KR20210054972A - Method and apparatus for controlling sessions with network quota in a wireless communication system - Google Patents

Abstract

Provided is a method for controlling a PDU session by an AMF in a wireless communication system. The method comprises the steps of: selecting a network slice; receiving a PDU session creation request for transmitting and receiving traffic for the network slice from a terminal; and generating or deleting a PDU session based on the request. Therefore, a service can be more effectively provided.

Description

Method and device for controlling sessions according to network quota in wireless communication system {METHOD AND APPARATUS FOR CONTROLLING SESSIONS WITH NETWORK QUOTA IN A WIRELESS COMMUNICATION SYSTEM}

The present disclosure relates to a method and apparatus for controlling a session according to a network quota in a wireless communication system.

Efforts are being made to develop an improved 5G (5th generation) communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of 4G (4th generation) communication systems. For this reason, the 5G communication system or the pre-5G communication system is called a Beyond 4G Network communication system or a Long Term Evolution (LTE) system (Post LTE) system.

In order to achieve a high data rate, 5G communication systems are being considered for implementation in an ultra-high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, in order to improve the network of the system, in 5G communication systems, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network ), Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation ) And other technologies are being developed.

In addition, in the 5G system, the advanced coding modulation (Advanced Coding Modulation, ACM) method of FQAM (Hybrid Frequency Shift Keying and Quadrature Amplitude Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technology, FBMC (Filter Bank Multi Carrier). ), NOMA (Non Orthogonal Multiple Access), and SCMA (Sparse Code Multiple Access) are being developed.

With the development of various information technology (IT) technologies, virtualization technology has been applied to network equipment, and communication equipment has evolved into a virtualized network function (NF). In addition, virtualized NFs can be installed/operated in various types of clouds or data centers (DCs) because they are implemented in software form without physical restrictions. In particular, the NF can be freely expanded or scaled, installed (initiation), or terminated according to service requirements, system capacity, and network load. It should be noted that even though these NFs are implemented in software form, they are not excluded from the physical configuration, since they must be driven on a basic physical configuration, for example, a predetermined device. In addition, NFs may be implemented only with a simple physical configuration, that is, hardware.

In order to support various services in these various network structures, network slicing technology has been introduced. Network slicing is a technology that logically composes a network as a set of network functions (NF) to support a specific service and separates it from other slices. One terminal can access two or more slices when receiving various services.

An embodiment of the present disclosure may provide a method and an apparatus for more effectively providing a service.

A method of controlling a PDU session by an AMF in a wireless communication system according to an embodiment of the present disclosure includes: selecting a network slice; Receiving a PDU session creation request for transmitting and receiving traffic for the network slice from a terminal; And generating or deleting a PDU session based on the request.

According to an embodiment of the present disclosure, a service can be more effectively provided.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present disclosure.
2 is a diagram illustrating a configuration of a wireless communication system according to an embodiment of the present disclosure.
3 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.
4 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.
5 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.
6 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.
7 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.
8 is a block diagram showing the configuration of an NF according to an embodiment of the present disclosure.
9 is a flowchart illustrating an operation between NFs according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the gist of the present disclosure by omitting unnecessary description.

For the same reason, some elements in the accompanying drawings are exaggerated, omitted, or schematically illustrated. In addition, the size of each component does not fully reflect the actual size. The same reference numerals are assigned to the same or corresponding components in each drawing.

Advantages and features of the present disclosure, and a method of achieving them will be apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the present disclosure complete, and those skilled in the art to which the present disclosure pertains. It is provided to fully inform the scope of the disclosure to the person, and the present disclosure is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

At this time, it will be appreciated that each block of the flowchart diagrams and combinations of the flowchart diagrams may be executed by computer program instructions. Since these computer program instructions can be mounted on the processor of a general purpose computer, special purpose computer or other programmable data processing equipment, the instructions executed by the processor of the computer or other programmable data processing equipment are described in the flowchart block(s). It creates a means to perform functions. These computer program instructions can also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular way, so that the computer-usable or computer-readable memory It is also possible for the instructions stored in the flow chart to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block(s). Since computer program instructions can also be mounted on a computer or other programmable data processing equipment, a series of operating steps are performed on a computer or other programmable data processing equipment to create a computer-executable process to create a computer or other programmable data processing equipment. It is also possible for instructions to perform processing equipment to provide steps for executing the functions described in the flowchart block(s).

In addition, each block may represent a module, segment, or part of code that contains one or more executable instructions for executing the specified logical function(s). In addition, it should be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in the reverse order depending on the corresponding function.

In this case, the term'~ unit' used in this embodiment refers to software or hardware components such as FPGA or ASIC, and'~ unit' performs certain roles. However,'~ part' is not limited to software or hardware. The'~ unit' may be configured to be in an addressable storage medium, or may be configured to reproduce one or more processors. Thus, as an example,'~ unit' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays, and variables. Components and functions provided in the'~ units' may be combined into a smaller number of elements and'~ units', or may be further separated into additional elements and'~ units'. In addition, components and'~ units' may be implemented to play one or more CPUs in a device or a security multimedia card. In addition, in an embodiment, the'~ unit' may include one or more processors.

A term for identifying an access node used in the following description, a term for network entities, a term for messages, a term for an interface between network objects, a term for various identification information And the like are illustrated for convenience of description. Accordingly, the present disclosure is not limited to terms to be described later, and other terms referring to objects having an equivalent technical meaning may be used.

For convenience of description below, the present disclosure uses terms and names defined in standards for 5G, New Radio (NR), and Long Term Evolution (LTE) systems. However, the present disclosure is not limited by terms and names, and may be equally applied to systems conforming to other standards.

In describing the embodiments of the present disclosure in detail, the communication standard defined by the 3GPP will be the main target, but the main subject of the present disclosure does not significantly depart from the scope of the present disclosure to other communication systems having a similar technical background. It may be applied with slight modifications in the range of, and this will be possible at the judgment of a person skilled in the technical field of the present disclosure.

In describing the embodiments of the present disclosure in detail, the vehicle communication service will be the main target, but the main gist of the present disclosure is, within the range not significantly departing from the scope of the present disclosure, even to other services provided in the 5G network. It can be applied as a modification, and this will be possible at the judgment of a person skilled in the technical field of the present disclosure. In other words, the ProSe layer dealt with in the present disclosure may mean the overall layer performing a control operation for a device to device (or D2D, or ProSe: Proximity Service) communication service. This exists on the AS layer and refers to a layer that exchanges signaling with the AS layer for terminal-to-terminal communication connection.

The 5G system is considering supporting various services compared to the existing 4G system. For example, the most representative services are mobile ultra-wideband communication service (eMBB: enhanced mobile broad band), ultra-reliable and low latency communication service (URLLC: ultra-reliable and low latency communication), and large-scale device-to-device communication service (mMTC: massive machine type communication), evolved multimedia broadcast/multicast service (eMBMS), and the like. In addition, a system providing a URLLC service may be referred to as a URLLC system, and a system providing an eMBB service may be referred to as an eMBB system. Also, the terms service and system may be used interchangeably.

Hereinafter, the present disclosure relates to a method and apparatus for supporting various services in a wireless communication system. Specifically, the present disclosure describes a technology for supporting various services by supporting mobility of a terminal in a wireless communication system.

A term for identifying an access node used in the following description, a term for a network entity or a network function (NF), a term for messages, and an interface between network objects. Terms, terms referring to various types of identification information, and the like are exemplified for convenience of description. Accordingly, the present disclosure is not limited to terms to be described later, and other terms referring to objects having an equivalent technical meaning may be used.

For convenience of description below, this disclosure uses terms and names defined in 3GPP 3rd generation partnership project long term evolution (LTE) and 5G standards. However, the present disclosure is not limited by the terms and names, and may be equally applied to systems conforming to other standards.

Hereinafter, for convenience of description, targets for exchanging information for access control and state management will be collectively described as NF. NF is, for example, an access and mobility management function (Access and Mobility Management Function, hereinafter referred to as AMF) device, a session management function (Session Management Function, hereinafter referred to as SMF) device, a network slice selection function device (Network slice selection function). , NSSF) may be at least one of the devices. However, the embodiments of the present disclosure may be equally applied even when NF is actually implemented as an instance (Instance, respectively AMF Instance, SMF Instance, NSSF Instance, etc.). When the embodiments of the present invention are composed of a plurality of steps, some steps may be omitted or executed in a changed order, or other operations may be included in the middle.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present disclosure.

Referring to FIG. 1, a radio access node (RAN) 110 and a user equipment (UE) 120 are illustrated as some of nodes using a radio channel in a wireless communication system. 1 shows only one base station 110 and one terminal 120, but another base station identical or similar to the base station 110 may be further included. In addition, in FIG. 1, only a case in which only one terminal 120 communicates within one base station 110 is illustrated. However, it is obvious that a plurality of terminals can communicate within one base station 110.

The base station 110 is a network infrastructure that provides wireless access to the terminal 120. The base station 110 has a coverage defined as a certain geographic area based on a distance at which a signal can be transmitted (not shown in FIG. 1). In addition to the base station, the base station 110 includes'access point (AP)','eNodeB, eNB', '5G node', and'wireless point'. , May be referred to as'transmission/reception point (TRP)' or another term having an equivalent technical meaning.

The terminal 120 is a device used by a user and performs communication with the base station 110 through a radio channel. In some cases, the terminal 120 may be operated without the user's involvement. For example, the terminal 120 is a device that performs machine type communication (MTC) and may not be carried by a user. The terminal 120 illustrated in FIG. 1 may include at least one user portable device, and may include at least one MTC. The terminal 120 of FIG. 1 is a'terminal', a'mobile station', a'subscriber station', a'remote terminal', a'wireless terminal', Alternatively, it may be referred to as'user device' or another term having a technical meaning equivalent thereto.

The AMF device 131 may be a network entity that manages the mobility of the terminal 120. The SMF device 132 may be a network entity that manages connection of a packet data network for providing packet data to the terminal 120. The connection between the terminal 120 and the SMF 132 may be a protocol data unit (PDU) session.

The user plane function (hereinafter referred to as UPF) device 133 may be a gateway through which packets transmitted and received by the terminal 120 are transmitted or a network entity that functions as a gateway. The UPF 133 may be connected to a data network (DN) 140 connected to the Internet, and may provide a path for transmitting and receiving data between the terminal 120 and the DN 140. Accordingly, the UPF 133 may route data to be transmitted to the Internet among packets transmitted by the terminal 120 to the Internet data network.

The network slice selection function (NSSF) device 134 may be a network entity that performs a network selection operation described in the present disclosure, for example, an operation of selecting a network slice. The operation of the NSSF device 134 will be described in more detail in the drawings to be described later.

The authentication server function (AUSF) device 151 may be a network entity that provides a subscriber authentication service.

The network exposure function (NEF) device 152 can access information managing the terminal 120 in a 5G network, subscribe to the mobility management event of the terminal, and a session of the terminal Network entity that can subscribe to session management events, request session-related information, set billing information for the terminal, request to change the PDU session policy for the terminal, and transmit small data about the terminal Can be.

NRF (Network Repository Function, 153) is a profile containing detailed information of each NF (Network Function), or an NF or network entity that stores status information of NF or NF Instance. The profile or status information of the stored NF can be delivered.

The policy and charging function (Policy and Charging Function, hereinafter referred to as PCF) device 154 may be a network entity that applies a service policy of a mobile communication service provider to the terminal 120, a charging policy, and a policy for a PDU session. have.

The integrated data management (Unified Data Management, hereinafter referred to as UDM) device 155 may be a network entity that stores information about the subscriber or/and the terminal 120.

The AF (Application Function) 156 may be a service application server or a network entity that provides a service by interworking with a network.

AMF device 131, SMF device 132, UPF device 133, NSSF device 134, AUSF device 151, NEF device 152, NRF device 153, PCF device 154 described above , The UDM device 155, the AF device 156, and the SCP device 157 may be software driven by at least one or more devices or/and systems, or may be in the form of firmware. In addition, the above-described devices 131, 132, 133, 134, 151, 152, 153, 154, 155, 156, and 157 may be implemented in the form of hardware, if necessary. In the following description, for convenience of description, the term “device” will be omitted. For example, the AMF device 131 will be described as AMF 131 and the SMF device 132 will be described in the same form as the SMF 132.

Meanwhile, in FIG. 1, symbols between lines connected between each network entity, the terminal 120 and the RAN 110 may be interfaces of each entity. For example, an N1 interface is used between the terminal 120 and the AMF 131, an N2 interface is used between the RAN 110 and the AMF 131, and an N3 interface is used between the RAN 110 and the UPF 133. It can mean that it is used. Similarly, the N4 interface is used between the SMF 132 and the UPF 133, the N9 interface is used between or inside the UPF 133, and the N6 interface may be used between the UPF 133 and the DN 140. .

2 is a diagram illustrating a configuration of a wireless communication system according to an embodiment of the present disclosure.

Referring to FIG. 2, a mobile communication system (a carrier network such as 5G or 4G) may be composed of a radio base station, for example, a radio access network (RAN) 110 and one or more core network slices. In FIG. 2, N core network slices 211, 212, ..., 21N are illustrated. The RAN 110 may transmit/receive data between a terminal (eg, the terminal 120 of FIG. 1 and the data network (DN) 140) through at least one core network slice. Accordingly, the core network can be configured in a slice form or without a slice, and coexistence between the two is also possible One core network slice may basically include NFs of one or more core networks One core network The NF corresponding to may include the AMF 131, the SMF 132, and the UPF 133. In addition, according to another embodiment, the NF is among the AMF 131, the SMF 132, and the UPF 133. According to another embodiment, the NF may further include other network function devices in addition to the AMF 131, the SMF 132, and the UPF 133. Another embodiment According to the NF, the AMF 131, the SMF 132, and the UPF 133 may include at least one or more components, and may further include at least one other device in addition to the above-described devices.

In an embodiment of the present disclosure, each of the network slices 211, 212, ..., 21N may provide a service suitable for each characteristic, and each of the network slices 211, 212, ..., 21N at the same time The capacity that can be provided may vary. The capacity of the network slices 211, 212, ..., 21N may be, for example, the maximum number of terminals (subscribers) and the number of sessions. Each of the network slices 211, 212, ..., 21N may control access to the network according to its capacity.

Referring to FIG. 2, a case in which 10,000 terminals can be connected to the first network slice 211 and 30,000 sessions can be accommodated is illustrated. A case in which 50,000 terminals can be connected to the second network slice 212 and 100,000 sessions can be accommodated is illustrated. In addition, the case where 1,000 terminals can be accessed and 5,000 sessions can be accommodated is exemplified in the N-th network slice 21N.

As shown in FIG. 2, the capacity of each of the network slices 211, 212, ..., 21N may be set differently for each slice according to the setting of the mobile communication service provider. If one specific slice is leased or sold to a separate service provider, the capacity may be set differently for each slice according to a service level agreement (SLA).

According to an embodiment of the present disclosure, the capacity (Quota or Capacity) of one network slice may be expressed as at least one of the following parameters.

One. Maximum number of subscribers, terminals, or users that can simultaneously access a network slice

2. The maximum number of PDU sessions that can be supported simultaneously in a network slice.

3. Maximum number of IP flows that can be simultaneously supported in network slice

4. Maximum number of QoS flows that can be simultaneously supported in network slice

5. Maximum number of GBR flows that can be supported simultaneously in network slice

According to an embodiment of the present disclosure, the capacity of one network slice is set as the number of terminals that can be simultaneously connected (parameter 1) and the maximum number of sessions that can be simultaneously supported (parameter 2), as shown in FIG. Can be. In addition, the capacity of one network slice may be set using at least one or two or more of the above-described parameters.

On the other hand, parameters related to session and flow (e.g., in the case of 2 to 5 of the above-described parameters) are expressed as predetermined values per slice (e.g., 10,000 sessions per network slice are supported), or It may be expressed as a specific value per one terminal (for example, up to four sessions are supported at the same time per terminal connected to a network slice).

According to an embodiment of the present disclosure, through capacity control for each network slice, a mobile communication network of a service provider is protected from overload, resources of the network are effectively used, and accurate billing between the mobile communication service provider and the network slice user can be performed. have.

Meanwhile, according to an embodiment of the present disclosure, when access control using a quota is performed for each network slice, a case may occur when a limit value of a quota set in an actual slice is reached. If the quota of the slice is set to the maximum number of sessions that can be accessed simultaneously, when a connection request exceeding the quota occurs, a technique for handling this is required. For example, if 1000 sessions can be created for a specific slice, and a high-priority service A and a low-priority service B coexist in the slice, the connection occurs when the maximum number of sessions is reached. For a request, it may be necessary to provide service A to two subscribers, rather than to provide both service A and B to one subscriber. In an embodiment of the present disclosure, the number of sessions per slice may be more specifically divided and controlled by the number of PDU sessions, the number of QoS flows, and the number of IP flows.

In an embodiment of the present disclosure, when the quota that can be supported in a specific slice is set to the maximum number of sessions that can be accessed simultaneously, if the number of sessions has already reached the maximum for the slice that is the target of session creation/addition requested by the terminal, Treatment can be carried out.

One) Rejection of session creation/addition: A Reject message notifies that the request has been rejected to the terminal 120 that requested the creation or addition of a session, and at this time, the reason for rejection to the terminal 120 is the quota of the slice. It is notified that it is due to control (ie, the maximum value set in the quota has been reached). In addition, a timer value allowing re-request may be additionally transmitted to the terminal 120. If the connection request is a session creation/addition request for a specific slice, and a Reject occurs during the control process for the maximum number of sessions, the timer is applied to the corresponding slice(s), and the terminal 120 Until it is terminated, the request for creating or adding sessions to the slice(s) must not be retransmitted. If the connection request is for a session (DNN) mapped to a specific slice, and a reject occurs during the control process for the maximum number of sessions, the timer is applied to the slice(s) and the mapped DNN(s). , The terminal 120 should not retransmit a session creation request for the corresponding slice(s) and the mapped DNN(s) until the timer expires. If the timer expires, the terminal 120 may retransmit a request for connection or session creation.

2) Accepting a new request after deleting a session: If the slice (or additionally mapped DNN with a slice) reaches the maximum number of sessions, the network requests the new request and the corresponding slice. Priorities of previously created sessions are compared, and if there is a session with a lower priority, a session and a terminal to be released are selected. A deletion procedure is performed for the selected session, and after the available resources are secured, a request for creating/adding a new session is processed. If there is no other session or terminal to be deleted, a rejection response is transmitted to the new request.

3) Acceptance after quality of service change: If the slice (or DNN mapped with the slice) reaches the maximum number of sessions, which is the target of session creation/addition requested by the terminal 120, QoS set by default by request or subscription information Services are provided with a lower level of QoS. According to an embodiment of the present disclosure, lowering the level of QoS may include one or more of the following.

A. Lower the maximum allowed data rate

B. Changed GBR (Guaranteed Bit Rate) Flow to Non-GBR Flow

C. 5QI adjustment (down to 5QI with a lower relative priority)

D. Lower Allocation and Retention Priority (ARP) to a lower one

E. Limit the maximum number of flows in a session

3 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.

In step S310, a registration process is performed between the terminal 120 and the network. During this process, slice selection for the terminal 120 and selection of the AMF 131 may be performed, and for this purpose, information on the slice from the NSSF 134 and the NRF 153 (maximum number of sessions that can be provided, etc.) Can be received. In addition, during this process, the AMF 131 may receive subscription information for the subscriber from the UDM 155, and at this time, the slices allowed for the subscriber (Subscribed S-NSSAIs) and mapping to the subscription information for access and mobility management. The information of the DNN may be included. In this case, the subscription information may include relative priority information for each slice or for each DNN, and may also include QoS parameters that can be provided by default for each DNN. Relative priority for each DNN may be provided using ARP among QoS parameters that can be basically provided for each DNN.

In step S320, the terminal 120 transmits a PDU session establishment request for transmitting and receiving traffic for a specific slice. The request of the terminal 120 may include a slice identifier (S-NSSAI) and a mapped DNN.

In step S330, the AMF 131 performs a process for selecting the slice and the SMF 132 belonging to the slice in order to create a session for the slice according to the request of the terminal 120. At this time, the AMF 131 exchanges a message with the NSSF 134 or the NRF 153, or the PCF 154 to obtain slice information (the aforementioned maximum quota), information of the SMF 132 (instance) belonging to the slice, and It is possible to receive information on the current slice status (the number of terminals currently connected, the number of sessions, etc.). In addition, during this process, if the maximum quota set for a specific slice is reached (for example, the maximum number of sessions accessible to the slice is reached), information about this may be received. If the terminal 120 reaches the limit of the quota that can be supported for the requested slice or the DNN associated with the slice, the AMF 131 secures resources by releasing the requested session instead of the requested session according to the priority per subscriber/service. You can choose which session to do. At this time, in the selection process, the AMF 131 searches for previously created sessions having a lower priority than the newly requested session (or subscriber) for the same slice as the requested slice (or slice and mapped DNN), If there is a previously created session having a lower priority than the newly requested session (or subscriber), a session with the lowest priority is selected among them, and a process for deleting the selected session is performed. Priority per subscriber or session may be received through the UDM 133, received through the PCF 154 as described above, or a value set in the AMF 133 may be used.

In step S340, the AMF 131 finds the SMF 132 for the selected session, requests to delete the PDU session (if a new request creates a PDU session) to the SMF 132, and sends a Nsmf_PDUSession_ReleaseSMContext message to the PDU Session ID. It can be delivered including, or the Nsmf_PDUSession_UpdateSMContext message can be delivered together with the PDU Session Release Request and PDU Session ID. In this case, the request message transmitted from the AMF 131 to the SMF 132 may include an indication indicating that the reason for the release of the PDU session is due to the quota control for the slice or that the session has a higher priority. .

In step S350, the SMF 132 performs deletion/update processing for the PDU session according to the PDU session deletion/update request received in step S340.

In step S360, the AMF 131 knows that a session available for the slice has occurred according to the result of step S350, and performs a new session creation procedure received from the terminal 120 in step S320.

Meanwhile, in the description of the above embodiment, it is assumed that the target of control is a new PDU Session, but the target of control may be a QoS Flow or IP Flow belonging to the PDU Session. That is, in step S320, when the terminal 120 transmits a request for adding a new QoS flow or IP flow, or when the condition for adding a new QoS flow or IP flow is satisfied in 5GC, the AMF 131 Check the quota of the slice targeted for the request, and if the maximum number of QoS flows or IP flows has already been reached, select and release a lower priority QoS flow (or IP flow), and then release the newly requested QoS flow. (Or IP Flow) can be created.

4 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.

In step S410, a registration process is performed between the terminal 120 and the network. During this process, slice selection for the terminal 120 and selection of the AMF 131 may be performed, and for this purpose, information on the slice from the NSSF 134 and the NRF 153 (maximum number of sessions that can be provided, etc.) Can be received. In addition, during this process, the AMF 131 may receive subscription information for the subscriber from the UDM 155, and at this time, the slices allowed for the subscriber (Subscribed S-NSSAIs) and mapping to the subscription information for access and mobility management. The information of the DNN may be included. In this case, relative priority information may be included for each slice or for each DNN, and QoS parameters that can be provided by default for each DNN may be included. Relative priority for each DNN may be provided using ARP among QoS parameters that can be basically provided for each DNN.

In step S420, the terminal 120 transmits a session creation request (PDU session establishment request) for transmitting and receiving traffic for a specific slice. The request of the terminal 120 may include a slice identifier (S-NSSAI) and a mapped DNN.

In step S430, the AMF 131 performs a process for selecting the slice and the SMF 132 belonging to the slice in order to create a session for the slice according to the request of the terminal 120. At this time, the AMF 131 exchanges a message with the NSSF 134 or the NRF 153, or the PCF 154 to obtain slice information (the aforementioned maximum quota), information of the SMF 132 (instance) belonging to the slice, and It is possible to receive information on the current slice status (the number of terminals currently connected, the number of sessions, etc.). In addition, during this process, if the maximum quota set for a specific slice is reached (for example, the maximum number of sessions accessible to the slice is reached), information about this may be received. If the terminal 120 reaches the limit of the quota that can be supported for the requested slice or the DNN associated with the slice, the AMF 131 secures resources by releasing the requested session instead of the requested session according to the priority per subscriber/service. You can choose which session to do. At this time, in the selection process, the AMF 131 searches for previously created sessions having a lower priority than the newly requested session (or subscriber) for the same slice as the requested slice (or slice and mapped DNN), and if If there is an existing created session having a lower priority than the newly requested session (or subscriber), a session with the lowest priority is selected among them, and a process for deleting the selected session is performed. Priority per subscriber or session may be received through the UDM 155 as described above, received through the PCF 154, or a value set in the AMF 131 may be used.

In step S440, the AMF 131 transmits a request (Nsmf_PDUSession_CreateSMContext) to create a PDU session according to the request received in step S320 to the selected SMF 132, and the message includes a new PDU Session ID, a subscriber ID, and S-NSSAI, DNN, etc. may be included.In addition, PDU Session ID, information on subscriber ID, and reason for deletion that must be deleted due to quota restrictions prior to creating this PDU Session are limited by quota (the maximum number of sessions). Restrictions) may include an indication to indicate that this is due.

In step S450, the SMF 132 searches for a PDU session to be deleted included in the PDU session creation request received in step S440 and performs deletion/update processing for the PDU session.

In step S460, when it is possible to create a new session for a slice (or sliced and mapped DNN), the SMF 132 performs a new PDU Session creation procedure received in step S440.

Meanwhile, in the description of the above embodiment, it is assumed that the target of control is a new PDU Session, but the target of control may be a QoS Flow or IP Flow belonging to the PDU Session. That is, if the terminal transmits a request for adding a new QoS flow or IP flow in step S420, or if the condition for adding a new QoS flow or IP flow is satisfied in 5GC, the AMF is the target slice of the request. Check the Quota of, and if the maximum number of QoS flows or IP flows has already been reached, select and release a lower priority QoS flow (or IP flow), and release the newly requested QoS flow (or IP flow). Can be created.

5 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.

In step S510, a registration process is performed between the terminal 120 and the network. During this process, slice selection for the terminal 120 and selection of the AMF 131 may be performed, and for this purpose, information on the slice from the NSSF 134 and the NRF 153 (maximum number of sessions that can be provided, etc.) Can be received. In addition, during this process, the AMF 131 may receive subscription information for the subscriber from the UDM 155, and at this time, the slices allowed for the subscriber (Subscribed S-NSSAIs) and mapping to the subscription information for access and mobility management. The information of the DNN may be included. In this case, the relative priority information for each slice or for each DNN may be included, and a QoS parameter that can be provided by default for each DNN may be included. Relative priority for each DNN may be provided using ARP among QoS parameters that can be basically provided for each DNN.

In step S520, the terminal 120 transmits a session creation request (PDU session establishment request) for transmitting and receiving traffic for a specific slice. The request of the terminal 120 may include a slice identifier (S-NSSAI) and a mapped DNN.

In step S530, the AMF 131 performs a process for selecting the slice and the SMF 132 belonging to the slice in order to create a session for the slice according to the request of the terminal 120. At this time, the AMF 131 exchanges a message with the NSSF 134 or the NRF 153, or the PCF 154 to obtain slice information (the aforementioned maximum quota), information of the SMF 132 (instance) belonging to the slice, and It is possible to receive information on the current slice status (the number of terminals currently connected, the number of sessions, etc.). In addition, during this process, if the maximum quota set for a specific slice is reached (for example, the maximum number of sessions accessible to the slice is reached), information about this may be received.

In step S540, the AMF 131 transmits a request (Nsmf_PDUSession_CreateSMContext) to create a PDU session according to the request received from the terminal 120 in step S520 to the selected SMF 132, and in this message, a new PDU session to be created ID, subscriber ID, S-NSSAI, DNN, etc. can be included, and if the maximum number of accessible sessions (Quota) for the requested S-NASSI (or DNN mapped with S-NSSAI) is reached, release for other sessions Indication may be included informing that it is necessary to perform.

In step S550, the SMF 132 processes the PDU Session creation request received in step S540, and during this process, the SMF 132 may receive subscription information for the subscriber's session from the UDM 155. In this case, the subscription information may include slices allowed for a subscriber, mapped DNN information, and relative priority information for each DNN, and may also include QoS parameters that can be provided by default for each DNN. Relative priority for each DNN may be provided using ARP among QoS parameters that can be basically provided for each DNN. In step S560, if the terminal 120 has reached a limit of the quota that can be supported for the requested slice or the DNN associated with the slice, or the message received in step S540 from the AMF 131 must be released for another session. When receiving the information, the SMF 132 may select a session for securing resources by releasing the requested session instead of the requested session according to the priority of each subscriber/service. At this time, in the selection process, the SMF 132 searches for previously created sessions having a lower priority than the newly requested session (or subscriber) for the same slice as the requested slice (or slice and mapped DNN), and if If there is an existing created session having a lower priority than the newly requested session (or subscriber), a session with the lowest priority is selected among them, and a process for deleting the selected session is performed. Priority per subscriber or session may be received through the UDM 155 as described above, received through the PCF 154, or a value set in the SMF 132 may be used.

In step S570, the SMF 132 searches for a PDU session to be deleted and performs deletion/update processing on the PDU session.

In step S580, when it is possible to create a new session for a slice (or sliced and mapped DNN), the SMF 132 performs a procedure for creating a new PDU Session received in step S540.

Meanwhile, in the description of the above embodiment, it is assumed that the target of control is a new PDU Session, but the target of control may be a QoS Flow or IP Flow belonging to the PDU Session. That is, if the terminal transmits a request for adding a new QoS flow or IP flow in step S520, or if the condition for adding a new QoS flow or IP flow is satisfied in 5GC, the SMF is the target slice of the request. Check the Quota of, and if the maximum number of QoS flows or IP flows has already been reached, select and release a lower priority QoS flow (or IP flow), and release the newly requested QoS flow (or IP flow). You can create it.

6 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.

In step S610, a registration process is performed between the terminal 120 and the network. During this process, slice selection and AMF 131 selection process for the terminal 120 may be performed, and for this purpose, information on slices (maximum number of sessions that can be provided, etc.) from NSSF 134, NRF 153, etc. You can receive it. In addition, during this process, the AMF 131 may receive subscription information for the subscriber from the UDM 155, and at this time, the slices allowed for the subscriber (Subscribed S-NSSAIs) and mapping to the subscription information for access and mobility management. The information of the DNN may be included. At this time, the subscription information may also include QoS parameters that can be provided by default for each slice or for each DNN, and if the maximum quota for a slice is reached, an indication indicating whether to provide a lower QoS is allowed. Can be included. According to an embodiment of the present disclosure, the quota may include the number of maximum PDU sessions allowed for each slice, the number of QoS flows having a specific 5QI, the number of GBR flows, and the like.

In step S620, the terminal 120 transmits a session creation request (PDU session establishment request) for transmitting and receiving traffic for a specific slice. The request of the terminal 120 may include a slice identifier (S-NSSAI) and a mapped DNN.

In step S630, the AMF 131 performs a process for selecting the slice and the SMF 132 belonging to the slice in order to create a session for the slice according to the request of the terminal 120. At this time, the AMF 131 exchanges a message with the NSSF 134 or the NRF 153, or the PCF 154 to obtain slice information (the aforementioned maximum quota), information of the SMF 132 (instance) belonging to the slice, and It is possible to receive information on the current slice status (the number of terminals currently connected, the number of sessions, etc.). In addition, during this process, if the maximum quota set for a specific slice is reached (for example, when the maximum number of sessions that can be accessed at the same time in the slice is reached), information about this may be received.

In step S640, the AMF 131 transmits a request (Nsmf_PDUSession_CreateSMContext) to create a PDU session according to the request received from the terminal 120 in step S620 to the selected SMF 132, and in this message, a new PDU session to be created ID, subscriber ID, S-NSSAI, DNN, etc. can be included, and if the maximum supportable (Quota) for the requested S-NASSI (or DNN mapped with S-NSSAI) is reached, even if the service is provided by lowering the QoS It may include an indication that it is done.

In step S650, the SMF 132 processes the PDU Session creation request received in step S640, and during this process, the SMF 132 may receive subscription information for the subscriber's session from the UDM 155. In this case, the subscription information may include slices allowed for a subscriber, mapped DNN information, and relative priority information for each DNN, and may also include QoS parameters that can be provided by default for each DNN. In addition, if the quota limit for the requested slice is reached, the subscription information may include an indication that a service may be provided by lowering the QoS. If the terminal 120 reaches the limit of the quota that can be supported for the requested slice or the DNN associated with the slice, and it is possible to provide a service by lowering the QoS according to the subscription information, the SMF 132 performs an operation to adjust the QoS. Perform. When changing QoS, a parameter to be referenced may be received from the UDM 155 in the form of subscription information, a setting value stored in the SMF 132 may be used, or may be received through the PCF 154 (steps S660 and S670).

In step S660, the SMF 132 establishes an SM (Session Management) Policy Assoication with the PCF 154 in order to receive a policy to be used for the subscriber. At this time, the request message Npcf_SMPolicyControl_Create request transmitted by the SMF 132 may include information such as subscriber ID, PDU session ID, S-NSSAI, and DNN, and additionally, QoS information to be applied when the quota limit for S-NSSAI is reached. Indication requesting for may be included.

In step S670, the PCF 157 generates a policy according to the request of the SMF 132, and for this purpose, it may exchange information with a UDR (Unified Data Repository) when necessary. In step S680, the PCF 157 includes the policy created in the response Npcf_SMPolicyControl_Create response sent to the SMF 132, and in particular, QoS information to be applied when the quota limit is reached according to the request in step S660 may be included in the response. . At this time, the policy delivered by the PCF (154) includes both QoS information to be applied when the quota limit is not reached and QoS information to be applied when the quota limit is reached, or when it is clear that the quota limit has already been reached. When the limit is reached, only QoS information to be applied may be included. At this time, the lower QoS information to be applied when the quota limit is reached, lower the maximum allowed data rate compared to when the quota limit is not applied, or change the guaranteed bit rate (GBR) flow to non-GBR flow (i.e. , GBR flow is not allowed), 5QI adjustment (down to 5QI with a lower relative priority), ARP (Allocation and Retention Priority) down to a lower one, or limiting the maximum number of flows belonging to the session. Can be.

In step S690, the SMF 132 performs a session creation procedure according to the set QoS information.

Meanwhile, in the description of the above embodiment, it is assumed that the target of control is a new PDU Session, but the target of control may be applied to QoS Flow or IP Flow belonging to the PDU Session. That is, when the terminal transmits a request for adding a new QoS flow or IP flow in step S620, or when the condition for adding a new QoS flow or IP flow is satisfied in 5GC, the SMF is the target slice of the request. Check the quota of, and if the maximum quota is reached, the QoS is lowered, and accordingly, a newly requested QoS flow (or IP flow) can be created.

7 is a flowchart illustrating a procedure for performing session control for each network slice according to an embodiment of the present disclosure.

In step S710, a registration process is performed between the terminal 120 and the network. During this process, slice selection and AMF 131 selection process for the terminal may be performed, and for this purpose, information on slices (maximum number of sessions that can be provided, etc.) can be received from NSSF 134 and NRF 153. I can. In addition, during this process, the AMF 131 may receive subscription information for the subscriber from the UDM 155, and at this time, the slices allowed for the subscriber (Subscribed S-NSSAIs) and mapping to the subscription information for access and mobility management. The information of the DNN may be included. In this case, the subscription information may also include an indication indicating whether DNN replacement is allowed if a quota restriction is applied to a specific slice and DNN for each slice or for each DNN. In addition, when DNN replacement is applicable, the DNN to be replaced may be included.

In step S720, the terminal 120 transmits a session creation request (PDU session establishment request) for transmitting and receiving traffic for a specific slice. The request of the terminal may include an identifier of a slice (S-NSSAI) and a mapped DNN.

In step S730, the AMF 131 performs a process for selecting the slice and the SMF 132 belonging to the slice in order to create a session for the slice according to the request of the terminal 120. At this time, the AMF 131 exchanges a message with the NSSF 134 or the NRF 153, or the PCF 154, and the slice information (the aforementioned maximum quota), information of the SMF (instance) belonging to the slice, and the current slice You can receive status (the number of terminals currently connected, the number of sessions, etc.) information. In addition, during this process, if the maximum quota set for a specific slice is reached (for example, the maximum number of sessions accessible to the slice is reached), information about this may be received. The AMF 131 may establish an association with the PCF 154 to receive a policy for the terminal. At this time, the policy for a subscriber received by the AMF 131 has a quota limit for slice or slice-DNN mapping. If applicable, an indication indicating whether DNN replacement is allowed may be included. In addition, the policy may include the DNN to be replaced when DNN replacement is applicable. The AMF 131 may perform a procedure for changing the requested DNN to another DNN if the maximum number of sessions that can be provided for the slice (or slice and DNN) requested by the terminal 120 has already been reached. The DNN information to be used may be determined based on the subscription information received from the UDM 155 and the policy received from the PCF 154. At this time, if the replaced DNN is before the PDU session has been created, a process of creating a new session with the corresponding DNN is performed. At this time, according to the DNN replacement operation, information of the requested DNN, not the replaced DNN, is transmitted to the terminal 120.

If there is an already created session belonging to the same slice for the corresponding terminal 120 with the replaced DNN, the two sessions are created/managed in a merged form. That is, if a PDU session has already been created with DNN #A for the UE, the same UE requests the creation of a PDU session with DNN #B, but the maximum support is based on the quota limit for a slice (or a DNN mapped to a slice). When the number of possible PDU sessions is reached, the AMF may check whether DNN replacement is allowed, and perform a replacement operation from DNN #B to DNN #A. The network may additionally perform an operation for this if QoS information (transmission rate, 5QI, ARP, packet filter, etc.) for a PDU session needs to be changed as DNN replacement for a slice is performed.

8 is a block diagram showing the configuration of an NF according to an embodiment of the present disclosure.

As described above, the NF may include the AMF 131, the SMF 132, and the UPF 133. In addition, NF may include NSSF (134), NFR (153), and SCP (157). As another example, NF may be implemented as a separate network entity.

Referring to FIG. 8, the network interface 810 may communicate with other network entities of the core network. For example, when the NF is the AMF 131, communication with the SMF 132, the UPF 133, the NSSF 134, the NFR 153 or/and the SCP 157 may be performed. As another example, when the NF is the SMF 132, communication with the AMF 131, the UPF 133, the NSSF 134, the NFR 153, or/and the SCP 157 may be performed. In another case, when the NF is the NSSF 134, communication with the AMF 131, the UPF 133, the SMF 132, the NFR 153, or/and the SCP 157 may be performed. Similarly, if the NF is one specific network entity, it can communicate with other entities in the core network.

The control unit 811 may be implemented as at least one processor or/and a program for performing the operation of the NF. For example, when the NF is the AMF 131, the controller 811 may perform the operation of the AMF 131 described above. As another example, when the NF is the NSSF 134, the above-described operation of the NSSF 134 may be performed. In the case of other network entities, control necessary for the above-described operation can be performed in the same manner.

The memory 812 may store programs required by the controller 811 and various types of control information, as well as each information described in the present disclosure. For example, when the NF is the AMF 131, the memory 812 may store information received from the AMF 131 described above or received from an external entity. As another example, when the NF is the NSSF 134, the necessary control information or/and received information from the above-described NSSF 134 may be stored. In the case of other network entities, information necessary for the operation described above may be stored in the same manner.

9 is a flowchart illustrating an operation between NFs according to an embodiment of the present disclosure.

In the present disclosure, the Acting NF may actually be one of the NFs that process the request of the UE. For example, Acting NF may be AMF for mobility management such as registration, and SMF for session management such as PDU Session Establishment.

In the present disclosure, the Counting NF may be any type of NF that collects slice state information (the number of terminals per slice currently connected, the number of sessions per current slice, the current data rate per slice, etc.) or provides a slice quota management function. . For example, a separate NF (e.g., SQMF: Slice Quota Management Function) providing the above function, or NF such as NSSF, NRF, PCF, NWDAF, etc. may be implemented to include the corresponding function.

In the present disclosure, the configuring NF is an NF having a function of transferring configuration information related to a specific slice to another NF, and may be a kind of OMA function connected to another NF. Configuring NF may have an integrated structure with Counting NF.

In step S910, the configuring NF may set information for providing the Acting NF with a slice management function in consideration of a quota for a specific slice. The set information is an operation based on the quota when the terminal requests the use of the S-NSSAI for each S-NSSAI supported by the Acting NF, that is, the current state information is collected for each target S-NSSAI and reported to the Counting NF. Information for, information for finding Counting NF, and conditions or periods for reporting may be included. In addition, the information may include information for accepting or rejecting the request only by a user having a specific priority or a specific service type (DNN, 5QI, etc.) if the Quota reaches the upper limit or is close to the upper limit. This information is a parameter that can determine that the quota has reached or is nearing the upper limit, for example, the ratio (percentage, etc.) to the current slice usage (number of registered terminals, number of sessions created, amount of data, etc.) compared to the maximum upper limit. The threshold value of or simply the threshold for the current slice usage, and the priority between subscribers or the type of subscriber to be allowed or denied preferentially, the priority between DNNs, or the priority between DNNs and 5QIs to be allowed or denied with priority Alternatively, it may include a target 5QI to be allowed or denied with priority, or a priority between ARPs or a target ARP to be allowed or denied with priority. Step S910 may be performed by exchanging messages with the Acting NF if the configuring NF exists separately, or may be set to Local Configuration in the Acting NF.

In step S920, the Acting NF transmits a reporting message for delivering slice state information to the Counting NF. The slice state information may include the number of access terminals for each current S-NSSAI, the number of sessions, and the amount of data transmission.

In step S930, the counting NF may update the slice state information using the information received in step S920. Also, using the information, it is possible to determine whether the current slice's Quota has reached the upper limit.

In step S940, the Counting NF may transmit the slice state information and additional parameters for control that it has aggregated to the Acting NF. If a parameter needs to be provided to dynamically perform an action for slice control, Counting NF is the information delivered by the Configuring NF in step S910, e.g., if the Quota reaches the upper limit or approaches the upper limit, a specific priority is given. Information for accepting the request or rejecting the request may be included only by a user having a priority or a specific service type (DNN, 5QI, etc.). Such information is a parameter that can determine that the upper limit has been reached or is approaching, for example, the threshold of the ratio (percentage, etc.) to the current slice usage (number of registered terminals, number of sessions created, amount of data, etc.) compared to the maximum upper limit. (Threshold) value or simply the threshold for the current slice usage, and the priority between subscribers or the type of subscriber to be allowed or denied preferentially, the priority between DNNs or the priority or priority between the DNNs and 5QIs to be allowed or denied with priority It may include the target 5QI to be allowed or rejected, or the priority between ARPs or the target ARP to be allowed or rejected with priority.

In step S950, the Acting NF performs an operation based on the information received in step S940. If the Quota for a slice is nearing the upper limit, a request for registration or session creation of a terminal that satisfies a specific condition may be preferentially processed or rejected according to steps S910, S940, or a method set by a separate method. If a threshold value for performing such an operation is set, the Acting NF may determine whether the condition is satisfied in consideration of the state of the current slice. For example, if a PDU session created for a specific S-NSSAI is set as the Threshold, the number of currently created sessions and the threshold are compared, and if the condition is satisfied, the request to create a session for a specific DNN is accepted or , Session creation request for a specific DNN can be rejected. Alternatively, if there is already a session created with another DNN for the S-NSSAI requested by the terminal, it may be rejected, and only when there is no session created for the S-NSSAI may be accepted. Alternatively, if the threshold condition is satisfied, referring to the default QoS parameter of the requested session, if it has a specific 5QI, allow/reject, or if it has a specific ARP, allow/reject.

The methods according to the embodiments described in the claims or the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in a computer-readable storage medium are configured to be executable by one or more processors in an electronic device (device). The one or more programs include instructions for causing the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure.

Such programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), and electrically erasable programmable ROM. (electrically erasable programmable read only memory, EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all of them. In addition, a plurality of configuration memories may be included.

In addition, the program is a communication network such as the Internet (Internet), Intranet (Intranet), LAN (local area network), WAN (wide area network), or SAN (storage area network), or a communication network composed of a combination thereof. It may be stored in an accessible storage device. Such a storage device may access a device performing an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may access a device performing an embodiment of the present disclosure.

In the above-described specific embodiments of the present disclosure, components included in the disclosure are expressed in the singular or plural according to the presented specific embodiments. However, the singular or plural expression is selected appropriately for the situation presented for convenience of description, and the present disclosure is not limited to the singular or plural constituent elements, and even constituent elements expressed in plural are composed of the singular or in the singular. Even the expressed constituent elements may be composed of pluralities.

Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, various modifications may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is limited to the described embodiments and should not be determined, and should be determined by the scope of the claims and equivalents as well as the scope of the claims to be described later.

Claims (1)

In a method for controlling a PDU session by AMF in a wireless communication system,
Selecting a network slice;
Receiving a PDU session creation request for transmitting and receiving traffic for the network slice from a terminal; And
And performing the creation or deletion of a PDU session based on the request.

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