility restriction limits the mobility handling or service access of the UE in 5G systems. Mobility restriction functionality is provided by the UE, radio access network and core network. Mobility restrictions apply only to 3GPP access and not to non-3GPP access.

When in the RRC Inactive state, mobility restrictions for the CM-IDLE state and the CM-CONNECTED state are enforced by the UE based on the information received from the core network. Mobility restrictions on the CM-CONNECTED state are enforced by the radio access network and the core network when in the RRC-Connected state.

In the CM-CONNECTED state, the core network provides mobility restrictions to the radio access network in the Handover Restriction List.

Mobility restrictions consist of: i) RAT restrictions, ii) prohibited areas, iv) service area restrictions, and iii) core network type restrictions:

Iii) RAT restriction:

Define a 3GPP radio access technology that the UE is not allowed to access the PLMN. In limited RAT, the UE is based on a subscription that is not authorized to initiate any communication to the PLMN. In the CM-CONNECTED state, when the radio access network determines the target RAT and target PLMN during the handover procedure, it may be considered according to the PLMN RAT restriction.

Ii) Forbidden Area:

In the forbidden area of a given RAT, the UE is based on a subscription that is not authorized to initiate any communication with the network for the PLMN. The UE behavior with respect to cell selection, RAT selection and PLMN selection depends on the network response that informs the UE of the forbidden area.

Iii) Service area restrictions:

Define an area where the UE may or may not initiate communication with the network as follows: ① Allowed area: In the allowed area of a given RAT, the UE initiates communication with the network as permitted by the subscription. Is permitted. 2. Non-Allowed area: In the non-allowed area of a given RAT, the UE may be limited in service area based on the subscription. The UE and the network are not allowed to initiate service request or SM signaling to acquire user service (both in CM-IDLE and CM-CONNECTED state). The RRC procedure while the UE is in the CM-CONNECTED state with the RRC inactive state is not changed compared to when the UE is in the allowed area. The RM procedure does not change compared to when the UE is in the allowed area. UEs in the disallowed region may respond to core network paging with service requests and RAN paging.

Iii) Core network type limitation:

Defines whether the UE is allowed to connect to 5GC for PLMN.

For a given UE, the core network determines mobility restrictions based on UE subscription information, UE location and local policy. Mobility restrictions may change due to, for example, subscription, location change and local policy of the UE. Optionally, the service area restricted or disallowed area may be further fine tuned by the PCF based on UE location, PEI and network policy. The service area restriction may be updated during the registration procedure or the UE configuration update procedure.

If the network sends a service area restriction to the UE, the network transmits only one of the allowed or unlicensed areas, but not both at the same time. If the UE receives an allowed area from the network, any TA that is not part of the allowed area is considered to be disallowed by the UE. If the UE receives an unlicensed area from the network, any TA that is not part of the unlicensed area is considered to be allowed by the UE. If the UE does not receive any service area restriction, any TA in the PLMN is considered to be allowed.

If the UE has an overlapping area between the RAT restriction, the prohibited area, the service area restriction, or any combination thereof, the UE may proceed with the following priorities:

Iii) the evaluation of the RAT restriction takes precedence over the evaluation of any other mobility restriction; And ii) the evaluation of prohibited areas takes precedence over the evaluation of service area restrictions.

The UE may override the RAT restriction, forbidden zone and unallowed zone restriction each time it accesses the network for emergency services and regulatory prioritized services such as MPS. The network can also override unacceptable area restrictions and RAT restrictions for emergency services and regulatory prioritized services such as MPS.

<Mobility pattern>

The mobility pattern is a concept that AMF can use to characterize and optimize UE mobility. The AMF determines and updates the mobility pattern of the UE based on the subscription of the UE, statistics of UE mobility, network local policy and UE assisted information, or any combination thereof. The statistics of UE mobility may be historical or expected UE moving trajectory.

The UE mobility pattern may be used to optimize the mobility support provided by the AMF to the UE (eg, registration area allocation).

<UE reachability of CM-IDLE state in 3GPP access>

Reachability management may serve to detect if the UE is reachable and provide the network with a UE location (ie, access node) for reaching the UE. This is done by paging UE and UE location tracking. UE location tracking includes both UE registration area tracking (ie UE registration area update) and UE reachability tracking (ie UE periodic registration area update). These functions can be located in 5GC (for CM-IDLE state) or NG-RAN (for CM-CONNECTED state).

The UE and AMF negotiate the UE reachability characteristics for the CM-IDLE state during the registration and registration update procedure.

Two UE reachability categories are negotiated between the UE and AMF for the CM-IDLE state:

Iii) UE reachability allows mobile termination data while the UE is in CM-IDLE state. The UE location is known by subdividing the tracking area list by the network. ② The paging procedure can be applied to these categories. ③ Mobile originating and mobile terminated data can be applied to this category for both CM-CONNECTED and CM-IDLE states.

Ii) Mobile Initiated Connection Only (MICO) mode: ① Mobile originated data can be applied to this category for both CM-CONNECTED and CM-IDLE status. ② Mobile terminated data may be supported only when the UE is in CM-CONNECTED state.

Each time a UE in the RM-REGISTERED state enters the CM-IDLE state, it starts a periodic registration timer according to the periodic registration timer value received from the AMF during the registration procedure.

The AMF assigns a periodic registration timer value to the UE based on local policy, subscription information and information provided by the UE. After the periodic registration timer expires, the UE may perform periodic registration. If the UE is out of network coverage when the periodic registration timer expires, the UE may perform a registration update when returning to coverage.

The AMF runs a mobile reachable timer for the UE. The timer starts with a value longer than the periodic registration timer of the UE whenever the CM state for the UE in the RM-REGISTERED state changes to CM-IDLE. If the AMF receives an elapsed time from the RAN when the RAN initiates a UE context release indicating that the UE is unreachable, the AMF is based on the elapsed time received from the RAN and a normal mobile reachable timer value. To deduce the mobile reachable timer value. The AMF may stop the mobile reachable timer when the UE CM state of the AMF moves to the CM-CONNECTED state. If the mobile reachable timer expires, the AMF determines that the UE is not reachable.

However, since the AMF does not know the period of time that the UE cannot reach, the AMF may not immediately deregister the UE. Instead, after expiration of the mobile reachable timer, the AMF may clear the PPF flag and start an implicit deregistration timer with a relatively large value. When the AMF moves the UE CM state of the AMF to the CM-CONNECTED state, the AMF may stop the implicit deregistration timer and set the PPF flag.

If the PPF is not set, the AMF does not page the UE and may reject any request to deliver DL signaling or data to the UE.

If the implicit deregistration timer expires before the UE connects to the network, the AMF implicitly deregisters the UE.

As part of deregistration for a specific access (3GPP or non-3GPP access), the AMF may request the relevant SMF of the UE to release the PDU session established for that particular access.

<UE reachability of CM-IDLE state in 3GPP access: UE reachability allows mobile terminated data while UE is in CM-IDLE state>

If the UE does not apply the MICO mode, the AMF may consider that the UE in the RM-REGISTERED state is reachable by CN paging if the UE CM state of the AMF is CM-IDLE state.

<Process paging strategy in 3GPP access>

Based on the operator configuration, 5GS allows AMF and NG-RAN to apply different paging strategies for different types of traffic.

For UEs in CM-IDLE state, the AMF performs paging and selects a paging strategy based on, for example, local configuration, why the NF triggered paging, and the information available in the request that triggered paging. Decide

For UEs CM-CONNECTED to RRC inactive, the NG-RAN performs paging and determines a paging strategy based on, for example, information received from local configuration, AMF and SMF.

In the case of a network triggered service request from the SMF, the SMF determines 5QI and ARP based on the notification of the downlink data or the downlink data received from the UPF. The SMF includes 5QI and ARP corresponding to the downlink PDUs received in the request sent to the AMF. If the UE is in CM IDLE, AMF can use 5QI and ARP to derive different paging strategies.

<Paging Policy Differentiation in 3GPP Access>

Paging policy differentiation is an optional feature that allows AMF to apply different paging strategies for different traffic or service types provided within the same PDU session based on operator configuration. This feature can only be applied to IP type PDU sessions.

When the 5GS supports the Paging Policy Differentiation (PPD) feature, the DSCP value (TC / IPv4 in IPv6) can be set by the application to indicate to the 5GS the paging policy that should be applied to specific IP packets.

The operator can configure the SMF in such a way that the paging policy differentiation feature applies only to specific HPLMNs, DNNs, and 5QIs. In the case of HR roaming, this configuration may be performed in the SMF of the VPLMN.

For network triggered service requests and UPF buffered downlink data packets, the UPF includes the DSCP in the TOS (IPv4) / TC (IPv6) value from the IP header of the downlink data packet, and in the data notification message sent to the SMF. It includes an indication of the corresponding QoS flow.

When the PPD is applied, the SMF determines a PPI (Paging Policy Indicator) based on the information received from the UPF. For network triggered service request and SMF buffered downlink data packet, when PPD is applied, SMF determines PPI based on DSCP in TOS (IPv4) / TC (IPv6) value from IP header of received downlink data packet. The indication of the corresponding QoS flow can be determined. SMF includes the PPI, ARP and 5QI of N11 messages sent to AMF. If the UE is in CM IDLE, the AMF uses the information to derive the paging strategy and sends a paging message to the NG-RAN via N2. The paging message sent to the NG-RAN may include a PPI.

The SMF configures the UPF to put different QoS flow traffic with different paging differentiation requirements, and sets the Paging Policy Indicator (PPI) for the QoS flow (QFI) of the PDU session to N2 for NG-RAN. Can be represented.

<Paging Priority in 3GPP Access>

Paging priority is a feature that allows the AMF to include an indication in the paging message sent to the NG-RAN so that the UE is paged with priority. Whether or not to include paging priority in the paging message is determined based on the ARP value of the message received from the SMF for the IP packet waiting for the AMF to be delivered in the UPF. If the ARP value is associated with a selection priority service (eg, MPS, MCS), the AMF includes the paging priority in the paging message. When the NG-RAN receives a paging message with a paging priority, it processes the page with the priority.

The AMF receives other messages from the SMF with the ARP associated with the Selective Priority Service (eg MPS, MCS) while waiting for the UE to respond to the page sent without priority, and the AMF receives another paging message containing the paging priority. Is transmitted to (R) AN.

<Manage Registration with Non-3GPP Access>

The UE enters the RM-DEREGISTERED state, and the AMF enters the RM-DEREGISTERED state for the UE with non-3GPP access as follows:

Iii) in the UE and AMF after performing an explicit deregistration procedure; Ii) in the AMF, after the network non-3GPP implicit deregistration timer expires. Iii) At UE, after UE non-3GPP deregistration timer expires.

Each time a UE registered via a non-3GPP access enters a CM-IDLE state for a non-3GPP access, it starts the UE non-3GPP deregistration timer according to the value received from the AMF during the registration procedure.

With non-3GPP access, the AMF runs a network non-3GPP implicit deregistration timer. The network non-3GPP implicit deregistration timer is set to a value longer than the UE's non-3GPP deregistration timer whenever the CM status for a UE registered via non-3GPP access changes to CM-IDLE for non-3GPP access. Is initiated.

For a UE registered via non-3GPP access, a change in attachment point (eg, a change in WLAN AP) does not lead the UE to perform a registration update procedure.

The UE must not provide 3GPP-specific parameters (eg, indicate preference for MICO mode) during registration via non-3GPP access.

<Manage Connections in Non-3GPP Access>

A UE that successfully establishes an NWu connection over unreliable Non-3GPP access transitions to CM-CONNECTED state for unreliable Non-3GPP access.

For unreliable Non-3GPP access to 5GC, the NWu signal is released as a result of an explicit deregistration procedure or AN release procedure. N3IWF can also explicitly release NWu signal connections due to NWu connection failures. The release of the NWu signal connection between the UE and the N3IWF may be interpreted as follows:

Iii) Release the N2 connection based on N3IWF.

Ii) As a criterion for the UE to transition to CM-IDLE, if the NWu connection release does not occur as part of the deregistration procedure for non-3GPP access where the UE enters the RM-DEREGISTERED state, then non-3GPP access is enabled. The UE registered through remains in the RM-REGISTERED state. When a UE in RM-REGISTERED transitions to CM-IDLE, the UE non-3GPP deregistration timer starts running at the UE. The UE non-3GPP deregistration timer stops when the UE moves to the CM-CONNECTED state or the RM-DEREGISTERED state.

For unreliable Non-3GPP access, when AMF releases the N2 interface, the N3IWF releases all resources associated with the UE, including the NWu connection with the UE. Release of the N2 connection by the AMF sets the CM status for the UE in the AMF to CM-IDLE.

The UE cannot be paged with unreliable Non-3GPP access.

If the UE registers simultaneously via 3GPP access and non-3GPP access and the UE moves all PDU sessions to one of the accesses, whether or not the UE initiates a deregistration procedure on an access that does not have a PDU session is implemented. Depends on

Release of a PDU session over non-3GPP access does not mean release of an N2 connection.

If a UE has a PDU session routed through non-3GPP access, and the UE state is CM-IDLE for non-3GPP access, this PDU session causes the UE to move PDU sessions through 3GPP access based on UE policies. It is not released to make it possible. The core network maintains PDU sessions but disables the N3 user plane connection for such PDU sessions.

<UE reachability of CM-IDLE on non-3GPP access>

The UE cannot be paged over unreliable non-3GPP access.

If the UE status in AMF is CM-IDLE and RM-REGISTER for non-3GPP access, there may be a PDU session last routed over non-3GPP access without user plane resources. If AMF receives a data notification from the SMF with a non-3GPP access type indication for a PDU session corresponding to a UE that is CM-IDLE for non-3GPP access and the UE is registered via 3GPP access in the same PLMN, then network triggered The service request may be performed via 3GPP access regardless of whether the UE is CM-IDLE or CM-CONNECTED through 3GPP access. In this case, the AMF provides an indication that the procedure involves downlink data hold for non-3GPP access. If the UE is in CM-IDLE via 3GPP access, the AMF does not include the PDU session ID of the specific PDU session with the access type set to non-3GPP access.

<UE reachability of CM-CONNECTED on non-3GPP access>

For UE in CM-CONNECTED state: i) AMF knows N3IWF node granular UE location. Ii) N3IWF releases the N2 connection when the UE becomes unreachable (ie, when released NWu).

Session Management

5G core networks support PDU connectivity services. PDU connectivity service provides the exchange of PDUs between a user terminal and a data network. PDU connectivity service is supported via PDU sessions established upon request from a user terminal.

The subscription information includes a plurality of data network names and a default data network name. If a valid data network name is not provided in the PDU session establishment request sent to the 5G core network, the user terminal is assigned to the default data network name.

Each PDU session supports one PDU session type. PDU sessions support the exchange of a single type of PDU session requested by a user terminal in the establishment of a PDU session.

The PDU session uses NAS SM signaling exchanged over the N1 between the UE and the SMF device, where the PDU session is established at the request of the user terminal and modified at the request of the user terminal and the 5G core network. In response to the request of the user terminal and the 5G core network, it may be released. At the request of the application server, the 5G core network may trigger a specific application of the UE. Upon receiving the corresponding trigger message, the user terminal delivers to the identified application. The application identified at the user terminal may establish a PDU session for a specific DNN.

The SMF device may support a PDU session for the LADN where access to the data network is available only in a particular LADN service area.

The SMF device checks whether the user terminal request is compliant with the user subscription. To do this, the UDM retrieves and requests update notifications for SMF device level subscription data. Such data may be represented per DNN and, if applicable, per S-NSSAI:

Iii) Allowed PDU session type and default PDU session type. Ii) Allowed SSC mode and default SSC mode. I) QoS information: subscribed Session-AMBR, Default 5QI and Default ARP. Iii) Fixed IP address / prefix.

A user terminal registered via a plurality of accesses selects an access for establishing a PDU session. The HPLMN may send a policy to the user terminal to guide the selection of access to establish a PDU session to the user terminal.

The user terminal may request to move the PDU session between 3GPP access and non-3GPP access. The decision to move the PDU session between 3GPP access and non-3GPP access is made on a PDU session basis. That is, the user terminal may have some PDU sessions using 3GPP access at a given time, and other PDU sessions may use non-3GPP access.

In the PDU session establishment request sent to the network, the user terminal provides a PDU session identifier. The PDU session ID is unique per user terminal and is an identifier used to uniquely identify one of the PDU sessions of the user terminal. The PDU session ID is stored in the UDM to support handover between 3GPP and non-3GPP access when different PLMNs are used for the two accesses. The UE may also provide:

Iii) PDU session type. Ii) S-NSSAI. V) the data network name (DNN). Iii) SSC mode.

The user terminal may establish multiple PDU sessions on the same data network or different data networks at the same time via the 3GPP and non-3GPP access networks.

The user terminal is serviced by another UPF device that establishes multiple PDU sessions for the same data network and terminates N6.

A user terminal having a plurality of established PDU sessions may be serviced by another SMF device.

The SMF device may be registered and deregistered on a PDU session granularity basis of the UDM.

User plane paths of different PDU sessions (for the same or different data network names) belonging to the same user terminal may be completely disjoint between the AN and the UPF device interfacing with the data network.

Session Management: Interaction Between AMF Devices and SMF Devices

The AMF device and the SMF device are separate network functions.

Interactions with N1 related SMF devices are as follows:

Iii) A single N1 termination point is located in the AMF device. The AMF device forwards SM related NAS information to the SMF device based on the PDU session ID of the NAS message. In addition, SM NAS exchanges (eg, SM NAS message responses) for N1 NAS signaling received by the AMF device via access (eg, 3GPP access or non-3GPP access) are sent via the same access. . Ii) The serving PLMN has a subsequent SM NAS exchange (e.g. SM NAS message response) for N1 NAS signaling received by the AMF device via access (e.g., 3GPP access or non-3GPP access). Ensure that it is sent over the same access. Iii) The SMF device handles the session management portion of NAS signaling exchanged with the user terminal. Iii) The user terminal initiates PDU session establishment in the RM-REGISTERED state. Iii) If an SMF device is selected to serve a particular PDU session, then the AMF device ensures that all NAS signaling related to the PDU session is handled by the same SMF device instance. I) Upon establishment of a successful PDU session, the AMF device and the SMF device store the access type with which the PDU session is associated.

The N11 related interactions with SMF devices are as follows:

Iii) The AMF device reporting the reachability of the user terminal based on the subscription of the SMF device, including the following, includes the user terminal location information on the ROI indicated by the SMF device. Ii) The SMF device informs the AMF device when the PDU session is released. Iii) Upon establishment of a successful PDU session, the AMF device stores the identifier of the serving SMF device of the user terminal, and the SMF device stores the identifier of the serving AMF device of the UE including the AMF device set. When attempting to reach an AMF device serving a user terminal, the SMF device needs to apply the behavior described for "other CP NFs".

Interactions with N2 related SMF devices are as follows:

Iii) Some N2 signaling (eg, handover related signaling) may require action of the AMF device and the SMF device. In this case, the AMF device guarantees coordination between the AMF device and the SMF device. The AMF device may forward SM N2 signaling toward the corresponding SMF device based on the PDU session ID in the N2 signaling. Ii) The SMF apparatus provides the NG-RAN with a PDU session ID to the NG-RAN in order to enable the NG-RAN to apply a header compression mechanism suitable for packets of other PDU types.

Interactions with N3-related SMF devices are as follows:

Iii) Selective activation and deactivation of an UP connection of an existing PDU session is defined.

Interactions with N4 related SMF devices are as follows:

I) When the UPF device recognizes that some DL data has arrived for the user terminal without downlink N3 tunnel information, the SMF device interacts with the AMF device to initiate a network triggered service request procedure. In this case, if the UE cannot reach or if the SMF device recognizes that the UE can only reach regulatory prioritized service and the PDU session is not for regulatory prioritized service, then the SMF device is DL data. Do not notify the AMF device.

The AMF device can select the SMF device according to the procedure. To this end, subscription data may be obtained from the UDM. It is also possible to retrieve the subscribed UE-AMBR from the UDM and send it to the (R) AN.

AMF device-SMF device interactions to support LADN are defined.

To support billing data collection and to meet regulatory requirements (NPLI-to provide network-provided location information) relating to the setup, modification and release of IMS voice calls, the following applies:

I) When establishing a PDU session, if the AMF device can use the PEI, the AMF device provides the PMF of the user terminal to the SMF device. Ii) or when delivering a UL NAS or N2 signaling to a peer NF (eg SMF device or SMSF) during UP connection activation of the PDU session, the AMF device receives the user location information received from 5G-AN and the UL NAS or N2 It provides the access type (3GPP or Non-3GPP) of the AN receiving the signaling and also the corresponding UE time zone.

The user location information, the access type, and the UE time zone may be further provided by the SMF apparatus or the PCF. PCFs can obtain information from SMF devices to provide NPLI to applications such as IMS.

User location information may correspond to:

Vi) for NG-RAN: Cell-Id. Ii) For N3IWF: User terminal local IP address (used to reach N3IWF) and optionally UDP or TCP source port number (if NAT is detected).

<Single PDU session with multiple PDU session anchors>

In order to support selective traffic routing to a data network (DN) or to support SSC mode 3, a Session Management Function (SMF) device establishes a Protocol Data Unit (PDU) session with a plurality of N6 interfaces. It is possible to control the data path of the PDU session so that it can cope with. The user plane function (UPF) device may terminate the plurality of N6 interfaces to support the PDU session anchor function. Each PDU session anchor that supports a PDU session provides different access to the same data network. And, the PDU session anchor assigned to establish a PDU session is associated with the SSC mode of the PDU session. And, additional PDU session anchors assigned to the same PDU session are independent of the SSC mode of the PDU session for selective traffic routing to the data network.

Selective traffic routing to the data network is supported. Some selected traffic is forwarded to the data network close to the access network provided to the user terminal at the N6 interface.

There are two processing methods for the PDU session as follows.

(1) Use of UL Classifier functionality for the PDU session, as shown in FIG.

(2) Use of IPv6 multi-homing for PDU sessions, as shown in FIGS. 6 and 7

<Use of Uplink Separator for PDU Session>

5 illustrates a user plane architecture of an uplink delimiter, according to one embodiment.

As illustrated in FIG. 5, in a PDU session of IPv4, IPv6, or Ethernet, the SMF device device may insert an uplink classifier (UL CL) into the data path of the PDU session. Here, inserting the uplink separator means inserting a UPF device corresponding to the uplink separator in the data path from the user terminal to the data network in the 5G core network. The SMF device may decide to insert the UPF supporting the UL CL function into the data path of the PDU session or to remove the UPF supporting the UL CL function after the PDU is established in the data path of the PDU session. The SMF device may include one or more UPFs that support the UL CL function in the data path of the PDU session. The uplink separator is a function supported by the UPF and is used to locally divert some traffic that matches the traffic filters provided by the SMF device device. Insertion and removal of the uplink separator is determined or controlled by the SMF device device using N4 and UPF capabilities. SMF Device The device includes one or more UPF devices that support the uplink separator function in the data path of the PDU session.

The user terminal does not recognize traffic diversion by the uplink delimiter. And, the user terminal does not participate in both insertion and removal of the uplink separator. In a PDU session according to an IPv4 or IPv6 type, the user terminal associates the PDU session with either a single IPv4 address or a single IPv6 prefix assigned by the network.

When the uplink separator function is inserted into the data path of a PDU session, there are a plurality of PDU session anchors for the PDU session. These PDU session anchors provide different access to the same data network (DN). In a PDU session of IPv4 or IPv6 type, only one PDU session anchor is an IP anchor point for the IPv4 address / IPv6 prefix of the PDU session provided to the user terminal.

The uplink delimiter provides forwarding of uplink traffic towards different PDU session anchors. The uplink delimiter then merges the downlink traffic to the user terminal. Here, traffic is aggregated on the link destined for the user terminal by different PDU session anchors. The integration of traffic is based on traffic detection and traffic forwarding rules provided by the SMF device apparatus.

The uplink delimiter applies filtering rules and determines how packets will be routed. Here, the filtering rule means examining the prefix of the destination IP address or the uplink IP packets transmitted by the user terminal. UPF device devices that support uplink delimiters are controlled by SMF device devices that support traffic measurement for traffic replication for LI and bit rate enforcement per PDU session AMBR. Can be.

UPF devices that support uplink delimiters may support PDU session anchors for connection to local access to the data network (including, for example, tunneling or support of NAT on N6). This is controlled by the SMF device.

Additionally, uplink separators (and additional PDU session anchors) may be inserted into the data path of the PDU session to create a new data path for the same PDU session. How to organize the data paths of all UL CLs in a PDU session depends on operator configuration and SMF device logic, and UPF devices that support uplink separators connected to (R) AN via the N3 interface. Is one.

The insertion of the uplink separator in the data path of a PDU session is shown in figure 5.6.4.2-1.

According to an embodiment, when a user terminal in an idle state moves to a new registration area, the user terminal may temporarily access the network in order to register in a new network according to the change of the registration area. At this time, the active traffic may not exist. While registering to a new network, the AMF device and the SMF device can manage the location of the user terminal, so that the SMF device can determine the control of the UPF device, such as relocation or I-UPF insertion, removal. Depending on the determination, operations such as I-UPF insertion, removal, and relocation may be performed in the session dormant state. That is, the UPF device is controlled while registering in a new network in session dormancy, so that the possibility of interruption can be reduced when the actual service is provided.

According to another embodiment, when I-UPF control such as I-UPF insertion, removal, and relocation in a session dormant state, control of the UPF device may be performed, but the interface between the base station and the UPF device may not be updated. Therefore, in the session dormant state, the signaling load between the RAN-core networks can be reduced by not updating.

According to another embodiment, the 5G network may perform relocation of a PDU Session Anchor (PSA), which is an UPF device that serves as an anchor gateway of a corresponding PDU session, in order to manage a fixed and flexible data path. . In addition, at least one intermediate UPF insertion may be possible between the base station and the PSA to support a network in which the base station and the PSA are not directly connected.

<Use IPv6 Multihome for PDU Sessions>

6 is a diagram illustrating a multi-homed PDU session: service continuity case according to an embodiment. 7 is a diagram illustrating a multi-homed PDU session: local access to the same data network, according to an embodiment.

The PDU session is associated with a plurality of IPv6 prefixes. This is called a multi home PDU session. Multihomed PDU sessions provide access to a data network through one or more PDU session anchors. Other user plane paths leading to other PDU session anchors are branched out in a common UPF, referred to as a UPF that supports a "branching point function." The branching point provides forwarding of uplink traffic towards other PDU session anchors and merges traffic from different PDU session anchors on the link destined for the user terminal.

UPF devices that support the branching point function can be controlled by SMF devices that support traffic measurement for traffic replication for LI and bit rate enforcement per PDU session AMBR. have. Insertion and removal of UPF devices supporting branching points are determined or controlled by the SMF device using generic N4 and UPF capabilities. The SMF device may determine to insert a UPF supporting branching point function in the data path of the PDU session during or after the PDU session is established. After the PDU session is established, the SMF device may determine to remove the UPF supporting the branching point function from the data path of the PDU session.

Multihomed PDU sessions may be applied to PDU sessions of IPv6 type. A request of PDU session type "IP" or "IPv6" implies supporting multi-homed PDU sessions for IPv6 at the user terminal.

Using a plurality of IPv6 prefixes in a PDU session has the following characteristics.

The UPF supporting the branching point function is configured by an SMF device that spreads uplink traffic between IP anchors based on the source prefix of the PDU. Here, the source prefix of the PDU may be selected by the user terminal based on routing information and preferences received from the network.

The IETF RFC 4191 is used to configure routing information and preferences that influence the selection of the source prefix at the user terminal. This corresponds to scenario 1 defined in the IETF RFC, "IPv6 Multi-homing without Network Address Translation." This allows the branching point to be created without knowledge of the routing table in the data network, and to maintain the first hop router function in the IP anchors.

According to an embodiment, when a user terminal in an idle state moves to a new registration area, the user terminal may temporarily access the network in order to register in a new network according to the change of the registration area. At this time, the active traffic may not exist. While registering to a new network, the AMF device and the SMF device can manage the location of the user terminal, so that the SMF device can determine the control of the UPF device, such as relocation or I-UPF insertion, removal. Depending on the determination, operations such as I-UPF insertion, removal, and relocation may be performed in the session dormant state. That is, the UPF device is controlled while registering in a new network in session dormancy, so that the possibility of interruption can be reduced when the actual service is provided.

According to another embodiment, when I-UPF control such as I-UPF insertion, removal, and relocation in a session dormant state, control of the UPF device may be performed, but the interface between the base station and the UPF device may not be updated. Therefore, in the session dormant state, the signaling load between the RAN-core networks can be reduced by not updating.

According to another embodiment, the 5G network may perform relocation of a PDU Session Anchor (PSA), which is an UPF device that serves as an anchor gateway of a corresponding PDU session, in order to manage a fixed and flexible data path. . In addition, at least one intermediate UPF insertion may be possible between the base station and the PSA to support a network in which the base station and the PSA are not directly connected.

<Selective activation and deactivation of UP connection of existing PDU sessions>

This applies when the UE has established a plurality of PDU sessions. Activation of an UP connection of an existing PDU session may cause activation of a UE-CN user plane connection (ie, data radio bearer and N3 tunnel).

For a UE in CM-IDLE state in 3GPP access, the UE or network triggered service request procedure may support independent activation of an UP connection of an existing PDU session. For UEs in CM-IDLE state in non-3GPP access, the UE triggered service request procedure may allow reactivation of UP connectivity of existing PDU sessions and support independent activation of UP connectivity of existing PDU sessions. .

The UE in the CM-CONNECTED state may call the service request procedure to request independent activation of the UP connection of existing PDU sessions.

Network triggered reactivation for an UP connection of an existing PDU session is handled as follows:

Iii) If the UE CM status in AMF is already CM-CONNECTED on access (3GPP, non-3GPP) associated with a PDU session in SMF, the network may reactivate the UP connection of the PDU session using a network initiated service request procedure. have.

Otherwise:

Ii) If the UE is registered for both 3GPP and non-3GPP accesses and the UE CM status in AMF is CM-IDLE in non-3GPP access, then the UE is in 3GPP access to the PDU session related to 3GPP access or non-3GPP access in SMF. It may be paged or notified via: ① If the UE CM status in AMF is CM-IDLE in 3GPP access, the paging message may include the access type associated with the PDU session in the SMF. Upon receiving a paging message that includes the access type, the UE will respond to 5GC over 3GPP access using a NAS service request message that includes a list of PDU sessions associated with the received access type and may reactivate the UP connection over 3GPP access. Can be. (I.e. the list does not include PDU sessions where UP connections cannot be reactivated in 3GPP according to UE policy). If the UE has paged PDU sessions in the PDU session list provided in the NAS service request, 5GC may reactivate the PDU session UP connection via 3GPP access. ② When the UE CM status of AMF is CM-CONNECTED in 3GPP access, the notification message may include a PDU session ID. Upon receiving the notification message, the UE may respond to 5GC via 3GPP access using a NAS service request message that includes an indication of whether the PDU session UP connection can be reactivated via 3GPP.

Iii) If the UE is registered with both 3GPP and non-3GPP accesses served by the same AMF, and the UE CM status in the AMF is CM-IDLE in 3GPP access and CM-CONNECTED in non-3GPP access, the UE is non- 3GPP allows the SMF to be notified of PDU sessions (ie last routed) associated with 3GPP access. The notification message includes the PDU session ID. Upon receiving the notification message, when 3GPP access is available, the UE may respond to 5GC via 3GPP access using a NAS service request message.

Deactivation of the UP connection of an existing PDU session causes the corresponding data radio bearer and N3 tunnel to be deactivated. UP connections of other PDU sessions can be independently deactivated when the UE is in CM-CONNECTED state in 3GPP access or non-3GPP access.

Session and service continuity

Supporting session and service continuity in the 5G system architecture can ensure the address of various continuity requirements of different applications and services for the user terminal. 5G systems support different session and service continuity modes (SSC). The SSC mode associated with a PDU session does not change during the lifetime of the PDU session.

Iii) In SSC mode 1, the network reserves a continuity service to be provided to the user terminal. In PDU sessions of IPv4, IPv6 type, the IP address is reserved. Ii) In SSC mode 2, the network may release the continuity service to be transmitted to the user terminal and may release a PDU session corresponding to the continuity service. In the IPv4, IPv6 type, the network may release IP addresses assigned to the user terminal. In SSC mode 3, a change in user plane may be visible to the user terminal. On the other hand, the network ensures that the user terminal does not cause loss of connectivity. Connection through the new PDU session anchor point is established before the previous connection is disconnected for better service continuity. In SSC mode 3, the IP address is not preserved when the PDU session anchor is changed for IPv4 and IPv6 types.

The addition or removal of additional PDU session anchors in the PDU session for local access to the data network is independent of the SSC mode of the PDU session.

<SSC Mode (Service & Session Continuity mode)>

(1) SSC mode 1

For a PDU session in SSC mode 1, the UPF device acting as a PDU session anchor in establishing a PDU session remains independent of access technology (ex / access type, cells) for the user terminal to successfully access the network. do.

For PDU sessions of IPv4 and IPv6 type, IP continuity is supported regardless of user terminal mobility events.

If an IPv6 multihomed or uplink separator is applied to a PDU session in SSC mode 1, the network assigns additional PDU session anchors to the PDU session based on local policy. And, additional PDU session anchors are released or assigned. The user terminal does not expect additional IPv6 prefixes to be maintained for the lifetime of the PDU session. SSC mode 1 can be applied to any PDU session type or any access type.

(2) SSC mode 2

If the PDU session in SSC mode 2 has a single PDU session anchor, the network may trigger the release of the PDU session and instruct the user terminal to immediately establish a new PDU session to the same data network. The trigger condition depends on the operator policy (e.g., a request from an application function based on the load condition). When a new PDU session is established, a new UPF device acting with a PDU session anchor may be selected.

On the other hand, if a PDU session in SSC mode 2 has a plurality of PDU session anchors (e.g., in case of an uplink separator or multihomed PDU session applied to a PDU session in SSC mode 2), an additional PDU session anchor Can be released or assigned.

SSC mode 2 can be applied to any PDU session type and any access type. In the uplink separator mode, the user terminal does not participate in the relocation process of the PDU session anchor so that the presence of the plurality of PDU session anchors is not visible to the user terminal.

(3) SSC mode 3

For PDU sessions in SSC mode 3, before the connectivity between the user terminal and the previous PDU session anchor is released, the network allows the user terminal to establish connectivity to the same data network through the new PDU session anchor. allow). When applying the trigger condition, the network may determine whether to select a suitable PDU session anchor for new conditions of the user terminal (eg, the point of attachment of the network).

SSC mode 3 applies to any PDU session type or any access type.

For IPv4 or IPv6 type PDU sessions, the following applies during the process of changing the PDU session anchor:

V) A new IP prefix anchored in a new PDU session anchor is assigned inside the same PDU session depending on IPv6 multihome. Ii) Or, a new IP address or new IP prefix may be assigned inside a new PDU session triggered by the user terminal to establish.

After a new IP address or new IP prefix is assigned, the existing IP address or existing IP prefix is maintained for a certain time indicated by the user terminal and then released.

If a PDU session in SSC mode 3 has multiple PDU session anchors (e.g., for multihomed PDU sessions, or an uplink delimiter that applies to PDU sessions in SSC mode 3), additional PDU session anchors are released. May be assigned or allocated.

<SSC mode selection>

The SSC mode selection policy is used to (i) determine the type of session or (ii) the type of session and service continuity mode (SSC mode) associated with the application or group of applications for the user terminal.

It is possible for the operator to provide the SSC mode selection policy to the user terminal. The SSC mode selection policy may include one or more SSC mode selection policy rules that the user terminal may use to determine the type of SSC mode associated with the application or groups of applications. The SSC mode selection policy may include a default SSC mode selection policy rule matching all applications of the user terminal.

When the application requests data transmission (for example, opening a network socket) and the application does not specify the SSC mode by itself, the user terminal may select the SSC mode associated with the application using the SSC mode selection policy. Additionally operations that apply to user terminals and networks are described below.

a) if the user terminal has an already established PDU session matching the SSC mode associated with the application, unless the user terminal does not allow the use of the already established PDU session, the user terminal has already established Routing application data within a PDU session. Conversely, if the user terminal does not have an already established PDU session matching the SSC mode associated with the application, the user terminal may request to establish a new PDU session matching the SSC mode associated with the application.

b) The SSC mode associated with the application is the SSC mode included in the non-default SSC mode selection policy rule matching the application or the SSC mode included in the default SSC mode selection policy rule. If the default mode selection policy rule is not included in the SSC mode selection policy and no other SSC mode selection policy rule matches the application, the user terminal may request a PDU session that does not provide the SSC mode. In this case, the network may determine the SSC mode of the PDU session.

The SSC mode selection policy rule provided by the user terminal may be updated by the operator.

The SMF device receives a list of SSC modes per Data Network Name (DNN) and a default SSC mode as part of subscription information from a unified data management (UDM) device.

If the user terminal provides the SSC mode when a new PDU session is requested, the SMF device can either accept the requested SSC mode or modify the requested SSC mode based on the subscription or local configuration. Select the mode.

If the user terminal does not provide the SSC mode when a new PDU session is requested, the SMF device may apply a local configuration to select the default SSC mode for the data network listed in the subscription or to select the SSC mode.

When a static IP address / IP prefix is assigned to a PDU session, SSC mode 1 uses a PDU session based on a static IP address / IP prefix subscription for Data Network Name (DNN) and Single Network Slice Selection Assistance Information (S-NSSAI). Is assigned to.

<Network Function Description: AMF>

AMF includes the following features: Some or all of the AMF functionality may be supported by a single instance of AMF.

1) Termination of the RAN CP interface N2. 2)-termination of NAS N1, NAS ciphering and integrity protection. 3) Registration Management. 4) Connection Management. 5) Reachability Management. 6) Mobility Management. 7) Legitimate intercepts (interfaces with AMF device events and LI systems). 8) Transmit SM message between user terminal and SMF device. 9) Transparent proxy for SM message routing. 10) Access authentication. 11) Authorization. 12) Provide SMS message transmission between user terminal and SMSF. 13) Security Anchor Function (SEAF). Interact with the AUSF and the user terminal and receive an intermediate key established as a result of the user terminal authentication process. For USIM-based authentication, the AMF device retrieves security data from AUSF. 14) Security Context Management (SCM). The SCM receives a key used to derive an access network unique key from SEAF. 15) Location Services Management for Regulatory Services. 16) Transmit location service messages between the RAN and the LMF as well as the UE and the LMF. 17) Assign EPS bearer ID for interworking with EPS.

Regardless of the number of network functions, there is one NAS interface instance per access network between the user terminal and the CN and terminates at least with one of the network functions implementing NAS security and mobility management.

In addition to the functions of the AMF device described above, the AMF device may include the following functions to support a non-3GPP access network:

V) N2 interface support with N3IWF. Some information (eg 3GPP cell identification) and procedures (eg handover related) defined through 3GPP access through the interface may not apply and non-3GPP access specific information not applicable to 3GPP access may apply. Ii) Support of NAS signaling to user terminals via N3IWF. Some procedures supported by NAS signaling over 3GPP access cannot be applied to untrusted non-3GPP (eg paging) access. Iii) Support for authentication of user terminals connected via N3IWF. Iii) Management of mobility, authentication and segregated security context status of user terminals connected via non-3GPP access or concurrently via 3GPP and non-3GPP access. Iii) support coordinated RM management context through 3GPP and non-3GPP access. Iii) Support dedicated CM management context for connection via non-3GPP access.

<Network Function Description: SMF>

The SMF device may perform the following functions. All or some of the functions of the SMF device may be supported in a single instance of the SMF device:

Iii) The SMF device may perform session management, eg, session establishment, modification and release, including a tunnel that maintains between the UPF device and the AN node. Ii) The SMF apparatus may perform UE IP address allocation and management (including selective grant). Iii) The SMF device may perform DHCPv4 (server and client) and DHCPv6 (server and client) functions. Iii) The SMF device may perform IPv6 Neighbor Solicitation Proxying specified in IETF RFC 4861 function and / or ARP proxying specified in IETF RFC 1027 for Ethernet PDUs. The SMF device may respond to the ARP and / or IPv6 Neighbor Solicitation Request by providing a MAC address corresponding to the IP address sent in the request. Iii) The SMF device controls the selection and control of the UP function, including forwarding all ARP / IPv6 neighbor solicitation traffic to the SMF device or controlling the UPF device with proxy ARP or IPv6 neighbor discovery for Ethernet PDU sessions. Can be done. Iii) The SMF device may perform traffic steering in the UPF device in order to route the traffic to the appropriate destination. The SMF device may suspend interfaces directed to policy control functions. The SMF device may perform lawful intercept (for the interface of SM events and LI). Iii) The SMF device may support support of charging interfaces and charging data collection. The SMF device may perform control and coordination of charging data collection in the UPF device. The SMF device may perform abort of the SM parts of NAS messages. The SMF device may perform downlink data notification. The SMF device may be an initiator of AN specific SM information transmitted from the N2 to the AN through the AMF device. The SMF device may determine the SSC mode of the session. Iii) The SMF device can (1) handle (VPLMN) local enforcement to apply QoS SLAs, (2) (VPLMN) charge interface and charge data collection, and (3) (SM events in VPLMN). Lawful intercept (for the interface of the server and the LI), (4) support for interaction with the external DN for the transmission of signaling for PDU session authentication / authorization by the external DN, and The same roaming function can be performed.

In an instance of a network slice, it is not required to support all of the functions of the above-described SMF device.

<Network Function Description: UPF Device>

The UPF device may perform the following functions. All or some of the functions of the UPF device may be supported in a single instance of the UPF device:

Iii) If applicable, the UPF device may perform the function of an anchor point for intra- / inter-RAT mobility. The UPF device may perform the function of an external PDU session point of the interconnection to the data network. Ii) The UPF device may perform routing and forwarding of the packet. For example, the UPF device may support an uplink separator that routes traffic flows to an instance of the data network. The UPF device may support a branching point to support multi-homed PDU sessions. Iii) The UPF device may perform packet inspection. For example, the UPF device may perform application detection based on the service data flow template and additionally PFDs received from the SMF device. Iii) The UPF device may perform a user plane portion of policy rule enforcement, eg, gating, redirection, traffic steering, and the like. The UPF device may perform lawful intercept (UP collection). The UPF device may perform traffic usage reporting. The UPF device may perform QoS handling for the user plane, for example, UL / DL rate enforcement, reflective QoS marking in the DL, and the like. The UPF device may perform uplink traffic verification (mapping from SDF device to QoS flow). The UPF device may perform downlink packet buffering and downlink data notification triggering. The UPF device may forward or send one or more "end markers" to the source NG-RAN node. Iii) The UPF device may perform IPv6 Neighbor Solicitation Proxying specified in IETF RFC 4861 function and / or ARP proxying specified in IETF RFC 1027 for Ethernet PDUs. The UPF device may respond to the ARP and / or IPv6 Neighbor Solicitation Request by providing a MAC address corresponding to the IP address sent in the request.

In an instance of the user plane function of the network slice, it is not required to support all of the functions of the UPF device described above.

<System Procedure>

<General>

The following describes network function services and procedures for a communication system according to an embodiment by end-to-end information flows. These information flows can use the NF service operation for communication in the 5GC control plane.

Connection, registration, and mobility management procedures

<General>

Connection management may be used to establish and release a control plane signaling connection between the UE and the AMF device. Registration management may be used to register or deregister a user terminal / user in a communication system according to one embodiment, and may be used to establish a user context in a communication system according to one embodiment. The mobility management function may be used to continuously track the current location of the user terminal. The communication system according to an embodiment may provide a connection, registration, and mobility management function described below.

<N4 Session Management Procedure>

The N4 session management procedure is used to control the function of the UPF device. The SMF device may create, update, and remove an N4 session context in the UPF device. There are the following N4 session management procedures initiated by the SMF device: N4 session establishment procedure, N4 session modification procedure and N4 session release procedure.

1.Establishing an N4 Session

The N4 session establishment procedure is used to create an initial N4 session context for a PDU session at the UPF device. The SMF device allocates a new N4 session ID and provides it to the UPF device. The N4 session ID is stored in the SMF and UPF devices and used to identify the N4 session context during the interaction. The SMF device also stores the relationship between the N4 session ID and the PDU session for the UE.

8 illustrates an N4 session establishment procedure according to an embodiment.

In step 1, the SMF device receives a trigger or changes the UPF device for the established PDU session to establish a new PDU session.

In step 2, the SMF device sends an N4 session establishment request message to the UPF device that includes structured control information that defines how the UPF should behave.

In step 3, the UPF device responds with an N4 session establishment response message containing any information that the UPF device should provide to the SMF device in response to the received control information.

In step 4, the SMF device interacts with the network function that triggered the N4 session establishment procedure.

2. N4 Session Modification Procedure

The N4 session modification procedure is used to update the N4 session context of the PDU session existing in the UPF device, and is executed between the SMF device and the UPF device whenever the PDU session related parameters are modified.

9 illustrates an N4 session modification procedure according to an embodiment.

In step 1, the SMF device receives a trigger for modifying an existing PDU session.

In step 2, the SMF device sends an N4 session modification request message to the UPF device that includes an update to the structured control information that defines how the UPF should behave.

In step 3, the UPF device identifies the N4 session context to be modified by the N4 session ID. The UPF device then updates the parameters of the N4 session context according to the list of parameters sent by the SMF device. In response to the received control information, the UPF device responds with an N4 session modification response message containing any information that the UPF device should provide to the SMF device.

In step 4, the SMF device interacts with a network entity (eg AMF or PCF) that triggered the N4 session modification procedure.

3. N4 Session Release Procedure

The N4 session release procedure is used to remove the N4 session context of the PDU session existing in the UPF device.

10 illustrates an N4 session release procedure according to an embodiment.

In step 1, the SMF device receives a trigger to remove the N4 session context for the PDU session.

In step 2, the SMF device sends an N4 session release request message to the UPF device.

In step 3, the UPF device identifies the N4 session context to be removed by the N4 session ID and removes the entire session context. The UPF device responds with an N4 Session Release Response message containing information that the UPF device should provide to the SMF device.

In step 4, the SMF device interacts with a network entity (eg AMF or PCF) that triggered the N4 session release procedure.

<Service Request Procedure: UE Triggered Service Request>

11 illustrates a UE triggered service request procedure according to an embodiment.

The UE in CM IDLE state initiates a service request procedure to send as a response to an uplink signaling message, user data or network paging request. The AMF device may perform authentication after receiving the service request message. After establishing a signaling connection for the AMF device, the UE or network may send a signaling message, such as establishing a PDU session from the UE to the SMF device, via the AMF device.

The service request procedure is used by the UE in CM-CONNECTED to activate the user plane connection for the PDU session and to respond to NAS notification messages from the AMF device.

For any service request, the AMF device responds with a service grant message if necessary to synchronize the PDU session state between the UE and the network. If the service request cannot be accepted by the network, the AMF device responds with a denial of service message to the UE. The denial of service message may include an indication or reason code requesting the UE to perform a registration update procedure.

In this procedure, both the affected SMF device and the UPF device are under the control of the PLMN serving the UE. For example, for home routed roaming, SLM devices and UPF devices in HPLMN are not related.

For service requests due to user data, additional actions may be taken on the network if the user plane connection activation is not successful. The UE triggered service request procedure can be applied to scenarios with or without intermediate UPF and with or without intermediate UPF reselection.

In step 1, the AN message from the UE to (R) AN, including (AN parameters, MM NAS service request (list of PDU sessions to be activated, list of allowed PDU sessions, security parameters, PDU session status)) Can be transmitted.

The PDU session list to be activated is provided by the UE when the UE wishes to reactivate the PDU session. The list of authorized PDU sessions is provided by the UE when the service request is a response of paging or NAS notification for a PDU session associated with a non-3GPP access and identifies the PDU sessions that can be sent with 3GPP access.

For NG-RAN:

Iii) AN parameter includes the selected PLMN ID and the establishment cause. The establishment cause provides a reason for requesting establishment of an RRC connection. Ii) The UE sends a NAS service request message to the RAN towards the AMF device encapsulated in the RRC message. The RRC message can be used to carry 5G-GUTI and this NAS message.

If a service request is triggered for user data, the UE uses the list of PDU sessions to identify the PDU session (s) in the NAS service request message that the UP connection will be activated. If a service request for signaling only is triggered, the UE does not identify a PDU session to be activated. If a procedure is triggered for the paging response and the UE has simultaneously user data to be transmitted, the UE identifies the PDU session (s) in the MM NAS service request message by which the UP connection will be activated by the list of PDU session (s). Otherwise, the UE does not identify any PDU session (s) in the service request message for the paging response.

If a service request via 3GPP is triggered in response to paging indicating a non-3GPP access, the NAS service request message identifies a list of PDU sessions associated with the non-3GPP access that are reactivated via 3GPP in the list of authorized PDU sessions. do.

PDU session state indicates a PDU session available at the UE.

When the UE is outside the available area of the LADN, the UE does not trigger a service request procedure for the PDU session corresponding to the LADN. In addition, the UE does not identify the PDU session in the list of PDU sessions to be activated when the service request is triggered for other reasons.

When in CM-CONNECTED state, only the list of PDU sessions to be activated and the list of allowed PDU sessions need to be included in the MM NAS service request.

In step 2, the N2 message (N2 parameter, MM NAS service request) is transmitted from the (R) AN to the AMF device. If the AMF device cannot handle the service request, it rejects the service request.

When NG-RAN is used, the N2 parameter includes 5G-GUTI, selected PLMN ID, location information, RAT type and establishment cause.

If the UE is in the CM-IDLE state, the RAN acquires 5G-GUTI in the RRC procedure. The RAN selects an AMF device according to 5G-GUTI. The location information and the RAT type are related to the cell in which the UE is camping.

Based on the PDU session state, the AMF device may initiate a PDU session release procedure in the network for the PDU session indicated by the UE that the PDU session ID is unavailable.

In step 3, if the integrity protection is not or the integrity protection check failed and no service request is sent, the AMF device starts the NAS authentication / security procedure. If the UE in the CM-IDLE state triggers only a service request to establish a signaling connection, after successful establishment of the signaling connection, the UE and the network may exchange NAS signaling and steps 4 to 10 and 13 to 20 may be skipped. .

Step 4 may be performed conditionally. The AMF device may transmit an Nsmf_PDUSession_UpdateSMContext request (PDU session ID (s), cause (s), UE location information, and access type) to the SMF device.

The Nsmf_PDUSession_UpdateSMContext request is called:

Iii) the UE identifies the PDU session (s) to be activated in the NAS service request message; Ii) the procedure is triggered by the SMF device but the PDU session identified by the UE correlates with a PDU session ID that is different than the PDU session ID that triggers the procedure; Iii) The procedure is triggered by the SMF device but the current UE location is outside the "effective area for N2 information" provided by the SMF device. In this case, the AMF device cannot transmit the N2 information provided by the SMF device.

The AMF device determines the PDU session to be activated and sends an Nsmf_PDUSession_UpdateSMContext request to the SMF device associated with the PDU session (s) whose cause is set to indicate the "establishment of user plane resources" for the PDU session.

If the procedure is triggered in response to paging indicating a non-3GPP access and the UE is not in the list of allowable PDU sessions provided by the UE, then the AMF device reactivates the user plane for the PDU session to the SMF device. Notify that it cannot be. For other PDU sessions in the allowed PDU session list, the service request procedure proceeds successfully without reactivating the user plane of the PDU session and the AMF device notifies the UE.

While maintaining the existing NAS signal connection to the UE via the NG-RAN, the AMF device may receive a service request to establish another NAS signal connection through the NG-RAN. In this case, the AMF device triggers the AN release procedure towards the existing NG-RAN to release the existing NAS signaling connection according to the following logic:

Iv) For the PDU session indicated in the "PDU session to be activated", the AMF device performs step 4 to request the SMF device to immediately activate the PDU session. Ii) For PDU sessions that are displayed in the "PDU Session ID List with Active N3 User Plane" but not in the "to be activated PDU Session", the AMF device deactivates the PDU session on the SMF device. Ask.

In step 5, if the SMF device determines that the PDU session ID corresponds to the LADN and the UE is outside the available area of the LADN based on the UE location change notification from the AMF device, the SMF device then (based on the local policy) Determine one of:

Iii) maintain the PDU session, but refuse to activate the user plane connection for the PDU session and notify the AMF device of this. If the procedure is triggered by a network triggered service request, the SMF device may notify the UPF device to discard the downlink data for the PDU session and not provide an additional data notification message. Or ii) PDU session release: The SMF device releases the PDU session and informs the AMF device that the PDU session has been released.

In both cases, the SMF device responds to the AMF device with an appropriate cause of rejection (step 10) and the user plane activation of the PDU session is stopped.

Otherwise, based on the location information received from the AMF device, the SMF device checks the UPF selection criteria and decides to do one of the following:

Iii) Accept the activation of the UP connection and continue to use the current UPF device. Ii) If the UE has left the service area of the UPF previously connected to the AN while maintaining UP acting as a PDU session anchor, select a new intermediate UPF (or add / remove the intermediate UPF). The UP grant confirms the activity of the UP connection. Performing the I-UPF add / change / remove is described as a conditional step in the following: or i) Reject the activation of the UP connection of the PDU session in SSC mode 2, and assign the assignment of the new UPF acting as the PDU session anchor. Triggers the re-establishment of the PDU session after the service request procedure to perform. For example, the UE is out of the service area of the anchor UPF connecting to the RAN.

In step 6a, which is performed conditionally, the SMF device transmits an N4 session establishment request to a new UPF (intermediate).

If the SMF device chooses a new UPF to act as an intermediate UPF for the PDU session, or if the SMF device chooses to insert an intermediate UPF for a PDU session that does not have an intermediate UPF, an N4 session establishment request message is sent to the new UPF. It provides enforcement and reporting rules, packet detection, and data delivery that are installed in the intermediate UPF. PDU session anchor addressing information (at N9) for the PDU session is also provided to the intermediate UPF.

If the SMF device selects a new UPF to replace the existing (middle) UPF, the SMF device includes a data forwarding indication. The data forwarding indication indicates to the UPF that the second tunnel endpoint needs to be reserved for buffered DL data from the existing I-UPF.

In step 6b, the new UP (middle) sends an N4 session establishment response to the SMF device. The new intermediate UPF sends an N4 session establishment response message to the SMF device. When the UPF allocates CN tunnel information, DL CN tunnel information for the UPF acting as a PDU session anchor and UL CN tunnel information (ie, CN N3 tunnel information) is provided to the SMF apparatus. When a data forwarding indication is received, the new (middle) UPF acting as the N3 termination point also sends DL CN tunnel information for the existing (middle) UPF to the SMF device. The SMF device is used to start the timer and release resources to the existing intermediate UPF in step 20a.

In step 7a, which is performed conditionally, the SMF device transmits an N4 session modification request to the UPF (PSA).

If the SMF device selects a new intermediate UPF for the PDU session or removes the I-UPF, the SMF device provides a data forwarding indication and DL tunnel information from the new intermediate UPF to request the PDU session anchor UPF to modify the N4 session. Send a message.

If a new intermediate UPF is added for the PDU session, the UPF (PSA) begins sending DL data to the new I-UPF as indicated in the DL tunnel information.

If a service request is triggered by the network and the SMF device removes the existing I-UPF but does not replace it with a new I-UPF, the SMF device includes a data forwarding indication for the request. The data forwarding indication indicates to the UPF (PSA) that the second tunnel endpoint needs to be retained for buffered DL data from the existing I-UPF. In this case, the UPF (PSA) starts to buffer DL data that can be received simultaneously from the N6 interface. UPF (PSA) to SMF device: N4 session fix response.

In step 7b, the UPF (PSA) transmits an N4 session modification response message to the SMF device.

When a data forwarding indication is received, the UPF (PSA) becomes an N3 end point and sends CN DL tunnel information for the existing (middle) UPF to the SMF device. The SMF device starts a timer and is used to release resources in the existing intermediate UPF in step 20a.

If the NMF UPF is UPF (PSA) and the SMF device determines that the PDU session is active when it receives the Nsmf_PDUSession_UpdateSMContext request in step 4, the cause is set to indicate "Establishing user plane resources" for the PDU session, then the RAN tunnel information Delete the tunnel information of the AN from the UPF by deleting the N4 session modification procedure.

In step 8a, which is performed conditionally, the SMF device transmits an N4 session modification request (new UPF address, new UPF DL tunnel ID) to an existing UPF (middle).

If a service request is triggered by the network and the SMF device removes the existing (middle) UPF, the SMF device sends an N4 session modification request message to the existing (middle) UPF to provide DL tunnel information for the buffered DL data. do. If the SMF device allocates a new I-UPF, the DL tunnel information is from the new (middle) UPF acting as the N3 end point. If the SMF device does not allocate a new I-UPF, the DL tunnel information is from the new UPF (PSA) acting as the N3 end point. The SMF device starts a timer to monitor the forwarding tunnel.

If the SMF device finds an active PDU session when it receives an Nsmf_PDUSession_UpdateSMContext request in step 4, the cause is set to indicate "Establishing user plane resources" for the PDU session, the RAN to remove the AN's tunnel information from the UPF. Delete the tunnel information and start the N4 session modification procedure.

In step 8b, the existing UPF (middle) sends an N4 session modification response to the SMF device. The existing (intermediate) UPF sends an N4 session modification response message to the SMF device.

In step 9, which is performed conditionally, the existing UPF (middle) forwards the downlink data buffered with the new UPF (middle).

If the I-UPF is changed and a forwarding tunnel is established at the new I-UPF, the existing (middle) UPF forwards the buffered data to the new (middle) UPF acting as the N3 end point.

In step 10, which is performed conditionally, the existing UPF (middle) forwards downlink data buffered with UPF (PSA).

If the existing I-UPF is removed, no new I-UPF is allocated for the PDU session, and a forwarding tunnel is established at the UPF (PSA), the existing (middle) UPF is buffered with UPF (PSA) acting as an N3 end point. Forwarded data.

In step 11 performed conditionally, the SMF device sends an Nsmf_PDUSession_UpdateSMContext response (N2 SM information (PDU session ID, QFI (s), QoS profile (s), CN N3 tunnel information, S-NSSAI), cause) to the AMF device. send.

In the case of the PDU session determined by the SMF device to approve activation of the UP connection in step 5, the SMF device generates only N2 SM information and transmits an Nsmf_PDUSession_UpdateSMContext Response to the AMF device to establish a user plane. The N2 SM information includes information provided by the AMF device to the RAN. If the SMF device determines to perform PSA UPF relocation for the SSC mode 3 PDU session, the SMF device approves UP activation of the PDU session and then triggers the relocation of the SSC mode 3 PDU session anchor.

In the following cases, the SMF device may refuse UP activation of the PDU session by including the cause in the Nsmf_PDUSession_UpdateSMContext Response:

Iii) if the PDU session corresponds to the LADN and the UE is outside the available area of the LADN as described in step 5; Ii) the AMF device notifies the SMF device that the UE is reachable only for regulatory prioritized service and the PDU session to be activated is not for regulatory prioritized service; Or iii) If the SMF device decides to change the PSA UPF for the requested PDU session as described in step 5, after sending an Nsmf_PDUSession_UpdateSMContext Response, the SMF device triggers another procedure to re-establish the PDU session in SSC mode 2.

In step 12, the AMF device sends an N2 request to the (R) AN (N2 SM information received from the SMF device, security context, AMF signaling connection ID, handover restriction list, subscribed UE-AMBR, MM NAS service authorization, recommended List of cells, TAs, NG-RAN node identifiers).

For the UE in the CM-CONNECTED state, if the service request procedure is triggered by the UE, only the N2 SM information received from the SMF device and the MM NAS service grant is included in the N2 request. When the service request procedure is triggered by the network, only N2 SM information received from the SMF device is included in the N2 request.

For a UE in CM-IDLE state, the RAN stores the N3 tunnel ID in the security context, AMF signaling connection ID, QoS information, and UE RAN context for the QoS flow of the activated PDU session.

The MM NAS service grant includes the PDU session state to the AMF device. If activation of the UP of the PDU session is rejected by the SMF device, the MM NAS service grant includes the PDU session ID and the reason that the user plane resource is not activated (eg, LADN is not available). Any local PDU session release during the session request procedure is indicated to the UE via the session state.

When there are a plurality of PDU sessions involving a plurality of SMF devices, the AMF device does not need to wait for a response from all SMF devices in step 3 before sending N2 SM information to the UE. However, the AMF device must wait for all responses from the SMF device before sending the MM NAS service approval message to the UE.

The AMF device includes at least one N2 SM information from the SMF when this step is triggered for PDU session user plane activation. The AMF device may transmit additional N2 SM information from the SMF device in a separate N2 message (eg, N2 tunnel establishment request). Alternatively, when a plurality of SMF devices are involved, the AMF device may send one N2 request message to (R) AN after all Nsmf_PDUSession_UpdateSMContext response service operations from all SMF devices associated with the UE are received. In this case, the N2 Request message includes the N2 SM information received in each of the Nsmf_PDUSession_UpdateSMContext Response and the PDU Session ID so that the AMF device can associate the response with the related SMF device.

If the NG-RAN node provided a list of recommended Cells / TAs / NG-RAN node identifiers during the AN release procedure, the AMF device includes it in the N2 request. The RAN may use this information to allocate the RAN notification area when determining to enable the RRC inactivity state for the UE.

In step 13, the (R) AN may perform the following to the UE: The RAN performs RRC connection reconfiguration with the UE according to QoS information for all QoS flows and data radio bearers of the PDU session for which the UP connection is activated. For a UE in CM-IDLE state, user plane security is established at this stage.

If the N2 request includes an MM NAS service grant message, the RAN forwards the MM NAS service grant to the UE. The UE locally deletes the context of PDU sessions that are not available in 5GC. Receipt of the service grant message does not indicate successful activation of the user plane radio resource.

After the user plane radio resource is established, uplink data from the UE may be forwarded to the RAN. The NG-RAN sends uplink data to the UPF address and tunnel ID provided in step 4.

In step 14, which is performed conditionally, (R) AN sends an N2 request Ack (N2 SM information (AN tunnel information, list of approved QoS flows for PDU session of active UP connection, PDU of activated UP connection) to AMF. List of rejected QoS flows for the session).

The message may include N2 SM information (s), such as AN tunnel information. Tunnel Information. If the AMF device transmits a separate N2 message in step 11, the RAN may respond with N2 SM information in a separate N2 message (eg, an N2 tunnel establishment response).

If the plurality of N2 SM information is included in the N2 request message in step 11, the N2 request Ack includes the plurality of N2 SM information and information for allowing the AMF device to associate a response with the associated SMF device.

In step 15, which is performed conditionally, the AMF device sends an Nsmf_PDUSession_UpdateSMContext request (N2 SM information, RAT type) to the SMF device for each PDU session for the SMF device.

If the AMF device receives the N2 SM information (one or more) in step 14, the AMF device forwards the N2 SM information to the associated SMF device. If the UE time zone has changed compared to the last reported UE time zone, the AMF device includes the UE time zone IE in the message.

In step 16, optionally performed, the SMF device performs the following as the PCF device: If a dynamic PCC is deployed, the SMF device performs a session management policy modification procedure to notify of new location information for the PCF device (if subscribed). You can start PCF devices may provide updated policies.

In step 17a, which is performed conditionally, the SMF device may send an N4 Session Modification Request (a list of AN tunnel information and approved QFI (s)) to the new intermediate UPF device.

If the SMF device selects a new UPF device and acts as an intermediate UPF for the PDU session in step 5, the SMF device starts the N4 session modification procedure for the new I-UPF and provides AN tunnel information. Downlink data from the new I-UPF may be sent to the RAN and the UE.

In step 17b, which is performed conditionally, the UPF device may transmit an N4 session modification response to the SMF device.

In step 18a, which is performed conditionally, the SMF device may transmit an N4 session modification request (AN tunnel information, list of rejected QoS flows) to the UPF (PSA).

If the user plane is set or modified and there is no I-UPF after modification, the SMF device starts the N4 session modification procedure for the UPF (PSA) and provides AN tunnel information. Downlink data from the UPF (PSA) may be forwarded to the RAN and the UE.

For QoS flows in the list of rejected QoS flows, the SMF device instructs the UPF device to remove a rule (eg, packet detection rule, etc.) associated with the QoS flow.

In step 18b, which is performed conditionally, the UPF device may transmit an N4 session modification response to the SMF device. In step 19, which is performed conditionally, the SMF device may transmit an Nsmf_PDUSession_UpdateSMContext Response to the AMF device.

In step 20a, which is performed conditionally, the SMF device may transmit an N4 session modification request to a new UPF (middle) device. When a forwarding tunnel is established with the new I-UPF and the timer SMF set up for the forwarding tunnel expires in step 8a, the SMF device sends an N4 session modification request to a new (middle) UPF device that acts as an N3 end point to release the forwarding tunnel. send.

In step 20b, which is performed conditionally, the new UPF (middle) device may send an N4 session modification response to the SMF device. A new (middle) UPF device acting as an N3 end point may send an N4 session modification response to the SMF device.

In step 21a, which is performed conditionally, the SMF device may transmit an N4 session modification request to UPF (PSA).

If a forwarding tunnel is established at the UPF (PSA) and the timer SMF set up for the forwarding tunnel in step 7a expires, the SMF device sends an N4 session modification request to the UPF (PSA) acting as the N3 end point to release the forwarding tunnel. Can be.

In step 21b, which is performed conditionally, the UPF (PSA) may transmit an N4 session modification response to the SMF device. The UPF (PSA) acting as the N3 end point sends an N4 session modification response to the SMF device.

In step 22a, which is performed conditionally, the SMF device may transmit an N4 session modification request or an N4 session release request to an existing UPF device.

If the SMF device decides to continue using the existing UPF in step 5, the SMF device sends an N4 session modification request providing the AN tunnel information.

If the SMF device selects a new UPF that acts as an intermediate UPF in step 5 and the existing UPF is not a PSA UPF, the SMF device sends an N4 session release request to the existing intermediate UPF after the timer in step 6b expires. Start the release.

In step 22b, the existing UPF device may transmit an N4 session modification response or an N4 session release response to the SMF device.

The existing UPF device may confirm the modification or release of the resource by using an N4 session modification response or an N4 session release response message.

The AMF device calls the Namf_EventExposure_Notify service operation to notify the mobility-related event.

Upon receiving Namf_EventExposure_Notify as an indication that the UE is reachable, if the SMF device has pending DL data, the SMF device calls the Namf_Communication_N1N2MessageTransfer service operation on the AMF device to establish the user plane for the PDU session, otherwise the SMF device In the case of DL data, the DL data notification for the AMF device is transmitted.

According to an embodiment, when a user terminal in an idle state moves to a new registration area, the user terminal may temporarily access the network in order to register in a new network according to the change of the registration area. At this time, the active traffic may not exist. While registering to a new network, the AMF device and the SMF device can manage the location of the user terminal, so that the SMF device can determine the control of the UPF device, such as relocation or I-UPF insertion, removal. Depending on the determination, operations such as I-UPF insertion, removal, and relocation may be performed in the session dormant state. That is, the UPF device is controlled while registering in a new network in session dormancy, so that the possibility of interruption can be reduced when the actual service is provided.

According to another embodiment, when I-UPF control such as I-UPF insertion, removal, and relocation in a session dormant state, control of the UPF device may be performed, but the interface between the base station and the UPF device may not be updated. Therefore, in the session dormant state, the signaling load between the RAN-core networks can be reduced by not updating.

According to another embodiment, the 5G network may perform relocation of a PDU Session Anchor (PSA), which is an UPF device that serves as an anchor gateway of a corresponding PDU session, in order to manage a fixed and flexible data path. . In addition, at least one intermediate UPF insertion may be possible between the base station and the PSA to support a network in which the base station and the PSA are not directly connected.

<Network triggered service request>

12 illustrates a network triggered service request procedure according to an embodiment.

The network triggered service request procedure is to enable user plane connection for the PDU session (s) for the network to communicate signals with the UE (e.g., N1 signaling to the UE, mobile-terminated SMS, mobile terminating user data). Used when you need to. When the network triggered service request procedure is triggered by the SMSF, PCF or UDM, Figure 12 SMF may be replaced by SMSF, PCF or UDM. If the UE is in CM IDLE state or CM-CONNECTED state in 3GPP access, the network starts a network triggered service request procedure. If the UE is in CM-IDLE state and asynchronous type communication is not activated, the network sends a paging request to (R) AN / UE. The paging request triggers a UE triggered service request procedure at the UE. When asynchronous type communication is activated, the network stores the received message and sends a message to the (R) AN and / or the UE when the UE enters the CM-CONNECTED state (i.e. (R) AN and / or UE). And contexts)

When SMF is triggered to send a second Namf_Communication_N1N2MessageTransfer with a higher priority than the first Namf_Communication_N1N2MessageTransfer was sent, SMF sends a new Namf_Communication_N1N2MessageTransfer indicating higher priority to AMF. If the SMF receives additional notification messages from the UPF for PDU sessions with the same or lower priority than the first Namf_Communication_N1N2MessageTransfer was sent, or if the SMF sends a second Namf_Communication_N1N2MessageTransfer indicating higher priority and for the UE. When receiving an additional notification message from the UPF, the SMF does not send a new Namf_Communication_N1N2MessageTransfer.

If the UE is in CM-IDLE state in non-3GPP access and the UE is registered at the same time via 3GPP access and non-3GPP access in PLMN, the network may initiate a network triggered service request procedure via 3GPP access.

If the UE is in CM-IDLE state in 3GPP access and CM-CONNECTED state in non-3GPP access, and the UE is registered at the same time through 3GPP access and non-3GPP access in the same PLMN, the network is connected via non-3GPP access. A network triggered service request procedure for 3GPP access can be initiated.

In a network triggered service request procedure, both the affected SMF and UPF are under the control of the PLMN serving the UE. (For example, for home routed roaming, the SMF and UPF of HPLMN are not involved.)

In step 1, if the UPF receives downlink data for the PDU session, and there is no AN tunnel information stored in the UPF for the PDU session, based on an instruction from the SMF, the UPF buffers the downlink data or Downlink data can be forwarded to SMF.

In step 2a, the UPF may send a data notification to the SMF that includes information for identifying the N4 session ID, DSCP, QFI.

V) On arrival of the first downlink data packet, the UPF sends a data notification to the SMF if the SMF has not previously notified the UPF not to send a data notification to the SMF (skip the next step).

Ii) If the UPF receives downlink data packets for different QoS flows in the same PDU session, the UPF sends another data notification to the SMF.

Iii) If UPF supports the paging policy differentiation feature and is enabled by SMF for N4 sessions, UPF also supports DSCP and DL data packets in TOS (IPv4) / TC (IPv6) values from the IP header of downlink data packets. Information identifying the QFI of the QoS flow for the.

In step 2b, the SMF may send a data communication reply to the UPF.

In step 2c, the UPF may forward the downlink data packet to the SMF. If the paging policy differentiation feature is supported by the SMF, the information identifying the QFI of the QoS flow for the DSCP and DL data packets in the TOS (IPv4) / TC (IPv6) value from the IP header of the received downlink data packet is included. Based on this, the SMF determines the paging policy indication.

In step 3a, which is performed conditionally, the SMF may send Namf_Communication_N1N2MessageTransfer to AMF. At this time, Namf_Communication_N1N2MessageTransfer is SUPI, PDU session ID, N2 SM information (QFI (s), QoS profile (s), CN N3 tunnel information, S-NSSAI, paging policy indication), validity area of N2 information, ARP, paging policy Indication, may include 5QI.

Upon receipt of the data notification, if the SMF determines that the PDU session corresponds to the LADN and that the UE is outside the range of availability of the corresponding LADN based on the UE location change notification from the AMF, the SMF does not trigger the notification to the AMF. Do not. The SMF may notify the UPF that sent the data notification to discard the downlink data for the PDU session and / or not provide any further data notification.

If not, the SMF can decide whether to connect to AMF. The SMF does not connect to the AMF if: i) the SMF has previously received a notification that the UE cannot reach it; Or ii) the UE can only reach regulatory prioritized service and the PDU session is for regulatory prioritized service.

The SMF determines the AMF and calls Namf_Communication_N1N2MessageTransfer on the AMF that contains the PDU session ID received in step 2a.

While waiting for a user plane connection to be activated, if the SMF receives any additional data notifications for the same PDU session, but at a higher priority (i.e., ARP priority level) than the first data notification for the PDU session, Calls a new Namf_Communication_N1N2MessageTransfer indicating the PDU session ID for the higher priority ARP and AMF.

If SMF receives a message from a new AMF other than calling Namf_Communication_N1N2MessageTransfer while SMF waits for the user plane to become active, SMF calls Namf_Communication_N1N2MessageTransfer back to the new AMF.

When supporting paging policy differentiation, the SMF instructs Namf_Communication_N1N2MessageTransfer to trigger a paging policy indication or data notification message related to the 5QI associated with QFI in step 2a or the packet received in step 2c, ARP, UPF or downlink data received in step 2c. ,

In step 3b, which is carried out conditionally, AMF can react with SMF.

If the UE is in CM-IDLE state in AMF and AMF is able to page the UE, AMF immediately sends a Namf_Communication_N1N2MessageTransfer response to the SMF for the reason that the N2 SM information is "attempting to reach the UE" indicating the SMF. If it is possible to reach and the SMF can be requested to provide the N2 SM information again, then the UE, provided in step 3a, can be ignored by the AMF.

If the UE is in the CM-CONNECTED state in the AMF, the AMF immediately sends a Namf_Communication_N1N2MessageTransfer response to the SMF, causing the "N1 / N2 transmission succeeded".

If the UE is in CM-IDLE state and the AMF determines that the UE cannot reach paging, then the AMF indicates that the UE cannot reach the one of the SMF or other network functions that the AMF received the request message in step 3a. May send a Namf_Communication_N1N2MessageTransfer response to the AMF or perform an asynchronous type communication and store the UE context based on the received message. When asynchronous type communication is called, when the UE enters the CM-CONNECTED state, the AMF starts communicating with the UE and (R) AN.

If the AMF determines that the UE cannot reach the SMF (for example, a UE or UE in MICO mode is registered only for non-3GPP access and its status is CM-IDLE), the AMF may reject the request from the SMF. have. If the SMF does not subscribe to the UE reachability event, the AMF may include an indication in the reject message that the SMF does not need to send a DL data notification to the AMF. The AMF stores an indication that the SMF has been notified that the UE cannot reach it.

If the AMF detects that the UE is in a disallowed zone unless the UE is not in MICO mode and the request from the SMF is for a regulatory prioritized service, then the AMF rejects the request from the SMF and the UE only for the regulatory prioritized service. Notify the SMF that is reachable. The AMF stores an indication that the SMF has been notified that the UE can only reach for regulatory priority services.

If a registration procedure with an AMF change is in progress when an existing AMF receives Namf_Communication_N1N2MessageTransfer, the existing AMF may reject the request with an indication that Namf_Communication_N1N2MessageTransfer has been temporarily rejected.

Upon receiving a Namf_Communication_N1N2MessageTransfer response with an indication that the request has been temporarily rejected, the SMF starts a locally configured guard timer and waits for any messages from the new AMF. Upon receiving the message from the AMF, the SMF calls Namf_Communication_N1N2MessageTransfer (including data notification) back to the AMF that received the message. Otherwise, the SMF performs step 3c when the guard timer expires. If the SMF determines that control plane buffering is to be applied, the SMF requests the UPF to begin downlink data PDU forwarding to the SMF.

In step 3c, which is performed conditionally, the SMF may respond to the UPF.

The SMF may notify the UPF about user plane setup failures.

If the SMF receives an indication from the AMF that the UE can only reach or cannot reach the UE for regulatory prioritized services, the SMF can do one of the following depending on network policy:

Iii) The SMF may instruct the UPF to stop sending data notification. Ii) the SMF may instruct the UPF to stop buffering the DL data and discard the buffered data; Iii) The SMF may instruct the UPF to stop transmitting the data notification, stop buffering the DL data, and discard the buffered data. Iii) or refrain from sending additional Namf_Communication_N1N2MessageTransfer messages for DL data to AMF while the UE is unreachable.

Based on the operator policy, the SMF may apply a suspension of the charging procedure.

If the SMF receives an indication from the AMF that the Namf_Communication_N1N2MessageTransfer message requested from the SMF is temporarily rejected, the SMF may instruct the UPF to apply temporary buffering based on network policy.

In step 4a performed conditionally, if the UE is in CM-CONNECTED state in 3GPP access and the PDU session ID received from the SMF in step 3a is related to 3GPP access, steps 12 to 22 of the UE triggered service request procedure May be performed to activate the user plane connection (ie, radio resource and N3 tunnel establishment) for the PDU session without sending a paging message to the (R) AN node and UE. In step 12 of the UE triggered service request procedure, the AMF does not send a NAS service grant message to the UE. The rest of the procedure can be omitted.

In step 4b, which is performed conditionally, the UE is in CM-IDLE state in 3GPP access, the PDU session ID received from SMF in step 3a is associated with 3GPP access and the UE is in CM-CONNECTED state for non-3GPP access. If based on a local policy that the AMF decides to notify the UE via 3GPP access, then the AMF may send a paging message to the RAN node (s) via the 3GPP access.

If the UE is simultaneously registered via 3GPP and non-3GPP access in the same PLMN, the UE is in CM-IDLE state in both 3GPP access and non-3GPP access, and in step 3a the PDU session ID is associated with the non-3GPP access The AMF may send the paging message to the RAN node (s) via 3GPP access.

The UE is in RM-REGISTERED state and CM-IDLE and reachable, and AMF sends paging message (NAS ID for registration, registration area list, paging DRX length, paging priority indication, access related to PDU session) Transmitting to the (R) AN node (s) belonging to the registration area (s), and the RAN node then pages the UE including access associated with the PDU session in the paging message received from the AMF.

When supporting paging policy differentiation, a paging strategy can be configured in AMF for other combinations of DNNs, paging policy indications, ARP, and 5QI.

In the RRC inactive state, the paging strategy may be configured at (R) AN for other combinations of paging policy indication, ARP and 5QI.

Paging priority indications can only be included if:

I) If the AMF receives a Namf_Communication_N1N2MessageTransfer message with an ARP value associated with the priority service (eg MPS, MCS), it is configured by the operator. Ii) One paging priority level may be used for multiple ARP values. Mapping ARP values to paging priority levels (or level (s)) is configured in accordance with AMF and RAN operator policies.

(R) AN may prioritize paging of UEs according to paging priority indication.

While waiting for a UE response to a paging request message sent without a paging priority indication, when AMF receives a Namf_Communication_N1N2MessageTransfer message indicating an ARP value associated with a priority service (e.g. MPS, MCS) as configured by the operator, The AMF may send another paging message with a suitable paging priority.

Paging strategies can include:

Iii) paging retransmission scheme (eg, frequency or time interval at which paging is repeated); Ii) determining whether to send the paging message to the (R) AN nodes during certain AMF high load conditions; Iii) Whether to apply sub-area based paging (e.g., last known cell-ID or retransmission from first page of TA and all registered TAs).

AMF and (R) AN may support additional paging optimization to reduce the signaling load and network resources used to successfully page a UE by one or several of the following means:

Iii) by the AMF implementing specific paging strategies (eg, an N2 paging message is sent to the (R) AN nodes that last served the UE); Ii) Consider the RAN node provided by the (R) AN when the AMF transitions to the CM-IDLE state and information about the recommended cell. The AMF determines (R) AN nodes to be paged in consideration of (R) AN nodes related to some of the information, and provides each (R) AN node with information about a recommended cell in an N2 paging message. Iii) (R) AN considers paging attempt count information provided by AMF during paging.

If UE radio capability for paging information is available in the AMF, the AMF adds UE radio capability for paging information in the N2 paging message to the (R) AN node.

If information about the recommended cell and (R) AN node for paging is available in AMF, AMF considers the information to determine the (R) AN node for paging, and AMF uses the information in the recommended cell. (R) may transparently convey to the AN node.

The AMF may include paging attempt count information in the N2 paging message (s). Paging attempt count information may be the same for all (R) AN nodes selected by AMF for paging.

In step 4c, which is performed conditionally, the UE simultaneously registers via 3GPP and non-3GPP access in the same PLMN, the UE is in CM-CONNECTED state in 3GPP access and in step 3a the PDU session ID is associated with the non-3GPP access. If so, the AMF sends a NAS notification message containing the PDU session ID to the UE via 3GPP access and sets a notification timer. Step 5 may be omitted.

If the UE registers simultaneously via 3GPP and non-3GPP access on the same PLMN, and the UE is in CM-CONNECTED state for non-3GPP access and CM-IDLE for 3GPP access, in step 3a the PDU session ID is 3GPP Based on the local policy associated with the access and determining to notify the UE via a non-3GPP access, send a NAS notification message to the UE via the non-3GPP access and set a notification timer.

In step 5 performed conditionally, the AMF may send Namf_EventExposure_Notify to the SMF.

AMF can use a timer to oversee the paging procedure. If the AMF does not receive a response to the paging request message from the UE, the AMF may apply additional paging according to any applicable paging strategy described in step 4b.

If the UE is unreachable, the AMF may notify the SMF unless the AMF is aware of an ongoing MM procedure that prevents the AMF from responding. That is, the AMF receives an N14 context request message indicating that the UE performs a registration procedure with another AMF.

If the UE receives a notification that it cannot reach, the SMF may inform the UPF.

In step 6, if the UE is in the CM-IDLE state in the 3GPP access, upon receiving the paging request for the PDU session associated with the 3GPP access, the UE initiates the UE triggered service request procedure. In step 4 of the UE triggered service request procedure, the AMF calls the Nsmf_PDUSession_UpdateSMContext request to the SMF (s) associated with the PDU session identified in the MM NAS service request message, except for the PDU session ID included in Namf_Communication_N1N2MessageTransfer in step 3a.

If the UE is in CM-IDLE state in both non-3GPP and 3GPP accesses, upon receiving a paging request for the PDU session related to the non-3GPP access, the UE will list the allowed PDU sessions that can be reactivated via 3GPP access. The UE-triggered service request procedure may be initiated. If the AMF receives a service request message from the UE via non-3GPP access (eg because the UE is successfully connected to the non-3GPP access), the AMF stops the paging procedure and processes the received service request procedure. If AMF receives the service request message and the list of allowed PDU sessions provided by the UE does not include a PDU session with which the UE is paged, then AMF did not approve the reactivation of the PDU session by calling the Namf_EventExposure_Notify service. Notify the SMF.

If the UE is in CM-IDLE state on non-3GPP access and CM-CONNECTED state on 3GPP access, when a NAS notification message is received via 3GPP access involving a PDU session associated with the non-3GPP access, it is determined by the UE policy. If allowed, the UE may initiate a UE triggered service request procedure with a list of allowed PDU sessions that can be reactivated via 3GPP access.

If the AMF does not receive a NAS service request message before the notification timer expires, the AMF notifies the SMF that the UE is reachable but does not approve to reactivate the PDU session by calling the Namf_EventExposure_Notify service. When the AMF receives a service request message from the UE via non-3GPP access (eg, because the UE successfully connects to a non-3GPP access), the AMF stops the notification timer and processes the received service request procedure.

If the UE is in CM-IDLE state in 3GPP access and CM-CONNECTED state in non-3GPP access, when a NAS notification message is received through non-3GPP access identifying a PDU session associated with 3GPP access, 3GPP access will be available. When via 3GPP access the UE initiates a UE triggered service request procedure. If the AMF does not receive the NAS service request message before the notification timer expires, the AMF can either page the UE via 3GPP access or notify the SMF that the UE could not reactivate the PDU session.

In step 7, the UPF transmits the buffered downlink data to the UE through the (R) AN node that has performed the service request procedure.

If the procedure is triggered by a request from another network entity described in step 3a, the network sends a downlink signal.

<Change of SSC Mode 2 PDU Session Anchor with Different PDU Sessions>

FIG. 13 is a diagram illustrating a change procedure of an SSC mode 2 PSA for a PDU session according to an embodiment. FIG.

FIG. 13 is a procedure illustrating that the SMF device is triggered to change a PDU session anchor serving a PDU session of SSC mode 2 for a UE when multi home or UL CL is not applied to a PDU session. This procedure releases an existing PDU session associated with an existing PDU session anchor (UPF1 in FIG. 13) and establishes a new PDU session anchor (UPF2 in FIG. 13) and a new PDU session in the same data network. Establish immediately.

The SMF device determines that the serving UPF device needs to be changed because of an event that would benefit from the change.

The PDU session release procedure with the existing PDU session anchor begins. The SMF device calls Namf_Communication_N1N2MessageTransfer to transmit N1 SM information to the UE through the AMF device. The PDU session release command message in the N1 SM information includes the PDU session ID and the cause indicating that a PDU session reestablishment for the same data network is needed.

Upon receipt of a PDU Session Release command with a cause indicating that a PDU session re-establishment for the same data network as sent above is received, the UE generates a new PDU session ID and starts the PDU session establishment procedure. The AMF device selects the SMF device and the SMF device can select a new UPF (ie UPF2) for the reestablished PDU session in SSC mode 2.

<Change of SSC Mode 3 PDU Session Anchor with Multiple PDU Sessions>

14 is a diagram illustrating a procedure of changing an SSC mode 3 PDU session anchor having a plurality of PDU sessions according to an embodiment.

14 illustrates a procedure triggered by an SMF device to change a PDU session anchor serving a PDU session in SSC mode 3 for a UE. This procedure is controlled by the same SMF device to establish a new PDU session with the same DN using a new PDU session anchor (UPF2 in FIG. 14) and then to an existing PDU associated with an existing PDU session anchor (UPF1 in FIG. 14). Release the session. The SMF device may determine that it needs to reallocate a new SMF device.

In step 1, the SMF device may determine that the serving UPF device or SMF device needs to be changed.

In step 2, the SMF device calls Namf_Communication_N1N2MessageTransfer (PDU session ID, SMF reassignment requested indication, N1 SM container (PDU session modify command (cause, PDU session release timer))). Here, the PDU session ID indicates an existing PDU session to be relocated, and the cause indicates a PDU session reestablishment for the same PDU data network.

The requested SMF reassignment request indication indicates whether the SMF device is requested to be reassigned. The release timer value indicates how long the network can hold a PDU session.

In step 3, the AMF device forwards the NAS message to the UE.

In step 4, when the UE receives a PDU session modification command, the UE may decide to initiate the PDU session establishment procedure:

According to the SSC mode, the UE generates a new PDU session ID and starts a PDU session establishment request using the new PDU session ID. The new PDU session ID is included as a PDU session ID in the NAS request message, and an existing PDU session ID indicating an existing PDU session to be released is also provided to the AMF device in the NAS request message.

If SMF reallocation is requested in step 2, the AMF device selects another SMF device. Otherwise, the AMF device sends an N11 message to the same SMF device serving the existing PDU session ID.

The AMF device includes both the PDU Session ID and the existing PDU Session ID in the Nsmf_PDUSession_CreateSMContext Request. The SMF device detects that the PDU session establishment request is associated with the trigger in step 2 based on the existence of the existing PDU Session ID in the Nsmf_PDUSession_CreateSMContext Request. The SMF device stores the new PDU session ID and selects a new PDU session anchor (ie UPF2) for the new PDU session.

Existing PDU sessions can be sent to the SMF device before the timer provided in step 1 expires (for example, when the UE consolidates all traffic in PDU # 2 or when the session is no longer needed) or when the timer expires. Is released at the UE.

<Other embodiment: network triggered service request procedure>

15 illustrates a network triggered service request procedure according to another embodiment.

The network triggered service request procedure is to enable user plane connection for the PDU session (s) for the network to communicate signals with the UE (e.g., N1 signaling to the UE, mobile-terminated SMS, mobile terminating user data). Used when you need to. When the network triggered service request procedure is triggered by the SMSF, PCF or UDM, Figure 12 SMF may be replaced by SMSF, PCF or UDM. If the UE is in CM IDLE state or CM-CONNECTED state in 3GPP access, the network starts a network triggered service request procedure. If the UE is in CM-IDLE state and asynchronous type communication is not activated, the network sends a paging request to (R) AN / UE. The paging request triggers a UE triggered service request procedure at the UE. When asynchronous type communication is activated, the network stores the received message and sends a message to the (R) AN and / or the UE when the UE enters the CM-CONNECTED state (i.e. (R) AN and / or UE). And contexts)

If the UE is in CM-IDLE state in a non-3GPP access and the UE is registered with the PLMN simultaneously via 3GPP and non-3GPP, the network initiates the network triggered service request procedure of FIG. 15 via 3GPP access.

In a network triggered service request procedure, both the affected SMF and UPF are under the control of the PLMN serving the UE. (For example, for home routed roaming, the SMF and UPF of HPLMN are not involved.)

In step 1, if the UPF receives downlink data for the PDU session and there is no (R) AN tunnel information stored in the UPF for the PDU session, the UPF is not previously notified by the SMF so that the UPF does not buffer the downlink. If not, buffer the downlink data.

In step 2a, the UPF may send a data notification including the PDU session ID and priority to the SMF.

V) On arrival of the first downlink data packet, the UPF sends a data notification to the SMF if the SMF has not previously notified the UPF not to send a data notification to the SMF (skip the next step).

Ii) If the UPF receives an additional downlink data packet for a QoS flow in the same PDU session that has a lower or equal priority than that used in any previous data notification sent for the PDU session, the UPF receives a new packet. Buffer downlink data packets without sending data notifications.

Iii) If the UPF receives an additional downlink data packet for a QoS flow in the same PDU session that has a higher priority than that used in the previous data notification for the PDU session, the UPF receives a data notification message indicating a higher priority. Send to SMF.

Iii) If UPF supports paging policy differentiation and is enabled by SMF for N4 sessions, UPF also supports DSCP and DL data packets in TOS (IPv4) / TC (IPv6) values from IP headers of downlink data packets. Information identifying the QFI of the QoS flow for the.

Iii) While the SMF waits for the user plane to be established in the UPF, if the SMF receives an N11 message from the new AMF indicating that the new AMF is currently serving the UE, the SMF retransmits the data notification message to the new AMF.

In step 2b, the SMF sends a data notification reply to the UPF.

In step 3a, which is performed conditionally, the SMF may send an N11 message (including SUPI, PDU session ID, N2 SM information (QoS profile, CN N3 tunnel information, S-NSSAI), priority) to the AMF.

Upon receiving the data notification message, if the PMF session corresponds to the LADN and the SMF determines that the UE is outside the area of availability of the corresponding LADN based on UE location reporting from the AMF, then the SMF determines that the AMF Does not trigger a notification. The SMF may notify the UPF that sent the data notification to discard the downlink data for the PDU session and / or not provide any further data notification.

If not, the SMF can decide whether to connect to AMF. The SMF does not connect to the AMF if: i) the SMF has previously received a notification that the UE cannot reach it; Or ii) the UE can only reach regulatory prioritized service and the PDU session is for regulatory prioritized service.

The SMF determines the AMF and sends the N11 message (SUPI, PDU session ID, N2SM information (PDU session ID, QoS profile, CN N3 tunnel) to AMF, including priority and PDU session ID received in the data notification message as part of step 2a. Information, S-NSSAI), priority, paging policy indication).

If SMF receives additional data notification messages for the same PDU session while waiting for the user plane connection to be activated, but has a higher priority than indicated in the previous data notification for the PDU session, the SMF is assigned a higher priority and PDU session ID. Sends a new N11 message indicating to AMF.

If the SMF receives an N11 message response from an AMF other than the AMF that sent the N11 message while the SMF is waiting for the user plane to be activated, the SMF sends the N11 message to the AMF.

When supporting paging policy differentiation, the SMF displays a paging policy indication in the N11 message related to the downlink data that triggered the data notification message.

In step 3b, which is performed conditionally, the AMF may respond to the SMF.

If the UE is in CM-IDLE state and AMF determines that the UE cannot reach paging, AMF sends N11 message to SMF or N11 message to other network function where AMF received request message in step 3a. Or AMF performs asynchronous type communication and stores the UE context based on the received message. When asynchronous type communication is invoked, the AMF starts communicating with the UE and (R) AN when the UE is reachable, such as when the UE enters the CM-CONNECTED state.

If the AMF determines that the UE cannot reach the SMF (for example, a UE or UE in MICO mode is registered only for non-3GPP access and its status is CM-IDLE), the AMF may reject the request from the SMF. have. If the SMF does not subscribe to the UE reachability event, the AMF may include an indication in the reject message that the SMF does not need to send a DL data notification to the AMF. The AMF stores an indication that the SMF has been notified that the UE cannot reach it.

If the AMF detects that the UE is in a disallowed zone unless the UE is not in MICO mode and the request from the SMF is for a regulatory prioritized service, then the AMF rejects the request from the SMF and the UE only for the regulatory prioritized service. Notify the SMF that is reachable. The AMF stores an indication that the SMF has been notified that the UE can only reach for regulatory priority services.

If a registration procedure with an AMF change is in progress when an existing AMF receives an N11 message, the existing AMF may reject the N11 message with an indication that the N11 message has been temporarily rejected.

Upon receiving an N11 message reply with an indication that the request has been temporarily rejected, the SMF starts a locally configured guard timer and waits for any N11 message from the new AMF. Upon receiving the N11 message from the AMF, the SMF sends an N11 message (including data notification) to the AMF that received the N11 message. Otherwise, the SMF performs step 3c when the guard timer expires. If the SMF determines that control plane buffering is to be applied, the SMF requests the UPF to begin downlink data PDU forwarding to the SMF.

In step 3c, which is performed conditionally, the SMF may respond to the UPF.

The SMF may notify the UPF about user plane setup failures.

If the SMF receives an indication from the AMF that the UE can only reach or cannot reach the UE for regulatory prioritized services, the SMF can do one of the following depending on network policy:

Iii) instruct the UPF to stop sending data notifications and / or stop DL data buffering or apply extended buffering, or ii) refrain from sending additional N11 messages for DL data to the AMF while the UE is unreachable. do.

Upon receiving information that the N11 message requested from the SMF has been temporarily rejected and receiving a downlink data notification from the UPF, the SMF may request the UPF to apply extended buffering.

In step 4a performed conditionally, if the UE is in CM-CONNECTED state in 3GPP access and the PDU session ID received from the SMF in step 3a is related to 3GPP access, steps 12 to 22 of the UE triggered service request procedure May be performed to activate the user plane connection (ie, radio resource and N3 tunnel establishment) for the PDU session without sending a paging message to the (R) AN node and UE. In step 12 of the UE triggered service request procedure, the AMF does not send a NAS service grant message to the UE. The rest of the procedure can be omitted.

In step 4b, conditionally performed, if the UE is in CM-IDLE state in 3GPP access, the AMF may send a paging message to the RAN node (s).

If the UE is in RM-REGISTERED state and CM-IDLE and reachable, then AMF sends a paging message (NAS ID for paging, registration area list, paging DRX length, paging priority indication, access related to PDU session). Transmits to the (R) AN node (s) belonging to the registered registration area (s), and the RAN node may then page the UE, including access associated with the PDU session in the paging message when received from the AMF.

When supporting paging policy differentiation, AMF may include paging policy indications in paging request messages.

The paging strategy can be configured in the AMF for various combinations of PNN session context information identified by the DNN, paging policy indication, PDU session IDs in the SMF, and PDU session ID received in the N11 message.

Paging strategies can include:

Iii) paging retransmission scheme (eg, frequency or time interval at which paging is repeated); Ii) determining whether to send a paging message to (R) AN nodes during certain AMF high load conditions; Iii) Whether to apply sub-area based paging (e.g., last known cell-ID or retransmission from first page of TA and all registered TAs).

AMF and (R) AN may support additional paging optimization to reduce the signaling load and network resources used to successfully page a UE by one or several of the following means:

Iii) by the AMF implementing a particular paging strategy (eg, an N2 paging message is sent to the (R) AN node that last served the UE); Ii) The AMF considers the RAN node provided by the (R) AN in the information about the recommended cell and the transition to the CM-IDLE state. The AMF determines the (R) AN node to be paged by considering the part related to the (R) AN node as part of the information, and provides information on the recommended cell in the N2 paging message to each of the (R) AN nodes. Iii) (R) AN considers paging attempt counting information provided by AMF during paging.

If UE radio capability for paging information is available in the AMF, the AMF adds the UE radio capability for paging information in the N2 paging message to the (R) AN node.

If information about recommended cells and (R) AN nodes for paging is available in AMF, AMF considers the information to determine the (R) AN nodes for paging, and AMF uses the information in the recommended cells. (R) Can be transparently delivered to the AN node.

The AMF may include paging attempt count information in the N2 paging message (s). Paging attempt count information may be the same for all (R) AN nodes selected by AMF for paging.

In step 5, which is performed conditionally, if the UE is CM-CONNECTED in 3GPP access and the PDU session ID is associated with a non-3GPP access, AMF sends a NAS user plane reactivation request message containing the PDU session ID to the UE. And user plane reactivation timer. In this case, step 6 may be omitted.

In step 6 performed conditionally, the AMF may send an N11 message reply to the SMF.

AMF uses a timer to oversee the paging procedure. If the AMF does not receive a response to the paging request message from the UE, the AMF may apply additional paging according to any applicable paging strategy described in step 4b.

If the AMF receives no response from the UE, the AMF considers the UE unreachable and the SM N2 message cannot be routed to the (R) AN, so the AMF is a proper "cause of failure" (eg, UE unreachable). "N11 message rejection" may be returned to the SMF or other network function to indicate a "message routing service" failure, unless the AMF is aware of an ongoing MM procedure that prevents the UE from responding, i.e. Receives an N14 context request message indicating that the AMF is performing a registration procedure with another AMF.

Upon receiving the "N11 message rejection", the SMF may inform the UPF.

In step 7, when the UE is in the CM-IDLE state in the 3GPP access, upon receiving the paging request for the PDU session associated with the 3GPP access, the UE starts the UE triggered service request procedure. In step 4 of the UE triggered service request procedure, the AMF sends an N11 message to the SMF (s) associated with the PDU session identified in the MM NAS Service Request message if no SMF (s) receiving the N11 message exist in step 3a. do.

If the UE is in CM-IDLE state in both non-3GPP access and 3GPP access, upon receipt of a paging request for a PDU session associated with the non-3GPP access, the UE will be connected to the non-3GPP allowed by the UE policy for 3GPP access. Initiate a UE triggered service request procedure indicating a list of related PDU sessions. In this case, when the AMF receives the service request message and the triggered PDU session ID, the AMF informs the SMF if the procedure is not included in the list of PDU sessions associated with non-3GPP allowed by UE policy via 3GPP access. Notifies that it is reachable but did not approve to reactivate the PDU session and that the service request procedure has been suspended.

If the UE is in CM-IDLE state on non-3GPP access and CM-CONNECTED state on 3GPP access, if a NAS user plane reactivation request message is received for a PDU session related to non-3GPP access, If allowed, the UE may initiate the UE triggered service request procedure for PDU session reactivation via 3GPP access. If AMF does not receive a service request message before the user plane reactivation timer expires, AMF acknowledges to reactivate the PDU session by sending an Nsmf_PDUSession_UpdateSMContext request to the SMF that reaches the UE but invokes the procedure to stop the service request procedure. Notify SMF not to.

In step 8, the UPF transmits the buffered downlink data to the UE through the (R) AN node that has performed the service request procedure. If the procedure is triggered by a request from another network entity described in step 3a, the network transmits a downlink signal.

<Embodiment: UE-triggered Service Request in CM-IDLE State>

16 is a diagram illustrating a user terminal triggered service request procedure in a CM-IDLE state according to an embodiment.

The service request procedure is used by the UE in the CM_IDLE state to request the establishment of a secure connection to the AMF. The UE in CM IDLE state initiates a service request procedure to transmit in response to an uplink signaling message, user data or network paging request. AMF can perform authentication after receiving the service request message, and AMF can perform security procedures. After establishing a secure signaling connection to the AMF, the UE or network establishes a signaling message (e.g. establishing a PDU session from the UE to the network or SMF via the AMF initiates user plane connection activation for the PDU session requested by the network, or And / or indicated in the service request message).

For any service request, the AMF device responds with a service grant message if necessary to synchronize the PDU session state between the UE and the network. If the service request cannot be accepted by the network, the AMF device responds with a denial of service message to the UE.

For service requests due to user data, additional actions may be taken on the network if the user plane connection activation is not successful. The UE-triggered service request procedure in the CM-IDLE state can be applied to scenarios with or without intermediate UPF and with or without intermediate UPF reselection.

In step 1, the UE may send an AN message (including AN parameters, MM NAS service request (PDU session (s) to be activated, security parameter, PDU session status)) to (R) AN.

For NG-RAN: i) AN parameter contains the cause of establishment. The cause of establishment provides a reason for requesting establishment of an RRC connection. Ii) UE sends NAS service request message to AMF encapsulated in RRC message to RAN. 5G-GUTI and RRC messages that can be used to carry this NAS message are described in the RAN specification.

If a service request is triggered for user data, the UE identifies the PDU session in which the UP connection will be activated in the NAS service request message. If a service request is triggered for signaling only, the UE does not identify any PDU session. When the procedure is triggered for a paging response, if the UE needs to use some PDU session (s), the UE identifies the PDU session in which the UP connection will be activated in the MM NAS service request message. Otherwise, the UE does not identify any PDU session in the service request message.

When a service request via 3GPP is triggered in response to paging indicating noo-3GPP access, the NAS service request message includes a list of PDU sessions associated with non-3GPP access that may be reactivated via 3GPP. PDU session state indicates a PDU session available at the UE. The UE shall not trigger the service request procedure for the PDU session corresponding to the LADN when it is outside the available area of the LADN.

In step 2, (R) AN may send an N2 message (N2 parameters, MM NAS service request) to AMF. If AMF cannot handle the service request, it rejects the request.

When NG-RAN is used, the N2 parameters include 5G-GUTI, location information, RAT type and setting cause. 5G-GUTI is obtained in the RRC procedure. The RAN selects AMF according to 5G-GUTI. The location information and the RAT type are related to the cell where the UE is camping.

Based on the PDU session state, the AMF may initiate a PDU session release procedure for the PDU session indicated by the UE that the PDU session ID is unavailable.

If the service request indicates Integrity Protection or Integrity Protection as Failed, then AMF can initiate the NAS authentication / security process. If the UE triggers the service request to establish only the signaling connection, after the secure exchange, the UE and the network can send signaling and the steps 4 to 8 and 11 to 17 below can be skipped.

In step 4 performed conditionally, the AMF may send an Nsmf_PDUSession_UpdateSMContext Request (PDU session ID (s), cause (s), UE location information access type) to the SMF.

The Nsmf_PDUSession_UpdateSMContext request is invoked when the UE identifies the PDU session to be activated in the MM NAS Service Request message or when the procedure is triggered by the SMF, but the PDU session identified by the UE correlates with the SMF and other SMFs that trigger the procedure. Sends an Nsmf_PDUSession_UpdateSMContext request to the SMF (s) associated with the PDU session whose cause is set to indicate "establishment of user plane resources" for the PDU session.

If the received service request is sent by the UE as a response to paging indicating non-3GPP access, and the triggered PDU session ID is not included in the list of PDU sessions associated with the non-3GPP allowed by the UE, then use the policy. The AMF sends an Nsmf_PDUSession_UpdateSMContext request to the SMF that triggered the procedure whose cause was set to indicate "UE reachable but not accepting to reactivate the PDU session." In this case, the service request procedure is stopped and the AMF does not transmit the N2 SM information for the PDU session to the (R) AN in step 11.

If the UE is in MICO mode and the AMF notifies the SMF that it cannot reach the UE, and the SMF does not need to send DL data notifications to the AMF, the AMF uses the Namf_EventExposure_Notify service action to inform the SMF that the UE is reachable. Notify.

In step 5, if the SMF determines that the PDU session ID corresponds to the LADN, and based on UE location reporting from the AMF, the UE is outside the availability area of the LADN, then the SMF determines one of the following (based on the local policy): do:

Iii) Maintain the PDU session but refuse to activate the user plane connection to the PDU session. If the procedure was triggered by a network triggered service request, the SMF may inform the UPF that sent the data notification to discard the downlink data for the PDU session and not provide an additional data notification message. Ii) or PDU session release. In both cases, the SMF responds to the AMF (step 10) with the appropriate cause of rejection and stops the service request procedure.

If not (ie, the service request procedure does not stop), based on the location information received from AMF, the SMF determines the UPF selection criteria and decides to do one of the following:

Iii) continue using the current UPF (s); Ii) selecting a new intermediate UPF (or adding / removing intermediate UPFs) if the UE moves out of the service area of the UPF that was previously connecting to the AN while maintaining the UPF acting as a PDU session anchor; Or iii) resetting the trigger of the PDU session to perform relocation of the UPF acting as a PDU session anchor. (For example, the UE is outside the service area of the anchor UPF connecting to the RAN.)

In step 6a, which is performed conditionally, the SMF sends an N4 session establishment request to a new UPF (middle).

When the SMF selects a new UPF and acts as an intermediate UPF for the PDU session, an N4 session establishment request message is sent to the new UPF, providing packet detection, data delivery, application, and reporting rules to be installed in the intermediate UPF. PDU session anchor addressing information (at N9) for a PDU session is provided in the intermediate UPF.

If a service request is triggered by the network and a new UPF is selected by the SMF to replace the existing (middle) UPF, the SMF includes a data delivery indication.

In step 6b, which is performed conditionally, the new UPF (middle) sends an N4 session establishment response to the SMF.

The new intermediate UPF sends an N4 Session Establishment Response message to the SMF. When the UPF allocates CN tunnel information, the UPF provides the SMF with CN DL tunnel information for the UPF that acts as a PDU session anchor and UL tunnel information (ie, CN N3 tunnel information). When a data forwarding indication is received, the new (middle) UPF acting as the N3 end point also sends CN DL tunnel information for the existing (middle) UPF to the SMF. The SMF is used to start a timer and release any resources in the existing intermediate UPF in step 20a.

In step 7a, which is performed conditionally, the SMF sends an N4 session modification request to UPF (PSA).

If the SMF chooses to operate the new UPF as an intermediate UPF for the PDU session, the SMF provides DL tunnel information from the new intermediate UPF and sends an N4 session modification request message to the PDU session anchor UPF.

In step 7b, the UPF (PSA) sends an N4 session modification response to the SMF. The UPF (PSA) sends an N4 Session Modification Response message to the SMF.

In step 8a, which is performed conditionally, the SMF may send an N4 session modification request (including a new UPF address and a new UPF DL tunnel ID) to an existing UPF (middle).

If a service request is triggered by the network and a new UPF is selected by the SMF to replace the existing (middle) UPF, the SMF sends an N4 session modification request message to the existing (middle) UPF so that the new (middle) UPF Serves as the N3 endpoint. The SMF starts a timer to monitor the forwarding tunnel.

In step 8b, the existing UPF (middle) may send an N4 session modification response to the SMF. Existing (intermediate) UPFs can send N4 session modification response messages to the SMF.

In step 9 performed conditionally, the existing UPF (middle) may forward the downlink data buffered with the new UPF (middle). Existing (middle) UPFs can forward the buffered data to a new (middle) UPF acting as an N3 endpoint.

In step 10, which is performed conditionally, SMF sends Nsmf_PDUSession_UpdateSMContext Response (N1 SM information (PDU session ID, indication of PDU session reestablishment)), N2 SM information (PDU session ID, QoS profile, CN N3 tunnel information, S-NSSAI) to AMF. ), Including the cause).

If in step 4, an Nsmf_PDUSession_UpdateSMContext Request is received with a cause including "Establishment of User Plane Resource", the SMF determines whether UPF reallocation is performed based on UE location information, UPF service area and operator policy: i) step In case of the PDU session in which the SMF decides to still be serviced by the current UPF, that is, the PDU session anchor or the intermediate UPF at 5, the SMF generates only N2 SM information and sends an Nsmf_PDUSession_UpdateSMContext Response to the AMF to set the user plane. N2 SM information includes information provided by the AMF to the RAN. Ii) In the case of the PDU session determined that the SMF needs a UPF relocation for the PDU session anchor UPF in step 5, the SMF sends an Nsmf_PDUSession_UpdateSMContext Response including only N1 SM information to the UE through the AMF. The N1 SM information includes the corresponding PDU session ID and PDU session reconfiguration indication.

Upon receiving Namf_EventExposure_Notify in step 4 as an indication that the UE is reachable, if the SMF has pending DL data, the SMF sends an N11 message to the AMF to establish a user plane for the PDU session, otherwise the SMF sends the DL. In case of data, the DL data notification transmission is resumed to the AMF.

In step 11, the AMF makes an N2 request to the (R) AN (N2 SM information received from the SMF, security context, AMF signaling connection ID, handover proposal list, MM NAS service authorization, recommended cell / TAs / NG-RAN node identifier). (Including a list of) can be sent.

The RAN stores the security context for the QoS flow of the activated PDU session, the AMF signaling connection ID, the QoS information and the N3 tunnel ID of the UE RAN context.

The MM NAS Service Authorization includes the PDU session state in AMF. If N1 SM information is received in step 10, the service approval message also includes N1 SM information. For any PDU session ID provided by the UE, if the PDU session corresponds to the LADN and the UE is outside of the LADN's availability area, then the MM NAS service grant indicates that the PDU session ID and the user plane resource are not active (eg : LADN may not be used).

When a procedure is triggered for PDU session user plane activation, the AMF includes at least one N2 SM information from the SMF. AMF can send additional N2 SM information from SMF in a separate N2 message (eg N2 tunnel setup request). Alternatively, if multiple SMFs are included, the AMF may send one N2 request message to the (R) AN after all Nsmf_PDUSession_UpdateSMContext response service operations from all SMFs associated with the UE have been received. At this time, the N2 request message includes N2 SM information received in each of the Nsmf_PDUSession_UpdateSMContext Response and information for allowing the AMF to associate the response with the related SMF.

If the NG-RAN node provided a list of recommended cell / TA / NG-RAN node identifiers during the NAS signaling link release procedure, the AMF includes it in the N2 request. The RAN may use this information to allocate RNA when determining to enable RRC inactivity for the UE. The AMF may include "RRC inactivity assistance information" of the UE.

In step 12, the (R) AN may perform the following with the UE: The RAN performs RRC connection reconfiguration with the UE according to the QoS information for all QoS flows and data radio bearers of the PDU session with the UP connection enabled. . User plane security is established at this stage.

The RAN conveys the MM NAS service grant to the UE. The UE locally deletes the context of PDU sessions that are not available in 5GC.

If the N1 SM information is indicated in the service grant and some PDU session needs to be reestablished, then the UE starts the PDU session reconfiguration for the PDU session (s) after the service request procedure is completed.

In step 13, after the user plane radio resource is established, uplink data from the UE may be forwarded to the RAN. The NG-RAN may transmit with the UPF address and tunnel ID provided in step 4.

In step 14, which is performed conditionally, (R) AN returns N2 request to AMF (N2 SM information (RAN tunnel information, list of approved QoS flows for PDU sessions with UP connection enabled, UP connection enabled). And a list of rejected QoS flows for the PDU sessions.

The message may include N2 SM information (s) (eg, RAN tunnel information). When the AMF sends a separate N2 message in step 11, the RAN may respond with N2 SM information in a separate N2 message (eg, an N2 tunnel establishment response).

If the plurality of N2 SM information is included in the N2 request message in step 11, the N2 request reply includes the plurality of N2 SM information and information allowing the AMF to associate a response with the associated SMF.

In step 15 performed conditionally, the AMF may transmit Nsmf_PDUSession_UpdateSMContext Request (including N2 SM information (RAN tunnel information) and RAT type) for each PDU session approved by the SMF.

If the AMF receives the N2 SM information (one or more) in step 14, the AMF delivers the N2 SM information to the relevant SMF. If the UE time zone has changed compared to the last reported UE time zone, the AMF includes the UE time zone IE in the message.

In step 16, optionally performed, the SMF does the following to the PCF: If a dynamic PCC is deployed, the SMF invokes the Nsmf_EventExposure_Notify service operation (if subscribed) to initiate notification of new location information for the PCF. Can be. PCF can provide updated policy by calling Npcf_SMPolicyControl_UpdateNotify operation.

In step 17a, which is performed conditionally, the SMF may send an N4 session modification request (including RAN tunnel information) to the new intermediate UPF.

If the SMF selected a new UPF to act as an intermediate UPF for the PDU session in step 5, the SMF initiates the N4 session modification procedure and provides RAN tunnel information.

In step 17b, which is performed conditionally, the UPF may send an N4 session modification response to the SMF.

In step 18 performed conditionally, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response to the AMF.

In step 19a, which is performed conditionally, the SMF may send an N4 session modification request to a new UPF (middle).

When the forwarding tunnel is established and the timer SMF set up for the forwarding tunnel expires in step 8a, the SMF sends an N4 session modification request to a new (middle) UPF acting as an N3 endpoint to release the forwarding tunnel.

In step 19b, which is performed conditionally, the new UPF (middle) sends an N4 session modification response to the SMF. The new (intermediate) UPF, acting as an N3 endpoint, sends an N4 session modification response to the SMF.

In step 20a, which is performed conditionally, the SMF may send an N4 session modification request or an N4 session release request to an existing UPF.

If the SMF decides to continue using the existing UPF in step 5, the SMF sends an N4 session modification request that provides (R) AN tunnel information.

If the SMF selects a new UPF to act as an intermediate UPF in step 5 and the existing UPF is not a PSA UPF, the SMF sends an N4 session release request (release cause) to the existing intermediate UPF after the timer in step 6b expires. Initiate a resource release.

In step 20b, the existing intermediate UPF may send an N4 session modification response or N4 session release response to the SMF.

The existing UPF returns a modification or release of a resource using an N4 Session Modification Response or N4 Session Release Response message.

<Other embodiment: UE triggered service request in CM-IDLE state>

17 illustrates a UE triggered service request procedure in a CM-IDLE state according to another embodiment.

The service request procedure is used by the 5G UE in CM IDLE state to request the establishment of a secure connection to the AMF. The UE in the CM IDLE state initiates a service request procedure to send a response to an uplink signaling message, user data, or network paging request. AMF can perform authentication after receiving the service request message, and AMF performs security procedures. After establishing a secure signaling connection to the AMF, the UE or network may send a signaling message (eg, establishing a PDU session from the UE to the network or SMF via AMF), requested by the network and / or The user plane resource establishment for the PDU session indicated in the service request message can be started.

For any service request, the AMF may respond with a service response message to synchronize the PDU session state between the UE and the network. If the service request cannot be accepted by the network, the AMF may also respond with a denial of service message to the UE.

For service requests due to user data, the network may take further action if the user plane resource setup is not successful.

In step 1, the UE may send an MM NAS service request (including PDU session ID (s), security parameters, PDU session status) to (R) AN.

The UE sends a NAS message service request to the RAN towards the AMF encapsulated in the RRC message.

If a service request is triggered for user data, the UE includes the PDU session ID in the NAS service request message to indicate the PDU session (s) the UE needs to use. If a service request is triggered for signaling, the UE does not include any PDU session ID. When the procedure is triggered for a paging response, if the UE needs to use some PDU session (s), the UE may specify the PDU session ID in the MM NAS service request message to indicate the PDU session (s) the UE needs. Include. Otherwise, the UE does not include any PDU session ID.

If a service request via 3GPP is triggered in response to paging that includes a RAT type set to non-3GPP access, the UE may list the last routed PDU session through non-3GPP access that can be reactivated via 3GPP access. It includes. PDU session state indicates a PDU session available at the UE.

In step 2, the (R) AN may send an N2 message (including MM NAS service request, 5G temporary ID, location information, RAT type, RRC establishment cause) to AMF. If the AMF cannot handle the service request, it will reject it.

The 5G temporary ID is obtained from the RRC process. The RAN selects AMF according to the temporary ID. The location information and the RAT type are related to the cell in which the UE is camping.

Based on the PDU session state, the AMF may initiate the PDU session release procedure if the PDU session is not available at the UE.

In step 3, if the service request indicates integrity protection or integrity protection as failed, the AMF initiates a NAS authentication / security procedure.

If the UE triggered a service request to establish a signaling connection, after the secure exchange, the UE and the network can send signaling and steps 4 and 7 to 12 below are skipped.

In step 4 performed conditionally, AMF may send an N11 message (including PDU session ID (s), cause (s), UE location information) to the SMF.

The N11 message may be sent according to one or more of the following scenarios: i) A PDU session in which the MM NAS service request message includes a PDU session ID or the procedure is triggered by the SMF, but the UE's PDU session ID triggers the procedure. If the ID correlates with another SMF, the AMF sends an N11 message to the SMF associated with the PDU session ID whose cause is set to indicate "establishment of user plane resources" for the PDU session. Ii) Service request via 3GPP is triggered in response to paging that includes a RAT type set to non-3GPP access and the AMF is associated with a PDU session ID found to be reactivated via 3GPP access by MM NAS service request. If so, the UE sends an N11 message to the SMF associated with the PDU session ID for the reason that the AMF is set to indicate "establishment of user plane resources" for the PDU session. Iii) If the UE is in MICO mode and the AMF cannot reach the UE, the SMF notifies the SMF if the SMF does not need to send a DL data notification to the AMF.

In step 5, based on the new location information, the SMF checks the UPF selection criteria and determines one of the following: i) Whether to continue using the current UPF (s) ii) The UE acts as a PDU session anchor Whether to select a new intermediate UPF if it moves out of the service area of the UPF connecting to the RAN while maintaining the UPF; Or iii) resetting the trigger of the PDU session to perform relocation of the UPF acting as a PDU session anchor.

In step 6a, which is performed conditionally, the SMF sends an N4 session establishment request to the new UPF.

When the SMF selects a new UPF and acts as an intermediate UPF for the PDU session, an N4 session establishment request message is sent to the new UPF, providing packet detection, enforcement and reporting rules to be installed in the intermediate UPF. PDU session anchor information for a PDU session is also provided to the intermediate UPF.

In step 6b, which is performed conditionally, an N4 session establishment response may be transmitted.

The new intermediate UPF sends an N4 session establishment response message to the SMF. When the UPF allocates CN tunnel information, the UPF provides CN DL tunnel information and UL tunnel information (ie CN N3 tunnel information) to the SMF. The SMF is used to start a timer and to release the resource in the existing intermediate UPF if it is present in step 17a.

In step 7a, which is performed conditionally, the SMF may send an N4 session modification request to UPF (PSA).

The SMF sends an N4 session modification request message from the new intermediate UPF to the PDU session anchors UPF and UPF (PSA) providing DL tunnel information.

In step 7b, the UPF (PSA) may send an N4 session modification response to the SMF.

In step 8, which is performed conditionally, the SMF sends to the AMF an N11 message (including N1 SM information (including PDU session ID, PDU session reestablishment indication)), N2 SM information (PDU session ID, QoS profile, CN N3 tunnel information, S -Including NSSAI)).

When the SMF receives an N11 message for a reason including "setting of user plane resources", the SMF determines whether UPF reassignment is performed based on UE location information, UPF service area and operator policy: i) The SMF performs step 5 In the case of the PDU session determined to be served by the current PDU session anchor UPF, the SMF generates only N2 SM information and transmits an N11 message to the AMF to set the user plane. N2 SM information includes information provided by the AMF to the RAN. Ii) In the case of the PDU session that the SMF determines that UPF reassignment is required for the PDU session anchor UPF in step 5, the SMF may transmit an N11 message including only the N1 SM information to the UE through the AMF. The N1 SM information includes the corresponding PDU session ID and PDU session reconfiguration indication.

When receiving an N11 message in step 4 as an indication that the UE can reach, if the SMF has pending DL data, the SMF sends an N11 message to the AMF to establish a user plane for the PDU session, otherwise the SMF Resumes sending a DL data notification to the AMF in the case of DL data.

In step 9, the AMF may send an N2 request (including N2 SM information, security context, AMF signaling connection ID, handover restriction list, MM NAS service authorization) to the (R) AN.

The RAN stores the security context, AMF signaling connection ID, QoS information and the N3 tunnel ID of the UE RAN context for the QoS flow of the activated PDU session.

The MM NAS Service Authorization contains the AMF's PDU Session Status. If N1 SM information is received in step 8, the service approval message also includes N1 SM information.

The AMF includes at least one N2 SM information from the SMF when the procedure is triggered for PDU session user plane setup. AMF can send additional N2 SM information from SMF in a separate N2 message (eg N2 tunnel setup request). Alternatively, if multiple SMFs are involved, the AMF may send one N2 request message to the (R) AN after all N11 messages from the SMF have been received. In this case, the N2 request message includes the N2 SM information received in the respective N11 messages and information that allows the AMF to associate the responses with related SMFs.

In step 10, the (R) AN may perform the following to the UE: The RAN performs RRC connection reconfiguration with the UE according to QoS information for all QoS flows of the activated PDU session and data radio bearer. User Plane security is set in step 10.

The RAN conveys the MM NAS service grant to the UE. The UE locally deletes the context of PDU sessions that are not available in the 5G CN.

If the N1 message is present in the service grant and any PDU session needs to be reset, the UE initiates PDU session re-establishment after the service request procedure is completed.

In step 11, after the user plane radio resource is established, uplink data from the UE may be forwarded to the RAN. The 5G RAN sends uplink data to the UPF address and tunnel ID provided in step 4.

In step 12, conditionally performed, (R) AN returns an N2 request to AMF (N2 SM information (RAN tunnel information, list of approved QoS flows for activated PDU session, rejected QoS for activated PDU session). Including a list of flows).

The message may include N2 SM information (s) (eg, RAN tunnel information). When the AMF transmits a separate N2 message in step 5, the RAN may respond with N2 SM information in a separate N2 message (eg, an N2 tunnel establishment response).

If the plurality of N2 SM information is included in the N2 request message in step 5, the N2 request response includes the plurality of N2 SM information and information for allowing the AMF to associate the response with the associated SMF.

In step 13 performed conditionally, the AMF may transmit an N11 message (including N2 SM information (RAN tunnel information) and a RAT type) for each PDU session approved by the SMF.

If the AMF receives N2 SM information (one or more) in step 8, the AMF forwards the N2 SM information to the relevant SMF. If the UE time zone has changed compared to the last reported UE time zone, the AMF includes the UE time zone IE in the message.

In step 14, optionally performed, the SMF performs the following with the PCF: Once the dynamic PCC is deployed, the SMF starts modifying the IP-CAN session and provides new location information to the PCF.

In step 15a, which is performed conditionally, the SMF may send an N4 session modification request (including RAN tunnel information) to the new intermediate UPF.

If the user plane is established or modified, the SMF initiates the N4 session modification procedure and provides RAN tunnel information.

In step 15b, which is performed conditionally, the UPF may send an N4 session update response to the SMF.

In step 16, which is performed conditionally, the SMF may send an N11 message reply to the AMF.

In step 17a, which is performed conditionally, the SMF may send an N4 session release request to an existing intermediate UPF.

If there is an existing intermediate UPF, after the timer in step 6b expires, the SMF starts the resource release by sending an N4 session release request (release cause) to the existing intermediate UPF.

In step 17b performed conditionally, the existing intermediate UPF may send an N4 session release response to the SMF.

The existing UPF returns an N4 Session Release Response message to confirm the release of the resource.

<Other embodiment: UE triggered service request in CM-CONNECTED state>

18 illustrates a UE triggered service request procedure in a CM-CONNECTED state according to another embodiment.

The service request procedure is used by the 5G UE in CM-CONNECTED state to request user plane resources for the PDU session. If user plane resource establishment is not successful, the network may take further action.

In step 1, the UE may send an MM NAS service request (PDU session ID (s)) to (R) AN.

The UE sends a NAS message service request to the RAN towards the AMF encapsulated in an RRC message. The MM NAS Service Request message is encrypted and integrity protected. The PDU session ID (s) in the NAS message service request message indicates the PDU session selected by the UE to activate.

If a service request via 3GPP access is triggered in response to an N1 notification that a PDU session requiring a RAT type of non-3GPP connection needs to be reactivated, the UE may be reactivated via 3GPP access. Contains a list of PDU sessions last routed through the 3GPP connection.

In step 2, (R) AN may send an N2 message (including MM NAS service request) to AMF. If the service request cannot be processed by the AMF, the AMF can refuse.

The (R) AN may forward the MM NAS service request message to the AMF based on the existing N2 connection.

In step 3 performed conditionally, the AMF may send an N11 message (PDU session ID (s)) to the SMF. The AMF may send an N11 message to the SMF (s) associated with the PDU session ID (s).

In response to an N1 notification that a PDU session requiring RAT type non-3GPP access should be reactivated, a service request via 3GPP access is triggered and the AMF detects that the associated PDU session ID may be reactivated. In 3GPP access by the MM NAS service request sent by AMF, the AMF sends an N11 message to the SMF associated with the PDU session ID with a reason set to indicate "establishment of user plane resources" for the PDU session.

In step 4, based on the new location information, the SMF checks the UPF selection criteria. If the UE is outside the service area of the UPF connected to the RAN, the SMF may select a new intermediate UPF.

In step 5a, which is performed conditionally, the SMF may send an N4 session establishment request to a new intermediate UPF.

When the SMF selects a new intermediate UPF for a PDU session, an N4 session establishment request message is sent to the new intermediate UPF, providing packet detection, enforcement and reporting rules to be installed in the T-UPF. PDU session anchor information for the PDU session is also provided to the T-UPF.

In step 5b, the new UPF may send an N4 session establishment response to the SMF.

The new UPF sends an N4 session establishment response message to the SMF. If the UPF allocates CN tunnel information, the UPF provides CN DL tunnel information and UL tunnel information (CN N3 tunnel information) to the SMF. The SMF starts a timer and is used to release the resources of the existing UPF if there is a resource in step 17a.

In step 6a, which is performed conditionally, the SMF may send an N4 session modification request to UPF (PSA).

The SMF may send an N4 session modification request message to the PDU session anchors UPF and UPF (PSA) providing DL tunnel information for the new intermediate UPF.

In step 6b, the UPF (PSA) may send an N4 session modification response to the SMF.

In step 7 performed conditionally, the SMF may send an N11 message (including N2 SM information (including PDU session ID, QoS profile, CN N3 tunnel information, S-NSSAI)) to the AMF.

The SMF may generate N2 SM information and send an N11 message to the AMF to establish user plane (s) for the PDU session. The N2 SM information may include information provided by the AMF to the RAN.

In step 8 performed conditionally, the AMF may send an N2 request (including N2 SM information (QoS profile, CN N3 tunnel information), MM NAS service authorization) received from the SMF to (R) AN.

If there are a plurality of PDU sessions including a plurality of SMFs, the AMF does not need to wait for a response from all the SMFs in step 3b.

In step 9, the (R) AN may perform the following with the UE: The RAN performs RRC connection reconfiguration with the UE according to QoS information for all QoS flows of the activated PDU session and data radio bearer. The RAN conveys the MM NAS service grant to the UE.

In step 10, after the user plane radio resource for the selected PDU session is established, uplink data from the UE may be forwarded to the RAN. The 5G RAN may send the UPF address and tunnel ID provided in step 7 to uplink data.

In step 11, which is performed conditionally, (R) AN returns N2 request to AMF (N2 SM information (RAN tunnel information, list of approved QoS flows for activated PDU sessions, rejection for activated PDU sessions). List of the QoS flows).

The message may include N2 SM information (s) (eg, RAN tunnel information). The RAN may respond with N2 SM information in a separate N2 message (eg, an N2 tunnel establishment response).

In step 12, which is performed conditionally, the AMF may send an N11 message (N2 SM information (RAN tunnel information, list of approved QoS flows, list of rejected QoS flows)) for each PDU session approved with the SMF.

In step 13, optionally performed, the SMF may perform the following with the PCF: Once the dynamic PCC is deployed, the SMF may initiate IP-CAN session modification and send new location information to the PCF.

In step 14a, performed conditionally, the SMF may send an N4 session update request (list of RAN tunnel information and approved QoS flows) to the UPF.

If you want to set up or modify the user plane, the SMF can initiate the N4 session modification procedure and provide RAN tunnel information.

In step 14b, which is performed conditionally, the UPF may send an N4 session update response to the SMF.

In step 15, which is performed conditionally, the SMF may send an N11 message reply to the AMF.

In step 16a, which is performed conditionally, the SMF may send an N4 session release request to an existing UPF (middle).

If there is an existing UPF (intermediate), after the timer of step 6b expires, the SMF may initiate a resource release by sending an N4 session release request (release cause) to the existing UPF.

In step 16b, the existing UPF (middle) may send an N4 session release response to the SMF.

The existing UPF (Intermediate) may return an N4 Session Release Response message to confirm the release of the resource.

<Other embodiments: network triggered service request>

19 illustrates a network triggered service request according to another embodiment.

The procedure is used when the network needs to signal with the UE (e.g., N1 signaling to the UE, mobile-terminated SMS, establishing PDU session user plane resources for delivering mobile incoming user data). If the UE is in CM IDLE state or CM-CONNECTED state in 3GPP access, the network starts the network trigger service request procedure. If the UE is in CM-IDLE state and asynchronous communication is not activated, the network sends a paging request to (R) AN / UE. The paging request triggers a service request procedure at the UE. When asynchronous type communication is activated, the network stores the received message and sends a message to the (R) AN and / or the UE when the UE enters the CM-CONNECTED state (ie (R) AN and / or UE And context).

If the UE is in CM-CONNECTED state in a non-3GPP access, the network initiates a network triggered service request procedure when it needs to send a signal. If the UE is in CM-IDLE state in non-3GPP access, the UE is registered at the same time via 3GPP and is non-3GPP access in PLMN, the network may initiate a network trigger service request via 3GPP access.

In step 1, if the UPF receives downlink data of the PDU session and there is no (R) AN tunnel information stored in the UPF for the PDU session, the UPF has not previously been notified by the SMF to ensure that the UPF does not buffer the downlink data. Buffer downlink data.

In step 2a, the UPF may send a data notification (including PDU session ID, priority) to the SMF.

Iii) Upon arrival of the first downlink data packet, the UPF sends a data notification message to the SMF if the SMF has not previously notified the UPF not to send a data notification to the SMF (if the next step is skipped).

Ii) If the UPF receives an additional downlink data packet for a QoS flow in the same PDU session with the same or lower priority than that used in any previous data notification for the PDU session, the UPF does not send a new data notification. Buffers downlink data packets without

I) UPF supports paging policy differentiation and, if enabled by SMF for N4 sessions, UPF includes DSCP in the TOS (IPv4) / TC (IPv6) value received from the IP header of the downlink data packet.

Iii) If the SMF receives an N11 message from the new AMF informing the new AMF serving the UE while waiting for the user plane to be established in the UPF, the SMF retransmits the data notification message only to the new AMF.

In step 2b, the SMF sends a data notification reply to the UPF.

In step 3a, the SMF may send an N11 message (including UE permanent ID, PDU session ID, N2 SM information (QoS profile, CN N3 tunnel information), priority) to the AMF.

Upon receipt of the data notification message, if the SMF has not been informed in advance that it cannot reach the UE, the SMF determines the AMF and the N11 message (UE permanent ID, PDU session ID, N2 SM information (PDU session ID, QoS profile, CN N3 tunnel information, S-NSSAI), priority, paging policy indication) are sent to the AMF including the priority and PDU session ID received in the data notification message as part of step 2a.

If the SMF receives additional data notification messages for the same PDU session while waiting for the user plane connection to be activated, but has a higher priority than indicated in the previous data notification for the PDU session, the SMF indicates a high priority and a PDU session ID. Send a new N11 message to AMF.

If the SMF receives an N11 message response from an AMF other than the AMF that sent the N11 message while the SMF is waiting for the user plane to be activated, the SMF sends the N11 message to the AMF.

When supporting paging policy differentiation, the SMF presents a paging policy indication associated with downlink data that triggered a data notification message in the N11 message.

In step 3b, which is carried out conditionally, AMF reacts with SMF.

If the UE is in CM-IDLE state and the AMF determines that the UE cannot reach paging, the AMF sends an N11 message to the SMF or other network function where the AMF received the request message in step 3a, or the UE can reach it. AMF indicating no, performs asynchronous type communication and stores the N11 message. If asynchronous type communication is invoked and the AMF stores an N11 message, the AMF initiates communication with the UE and (R) AN when it can reach the UE (e.g., when the UE enters CM-CONNECTED state). do.

If the UE is in MICO mode, the AMF rejects the request from the SMF and the AMF indicates that the UE is unreachable (if the SMF has not subscribed to the UE reachability) as an indication that the SMF does not need to send DL data. Can be notified. The AMF stores an indication that the SMF has been notified that the UE cannot reach it.

If the UE is in CM-IDLE state and the UE is registered only through non-3GPP access in the PLMN, the AMF rejects the request from the SMF if it is associated with a PDU session established through non-3GPP access, and the SMF notifies the DL data. May be unreachable (if the SMF has not subscribed to the UE reachability) with an indication that it does not need to send the AMF. The AMF stores an indication that the SMF has been notified that the UE cannot reach it.

If a registration procedure with an AMF change is in progress when an existing AMF receives an N11 message, the existing AMF may reject the N11 message as an indication that the N11 message has been temporarily rejected.

In step 3c, which is performed conditionally, the SMF may respond to the UPF.

The SMF may notify the UPF of the user plane setup failure.

Upon receipt of an indication from the AMF that the UE cannot reach based on network policy, the SMF may: i) Instruct the UPF to stop sending data notifications and stop DL data buffering or apply extended buffering; Or ii) refrain from sending additional N11 messages for DL data to the AMF while the UE is in MICO mode.

Upon receiving information that the N11 message requested from the SMF has been temporarily rejected and receiving a downlink data notification from the UPF, the SMF may request the UPF to apply extended buffering.

In step 4 performed conditionally, the AMF may send a paging message to the (R) AN node.

If the UE is in the CM-CONNECTED state, the AMF performs steps 9 through 17 in the UE triggered service request procedure of FIG. 17 to activate the user plane connection for the PDU session (ie, radio resource and N3 tunnel establishment). The rest of the procedure is omitted.

If the UE is in RM-REGISTERED state and CM-IDLE in non-3GPP access and the UE is CM-CONNECTED in 3GPP access, the AMF will route the last non-routed notification with the PDU session ID in the N1 NAS message via 3GPP access. Send to reactivate the PDU session via 3GPP access.

If the UE is able to reach the RM-REGISTERED state and CM-IDLE and is reachable, then AMF sends a paging message (NAS ID for paging, registration area list, paging DRX length, paging priority indication) to the registration area where the UE is registered. Transmit to the (R) AN node belonging to the (s).

If the UE is in RM-REGISTERED state on non-3GPP access and CM-IDLE and the UE is in RM-REGISTERED state on 3GPP access, CM-IDLE and reachable, then AMF will finalize the paging message through 3GPP access through non-3GPP access. Send to reactivate a routed PDU session.

When supporting paging policy differentiation, AMF may include paging policy indications in paging request messages.

The paging strategy can be configured in AMF for various combinations of other PDU session context information identified by the DNN, paging policy representation, PDU session ID in SMF, and PDU session ID received in N11 messages.

Paging strategies can include:

Iii) paging retransmission scheme (eg, at a frequency or time interval at which paging is repeated); Ii) determining whether to send a paging message to (R) AN nodes during certain AMF high load conditions; Iii) Whether to apply sub-area based paging (e.g., last known cell-ID or retransmission from first page of TA and all registered TAs).

AMF and (R) AN may support additional paging optimization to reduce the signaling load and network resources used to successfully page a UE by one or several of the following means: i) Specific paging By the AMF implementing the strategy (eg, an N2 paging message is sent to the (R) AN node that last served the UE); Ii) consider the RAN node provided by the (R) AN when the AMF transitions to information about the recommended cell and to the CM-IDLE state. The AMF determines the (R) AN nodes to be paged in consideration of the (R) AN node related portion of the information, and provides information on the recommended cell in the N2 paging message to each of the (R) AN nodes. Iii) (R) AN considers paging attempt count information provided by AMF during paging.

If UE radio capability for paging information is available in the AMF, the AMF adds the UE radio capability for paging information in the N2 paging message to the (R) AN node.

If AMF has information about the recommended cell and (R) AN node for paging, AMF considers the information to determine the (R) AN node for paging, and AMF uses the information in the recommended cell for (R) AN You can pass it transparently to the node.

The AMF may include paging attempt count information in the N2 paging message (s). Paging attempt count information is the same for all (R) AN nodes selected by AMF for paging.

In step 5 performed conditionally, the (R) AN node may page the UE.

If the (R) AN node receives a paging message from the AMF, the UE may be paged by the (R) AN node.

In step 6 performed conditionally, the AMF may send an N11 message reply to the SMF.

AMF uses a timer to oversee the paging procedure. If the AMF does not receive a response to the paging request message from the UE, the AMF may apply additional paging according to the applicable paging strategy described in step 3.

If the AMF does not receive a response from the UE, then the AMF considers the UE unreachable and the SM N2 message cannot be routed to the (R) AN, so if the AMF is not aware of an ongoing MM procedure that prevents the UE from responding (ie The AMF does not receive an N14 context request message indicating a UE performing a registration procedure with another AMF.) The AMF sends an SMF or "N11 message rejection" with an appropriate "cause of failure" (eg, UE unreachable). Return to another network function indicating the failure of the "message routing service".

In step 7, when the UE receives the paging request and is in the CM-IDLE state, the UE starts the UE triggered service request procedure in the CM-IDLE state of FIG. 17. In step 4a of the UE-triggered service request procedure in CM-IDLE state of FIG. 17, if there is no SMF (s) receiving the N11 message in step 3a, the AMF is in the PDU session ID (s) of the MM NAS service request message. Sends an N11 message to the SMF (s) associated with the PDU session identified by.

If the UE is in RM-REGISTERED state and CM-IDLE in 3GPP access and the CM-CONNECTED in 3GPP access, if AMF sends a notification with PDU session ID in N1 NAS message via 3GPP access in step 4, The UE initiates a UE triggered service request in the CM-CONNECTED state of FIG. 18.

In step 8, the UPF transmits the buffered downlink data to the UE through the (R) AN node that has performed the service request procedure. If the procedure is triggered by a request from another network entity described in step 3a, the network transmits a downlink signal.

The embodiments described above may be implemented as hardware components, software components, and / or combinations of hardware components and software components. For example, the devices, methods, and components described in the embodiments may include, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable gates (FPGAs). It may be implemented using one or more general purpose or special purpose computers, such as an array, a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of understanding, one processing device may be described as being used, but a person of ordinary skill in the art may appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described with reference to the accompanying drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Alternatively, even if replaced or replaced by equivalents, appropriate results can be achieved.

Claims (20)

In the service request method triggered by the network performed by the AMF device,
Receiving, by the AMF device, a Namf_Communication_N1N2Message Transfer message from an SMF device that receives a data notification message from the UPF device indicating that a UPF device that does not include access network tunnel information for a PDU session has received downlink data;
Transmitting a paging message for a PDU session between the AMF device and a user terminal to an access network based on the PDU session ID included in the Namf_Communication_N1N2Message Transfer message;
Including,
And the user terminal receiving the paging message from the access network starts a service request procedure according to the connection management state of the user terminal.
The method of claim 1,
The user terminal,
If the connection management state for the Non-3GPP access is CM-IDLE and the connection management state for the 3GPP access is CM-CONNECTED, send a list of allowed PDU sessions that can be reactivated in the 3GPP access to the AMF device. Service request method triggered by the network while initiating the service request procedure.
The method of claim 2,
The list of PDU sessions,
A service request method triggered by the network, the session including a session allowed to be used through the 3GPP access, among the PDU sessions associated with the Non-3GPP access.
The method of claim 1,
The user terminal,
And if the connection management state for 3GPP access is CM-IDLE, triggering the service request procedure upon receiving the paging message for the PDU session associated with the 3GPP access.
The method of claim 1,
The user terminal,
If the connection management state for 3GPP access and Non-3GPP access is CM-IDLE, a network that initiates the service request procedure while sending a list of allowed PDU sessions that can be reactivated in the 3GPP access to the AMF device Service request method triggered by.
In the service request method triggered by the network performed by the UPF device,
Receiving downlink data for a PDU session;
Transmitting a Data Notification Message to the SMF device indicating that the downlink data has been received;
Transmitting the downlink data to the SMF device when receiving a data notification acknowledgment message from the SMF device that has received the data notification message;
Including,
The AMF device that receives the Namf_Communication_N1N2Message Transfer message from the SMF device transmits a paging message for a PDU session between the AMF device and the user terminal to an access network to start a service request procedure according to the connection management state of the user terminal. Service request method triggered by.
The method of claim 6,
The UPF device that receives the downlink data,
And if there is no access network tunnel information for the PDU session, a service request triggered by the network buffering the downlink data.
The method of claim 6,
The step of transmitting a data notification message to the SMF device indicating that the downlink data has been received,
If the UPF device receives additional downlink data for a QoS flow of a PDU session having the same or lower priority as the PDU session, the UPF device buffers the additional downlink data without sending a new data notification message. The service request method triggered by the network.
In the service request method triggered by the network performed by the SMF device,
Receiving a data notification message from a UPF device having received downlink data for a PDU session;
Receiving downlink data from the UPF device when sending a Data Notification Acknowledge Message to the UPF device indicating that the data notification message has been received;
After receiving the downlink data, transmitting a Namf_Communication_N1N2Message Transfer message including a PDU session ID included in the data notification message to an AMF device;
Including,
And the AMF device triggers a paging message for a PDU session between the AMF device and the user terminal to an access network to start a service request procedure according to the connection management state of the user terminal.
The method of claim 9,
Receiving a data notification message from the UPF device indicating that the downlink data has been received,
If the UPF device receives additional downlink data for a QoS flow of a PDU session having the same or lower priority as the PDU session, the UPF device buffers the additional downlink data without sending a new data notification message. The service request method triggered by the network.
In the service request method triggered by the network performed by the user terminal (UE),
Paging a PDU session between the user terminal and the AMF device when the AMF device receives a Namf_Communication_N1N2Message Transfer message including a PDU session ID transmitted by the SMF device receiving the data notification message from the UPF device receiving the downlink data Receiving a message from an access network;
Downloading downlink data from the UPF device by performing a service request procedure according to a connection management state of the user terminal;
Including,
And the paging message is triggered by the network according to a paging strategy managed by the AMF device.
The method of claim 11,
The UPF device that receives the downlink data,
And if there is no access network tunnel information for the PDU session, a service request triggered by the network buffering the downlink data.
The method of claim 11,
The paging strategy,
A paging strategy is set by a timer supervised by the AMF device, determines whether the AMF device transmits the paging message according to load conditions, or in a sub-area. Method of service request triggered by network to decide whether to apply based paging.
In the service request method triggered by the user terminal performed by the SMF apparatus,
Receiving a location change notification message of a dormant user terminal from an AMF device, determining that the user terminal is located outside an available area of the LADN;
In accordance with the determination, determining control of the UPF device for managing the PDU session.
Including,
The control of the UPF device for forwarding uplink data from the user terminal to the UPF device is triggered by the user terminal to insert an intermediate UPF or to remove the intermediate UPF.
The method of claim 14,
The inserted intermediate UPF is,
A service request method triggered by a user terminal receiving downlink data from a UPF operating as a PDU session anchor (PSA).
The method of claim 14,
The removed intermediate UPF,
A service request method triggered by a user terminal for transmitting buffered data to a UPF operating as a PDU session anchor (PSA).
In the service request method triggered by a user terminal performed by an access and mobility management function (AMF) device,
When an N2 message including a service request message is received from an access network (AN), an Nsmf_PDUSession_UpdateSMContext Request message including a PDU session ID, location information and access type of a user terminal is received. Transmitting to a session management function (SMF) device;
If an Nsmf_PDUSession_UpdateSMContext Response message including N2 SM information is received from the SMF device, transmitting an N2 request including N2 SM information received from the SMF device to the access network;
Including,
And the SMF device triggers the user terminal to control the UPF device to forward the uplink data from the user terminal to the UPF device by determining that the user terminal is located outside the available area of the LADN.
The method of claim 17,
The AMF device that receives the N2 message from an access network,
If the service request message is not integrity protected or integrity protection verification failed, the NAS authentication procedure and authentication server function (AUSF) and security procedure with the user terminal are started. The service request method triggered by the user terminal.
In the service request method triggered by a user terminal performed by a new UPF device,
Receiving an N4 session establishment request message from the SMF device when the new UPF device is selected by the SMF device to operate as an intermediate UPF for the PDU session;
Transmitting to the SMF device an N4 session establishment response message indicating that an N4 session between the new UPF and the SMF device is established in place of the existing UPF;
Including,
And a service request triggered by the user terminal in which the SMF device receiving the position change notification message of the user terminal in the dormant state selects the new UPF device.
The method of claim 19,
The new UPF device that receives the N4 session establishment request message,
Service request method triggered by a user terminal for allocating DL CN tunnel information and UL CN tunnel information for the new UPF acting as a PDU session anchor.

Images