Patent Description:
To meet the demand for wireless data traffic having increased since deployment of <NUM>th generation (<NUM>) communication systems, efforts have been made to develop an improved <NUM>th generation (<NUM>) or pre-<NUM> communication system. Therefore, the <NUM> or pre-<NUM> communication system is also called a beyond <NUM> network communication system or a post long term evolution (post LTE) system.

The <NUM> communication system is considered to be implemented in higher frequency (mmWave) bands (e.g., <NUM> bands) so as to accomplish higher data rates. To decrease propagation loss of radio waves and increase a transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beamforming, and large scale antenna techniques are discussed in <NUM> communication systems.

In addition, in <NUM> communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation, and the like.

In the <NUM> system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

With the development of various information technology (IT) technologies, network equipment has evolved into a network function (NF) virtualized by applying virtualization technology, and such virtualized NFs are implemented in a software form beyond physical limitations, thus being installed/operated in various types of clouds or data centers (DCs). In particular, the NF may be freely expanded/reduced (scaling), installed (initiation), or ended (termination), depending on service requirements, system capacity, or network load. Even if these NFs are implemented in the form of software, a physical constitution is not excluded because they have to be basically driven in the physical constitution, for example, certain equipment. Also, it is possible to implement the NFs with a simple physical constitution, that is, only hardware. Therefore, because of having a physical component, each NF may also be referred to as an "NF device".

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

<CIT> describes a slice information update method and an apparatus to notify a corresponding terminal when a network slice not supported by a PLMN is updated to be supported by the PLMN.

XP51744716A; Author: 3rd Generation Partnership Project; Reference: Technical Specification Group Core Network and Terminals; <NUM> System; Network Slice Selection Services; Stage <NUM> describing in sections <NUM>. <NUM> and <NUM>. <NUM> updating of the S-NSSAIs the AMF supports and updating the AMF with any S-NSSAIs restricted per TA.

Although a network slicing technique has been introduced in various forms of wireless communication networks, a specific plan to allocate network resources by using the network slicing technique is not provided.

The disclosure provides a method and apparatus for managing a network slice in a wireless communication system and accessing the network slice.

The disclosure provides a method and apparatus for selecting a network slice in a wireless communication system.

The disclosure provides a procedure for accessing and selecting a network slice in a wireless communication system.

The invention is set out in the appended set of claims, wherein the figures and respective description relate to advantageous embodiments thereof.

According to the disclosure, it is possible to access a network slice, select the network slice, and thus achieve manage smooth network slice management in a wireless communication system.

Terms in the disclosure are used merely to describe a specific embodiment and may not be intended to limit the scope of other embodiments. The singular expressions may include plural expressions unless the context clearly dictates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those skilled in the art. Among terms used herein, some terms defined in a normal dictionary may be interpreted as having the same or similar meaning as the contextual meanings in the related art and are not to be construed as an ideal or overly formal sense unless expressly defined to the contrary herein. In some cases, the terms defined herein cannot be construed to exclude embodiments of the disclosure.

In various embodiments of the disclosure described hereinafter, a hardware approach will be exemplarily used for description. However, because various embodiments of the disclosure include a technology using both hardware and software, the various embodiments of the disclosure do not exclude a software-based approach.

The disclosure relates to a method and apparatus for supporting various services in a wireless communication system. Specifically, the disclosure describes a technology for supporting various services by supporting mobility of a user equipment (UE) in a wireless communication system.

In the following description, terms for identifying access nodes, terms referring to network entities or network functions (NFs), terms referring to messages, terms referring to interfaces between network objects, terms referring to various kinds of identification information, etc. are exemplified for convenience of description. Therefore, the disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

Hereinafter, for convenience of description, the disclosure uses terms and names defined in the <NUM>rd generation partnership project long term evolution (3GPP LTE) and <NUM> standards. However, the disclosure is not limited by such terms and names and may be equally applied to systems conforming to other standards.

In the following, objects that exchange information for access control and state management will be collectively referred to as an NF. The NF may include, for example, an access and mobility management function (hereinafter, AMF) device, a session management function (hereinafter, SMF) device, and a network slice selection function (hereinafter, NSSF) device. However, embodiments of the disclosure can be equally applied even when the NF is actually implemented as an instance (Instance, i.e., an AMF instance, an SMF instance, an NSSF instance, etc.).

In the disclosure, the term 'instance' may mean that a specific NF exists in the form of software code and, in order to perform the function of the NF in a physical computing system (e.g., a specific computing system existing on the core network), is in an executable state by being allocated physical and/or logical resources from the computing system. Therefore, the AMF instance, the SMF instance, and the NSSF instance may mean that, for AMF, SMF, and NSSF operations, physical and/or logical resources are allocated from a specific computing system existing on the core network and thus become usable. As a result, the AMF instance, the SMF instance, and the NSSF instance that are allocated physical and/or logical resources for AMF operation, SMF operation, and NSSF operation from a specific computing system existing on the network can perform the same operations as a physical AMF device, a physical SMF device, and a physical NSSF device, respectively. Therefore, in embodiments of the disclosure, items described as an NF (e.g., AMF, SMF, UPF, NSSF, NRF, SCP, etc.) device may be replaced with an NF instance or, conversely, items described as an NF instance may be replaced with an NF device. Similarly, in embodiments of the disclosure, items described as an NW slice may be replaced with an NW slice instance, or items described as an NW slice instance may be replaced with an NW slice.

<FIG> illustrates a wireless communication system according to various embodiments of the disclosure.

With reference to <FIG>, as a part of nodes using a radio channel in the wireless communication system, a radio access node (RAN) <NUM> and a user equipment (UE) <NUM> are illustrated. Although <FIG> illustrates only one RAN <NUM> and only one UE <NUM>, other RANs identical or similar to the RAN <NUM> may be further included. In addition, <FIG> illustrates that only one UE <NUM> communicates with one RAN <NUM>. However, in actual, a plurality of UEs can communicate with one RAN <NUM>.

The RAN <NUM> is a network infrastructure that provides a radio access to the UE <NUM>. The RAN <NUM> has coverage (not shown in <FIG>) defined as a certain geographic area based on a signal transmittable distance. The RAN <NUM> may be referred to as 'base station', 'access point (AP)', 'eNodeB (eNB)', '5th generation (<NUM>) node', 'wireless point', 'transmission/reception point (TRP)', 'access network (AN)', or any other term having an equivalent technical meaning.

The UE <NUM> is a device used by a user and communicates with the RAN <NUM> through a radio channel. In some cases, the UE <NUM> may be operated without the user's involvement. For example, the UE <NUM> may be a device that performs machine type communication (MTC) and may not be carried by the user. The UE <NUM> illustrated in <FIG> may include at least one portable user device and may include at least one MTC. The UE <NUM> of <FIG> may be referred to as 'terminal', 'mobile station', 'subscriber station', 'remote terminal', 'wireless terminal', 'user device', or any other term having an equivalent technical meaning.

An AMF device <NUM> may be a network entity that manages wireless network access and mobility for the UE <NUM>. An SMF device <NUM> may be a network entity that manages a connection of a packet data network for providing packet data to the UE <NUM>. The connection between the UE <NUM> and the SMF <NUM> may be a protocol data unit (PDU) session.

A user plane function (hereinafter, UPF) device <NUM> may be a gateway for delivering packets transmitted or received by the UE <NUM>, or a network entity serving as a gateway. The UPF <NUM> may be connected to a data network (DN) <NUM> connected to the Internet and thereby provide a path for data transmission/reception between the UE <NUM> and the DN <NUM>. Thus, the UPF <NUM> may route, to the Internet data network, data to be transmitted to the Internet among packets transmitted by the UE <NUM>.

A network slice selection function (NSSF) device <NUM> may be a network entity that performs a network selection operation described in the disclosure, for example, an operation of selecting a network slice. The operation of the NSSF device <NUM> will be described later in detail with reference to the drawings.

An authentication server function (AUSF) device <NUM> may be an equipment (network entity) that offers a service for processing subscriber authentication.

A network exposure function (NEF) device <NUM> may be a network entity that can access information to manage the UE <NUM> in the <NUM> network, subscribe to a mobility management event of the UE, subscribe to a session management event of the UE, request session-related information, configure charging information for the UE, request a change in a PDU session policy for the UE, and transmit small data about the UE.

A network repository function (NRF) device <NUM> may be an NF (network entity) that stores status information of NFs and has a function of processing a request to find an NF accessible by other NFs.

A policy and charging function (hereinafter, PCF) device <NUM> may be a network entity that applies a service policy, charging policy, and PDU session policy of a mobile communication operator for the UE <NUM>.

A unified data management (hereinafter, UDM) device <NUM> may be a network entity that stores information about a subscriber and/or the UE <NUM>.

An application function (AF) device <NUM> may be an NF (network entity) having a function of providing various services to users by interworking with a mobile communication network. Therefore, the AF device <NUM> may exist for each service.

A service communication proxy (SCP) device <NUM> is an NF (network entity) that provides functions such as NF discovery for communication between NFs and message transfer between NFs. The SCP <NUM> may operate in an integrated form with the NRF <NUM> according to an operator's selection, and in this case, the SCP <NUM> may include the function of the NRF <NUM>, or conversely the NRF <NUM> may include the function of the SCP <NUM>.

The above-described AMF device <NUM>, SMF device <NUM>, UPF device <NUM>, NSSF device <NUM>, AUSF device <NUM>, NEF device <NUM>, NRF device <NUM>, PCF device <NUM>, UDM device <NUM>, AF device <NUM>, and SCP device <NUM> may be implemented as instances in the form of software or firmware that runs in at least one or more devices and/or systems. In addition, the above-described devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may also be implemented in a hardware form if necessary. In the following description, the term "device" will be deleted for convenience of description. For example, the AMF device <NUM> will be referred to as the AMF <NUM>, and the SMF device <NUM> will be referred to as the SMF <NUM>.

Meanwhile, in <FIG>, symbols on lines connected among each network entity, the UE <NUM>, and the RAN <NUM> may refer to interfaces of respective entities. For example, an N1 interface may be used between the UE <NUM> and the AMF <NUM>, an N2 interface may be used between the RAN <NUM> and the AMF <NUM>, and an N3 interface may be used between the RAN <NUM> and the UPF <NUM>. Similarly, an N4 interface may be used between the SMF <NUM> and the UPF <NUM>, an N9 interface may be used between or inside the UPFs <NUM>, and an N6 interface may be used between the UPF <NUM> and the DN <NUM>. Also, the AUSF <NUM> may use an Nausf interface, and the NSSF <NUM> may use an Nnssf interface.

<FIG> illustrates a constitution of a wireless communication system according to various embodiments of the disclosure.

With reference to <FIG>, a mobile communication system (an operator network such as <NUM>, <NUM>, etc.) may be composed of a wireless base station, for example, a radio access network (RAN) <NUM>, and one or more core network slices. <FIG> exemplarily shows N core network slices <NUM>, <NUM>,. The RNA <NUM> may perform data transmission/reception between a UE (e.g., the UE <NUM> in <FIG>) and the data network (DN) <NUM> through at least one core network slice. Depending on the constitution of the operator network, a core network may be constructed in a slice form or without a slice, and coexistence of both is also possible. Basically, one core network slice may include NFs of one or more core networks. In general, one NF corresponding to one core network includes the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to another embodiment, the NF may be constructed without at least one of the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to still another embodiment, the NF may include other network function devices in addition to the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to yet another embodiment, the NF does not have at least one component among the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>, and may include at least one device other than the above-described devices.

In an embodiment of the disclosure, the respective network slices <NUM>, <NUM>,. , 21N may provide services suitable for their characteristics, and the capacity that the respective network slices <NUM>, <NUM>,. , 21N can provide at the same time may be different. The capacity of the network slices <NUM>, <NUM>,. , 21N may be, for example, the maximum number of UEs (subscribers) and the number of sessions. Each of the network slices <NUM>, <NUM>,. , 21N may control access to the network according to its capacity.

In <FIG>, a first network slice <NUM> (Core NW Slice #<NUM>) allows access of <NUM>,<NUM> UEs and can accommodate <NUM>,<NUM> sessions. A second network slice <NUM> (Core NW Slice #<NUM>) allows access of <NUM>,<NUM> UEs and can accommodate <NUM>,<NUM> sessions. In addition, an Nth network slice 21N (Core NW Slice #N) allows <NUM>,<NUM> UEs and can accommodate <NUM>,<NUM> sessions.

As illustrated in <FIG>, the capacity of the network slices <NUM>, <NUM>,. , 21N may be configured differently for respective slices according to a setting of a mobile communication operator. If a certain slice is leased or sold to a separate service provider, the capacity may be configured differently for respective slices in accordance with a service level agreement (SLA).

According to various embodiments of the disclosure, the capacity of one network slice may be expressed by at least one of the following parameters.

According to various embodiments of the disclosure, the capacity of one network slice may be configured as the number of UEs of the above parameter <NUM> and the maximum number of sessions of the above parameter <NUM> as shown in <FIG>. According to another embodiment, the capacity of one network slice may be configured using at least one or two or more parameters among the parameters <NUM> to <NUM>.

On the other hand, the parameters related to session and flow, such as <NUM>, <NUM>, <NUM>, and <NUM> of the above examples, may be expressed as a value for each slice (e.g., <NUM>,<NUM> sessions supported per network slice) or expressed as a specific value per accessing UE (e.g., up to four sessions supported at the same time for each UE accessing a network slice).

According to various embodiments of the disclosure, through the capacity control for each network slice as described above, it is possible to protect the operator's mobile communication network from overload, effectively use the network resources, and perform accurate charging between the mobile communication operator and the network slice user.

<FIG> is a signal flow diagram illustrating an operation of performing access control for each network slice according to various embodiments of the disclosure.

Before the description with reference to <FIG>, an NF <NUM> may have the constitution as described with reference to <FIG>. For example, the NF <NUM> may include the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to another embodiment, the NF <NUM> may include at least one of the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to still another embodiment, the NF <NUM> may further include a network function device other than the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. According to yet another embodiment, the NF <NUM> may include at least one of the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> and at least one other device in addition to the above-mentioned devices. According to further another embodiment, a separate function device for controlling the operation performed in the NF <NUM> of <FIG> may be additionally provided.

With reference to <FIG>, at operation <NUM>, the NF <NUM> belonging to one specific network slice may call a service for notifying its own network slice related information to the network slice selection function (NSSF) <NUM>. At the operation <NUM>, the service used by the NF <NUM> may use a "Nnssf_NSSAIAvailability_Update" message. The Nnssf_NSSAIAvailability_Update message may be a network slice selection assistance information (NSSAI) availability update message.

In the following embodiment of the disclosure, the description will be made using the NSSF <NUM>. According to another embodiment, without using the NSSF <NUM>, it may be implemented using another specific network device having a function of storing information about a network slice and assisting the selection of a network slice. A SupportedNssaiAvailabilityData message, which is a supported NSSAI availability data message delivered to the NSSF <NUM> by the NF <NUM>, may contain a location of the NF <NUM> (tracking area indicator, TAI) and a list of identifiers (S-NSSAI) of network slices to which the NF <NUM> belongs. Also, if a network slice instance is used, a slice instance identifier to which the NF (or NF instance) belongs may be contained. Specifically, the NF, the NF instance, and the NW slice instance may all be separate concepts. For example, because the NF instance is allocated physical and/or logical resources from a specific system of the core network to perform the function of the NF as described above, the NF instance can perform the same operation as the NF. However, the NF and the NF instance may exist for the same NF. For example, a case in which a plurality of SMFs exist will be described as an example. For example, when there are two SMFs, one may be implemented as a physical device, and the other may be implemented as an NF instance. This can be equally applied even when there are three or more SMFs. Conversely, when there are two or more SMFs, all the SMFs may be implemented only as physical devices, or all the SMFs may be implemented as SMF instances.

From this point of view, the NW slice instance may also be implemented in the form of being combined with physical NFs, and all may be implemented as NFs allocated physical and/or logical resources from a specific system of the core network.

In this case, for capacity control for each network slice, a capacity parameter may be contained for each network slice identifier (NW slice ID). The capacity parameter may be one or more of the above-described parameters <NUM> to <NUM>.

According to various embodiments of the disclosure, information contained in a message transmitted by the NF <NUM> may have various forms. Hereinafter, the form of a message transmitted by the NF <NUM> according to the disclosure will be described with reference to <FIG>.

<FIG> are diagrams illustrating information contained in a message transmitted by an NF <NUM> according to various embodiments of the disclosure.

<FIG> shows the constitution of a SupportedNssaiAvailabilityData message according to an embodiment of the disclosure. With reference to <FIG>, attribute name fields may include 'tai', 'NF Type', 'supportedSnssaiList', and 'supportedSnassiCapacity'. Because the attribute name fields shown in <FIG> are fields according to an embodiment of the disclosure, additional fields may be further included.

Among the attribute name fields, 'tai' is an element containing the identifier of a tracking area. Among the attribute name fields, 'NF Type' is an element containing the type of a consumer NF. Among the attribute name fields, 'supportedSnssaiList' may contain a list of S-NSSAIs supported by the NF <NUM>, and if the TAI is included, this information is valid for the TA. Among the attribute name fields, 'supportedSnassiCapacity' may be an element containing the capacity of each corresponding single network slice selection assistance information (S-NSSAI).

<FIG> shows the constitution of SliceCapacity corresponding to the 'supportedSnassiCapacity' attribute in the message as shown in <FIG> according to an embodiment of the disclosure.

With reference to <FIG>, the attribute name fields of SliceCapacity may include at least one of 'maxUEs', 'maxSessions', 'maxIPFlows', 'maxQoSFlows', and 'maxGBRFlows'.

Among the attribute name fields of <FIG>, 'maxUEs' indicates the maximum number of UEs supported by the corresponding network slice. Among the attribute name fields of <FIG>, 'maxSessions' indicates the maximum number of sessions supported by the corresponding network slice. Among the attribute name fields of <FIG>, 'maxIPFlows' indicates the maximum number of IP flows supported by the corresponding network slice. Among the attribute name fields of <FIG>, 'maxQoSFlows' indicates the maximum number of QoS flows supported by the corresponding network slice. Among the attribute name fields of <FIG>, 'maxGBRFlows' indicates the maximum number of GBR flows supported by the corresponding network slice.

The above-described attribute name fields of <FIG> may be information corresponding to the capacity of the network slice described above with reference to <FIG>.

<FIG> shows the constitution of a SupportedNssaiAvailabilityData message according to another embodiment of the disclosure. With reference to <FIG>, attribute name fields may include 'Tai', 'NF Type', and 'supportedSnssaiList'. Because the attribute name fields shown in <FIG> are fields according to an embodiment of the disclosure, additional fields may be further included.

The attribute name fields of 'Tai' and 'NF Type' in <FIG> may be the same information as the attribute name fields described above in <FIG>. However, in <FIG>, the field of 'supportedSnssaiList' may contain network slice information supported by the NF <NUM>, and if the TAI is included, this information is valid for the TA. In case of constructing the SupportedNssaiAvailabilityData message as shown in <FIG>, the attribute for each array constituting the 'supportedSnssaiList' may be defined as in <FIG>.

With reference to <FIG>, the attribute name fields of SliceCapacity may include at least one of 'supportedSlice' and 'supportedSliceCapacity'. The 'supportedSlice' field of <FIG> may contain the identifier of a tracking area, and the 'supportedSliceCapacity' field of <FIG> may indicate the capacity of a corresponding network slice and may contain one or a plurality of parameters.

<FIG> shows the constitution of SliceCapacity corresponding to the 'supportedSliceCapacity' attribute name field of <FIG> according to an embodiment of the disclosure.

With reference to <FIG>, the attribute fields of SliceCapacity may include at least one of 'maxUEs', 'maxSessions', 'maxIPFlows', 'maxQoSFlows', and 'maxGBRFlows'.

Returning to <FIG>, at the operation <NUM> as described above, the NF <NUM> may transmit the "Nnssf_NSSAIAvailability_Update" message to the NSSF <NUM> in order to call a service for notifying its own network slice related information.

Then, at operation <NUM>, the NSSF <NUM> may store the information received from the NF <NUM> and, in response to the service request, transmit an NSSAI Availability Update response message to the NF <NUM> that has transmitted the Nnssf_NSSAIAvailability_Update message. Thereafter, when a request for providing information about a specific network slice or selecting a network slice is received from the NF <NUM>, the NSSF <NUM> may respond using the stored information.

At operation <NUM>, the NSSF <NUM> may request the NF <NUM> to notify a status or configuration when it is changed, or request the NF <NUM> to periodically inform the current status/configuration information. This request may be implemented as a subscribe message for an NF status change or a request message for reporting on a specific event. In this case, the request message may contain information (identifier) about the corresponding network slice to be a target, and status/configuration information to be received. The status information to be received may contain the following parameters. If a response is received only when a specific condition is met, the condition (threshold for a specific value, etc.) may be contained. If periodic information reporting is requested, the request message may contain a period for response.

The status information to be received by the NSSF <NUM> may contain the following values.

The current status per network slice may contain the following information.

As such, the current usage per network slice is in the form of dividing the current usage by the maximum supportable usage and multiplying it by <NUM>, thus being percentage (%) information.

At operation <NUM>, in response to the request of the NSSF <NUM>, the NF <NUM> may generate and transmit a reporting (NF status change notification) message about network slice information of the NF <NUM>. If a condition for reporting is configured, the NF <NUM> may generate the reporting message and transmit it to the NSSF <NUM> only when the condition is satisfied. Accordingly, the NSSF <NUM> may receive the reporting message. Also, the NSSF <NUM> may update pre-stored data, based on the received reporting message.

On the other hand, in an embodiment of the disclosure, when a specific network slice instance is selected as a result of network slice selection, and a network slice instance (NSI) ID is contained in the response message, subsequent selection of an NF belonging to the network slice may be made using an NSI ID. A basic operating principle is as follows.

<FIG> is a signal flow diagram illustrating a control operation in consideration of the capacity of a network slice during registration management, mobility management, and session management of a UE according to an embodiment of the disclosure.

Although <FIG> shows the entire procedure that the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> are included in a network slice and operate, it may be applied only to some NFs or the operation sequence for each NF may be changed, depending on network slice constitution or configuration. However, it should be noted that <FIG> illustrates a signal flow for explaining operations in an overall perspective.

In the following description, the NF <NUM> is described in a form including the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>, and the NF <NUM> may have a meaning to collectively refer to the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>. In addition, the NF <NUM> may correspond to one network slice. For example, the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> included in the NF <NUM> may be implemented as a device and/or software and/or firmware for operating in the same single network slice. Also, the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> included in the NF <NUM> may be some functions allocated to the corresponding network slice in the AMF device, the SMF device, and the UPF device.

At operation <NUM>, the NF <NUM>, for example, the AMF <NUM>, the SMF <NUM>, and the UPF <NUM>, may call a service for notifying its own network slice related information to the network slice selection function (NSSF) <NUM>. In the example of <FIG>, the service used by the NF <NUM> may be an Nnssf_NSSAIAvailability_Update message. Although the description is made using the NSSF <NUM> in this embodiment, it may be performed by another specific network entity having a function of storing information of a network slice and assisting the selection of a network slice according to various embodiments of the disclosure.

In an example of operation 510a, if the NF <NUM> is the AMF <NUM>, the NF type is configured as AMF (NF type = AMF), and the information (SupportedNssaiAvailabilityData) message transmitted to the NSSF <NUM> by the AMF <NUM> may contain a location (TAI) of the AMF <NUM> and an identifier (S-NSSAI) list of a network slice to which the AMF <NUM> belongs. In this case, for capacity control per network slice, a capacity parameter per network slice identifier may be contained. The capacity parameter may be one or more of the parameters described above in the embodiments of <FIG> and <FIG>. For example, for the AMF <NUM>, the maximum number of UEs (subscribers or users) capable of being provided in a network slice may be contained.

In an example of operation 510b, if the NF <NUM> is the SMF <NUM>, the NF type is configured as SMF (NF type = SMF), and the information (SupportedNssaiAvailabilityData) message transmitted to the NSSF <NUM> by the SMF <NUM> may contain a location (TAI or service area ID) of the SMF <NUM> and an identifier (S-NSSAI) list of a network slice to which the SMF <NUM> belongs. In this case, for capacity control per network slice, a capacity parameter per network slice identifier may be contained. The capacity parameter may be one or more of the parameters described above in the embodiments of <FIG> and <FIG>. For example, for the SMF <NUM>, the maximum number of sessions and the maximum number of flows (IP flow, QoS flow, GBR flow) capable of being provided in a network slice may be contained.

In an example of operation 510c, if the NF <NUM> is the UPF <NUM>, the NF type is configured as UPF (NF type = UPF), and the information (SupportedNssaiAvailabilityData) message transmitted to the NSSF <NUM> by the UPF <NUM> may contain a location (TAI or service area ID) of the UPF <NUM> and an identifier (S-NSSAI) list of a network slice to which the UPF <NUM> belongs. In this case, for capacity control per network slice, a capacity parameter per network slice identifier may be contained. The capacity parameter may be one or more of the parameters described above in the embodiments of <FIG> and <FIG>. For example, for the UPF <NUM>, the maximum data rate capable of being provided in a network slice may be contained.

At operation <NUM>, the NSSF <NUM> may store the information received from the NF <NUM> and, in response to the service request, transmit a response message to the requesting NF <NUM>. Thereafter, when a request for providing information about a specific network slice or selecting a network slice is received from the NF <NUM>, the NSSF <NUM> may respond using the stored information.

According to an embodiment, if the NF <NUM> is the UPF <NUM>, the NSSF <NUM> may store the information received from the UPF <NUM> at the operation 510c and transmit a response message to the UPF <NUM> at operation 520a. According to another embodiment, if the NF <NUM> is the SMF <NUM>, the NSSF <NUM> may store the information received from the SMF <NUM> at the operation 510b and transmit a response message to the SMF <NUM> at operation 520b. According to still another embodiment, if the NF <NUM> is the AMF <NUM>, the NSSF <NUM> may store the information received from the AMF <NUM> at the operation 510a and transmit a respond message to the AMF <NUM> at operation 520c.

At operation <NUM>, the NSSF <NUM> may request the NF <NUM> to notify a status or configuration when it is changed, or request the NF <NUM> to periodically inform the current status/configuration information. This request may be implemented as a subscribe message for an NF status change or a request message for reporting on a specific event. In this case, the subscribe message or request message may contain information (identifier) about the network slice to be a target, and status/configuration information to be received. The status information to be received may contain following parameters.

If a response is received only when a specific condition is met, the condition (threshold for a specific value, etc.) may be contained. If periodic information reporting is requested, the request message may contain a period for response.

If the NF <NUM> is the AMF <NUM>, the NSSF <NUM> may request, at operation 530a, reporting on the number of currently registered UEs and the number of accessing UEs in relation to a specific network slice among the status information of the AMF <NUM>. If the NF <NUM> is the SMF <NUM>, the NSSF <NUM> may request, at operation 530b, reporting on the number of currently established sessions and the number of activated sessions in relation to a specific network slice among the status information of the SMF <NUM>. In addition, if the NF <NUM> is the SMF <NUM>, the NSSF <NUM> may additionally request information for each specific data network name (DNN) or data network access identifier (DNAI). If the NF <NUM> is the UPF <NUM>, the NSSF <NUM> may request, at operation 530c, reporting on the current data rate in relation to a specific network slice among the status information of the UPF <NUM>, and request information for each specific DNN or DNAI.

Meanwhile, in the above embodiment, instead of the NSSF <NUM> that stores information about a network slice and provides the information upon selecting the network slice, the NRF <NUM> (or a service communication proxy (SCP) <NUM>) that stores information for each NF and provides the information upon selecting the NF may be used alternatively. For example, the NFR <NUM> may basically store NF information, and the NF information may include information about a network slice to which the corresponding NF belongs. Therefore, when providing selection information to a specific NF in a state where information is stored for each NF, the NRF <NUM> may provide the stored NF information together with network slice information to which the corresponding NF belongs. In the same way as above, the SCP <NUM> may perform the operation of the NRF <NUM>.

If the NRF <NUM> is used, an operation that each NF (AMF, SMF, or UPF) transmits its own information and associated network slice information to the NRF <NUM> may be performed in the NF service registration operation. In this case, the NF profile transmitted by each NF may contain not only basic NF information but also the network slice information described at the operation <NUM>. Similarly, for the NF <NUM>, the NRF <NUM> may request and receive reporting on the current status information of the network slice from the corresponding NF. In this case, similar to the operation <NUM>, the subscribe message for status change reporting or a status check function (heartbeat) between the NRF <NUM> and the NF may be used. In addition, request information and response information may contain the parameters described above in the operation <NUM>.

<FIG> is a signal flow diagram illustrating an operation of performing access control of a UE according to an embodiment of the disclosure.

The signal flow diagram of <FIG> exemplarily shows a case in which the NSSF <NUM> becomes a subject according to the disclosure. However, as described above with reference to <FIG>, the NRF <NUM> or the SCP <NUM> may be substituted for the NSSF <NUM>.

At operation <NUM>, the UE <NUM> may select a network slice desired to access and transmit a connection request (RRC Connection (NSSAI)) message to the RAN <NUM>. In <FIG>, the NG-RAN is only illustrated as an example of a base station and is not construed as a limitation. That is, any base station among the various types of base stations described above with reference to <FIG> may be used.

At operation <NUM>, the NG-RAN <NUM> may select a first AMF 131a by using a network slice identifier specified by the UE <NUM> and transmit, to the first AMF 131a, an initial UE message (Initial UE message - Registration Req (Requested NSSAI)) containing a registration request, based on the connection request message transmitted by the UE, for example, an N1 (NAS) message (the registration request message described in embodiments of the disclosure). If the UE does not specify a network slice identifier at the operation <NUM> or if it is not possible to select the first AMF 131a with the network slice information specified by the UE, the NG-RAN <NUM> may select one AMF in accordance with an AMF selection rule. As such, the NG-RAN <NUM> may select the first AMF 131a, based on the network slice information specified by the UE <NUM>, or in accordance with the AMF selection rule, and transmit the initial UE message (Initial UE message - Registration Req (Requested NSSAI)) to the first AMF 131a.

At operation <NUM>, the first AMF 131a may perform an operation of processing a registration request message transmitted by the UE <NUM> through the NG-RAN <NUM>. If it is necessary to select a new network slice for the UE <NUM>, change a network slice, or select a new AMF belonging to a network slice, the first AMF 131a may transmit a network slice selection request (NSSelection Req) message to the NSSF <NUM>. The network slice selection request (NSSelection Req) message may be performed through a GET operation of the Nnssf_NSSelection Service provided by the NSSF <NUM>.

On the other hand, if the first AMF 131a does not need to select a new network slice, change a network slice, or select a new AMF belonging to a network slice, it may not perform operations after the operation <NUM>.

When transmitting the network slice selection request (NSSelection Req) message at the operation <NUM>, the first AMF 131a may add the network slice identifiers (Requested NSSAI) requested by the UE <NUM>, and the network slice identifiers (Subscribed NSSAI) contained in the subscription information. In addition, when transmitting the network slice selection request (NSSelection Req) message, the first AMF 131a may inform that a selection target is all NFs included in the network slice, or may designate a specific NF type in the network slice as a selection target.

At operation <NUM>, the NSSF <NUM> may perform an operation of selecting a network slice in response to the request of the first AMF 131a. At this time, information for each slice (maximum capacity for each slice, current load (usage)) received or stored through the above-described embodiments of <FIG> may be considered. If the request of the first AMF 131a is the entire network slice, the selection of a network slice and the selection of candidate NFs included in the network slice may be made in consideration of the overall status of the network slice. For example, if the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> are included in the network slice, all of them may be included in candidate NFs. If the request of the first AMF 131a designates a specific NF belonging to the network slice, candidate NFs having the corresponding NF type may be selected. If the network slice is formed of an instance, one network slice instance may be selected. If there are multiple NFs or instances as a selection target, the selection may be made so as to distribute the load in consideration of the received maximum capacity and current load status.

At operation <NUM>, in response to the network slice selection request (NSSelection Req) message from the first AMF 131a, the NSSF <NUM> may transmit, to the first AMF 131a, a network slice selection response (NSSelection Resp) message containing network slice information. In this case, the network slice selection response may be implemented in the form of Nnssf_NSSelection Service and may include authenticated network slice information (AuthorizedNetworkSliceInfo) containing the previously selected network slice information. For example, if the request of the first AMF 131a is the entire network slice, the AuthorizedNetworkSliceInfo may contain information on the network slice and candidate NFs therein, selected in consideration of the overall status of the network slice. If the network slice includes the AMF <NUM> (referring to both the first AMF 131a and the second AMF 131b), the SMF <NUM>, and the UPF <NUM>, their candidate information may be contained. If the request of the first AMF 131a designates a specific NF belonging to the network slice, information on the selected candidate NFs having the corresponding NF type may be contained. If the network slice is formed of an instance, the selected one slice instance may be contained. Information containing the network slice may be constructed in the form of a name or identifier that allows the selected candidate or selected instance to be identified. If the selection of the network slice or NF that can process the request fails, for example, if the allowable capacity in the corresponding network slice is exceeded, the NSSF <NUM> may add a failure result and reason in the network slice selection response message. Through this, the NSSF <NUM> may inform the first AMF 131a of the reason that the selection of the NF has failed.

At operation <NUM>, the first AMF 131a that has received the network slice selection response message through the operation <NUM> may identify whether the selection of a new AMF is necessary, by using the received information. If the new AMF selection is required, and if additional information is required for the new AMF selection, an AMF selection process may be performed through the NRF <NUM> (or the SCP <NUM>) (not shown in <FIG>). In this case, the AMF selection may consider the network slice information and candidate AMFs previously received at the operation <NUM>.

At operation <NUM>, if the AMF needs to be changed, the first AMF 131a transmit to the NF-RAN <NUM> a reroute request message (Reroute NAS message) for rerouting the registration process for the UE <NUM> to the selected AMF, for example, the new second AMF 131b in <FIG>. The Reroute NAS message transmitted to the NG-RAN <NUM> by the firstAMF 131a may contain the N1 (NAS) message received from the UE <NUM>, an identifier of the selected new second AMF 131b, and the network slice information received from the NSSF <NUM> at the operation <NUM>. If it is unnecessary to change the AMF after reroute, the network slice information may be transmitted without AMF information.

At operation <NUM>, the NG-RAN <NUM> may transmit an initial UE message to the second AMF 131b selected based on the Reroute NAS message received from the first AMF 131a. In this case, the initial UE message may be referred to as different names, and may contain the message transmitted to the NG-RAN <NUM> by the UE <NUM> at the operation <NUM> and the NAS message and network slice information acquired from the first AMF 131a.

Thereafter, at operation <NUM>, a registration procedure for the UE <NUM> may be performed between the first AMF 131a and the new second AMF 131b. Here, the registration procedure may be performed when there is additionally necessary information in addition to the information transmitted through the NG-RAN <NUM>.

<FIG> is a signal flow diagram based on a network slice status in a session establishment procedure according to an embodiment of the disclosure.

With reference to <FIG>, at operation <NUM>, a specific network slice may be selected during the registration procedure among the UE <NUM>, the AMF <NUM>, and the NFs.

At operation <NUM>, when a PDU session establishment is required, the UE <NUM> may transmit a PDU session establishment request message to the AMF <NUM>. The PDU session establishment message may contain information about a target of PDU session establishment, for example, a DNN and a slice identifier.

At operation <NUM>, when there is a need to select a network slice or a specific NF (SMF/UPF) belonging to a network slice in the session establishment requested by the UE <NUM>, the AMF <NUM> may transmit a network slice selection request (NSSelection Req) message to the NSSF <NUM>. The network slice selection request message may use a GET operation of the Nnssf_NSSelection Service provided by the NSSF <NUM>. Upon transmitting the network slice selection request message, the AMF <NUM> may add network slice identifiers requested by the UE <NUM> and network slice identifiers contained in subscription information. In addition, upon transmitting the network slice selection request message, the AMF <NUM> may inform that a selection target is all NFs included in the network slice during the session establishment, or may designate a specific NF type (SMF and/or UPF) in the network slice as a selection target. Also, the AMF <NUM> may additionally transmit information about the session by using DNN or DNAI during the session establishment.

At operation <NUM>, the NSSF <NUM> may perform an operation of selecting a network slice in response to the request of the AMF <NUM>. At this time, information per network slice (maximum capacity per slice, current load (usage)) received or stored through the above-described embodiments may be considered. If the request of the AMF <NUM> is the entire network slice, the selection of the network slice and the selection of candidate NFs included in the network slice may be made in consideration of the overall status of the network slice. If the SMF <NUM> and the UPF <NUM> are included in the network slice, both may be included. If the request of the AMF <NUM> designates a specific NF belonging to the network slice, candidate NFs having the corresponding NF type may be selected. If the network slice is formed of an instance, one slice instance may be selected. If there are multiple NFs or instances as a selection target, the selection may be made so as to distribute the load in consideration of the received maximum capacity and current load status. If DNN or DNAI is specified, supportability may be considered when selecting a slice and an NF belonging to the slice.

At operation <NUM>, the NSSF <NUM> may generate a network slice selection response (NSSelection Resp) message in response to the network slice selection request message and transmit it to the AMF <NUM>. The network slice selection response message may contain selected network slice information. In this case, the network slice selection response message may use the Nnssf_NSSelection Service, and more specifically, may include authenticated network slice information (AuthorizedNetworkSliceInfo) containing the previously selected slice information. For example, if the request of the AMF <NUM> is the entire network slice, the authenticated network slice information (AuthorizedNetworkSliceInfo) may contain information on the network slice and candidate NFs therein, selected in consideration of the overall status of the network slice. If the network slice includes the SMF <NUM> and the UPF <NUM> related to the session, their information may be contained. If the request of the AMF <NUM> designates a specific NF belonging to the network slice, information on the selected candidate NFs having the corresponding NF type may be contained. If the network slice is formed of an instance, the selected one slice instance may be contained. Contained information may be constructed in the form of a name or identifier that allows the selected candidate or selected instance to be identified. If the selection of the network slice or NF that can process the request fails, for example, in case of exceeding the capacity of the network slice, the NSSF <NUM> may notify a failure result and reason for the network slice selection.

At operation <NUM>, the AMF <NUM> may identify whether the selection of the SMF is necessary, by using information contained in the received network slice selection response message. If the SMF selection is required, and if additional information is required for the SMF selection, an SMF selection process may be performed through the NRF <NUM> (or the SCP <NUM>) (not shown in <FIG>). In this case, the SMF selection may consider the network slice information and candidate SMFs previously received at the operation <NUM>.

At operation <NUM>, the AMF <NUM> may perform the remaining session establishment procedure for the UE <NUM> through the selected SMF <NUM>. If the network slice information is received at the operation <NUM> and information for the SMF or UPF selection is contained in the network slice information, the AMF <NUM> may transmit it to the SMF <NUM> and/or the UPF <NUM>.

Included in the disclosure described below are conditions for selecting a slice (S-NSSAI) to be used in the UE's network (5GS) registration process or the PDU session establishment process, and a procedure and information related to deregistration for unused slices. In the disclosure, one NF in the operator network transmits a policy or UE configuration to be used upon selecting a network slice to the UE. The NF may be the UDM (based on subscription information), the PCF (based on policy), or any other NF that stores information for slice control. The NF may firstly transmit information to another NF (e.g., the AMF or the SMF) that manages the slice status for each UE during the communication process with the UE, which may be converted into a NAS layer message and delivered to the UE. The policy/configuration to be used for slice selection may include the following information.

In addition, the status of each slice managed by the UE and the network (5GS) may be one of the following statuses.

The status for each slice should be simultaneously managed by the UE and one or more NFs in the network that manages the status of the UE, and the corresponding NF may be, for example, the AMF.

If the UE establishes at least one PDU session for an allowed slice, the slice may be considered in the active status. If the UE does not establish a PDU session for an allowed slice, or if all PDU sessions are released, the slice may be considered in the inactive status.

If a PDU session is not created (established) for a time set in a timer, for example, the above-mentioned slice duration timer, configured for an active slice, the UE or the network may change the slice to the inactive status. The timer may be configured so that the network transmits it to the UE through a NAS message. The UE may explicitly transmit a request to change the status of a specific slice from active to inactive to the network (5GS). The network (5GS) may explicitly transmit a command to change the status of a specific slice from inactive to active to the UE.

If an inactive slice is not changed to an active slice during the configured timer, the UE or the network (5GS) may exclude the slice from allowed slices. The timer may be configured so that the network (5GS) transmits it to the UE through a NAS message. The UE may explicitly transmit a message to the network (5GS) to inform that the status of a specific slice is out of permission. The network (5GS) may explicitly transmit a command for excluding a specific slice from allowed slices to the UE.

If the network (5GS) applies a quota limit (the number of simultaneous access UEs, the number of concurrently established sessions, the maximum transfer rate for each slice, etc.) to the slice, the detailed status of the slice may be considered. An example of applying such a quota limit is as follows.

In the disclosure, the value of the above-described timer may be differentially applied depending on user and service characteristics and may be contained in a part of subscription information or policy. In case of being contained in the subscription information, the corresponding information may be transmitted from the UDM to an NF that controls the slice. In case of being contained in the policy, the corresponding information may be transmitted from the PCF to an NF that controls the slice. For example, by configuring the value of the timer to be long for a subscriber whose service quality is important or with high priority/grade, the corresponding slice can be maintained in the allowed/active status for a long time. In the disclosure, the NF that controls the slice is an NF that determines the parameters delivered to the UE in accordance with the policy or subscription information and manages the slice status (allowed, requested, active, inactive, etc.) for the UE. In the <NUM> system, such an NF may be the AMF or the SMF.

<FIG> is an internal functional block diagram of an NF according to the disclosure.

Before the description with reference to <FIG>, the NF <NUM> may include the AMF <NUM>, the SMF <NUM>, and the UPF <NUM> as described above. In addition, the NF <NUM> may include other network entities or network instances such as the NSSF <NUM>, the NFR <NUM>, the SCP <NUM>, the PCF <NUM>, and the UDM <NUM>. In another example, the NF <NUM> may be a separate network entity or instance not mentioned above.

With reference to <FIG>, a network interface <NUM> may communicate with other network entities and/or instances in the core network. For example, if the NF <NUM> is the AMF <NUM>, it may perform communication with the SMF <NUM>, the UPF <NUM>, the NSSF <NUM>, the NFR <NUM>, the PCF <NUM>, the UDM <NUM>, and/or the SCP <NUM>. In another example, if the NF <NUM> is the SMF <NUM>, it may perform communication with the AMF <NUM>, the UPF <NUM>, the NSSF <NUM>, the NFR <NUM>, the PCF <NUM>, the UDM <NUM>, and/or the SCP <NUM>. In still another example, if the NF <NUM> is the NSSF <NUM>, it may perform communication with the AMF <NUM>, the UPF <NUM>, the SMF <NUM>, the NFR <NUM>, the PCF <NUM>, the UDM <NUM>, and/or the SCP <NUM>. Similarly, if the NF <NUM> is one specific network entity, it may perform communication with another entity in the core network.

A controller <NUM> may be implemented as at least one processor and/or a program driven by the processor for performing the operations of the NF. For example, if the NF <NUM> is the AMF <NUM>, the controller <NUM> may perform the above-described operations of the AMF <NUM>. In another example, if the NF <NUM> is the NSSF <NUM>, the controller <NUM> may perform the above-described operations of the NSSF <NUM>. Similarly, in case of any other network entity, the controller <NUM> may perform the control necessary for the above-described operations.

A memory <NUM> may store a program and various kinds of control information required for the controller <NUM> and may also store each information described in the disclosure. For example, if the NF <NUM> is the AMF <NUM>, the memory <NUM> may store the above-described information received by the AMF <NUM> or received from an external entity. In another example, if the NF <NUM> is the NSSF <NUM>, the memory <NUM> may store the above-described control information required for the NSSF <NUM> and/or received information. Similarly, in case of any other network entity, the memory <NUM> may store information necessary for the above-described operations.

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

In case of implementation using software, a computer-readable storage medium for storing one or more programs (software modules) may be provided as hardware. One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to perform the methods according to claims or embodiments described herein.

Such programs (software module, software) may be stored in a random access memory, a non-volatile memory including a flash memory, a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a compact disc ROM, digital versatile discs (DVDs) or other optical storage devices, and a magnetic cassette. Alternatively, the programs may be stored in a memory combining part or all of the above recording media. A plurality of memories may be equipped.

In addition, the programs may be stored in an attachable storage device accessible via a communication network formed of Internet, Intranet, local area network (LAN), wide area network (WAN), or storage area network (SAN) alone or in combination. This storage device may access an apparatus performing embodiments of the disclosure through an external port. In addition, a separate storage device in the communication network may access an apparatus performing embodiments of the disclosure.

In the above-described embodiments, components or elements have been expressed as a singular or plural form. It should be understood, however, that such singular or plural representations are selected appropriately according to situations presented for the convenience of description, and the disclosure is not limited to the singular or plural form. Even expressed in a singular form, a component or element may be construed as a plurality of components or elements, and vice versa.

While the disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the subject matter as defined by the appended claims.

Claim 1:
A method for managing a network slice by a first network function (<NUM>) in a wireless communication system, the method comprising:
receiving (step <NUM>), from at least one second network function (<NUM>) associated with the network, NW, slice, a network slice selection assistance information, NSSAI, availability update message, wherein the NSSAI availability update message includes a capacity parameter of the NW slice;
storing (step <NUM>) information included in the NSSAI availability update message;
transmitting (step <NUM>), to the second network function (<NUM>), a response message to the NSSAI availability update message;
transmitting (step <NUM>), to the second network function (<NUM>), a message requesting changed information in case that a status or a configuration of the second network function (<NUM>) is changed;
receiving, from the second network function (<NUM>), a network slice selection request message;
performing a selection of a network slice based on the capacity parameter of the NW slice; and
transmitting, to the second network function (<NUM>), a network slice selection response message including network slice information.