KR102290784B1 - Method for updating pdu session connection between terminal and network by the network - Google Patents

Abstract

The present disclosure relates to a communication technique that converges a 5G communication system for supporting a higher data rate after a 4G system with IoT technology, and a system thereof. The present disclosure provides intelligent services (eg, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, etc.) based on 5G communication technology and IoT-related technology. ) can be applied to The present invention discloses a method for managing a data transmission connection of a PDU session for transmitting data between a terminal and a network according to a network decision in a mobile communication system.

Description

Update method of PDU session connection between the terminal and the network by the network

In a mobile communication system, the present invention relates to a method for managing a data transmission connection of a PDU session for transmitting data between a terminal and a network according to a network decision.

Efforts are being made to develop an improved 5G communication system or pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of the 4G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) or after the LTE system (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the very high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway. In addition, in the 5G system, FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (ACM) methods, and FBMC (Filter Bank Multi Carrier), which are advanced access technologies, NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, an intelligent IT (Internet Technology) service that collects and analyzes data generated from connected objects and creates new values in human life can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, in technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC), 5G communication technology is implemented by techniques such as beam forming, MIMO, and array antenna. there will be The application of a cloud radio access network (cloud RAN) as the big data processing technology described above is an example of the convergence of 5G technology and IoT technology.

Recently, with the development of LTE (Long Term Evolution) and LTE-Advanced, research on a technology for operating a mobile communication system is being actively conducted. In particular, in a mobile communication system, data between a terminal and a network is transmitted according to a network decision There is a need for a method and apparatus for managing a data transmission connection of a PDU session.

An object of the present invention is, in a mobile communication system, a user plane network function responsible for data transmission and reception of a PDU session for data transmission with a terminal, a session management network function responsible for controlling the user plane network function, and data transmission in a wireless section In a situation where there is a base station device for Define how to manage

Another object of the present invention is to define a network slice composed of network resources that can satisfy the requirements for each service in 5G mobile communication. A mobile communication operator may define a network slice specialized for each operator. The technical problem to be achieved by the present invention is to propose a method for providing a network slice specialized for each operator in a roaming network other than the corresponding operator in a 5G mobile communication system.

The present invention for solving the above problems is a control signal processing method in a wireless communication system, the method comprising: receiving a first control signal transmitted from a network; processing the received first control signal; and transmitting a second control signal generated based on the processing to the network.

According to an embodiment of the present invention, by providing a method for transmitting terminal signaling between devices in charge of a network function configured by a mobile communication service provider in a mobile communication service provider network through the present invention, operation of network devices in various environments support and efficient operation of network resources through this.

In addition, according to another embodiment of the present invention, slice information can be managed between mobile communication operators that have entered into a roaming contract in a wireless communication system. In addition, the UE may obtain slice information usable in the roaming network and provide information on how to manage and use slice information of the roaming network.

1A shows an example of a network structure of a mobile communication system to which the present invention is applied.
1B illustrates a procedure for setting the state of a PDU Session to IDLE for a terminal and a base station according to a determination in an SM Network Function and releasing a User Plane Connection according to an embodiment of the present invention.
FIG. 1c illustrates a procedure for setting the state of a PDU Session to IDLE for a terminal and a base station according to a determination in the MM Network Function and releasing the User Plane Connection according to an embodiment of the present invention.
1D illustrates a procedure for managing PDU connection configuration inside the terminal for data processing of the terminal according to an embodiment of the present invention.
2A is a diagram illustrating a network structure according to an embodiment of the present invention.
2B is a diagram illustrating information stored in a terminal and an HPLMN according to an embodiment of the present invention.
2C is a diagram illustrating a terminal registration process in a roaming network according to an embodiment of the present invention.
2D is a diagram illustrating a terminal operation flowchart and information changes stored in the terminal according to an embodiment of the present invention.
2E is a diagram illustrating an operation flow of a VPLMN NF according to an embodiment of the present invention.
2F is a diagram illustrating an operation flow of an HPLMN NF according to an embodiment of the present invention.
2G is a diagram illustrating a terminal registration process in a roaming network according to an embodiment of the present invention.
2H is a diagram illustrating a session establishment process in a roaming network according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Advantages and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

<First embodiment>

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

A term for identifying an access node used in the following description, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, a term referring to various identification information and the like are exemplified for convenience of description. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

For convenience of description, the present invention uses terms and names defined in the 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) standard. However, the present invention is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.

1A shows an example of a network structure of a mobile communication system to which the present invention is applied. Referring to FIG. 1A , the mobile communication system includes a terminal 1a-01, a base station 1a-02, a Mobility Management (MM) function 1a-03, and a Session Management (SM) function 1a-04 ( 1a-06), Subscriber Data (1a-10), Control function (1a-12) including NF Repository (1a-11), and UP (user plane) function (1a-05) (1a-07). In the mobile communication system, a set of devices including the control functions and user plane functions excluding the terminal and the base station is referred to as a core network (CN). The mobile communication system receives service data related to an external service through DN (Data Network) 1a-08 and 1a-09 for interworking with an external application.

The base station 1a-02 provides wireless access to terminals. That is, the base station 1a-02 supports a connection between the terminals and a core network (CN) by scheduling and allocating radio resources to service users' traffic.

The MM 1a-03 performs a mobility management function of the terminal, and transmits a control signal related to mobility management to the terminal in connection with the base station.

The SM (1a-04) (1a-06) manages a session in which the terminal can perform a service through the Data NW, and communicates with the UP function (1a-05) (1a-07) to connect the terminal Manages the transmission of service data for

The UP function (1a-05) (1a-07) processes a packet arriving from the base station (1a-02) or a packet to be transmitted to the base station (1a-02).

A connection established for the Control Functions 1a-12 to send and receive control signals to and from the terminal 1a-01 is referred to as an NG1 connection.

A connection established for the Control Functions 1a-12 to send and receive control signals to and from the base station 1a-02 is referred to as an NG2 connection. Packets exchanged by the terminal 1a-01 with the Control Functions 1a-12 through the NG1 connection are transferred between the terminal 1a-01 and the base station 1a-02 through a wireless connection, It is transmitted between the base station and the Control Functions through the NG2 connection.

A connection through which the UP function (1a-05) (1a-07) exchanges packets with the base station (1a-02) in order to send and receive packets with the terminal is referred to as an NG3 connection.

The mobile communication system includes a plurality of the Data Networks 1a-09 (1a-08) and a plurality of the UP functions (1a-05) so that the terminal 1a-01 can perform various types of external services. Data can be exchanged through (1a-07). At this time, the Data Networks 1a-08 and the Data Networks 1a-09 respectively transmit data through the terminal 1a-01 through the UP function 1a-05 and the UP function 1a-07, respectively. can be exchanged

In this case, the control of the UP function 1a-05 for the connection between the UP function 1a-05 and the terminal 1a-01 and the base station 1a-02 is performed by the SM function 1a-04. can be done through In addition, the control of the UP function 1a-07 for the connection between the UP function 1a-07 and the terminal 1a-01 and the base station 1a-02 is another SM function 1a-06 ) can be done through At this time, the connection for exchanging control signals between the terminal 1a-01 and the SM 1a-04 and the SM 1a-06 is NG1 between the MM 1a-03 and the terminal 1a-01. This is done through connection. In addition, the connection for exchanging control signals between the base station 1a-02 and the SM 1a-04 and the SM 1a-06 is the NG2 connection between the MM 1a-03 and the base station 1a-02. is done through

At this time, the MM does not process the signaling message for establishing a PDU connection with the SM (1a-04) (1a-06) received from the terminal (1a-01), the SM (1a-04) or the SM (1a-06). In this case, the MM selects an appropriate SM function to process the PDU connection establishment received from the terminal 1a-01 in the SM 1a-04 or the SM 1a-06 and delivers the PDU connection establishment message. do.

1B illustrates a procedure for setting the state of a PDU Session to IDLE for a terminal and a base station according to a determination in an SM Network Function and releasing a User Plane Connection according to an embodiment of the present invention.

The SM Network Function (hereinafter, SM) (1b-04) may determine to change the state of the PDU Session to Idle when it is expected that there will be no data transmission to the UE through the PDU Session for a while (1b-06). At this time, the condition for determining that it is necessary to change the state of the PDU Session to Idle is when transmission and reception of data through the PDU Session in the UP 1b-05 does not exist for a certain period of time, or the PDU Session is It is possible only in a certain range, but when the terminal is recognized as out of the service range of the PDU Session, or the terminal is out of an area where data service can be received in the mobile communication system, or an area in which transmission and reception of service data is prohibited may include a case where the SM determines that data transmission/reception through the PDU Session is temporarily difficult for various reasons.

When the SM 1b-04 determines that it is necessary to change the PDU Session to the Idle state, the UP 1b-05 and the In order to release the connection between the base stations 1b-02, an N3 path release request (1b-07) is transmitted. In this case, the N3 path release request may include information indicating the PDU Session, such as an ID of the PDU Session.

When the SM 1b-04 transmits the N3 path release request to the UP 1b-05, when the UP 1b-05 receives data related to the PDU Session from the outside, the UP 1b -05) transmits a Downlink Data Notification indicating that the data has been received to the SM 1b-04, or a packet associated with the PDU session indicating whether to discard the data until there is no other request. Discard-related information can be transmitted.

When the UP 1b-05 receives the N3 path release request 1b-07, the UP 1b-05 releases the connection between the UP 1b-05 and the base station 1b-02, and the SM 1b-04 ) to the N3 path release response (1b-08). In this case, the UP 1b-05 may remove information necessary for managing the PDU session while releasing the connection related to the PDU session.

When the UP 1b-05 receives the N3 path release request 1b-07 from the SM 1b-04, when receiving the Packet Discard related information related to the PDU session, the Packet Discard related According to the information, it is determined whether to discard the externally received data related to the PDU Session or to transmit a Downlink Data Notification informing the SM 1b-04 that the data has been received and process the data. .

After receiving the N3 path release response (1b-08) from the UP (1b-05), the SM (1b-04) sends the MM (1b-03) to the base station (1b-02) with the PDU session and An N3 path release request for releasing a connection with the related UP (1b-05) may be transmitted (1b-09).

When the MM 1b-03 receives the N3 path release request from the SM 1b-04, the MM 1b-03 sends the N3 path release request to the base station 1b-02 to which the terminal 1b-01 is connected. In order to request to release the connection related to the PDU session, an N3 path release request is transmitted (1b-10).

When the base station 1b-02 receives the N3 path release request from the MM 1b-03, it releases the connection with the UP 1b-05 associated with the PDU Session, releases the radio resource interval, and Information necessary to control the PDU session can be removed.

In this case, the base station 1b-02 may transmit an RRC configuration reconfiguration to the terminal 1b-01 to inform that the radio resource section associated with the PDU session is released (1b-11).

When the terminal 1b-01 receives the RRC Connection Reconfiguration informing that the radio resources related to the PDU session are released from the base station 1b-02, it recognizes that the connection related to the PDU session is not maintained and , manages the state of the PDU session as Idle. When the PDU Session is managed in an Idle state, when the terminal wants to transmit data through the PDU Session, the base station 1b-02 and the MM 1b-03 for data transmission through the PDU Session. It is necessary to request the re-establishment of the connection of the radio section and the re-establishment of the connection between the base station 1b-02 and the UP capable of transmitting and receiving data through the PDU session.

The base station 1b-02 may release the connection for the PDU session and transmit an N3 path release response to the MM 1b-03 to inform that the connection is released. (1b-13)

After receiving the N3 path release response from the base station 1b-02, the MM 1b-03 connects the base station 1b-02 and the UP 1b-05 to the SM for the PDU session. It can transmit an N3 path release response indicating that this has been released. (1b-14)

In another embodiment of the present invention, the SM 1b-04 sends the N3 path release request to the MM 1b-03 before requesting the N3 path release request 1b-07 to be transmitted from the UP 1b-05. Request to release the connection related to the PDU session in the base station 1b-02 related to the PDU session by first sending a request, and receive an N3 path release response (1b-14) from the MM in response After that, the UP (1b-05) may request an N3 path release request (1b-07) to be transmitted.

FIG. 1c illustrates a procedure for setting the state of a PDU Session to IDLE for a terminal and a base station according to a determination in the MM Network Function and releasing the User Plane Connection according to an embodiment of the present invention.

The MM 1c-03 temporarily provides service with the terminal 1c-01 through the PDU Session, including when it is recognized that the terminal 1c-01 is out of the service range of the PDU Session. If it is determined that it is impossible, it may be determined to change the state of the PDU Session to Idle. (1c-06)

The MM may determine to change the PDU Session to an Idle state and transmit an N3 path release request (1c-07) requesting the SM to release the connection of the PDU Session. When the MM transmits the N3 path release request to the SM, when it occurs by entering an area where data service is not possible, such as out of the service range of the PDU session of the terminal 1c-01, the SM can inform that the service of the PDU session is not possible.

When the SM receives the N3 path release request, the SM establishes a connection between the UP (1c-05) and the base station (1c-02) configured to deliver data related to the PDU session to the UP (1c-05). In order to release, the N3 path release request (1c-08) is transmitted. In this case, the N3 path release request may include information indicating the PDU Session, such as an ID of the PDU Session.

When the SM receives data related to the PDU Session from the UP (1b-05) from the outside in the N3 path release request (1c-08) transmitted to the UP (1c-05), the UP (1b-05) ) related to the PDU session related to the PDU session indicating whether to transmit a Downlink Data Notification indicating that the data has been received to the SM 1b-04, or to discard the data until there is no other request. information may be transmitted. In this case, the Packet Discard related information related to the PDU session is a case in which the SM receives a state that the service of the PDU session is not possible when the SM receives the N3 path release request from the MM, or the policy of the operator set in the SM. It can be set according to several conditions including.

When the UP 1c-05 receives the N3 path release request, the UP 1c-05 releases the connection between the UP 1c-05 and the base station 1c-02, and N3 path release to the SM 1c-04 Transmit the response (1c-09). In this case, the UP 1c-05 may remove information necessary for managing the PDU session while releasing the connection related to the PDU session.

When the UP 1c-05 receives the N3 path release request from the SM 1c-04, upon receiving the Packet Discard related information associated with the PDU session, according to the Packet Discard related information, The data is processed after determining whether to discard the externally received data related to the PDU Session or to transmit a Downlink Data Notification informing the SM 1b-04 that the data has been received.

After receiving the N3 path release response (1c-08) from the UP (1c-05), the SM (1c-04) sends the UP (1c-05) to the MM (1c-03) with the PDU session An N3 path release response indicating that the related connection has been released may be transmitted. (1c-10)

After receiving the N3 path release response from the SM 1c-04, the MM 1c-03 connects to the base station 1c-02 to which the terminal 1c-01 is connected in relation to the PDU session. Transmits N3 path release request to request release. (1c-11)

When the base station 1c-02 receives the N3 path release request from the MM 1c-03, the base station 1c-02 releases the connection with the UP 1c-05 associated with the PDU Session, releases the radio resource interval, and Information necessary to control the PDU session can be removed.

In this case, the base station 1c-02 may transmit an RRC configuration reconfiguration to the terminal 1c-01 to inform that the radio resource section associated with the PDU session has been released (1c-12).

When the terminal 1c-01 receives the RRC Connection Reconfiguration informing that the radio resources related to the PDU session are released from the base station 1c-02, it recognizes that the connection related to the PDU session is not maintained and , manages the state of the PDU session as Idle. When the PDU Session is managed in the Idle state, when the terminal wants to transmit data through the PDU Session, the base station 1c-02 and the MM 1c-03 for data transmission through the PDU Session. It is necessary to request the re-establishment of the connection of the radio section and the re-establishment of the connection between the base station 1c-02 and the UP capable of transmitting and receiving data through the PDU session.

The base station 1c-02 may release the connection for the PDU session and transmit an N3 path release response to the MM 1c-03 to inform that the connection is released. (1c-14)

After receiving the N3 path release response from the base station 1c-02, the MM 1c-03 connects the base station 1c-02 and the UP 1c-05 to the SM for the PDU session. An N3 path release Confirm indicating that this has been released can be transmitted. (1c-15)

In another embodiment of the present invention, the MM 1c-03 sends the N3 path release request to the base station 1c-02 before requesting the N3 path release request 1c-07 to the SM 1c-04. first to request to release the connection related to the PDU session, and after receiving an N3 path release response (1c-14) from the base station 1c-02 in response ) may transmit an N3 path release request (1c-07) requesting to release the connection of the PDU Session.

1D illustrates a procedure for managing PDU connection configuration inside the terminal for data processing of the terminal according to an embodiment of the present invention.

When the terminal generates data to be transmitted to the mobile communication system according to the use of an application in the terminal, and is requested to transmit it through the mobile communication system, (1d-01)

It is determined whether the PDU Session associated with the generated data maintains a valid wireless connection connection and a network connection. (1d-02)

At this time, if the PDU Session associated with the data has a valid radio access connection, resources are allocated through the radio access connection and data is transmitted through the radio resource (1d-03).

In the specific embodiments of the present invention described above, elements included in the invention are expressed in the singular or plural according to the specific embodiments presented. However, the singular or plural expression is appropriately selected for the situation presented for convenience of description, and the present invention is not limited to the singular or plural element, and even if the element is expressed in plural, it is composed of the singular or singular. Even an expressed component may be composed of a plurality of components.

Meanwhile, although specific embodiments have been described in the detailed description of the present invention, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments and should be defined by the claims described below as well as the claims and equivalents.

<Second embodiment>

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that in the accompanying drawings, the same components are denoted by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Also, in describing the embodiments of the present invention in detail, 3GPP will mainly focus on the communication standard set by the standard, but the main gist of the present invention is not significantly outside the scope of the present invention in other communication systems having a similar technical background. It can be applied with some modifications in the range not specified, which will be possible at the discretion of a person having technical knowledge skilled in the technical field of the present invention.

Also, in describing embodiments of the present invention, slice, service, network slice, network service, application slice, application service, and the like may be mixed and used.

Slice information means Network Slice Selection Assistance Information (NSSAI) or S-NSSAI. NSSAI is composed of a set of S-NSSAI. Slice info for HPLMN refers to the slice information value determined by the HPLMN mobile operator, that is, NSSAI or S-NSSAI that can be used in HPLMN. Slice info for VPLMN means a slice information value determined by a VPLMN mobile operator, that is, an NSSAI or S-NSSAI that can be used in the VPLMN.

A mobile communication operator may allocate a core network node suitable for a corresponding service for each slice or for each set of a specific slice. 2A shows an example of a corresponding network configuration diagram. The UE may access the 3GPP 5G Core Network (CN) through a Radio Access Network (RAN) defined in 3GPP or an Access Network (AN, eg, WiFi) defined in non-3GPP. 5G CN is divided into Control Plane (CP) that transmits control signals and User Plane (UP) that transmits data traffic. The CP function may have a part shared by all slices and a part belonging to a specific slice. The UP function may belong to a specific slice. When the terminal initially accesses the network, it sends a Registration Request message. In this case, slice information that the terminal intends to use after accessing the network may be included in the registration request message. Each of the network entities constituting FIG. 2-a transmits a registration request message by selecting an entity capable of supporting the corresponding slice based on the corresponding slice information. After connecting to the network, the terminal may send a PDU session setup request message for data transmission. In this case, slice-related information may be included in the session establishment request message to indicate which slice the requested PDU session corresponds to. The Shared CN CP function receiving the session establishment request message may select a slice specific CN CP based on the requested slice information. The slice information described in a series of processes is defined as a standard value and may be a value that all mobile communication operators can understand, or it may be an arbitrary value determined by a specific mobile communication operator.

Figure 2-b diagrams slice-related information stored in the terminal and HPLMN. A UE can use a specific slice by subscribing to HPLMN. Slice information usable by the terminal is stored in the terminal, and may include slice information associated with each application installed in the terminal. HPLMN stores subscription information for each terminal in a subscriber information database (UDM). In the example described in FIG. 2-b , subscription information of UE A is stored in UDM, and slice information available to UE A may also be included.

Figure 2-c describes a registration process when the terminal accesses a roaming network other than HPLMN. The terminal transmits a Registration Request message to access the VPLMN (step 1). Upon receiving the Registration Request message, the AMF of the VPLMN (corresponding to the shared CN CP function of FIG. 2-a) accesses the UDM of the HPLMN and checks the subscription information of the terminal (steps 2 and 3). After confirming whether the terminal is accessible based on the terminal's subscription information and local policy received from the UDM, the AMF transmits a Registration Accept message to the terminal for access approval (step 4). In this case, information included in each step may vary according to information stored in the terminal and an operation method of the network.

If slice information usable in the VPLMN is stored in the UE before the access process occurs, the UE transmits the requested slice info for VPLMN in the message of step 1. Upon receiving the message of step 1, the AMF can check whether the slice information included in the message is the slice provided by the VPLMN based on local policy and roaming agreements. This verification process may occur after step 3. Through the steps 2 and 3, the UE checks the subscription information to see if the corresponding slice can be used. Specifically, in step 2, the requested slice info for VPLMN information sent by the terminal is sent to the UDM along with the terminal information. The UDM checks whether the UE can use the corresponding slice based on the UE's subscription information and roaming agreements between HPLMN and VPLMN, and in step 3, AMF provides slice information for the UE to use in the VPLMN. send to AMF can check whether slice info for VPLMN received from UDM is a slice currently available from VPLMN based on local policy and roaming agreements. In step 4, a Registration Accept message including the finally determined allowed slice info for VPLMN is sent to the UE.

In another case, if there is no slice information available in the VPLMN in the terminal before the access process occurs, the terminal may not include the slice information in the message of step 1. Upon receiving the message of step 1, the AMF can check which slices can be provided to the UE, which is a subscriber of HPLMN, based on local policy and roaming agreements. This verification process may occur after step 3. Through steps 2 and 3, the UE may check available slice information. Specifically, in step 2, the terminal information is sent to the UDM. The UDM selects which slices the UE can use based on the UE's subscription information and information on roaming agreements between the HPLMN and the VPLMN. Since the UE did not request any slices in step 1, the HPLMN can select default slices based on the subscription information stored in the UDM. This information is slice info for HPLMN, not slice info for VPLMN. In step 3, the UE sends slice information (slice info for HPLMN or slice info for VPLMN) usable in the VPLMN to the AMF. If slice info for HPLMN is included in step 3, AMF mirrors the slice info for HPLMN received from UDM based on local policy and roaming agreements with the value corresponding to VPLMN, slice info for VPLMN, and is currently provided by VPLMN. You can check if the slice is possible. Alternatively, the UDM may change the selected slice info for HPLMN to the slice info for VPLMN value based on the roaming aggregation and include slice info for VPLMN in step 3. AMF can check whether slice info for VPLMN received from UDM is a slice currently available from VPLMN based on local policy and roaming agreements. In step 4, a Registration Accept message including the finally decided slice info for VPLMN is sent to the UE.

At this time, slice info for VPLMN and corresponding slice info for HPLMN values may be delivered to Registration Accept. Upon receiving the Registration Accept message, the UE performs an operation as described in FIG. 2-d. That is, mapping information of application and HPLN S-NSSAI mapping information stored in the terminal and Slice info for HPLMN (a set of S-NSSAIs) and slice info for VPLMN (a set of S-NSSAIs) included in the Registration Accept message. By using , it is possible to derive the mapping between the application of the terminal and the S-NSSAI value used in the VPLMN.

Since the UE did not request any slices in step 1, the slices allowed to the UE in step 4 may be default slices based on the subscription information stored in the UDM. In the subsequent operation, when the terminal requests PDU session setup, the terminal sends a PDU session setup request including the S-NSSAI value of the VPLMN mapped to the application.

In another case, if there is no slice information available in the VPLMN in the terminal before the access process occurs, the terminal transmits the requested slice info for HPLMN in the message of step 1. Upon receiving the message in step 1, the AMF may include the requested slice info for HPLMN information received from the terminal in step 2 and deliver it to the UDM. The UDM may finally select a slice that the UE can use based on the subscription information, and may send the corresponding slice information, allowed slice info for HPLMN, to the AMF in step 3 . AMF may change allowed slice info for HPLMN to slice info for VPLMN with a value corresponding to VPLMN based on roaming agreements. In addition, the allowed slice info for VPLMN, which is a slice that can be provided to the UE, may be finally determined based on local policy or the like. The AMF transmits a step 4 message including allowed slice info for VPLMN and corresponding slice info for HPLMN information to the UE. After step 2, the UDM determines the allowed slice info for HPLMN, and then changes the allowed slice info for HPLMN to slice info for VPLMN based on the roaming aggregation to be included in the step 3 message. The AMF may finally determine the allowed slice info for VPLMN, which is a slice that can be provided to the UE, based on local policy or the like. The AMF transmits a step 4 message including allowed slice info for VPLMN and corresponding slice info for HPLMN information to the UE.

In step 3 of FIG. 2-c , the UDM does not include specific slice information, but may provide network requirement information (eg, QoS profile) to be provided to the UE. Upon receiving the information, the AMF may select a slice of the VPLMN that meets the requirements, that is, determine allowed slice info for VPLMN, and include it in step 4 and send it to the UE.

FIG. 2-d is a schematic diagram of a terminal operation flow chart of the embodiment described in FIG. 2-c. In addition, when there is no slice info available in the VPLMN in the terminal at the time of initial access, it indicates a change in slice information stored in the terminal before and after registration.

Fig. 2-e schematically illustrates an AMF operation flow chart of the embodiment described in Fig. 2-c.

Fig. 2-f illustrates a flow chart of UDM operation of the embodiment described in Fig. 2-c.

FIG. 2-g is a diagram illustrating a case in which slice selection and mapping related operations of the embodiment described in FIG. 2-c occur in network functions other than AMF and UDM. The AMF delivers the slice information requested from the UE to the vNF in step 4. The vNF may communicate with the hNF to determine a slice usable by the UE. vNF may be a Network Slice Selection Function that manages a network slice of a VPLMN or a Network Repository Function that manages a network node of a VPLMN. The hNF may be a Network Slice Selection Function for managing a network slice of the HPLMN, a Network Repository Function for managing a network node of a VPLMN, or a UDM for managing subscriber information. Also, steps 2 and 3 may be performed after step 7.

A UE that obtains allowed slice info for VPLMN usable in the VPLMN through the registration process uses this value in the subsequent session establishment process. Figure 2-h diagrams a PDU session setup procedure. The terminal checks the slice info for VPLMN value mapped to the application the user wants to use. If a PDU session corresponding to the slice does not currently exist or if it is impossible to use even if there is, a new PDU session setup request message is transmitted to the network in step 2. At this time, the corresponding slice info for VPLMN value is included and transmitted to the AMF. The AMF transmits an NF discovery request message to the vNRF to find an SMF supporting the slice (step 3). Three methods are possible with the subsequent operation in step 3. 4a is a method in which vNRF receives vSMF(s) information as an NF discovery response. AMF sends a PDU session setup request to vSMF without knowing the hSMF information of HPLMN. After 4a, 5a or 5b is possible. 4b is a method in which the AMF, which has received vSMF(s) information as an NF discovery response, requests and obtains hSMF(s) information from the hNRF of HPLMN. 4c is a method in which the vNRF, having received the step 3 message, communicates with the hNRF to obtain hSMF(s) information, and includes both vSMF(s) information and hSMF(s) information in the NF discovery response and returns to the AMF. The AMF that has obtained vSMF(s) information in these three ways selects one vSMF among vSMF(s) and transmits a PDU session setup request (step 5). vSMF that has received the PDU session setup request can operate in three ways. 5a is a case in which, when hSMF(s) information is not received from the AMF, the vSMF requests and obtains hSMF(s) information capable of providing a corresponding slice to the hNRF. vSMF having obtained hSMF(s) information selects one hSMF among them and transmits a PDU session setup request message in step 6. 5b is a method in which vSMF does not communicate directly with hNRF, but obtains hSMF(s) information through vNRF. vSMF having obtained hSMF(s) information selects one hSMF among them and transmits a PDU session setup request message in step 6. 5c is a method in which the AMF acquires hSMF(s) information through the process of step 4b or 4c and delivers hSMF(s) information to vSMF. In this case, the AMF may select one hSMF from among the hSMF(s) and deliver it to the vSMF, and the vSMF transmits a PDU session setup request to the corresponding hSMF as in step 6. Alternatively, the AMF may deliver the hSMF(s) information to the vSMF as it is, and the vSMF selects one of them and transmits a PDU session setup request to the corresponding hSMF as in step 6. The PDU session setup request of step 6 may include a slice info for VPLMN value. If necessary, the hSMF receiving the PDU session setup request of step 6 may communicate with the hNF to obtain a slice info for HPLMN value that is a value of HPLMN mapped to slice info for VPLMN (steps 7 and 8). The vNF performing this role may be an NSSF, an NRF, a UDM, or other network entities constituting a 5G CN. A PDU session setup response is transmitted to the terminal through the process of steps 9 to 11.

Claims (20)

A method performed by a session management function (SMF) entity of a wireless communication system, the method comprising:
identifying whether the terminal is out of a service area corresponding to a protocol data unit (PDU) session;
determining, when the terminal leaves the service area corresponding to the PDU session, to change a state associated with the PDU session of the terminal to an idle state; and
In response to determining that the state associated with the PDU session is to be changed to the idle state, a first request message for removing information on a connection between a user plane function (UPF) entity associated with the PDU session and a base station is UPF and sending to the entity. The method of claim 1,
determining to change the state of the PDU session to the idle state when transmission and reception of data through the PDU session does not exist for a set period; or
The method further comprising the step of determining to change the state of the PDU session to the idle state when the terminal is out of the allowed range. The method of claim 1, wherein the first request message includes information notifying the UPF entity to discard downlink data related to the PDU session. The method of claim 1, wherein the first request message includes information for notifying the UPF entity not to provide a data notification message when the UPF entity receives data associated with the PDU session. The method of claim 1,
The connection between the UPF entity and the base station is a connection between the base station controlling the terminal and the UPF entity. The method of claim 1,
The method further comprising the step of transmitting a second request message for releasing a radio resource associated with the PDU session to a mobility management function (MMF) entity by the base station controlling the terminal. A method performed by a user plane function (UPF) entity of a wireless communication system, the method comprising:
A session management function (SMF) entity has determined that the terminal moves out of a service area corresponding to a protocol data unit (PDU) session and changes the state associated with the PDU session of the terminal to an idle state. case, receiving a request message for removing information on a connection between the UPF entity and the base station associated with the PDU session of the terminal from the SMF entity; and
and transmitting a response message according to the request message to the SMF entity. 8. The method of claim 7,
When transmission and reception of data through the PDU session does not exist for a set period, it is determined that the state of the PDU session is changed to the idle state, or
When the terminal is out of the allowed range, the method characterized in that it is determined that the state of the PDU session is changed to the idle state. 8. The method of claim 7, wherein the request message includes information notifying the UPF entity to discard downlink data related to the PDU session. 8. The method of claim 7, wherein the request message includes information notifying the UPF entity not to provide a data notification message when the UPF entity receives data associated with the PDU session. 8. The method of claim 7,
The connection between the UPF entity and the base station is a connection between the base station controlling the terminal and the UPF entity. In a session management function (SMF) entity of a wireless communication system,
transceiver; and
Identifies whether the terminal leaves a service area corresponding to a protocol data unit (PDU) session, and when the terminal leaves the service area corresponding to the PDU session, the terminal's PDU session and According to determining to change the associated state to the idle state, and determining to change the state associated with the PDU session to the idle state, a connection between a user plane function (UPF) entity associated with the PDU session and a base station ) SMF entity comprising a control unit for transmitting a first request message for removing the information to the UPF entity through the transceiver. 13. The method of claim 12, wherein the control unit,
When data transmission/reception through the PDU session does not exist for a set period, it is determined to change the state of the PDU session to the idle state, or
SMF entity, characterized in that it is determined to change the state of the PDU session to the idle state when the terminal is out of the allowed range. 13. The SMF entity of claim 12, wherein the first request message includes information notifying the UPF entity to discard downlink data related to the PDU session. 13. The SMF entity of claim 12, wherein the first request message includes information for notifying the UPF entity not to provide a data notification message when the UPF entity receives data associated with the PDU session. 13. The method of claim 12, wherein the control unit,
SMF entity, characterized in that the base station controlling the terminal transmits a second request message for releasing the radio resource associated with the PDU session to a mobility management function (MMF) entity through the transceiver. In a user plane function (UPF) entity of a wireless communication system,
transceiver; and
A session management function (SMF) entity has determined that the terminal moves out of a service area corresponding to a protocol data unit (PDU) session and changes the state associated with the PDU session of the terminal to an idle state. In this case, a request message for removing information on the connection between the UPF entity and the base station associated with the PDU session of the terminal is received from the SMF entity through the transceiver, and to the SMF entity according to the request message UPF entity comprising a control unit for transmitting a response message through the transceiver. 18. The method of claim 17,
When transmission and reception of data through the PDU session does not exist for a set period, it is determined that the state of the PDU session is changed to the idle state, or
The UPF entity, characterized in that it is determined that the state of the PDU session is changed to the idle state when the terminal is out of the allowed range. 18. The UPF entity of claim 17, wherein the request message includes information notifying the UPF entity to discard downlink data related to the PDU session. 18. The UPF entity of claim 17, wherein the request message includes information notifying the UPF entity not to provide a data notification message when the UPF entity receives data associated with the PDU session.

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