Patent ID: 12262307

DETAILED DESCRIPTION

Hereinafter, various embodiments of the disclosure will be described in detail in conjunction with the accompanying drawings. In the following description of the disclosure, a detailed description of known functions or configurations incorporated herein will be omitted when it is determined that the description may obscure the subject matter of the disclosure. The terms which will be described below are defined in consideration of the functions in the disclosure, and may be different according to users, intentions of the users, or customs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

Advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following embodiments are provided only to completely disclose the disclosure and inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the appended claims.

Throughout the specification, the same or like reference numerals designate the same or like elements.

The disclosure provides an apparatus and a method for providing network slice (or network slicing) in a wireless communication system. Specifically, through the disclosure, a description will be made of a technology of managing network slice information in a wireless communication system for providing a network slice function. Furthermore, a technology for interworking between a wireless communication system and a terminal will be described.

In the following description, terms referring to signals, terms referring to control information, terms referring to network entities, terms referring to device elements, and the like are illustratively used for the sake of convenience. Therefore, the disclosure is not limited by the terms as used below, and other terms referring to subjects having equivalent technical meanings may be used.

Further, in the following description, various embodiments of the disclosure will be described using terms and names defined in some communication standards (e.g., 3rd generation partnership project (3GPP)) standards for the sake of illustration. However, various embodiments of the disclosure may be applied to other communication systems through modifications.

In 3GPP standards, a 5G network system architecture and procedure is standardized. A mobile communication provider may provide various services in a 5G network. In order to provide each service, the mobile communication provider should satisfy different service requirements (e.g., latency communication coverage, data rate, bandwidth, reliability, etc.) according to services. To this end, the mobile communication provider may configure a network slice, and may allocate network resources suitable for a specific service for each network slice or each set of network slices. The network resources may imply a network function (NF), a logical resource provided by the NF, and/or a wireless resource allocated by a base station.

For example, the mobile communication provider may configure a network slice A in order to provide a mobile broadband service, may configure a network slice B in order to provide a vehicle communication service, and may configure a network slice C in order to provide an IoT service. That is, in a 5G network, a pertinent service may be efficiently provided to a terminal through a network slice specialized to correspond to the characteristics of each service.

FIG.1illustrates a mobile communication system according to an embodiment.

Referring toFIG.1, a 5G system includes a terminal (e.g., a UE), a base station (e.g., a (R)AN), and a 5G core network (5GC).

The 5G core network also includes an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a policy control function (PCP), unified data management (UDM), a network slice selection function (NSSF), a network slice admission control function (NSACF), an authentication server function (AUSF), and a unified data repository (UDR), an Application Function (AF), and a Data Network (DN). The terminal may access the 5G core network through the base station.

The AMF is a network function (NF) for managing wireless network access and mobility of a terminal.

The SMF is an NF for managing a session for a terminal, and session information includes quality-of-service (QoS) information, charging information, and information about packet processing.

The UPF is an NF for processing user traffic (e.g., user plane traffic), and is controlled by the SMF.

The PCF is an NF that manages an operator policy (e.g., a public land mobile network (PLMN) policy) for providing a service in a wireless communication system. In addition, the PCF may be divided into a PCF responsible for an access and mobility (AM) policy and a UE policy and a PCF responsible for a session management (SM) policy. The PCF responsible for AM/UE policies and the PCF responsible for an SM policy may be logically or physically separate NFs or may be a logically or physically single NF.

The UDM is an NF for storing and managing terminal subscription information (e.g., a UE subscription).

The UDR is an NF or a database (DB) for storing and managing data. The UDR may store terminal subscription information and may provide the terminal subscription information to the UDM. Further, the UDR may store operator policy information, and may provide the operator policy information to the PCF.

The NSSF may be an NF for selecting network slice instances, which service a terminal, or for determining network slice selection assistance information (NSSAI).

The NSACF may be an NF for managing a network slice use situation (e.g., the number of registered terminals for each network slice, the number of sessions established, etc.) and determining whether to allow registration of a terminal and session establishment.

The AUSF may be an NF for performing a function of supporting authentication for 3GPP access and non-3GPP access.

The AF may be an NF for providing a function for a service according to the disclosure.

The DN may be a data network capable of providing operator service, Internet access, a 3rd party service, etc.

FIG.2illustrates a network slice IE according to an embodiment. Specifically, as single-network slice selection assistance information (S-NSSAI) defined in 3GPP may be used as a differentiator for differentiating a network slice,FIG.2provides an example of an S-NSSAI IE.

Referring toFIG.2, an S-NSSAI includes a slice/service type (SST)216used in a home PLMN (HPLMN), a slice differentiator (SD)218used in HPLMN, an SST212used in a serving PLMN, and an SD214used in a serving PLMN. The S-NSSAI IE further includes a field210indicating the length of a content included in the S-NSSAI IE.

In a non-roaming situation, the SST212used in the serving PLMN may be the same as the SST216used in the HPLMN. Further, the SD214used in the serving PLMN may be the same as the SD218used in the HPLMN.

In a roaming situation, the SST212used in the serving PLMN may be an SST used in a visited PLMN (VPLMN), and the SD214used in the serving PLMN may be an SD used in the VPLMN.

SST and SD values constituting one piece of S-NSSAI may be present or not present depending on the situation.

The NSSAI may include one or more pieces of S-NSSAI. Examples of the NSSAI may include configured NSSAI (or configured S-NSSAI) stored in a terminal, requested NSSAI (or requested S-NSSAI) requested by the terminal, allowed NSSAI (or allowed S-NSSAI) which the terminal is allowed to use, rejected NSSAI (or rejected S-NSSAI) which the terminal is rejected from using, pending NSSAI (or pending S-NSSAI) indicating that whether use by the terminal is possible (allowance or rejection) is being processed, subscribed NSSAI stored as terminal subscription information in the UDM, etc. However, these are only examples, examples of the NSSAI are not limited to the above-mentioned examples.

In accordance with an embodiment, the disclosure provides an example of a method for managing the number of sessions established for each network slice.

An NSACF may store information about the maximum number of sessions for each network slice (identifiable as S-NSSAI) subject to network slice admission control (NSAC) (S-NSSAI subject to NSAC). The S-NSSAI subject to the NSAC may include information about whether a corresponding slice is subject to control of the maximum number of terminals or information about whether the corresponding slice is subject to control of the maximum number of sessions. When a specific slice is subject to NSAC (or when the specific slice is subject to NSAC related to control of the maximum number of sessions), the NSACF may receive and store the slice-specific maximum number of sessions in the corresponding slice from another 5G NF (e.g., an AMF, an SMF, a PCF, a UDM, a UDR, etc.). Alternatively, in the NSACF, information about maximum session number for each slice may be configured through operations, administration, and maintenance (OAM) (or operations and maintenance (O&M)).

The NSACF may control the number of sessions currently established for each slice. Controlling the number of currently established sessions may include increasing the number of currently established sessions by one when a new session is established. The NSACF may perform control such that the number of currently established sessions does not exceed the maximum number of sessions. Controlling the number of currently established sessions may also include decreasing the number of currently established sessions by one when an established session is released.

The NSACF may manage a list of PDU session ID(s) established in connection with a network slice. The NSACF may manage a network slice, terminal Ms of PDU session ID(s) established in connection with the network slice (e.g., a list of UE IDs), and a list of the PDU session IDs. The NSACF may identify one PDU session as a combination of a terminal ID and a PDU session ID (e.g., a combination of UE ID and PDU Session ID). Alternatively, the NSACF may manage a list of PDU session IDs established for each terminal indicated by a terminal ID (per UE or per UE ID).

One PDU session ID may be used as a unique session identifier in one terminal. That is, different PDU sessions established by different terminals may use an identical PDU session ID, and thus, in a network supporting multiple terminals, one PDU session may be uniquely identified by using a PDU session ID. Therefore, the NSACF may use a UE ID together with a PDU session ID to uniquely identify one PDU session.

In order to increase the number of currently established sessions, the NSACF may determine whether a PDU session indicated by a requested PDU session ID and a requested terminal ID has been already included in a list managed by the NSACF. If the PDU session is not included in the list managed by the NSACF, the NSACF may add the PDU session ID and the terminal ID, which are requested, to the list managed by the NSACF, and may increase the number of currently established sessions.

An SMF may perform PDU session establishment in a network slice subject to NSAC (S-NSSAI subject to NSAC) (or a network slice subject to NSAC related to control of the maximum number of sessions). The SMF may receive, from another 5G NF (e.g., an AMF, a PCF, UDM, a UDR, an NSACF, etc.), information about whether a specific network slice is subject to NSAC. Alternatively, in the SMF, information about whether a specific network slice is subject to NSA may be configured through OAM.

In order to perform PDU session establishment in a network slice subject to NSAC, the SMF may determine to check whether a current corresponding network slice is available.

The SMF may discover and select, based on the determination, an NSACF responsible for NSAC related to the maximum number of sessions of the corresponding network slice.

The SMF may transmit an NF (NSACF) discovery request message to an NRF. The NF (NSACF) discovery request message may include network slice information (e.g., S-NSSAI) and an indicator indicating that an NSACF (e.g., target NF or target NSACF) desired to be discovered has to provide an NSAC function related to control of the number of sessions. The NRF may search for an NSACF satisfying a condition requested by the SMF. The NRF may transmit an NF (NSACF) discovery response message to the SMF. The NF (NSACF) discovery response message may include information about an NSACF discovered by the NRF.

Alternatively, NSACF information may be configured in the SMF, and thus the SMF may use the configured NSACF information.

The SMF may send a maximum session number control request message to an NSACF received from the NRF or configured in the SMF.

For convenience of a description, the disclosure has been made with reference to an SMF operation, but the disclosure is not limited thereto. For example, an embodiment described in the disclosure may also be performed by an AMF.

FIG.3is a signal flow diagram illustrating an availability check procedure based on a number of sessions established for each network slice according to an embodiment. For convenient description, an NF301is described as being performed by an SMF inFIG.3, but the disclosure may also be applied to an AMF.

Referring toFIG.3, in step310, a terminal300transmits a PDU session establishment request message to the NF301via an AMF. The PDU session establishment request message may include at least one of a PDU session ID, a terminal ID, or S-NSSAI.

In step315, the NF301determines, based on at least one of a policy configured in the NF301and information received from another 5G NF (e.g., an AMF, a PCF, UDM, a UDR, an NSACF etc.), whether S-NSSAI requested by the terminal300(or S-NSSAI received from the AMF) is subject to NSAC (or is subject to NSAC related to control of the number of sessions established).

Alternatively, when the NF301is performed by an AMF and when S-NSSAI is not included in the PDU session establishment request message in step310, the NF301may select one piece of S-NSSAI, based on a policy configured in the NF301. The NF301may then determine, based on at least one of the policy configured in the NF301and information received from another 5G NF (e.g., a PCF, UDM, a UDR, an NSACF, etc.), whether S-NSSAI requested by the terminal (or S-NSSAI selected by the AMF) is subject to NSAC (or is subject to NSAC related to control of the number of sessions established).

In step320, the NF301(i.e., the SMF) transmits an NF discovery request message to an NRF303. The NF discovery request message may include at least one among S-NSSAI and information about the capability of a required target NSACF. The capability of the required target NSACF may indicate that the target NSACF has to support an NSAC function related to control of the number of sessions.

The NRF303may discover and select the required target NSACF.

In step325, the NRF303transmits an NF discovery response message to the NF301. The NF discovery response message may include information about target NSACF selected by the NRF.

In step330, the NF301transmits a slice availability request message to an NSACF302. The NSACF302may be selected by the NF301based on information received from the NRF303in step325and/or the information configured in the NF301. The NF301may store the selected NSACF information, and then may perform, as necessary, interaction with NSACF.

The slice availability request message may include information for uniquely identifying one PDU session, e.g., a PDU session ID and/or a terminal ID. Further, the slice availability request message may include S-NSSAI.

In step335, the NSACF302checks the number of sessions established in a network slice identified using the S-NSSAI. The NSACF302may check whether a PDU session indicated by the received PDU session ID and the received terminal ID is included in a list managed by the NSACF. If the PDU session is not included in the list managed by the NSACF302, the NSACF302may add a received PDU session ID and terminal ID to the list managed by the NSACF, and may increase the number of currently established sessions.

The NSACF302may control/manage the number of currently established sessions, based on information about the maximum number of sessions that is configured in the NSACF302or is received from another 5G NF (e.g., an AMF, an SMF, a PCF, UDM, a UDR, etc.). For example, The NSACF302may compare the number of currently established sessions, managed by the NSACF302, with the maximum number of sessions, and may determine whether the number of currently established sessions does not exceed the maximum number of sessions.

In step340, the NSACF302transmits a slice availability response message to the NF301.

When the PDU session indicated by the PDU session ID and the terminal ID, received in step330, is not included in the list managed by the NSACF, and when the number of currently established sessions does not exceed the maximum number of sessions, the NSACF302may include, in the slice availability response massage, information indicating that S-NSSAI is available (e.g., information indicating that PDU session establishment for the S-NSSAI is allowed).

When the PDU session indicated by the PDU session ID and the terminal ID received in step330is not included in the list managed by the NSACF, and when the number of currently established sessions exceeds the maximum number of sessions, the NSACF302may include, in the slice availability response message, information including that S-NSSAI is unavailable (e.g., information indicating that PDU session establishment for the S-NSSAI is not allowed).

When the PDU session indicated by the PDU session ID and the terminal ID received in step330is already included in the list managed by the NSACF, the NSACF302may include, in the slice availability response message, information indicating that the PDU session requested in step330is already counted, or information indicating that S-NSSAI is available (e.g., information indicating that PDU session establishment for the S-NSSAI is allowed).

In step345, the NF301transmits a PDU session establishment response message to the terminal300.

When the NF301has received, in step340, from the NSACF302, the information indicating that S-NSSAI is available or the information indicating that the requested PDU session has been already counted, the NF301may determine that the corresponding network slice is available. Thus, the NF301may perform a PDU session establishment procedure. When the PDU session establishment procedure is successfully performed, the NF301transmits a PDU session establishment admission message to the terminal300in step345.

When the NF301has received, in step340, from the NSACF302, the information indicating that S-NSSAI is unavailable, the NF301may determine that the corresponding network slice is currently unavailable. Thus, the NF301may determine to reject PDU session establishment without performing the PDU session establishment and may transmit a PDU session establishment rejection message to the terminal300in step345.

FIG.4is a signal flow diagram illustrating a procedure of updating availability based on a number of sessions established for each network slice according to an embodiment. For convenient description, the NF301is described as being performed by an SMF, but is not limited thereto. For example, the NF301may be performed by an AMF.

Referring toFIG.4, in step415, the NF301determines to release an established PDU. The determination may be based on a PDU session release request received from a terminal300or a request (a PDU session release request, a session management (SM) policy end request, etc.) received from another 5G NF (e.g., an AMF, a PCF, UDM, a UDR, etc.) in step410.

The NF301may determine, based on a method described in the disclosure, whether S-NSSAI linked with a corresponding PDU session is a network slice subject to NSAC (or is subject to NSAC related to control of the number of sessions established).

When the S-NSSAI linked with the corresponding PDU session is a network slice subject to NSAC, the NF301transmits a slice availability update request message to an NSACF302in step420. The slice availability update request message may include information for uniquely identifying a PDU session to be released, e.g., a PDU session ID and/or a terminal ID. Further, the slice availability update request message may include S-NSSAI.

In step425, the NSACF302updates the number of sessions established in a network slice identified using the S-NSSAI. The NSACF302may check whether a PDU session indicated by the received PDU session ID and the received terminal ID has been already included in a list managed by the NSACF302. When the PDU session is included in the list managed by the NSACF302, the NSACF302may delete the received PDU session ID and the received terminal ID from the list managed by the NSACF, and may decrease the number of currently established sessions.

In step430, the NSACF302transmits a slice availability update response message to the NF301. The slice availability update response message may include result information (e.g., success, failure, etc.) related to updating the number of sessions established in the network slice.

The NF301may continuously perform a PDU session release procedure.

When PDU session release was begun in response to a request from the terminal300(in step410), the NF301may transmit a PDU session release message to the terminal300in step435.

FIG.5illustrates a terminal according to an embodiment.

Referring toFIG.5, a terminal includes a transceiver510, a controller520, and a storage530. The controller may be a circuit, an application-specific integrated circuit, and/or at least one processor.

The transceiver510may transmit or receive signals to or from another network entity. The transceiver510may receive system information from a network entity, and may receive a synchronization signal or a reference signal.

The controller520may control overall operations of the terminal.

The storage530may store at least one of information transmitted or received through the transceiver510and information generated through the controller520.

FIG.6illustrates a network entity according to an embodiment.

Referring toFIG.6, a network entity includes a transceiver610, a controller620, and a storage630. The controller may be a circuit, an application-specific integrated circuit, and/or at least one processor.

The transceiver610may transmit or receive signals to or from another network entity. The transceiver610may receive system information from a network entity, and may receive a synchronization signal or a reference signal.

The controller620may control overall operations of a network entity.

The storage630may store at least one of information transmitted or received through the transceiver610and information generated through the controller620.

FIG.7is a signal flow diagram illustrating a terminal registration procedure according to an embodiment.

Referring toFIG.7, a terminal300may access a registration procedure with a first base station700and a second base station701to perform a registration procedure with an AMF702. The first base station700may support 3GPP access and the second base station701may support non-3GPP (N3GPP) access. AlthoughFIG.7illustrates the first base station700and the second base station701being connected to the same AMF702, the first base station700and the second base station701may also be connected to different AMFs.

In step710, the terminal300accesses the first base station700to transmit a registration request message. The registration request massage may include information about a requested slice (requested NSSAI, S-NSSAI A) which the terminal300desires to use.

In step712, the first base station700having received the registration request message may transmit, selects, based on requested NSSAI received from the terminal300, an AMF to which the registration request is to be transmitted. For example, the first base station700may select an AMF capable of supporting the requested NSSAI.

In step714, the first base station700transmit the registration request message to the AMF702selected in step in712. The AMF702may determine an allowed slice (allowed NSSAI), based on a request slice (requested NSSAI) of the terminal, a terminal subscription slice (subscribed S-NSSAI), a terminal access network (3GPP access network (access type)), or an operator policy. The AMF702may include the requested slice (e.g., S-NSSAI A) of the terminal in the allowed slice (e.g., S-NSSAI A).

In step716, the AMF702checks slice availability from the NSACF302of a 5G core network before determining to allow an allowed slice to the terminal300. To this end, the AMF702transmits a slice availability request message to the NSACF302in step716. The slice availability request message may include at least one among target slice information (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.), terminal access network information (e.g., 3GPP access), terminal position information (e.g., TA, etc.), and terminal information (e.g., SUPI, 5G-GUTI, etc.).

In step718, the NSACF302checks a slice policy of a target slice (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.), which is received from the AMF702, and the number of currently accessed terminals of the target slice.

For example, the NSACF302may check whether a terminal ID (e.g., SUPI, 5G-GUTI, etc.) is included in a terminal ID list managed by the NSACF302in order to monitor the number of S-NSSAI terminal registrations. In addition, the NSACF302may check whether access network information is included in the terminal ID list managed by the NSACF302in order to monitor the number of S-NSSAI terminal registrations. When a terminal ID and/or an access network is not included in the terminal ID list, the NSACF302may include the terminal ID and/or the access network in the terminal ID list, and may increase counting of the number of terminals.

In step720, the NSACF302transmits a slice availability response message to the AMF702. The slice availability response message may include at least one of target slice information (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.) and information about whether target slice is available (e.g., an indication indicating availability or unavailability, a cause value, etc.).

The AMF702may determine an allowed slice, based on the information about whether the slice is available that is received from the NSACF302. For example, when the information indicating that a slice (S-NSSAI) is available has been received from the NSACF302, the AMF702may include the slice (S-NSSAI) in an allowed slice. In another example, when the NSACF302has transmitted a message indicating that a slice (S-NSSAI) is unavailable, the AMF702may include the slice (S-NSSAI) in a rejected slice (rejected NSSAI) without including the slice (S-NSSAI) in an allowed slice.

In step722, the AMF702transmits, to the terminal300, a response message (e.g., a registration accept or registration reject message) responding to the registration request message received in step714. The registration accept message may include at least one of an allowed slice (allowed NSSAI) and a rejected slice (rejected NSSAI). When there is no slice available by the terminal, the AMF702may transmit a registration reject message.

In step724, the first base station700transmits, to the terminal300, the registration accept or registration reject message received from the AMF702.

In step740, the terminal300accesses the second base station701to transmit a registration request message. The registration request message may include a requested slice (requested NSSAI, e.g., S-NSSAI A) to be used by the terminal.

In step742, the second base station701having received the registration request message selects, based on the requested NSSAI and/or a terminal ID (e.g., 5G-GUTI, etc.) received from the terminal300, an AMF to which the registration request is to be transmitted. For example, the second base station701may select an AMF which may be indicated by the terminal ID (e.g., 5G-GUTI, etc.).

In step744, the second base station701transmits the registration request message to the AMF702selected in step742. The AMF702may determine an allowed slice (e.g., allowed NSSAI), based on a requested slice (requested NSSAI) of the terminal300, terminal subscription slice (subscribed S-NSSAI), a terminal access network (non-3GPP AN), or an operator policy. Further, in determining the allowed slice, the AMF702may consider the allowed slice and/or the rejected slice determined steps710to724. For example, the AMF702may include the requested slice (e.g., S-NSSAI A) of the terminal to the allowed slice (e.g., S-NSSAI A).

In step746, the AMF702checks slice availability from the NSACF302of a 5G core network before determining to allow an allowed slice to the terminal300. To this end, the AMF702transmits a slice availability request message to the NSACF302in step746. The slice availability request message may include at least one among target slice information (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.), terminal access network information (e.g., non-3GPP access), terminal position information (e.g., TA, etc.), and terminal information (e.g., SUPI, 5G-GUTI, etc.).

In step748, an NSACF302checks a slice policy of a target slice (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.), which is received from the AMF702, and the number of currently accessed terminals of the target slice.

For example, the NF302may check whether a terminal ID (e.g., SUPI, 5G-GUTI, etc.) is included in a terminal ID list managed by the NSACF302in order to monitor the number of S-NSSAI terminal registrations. In addition, the NSACF302may check whether access network information is included in the terminal ID list managed by the NSACF302in order to monitor the number of S-NSSAI terminal registrations. When a terminal ID and/or an access network are included in the terminal ID list, the NSACF302may determine that the terminal is already included in the number of terminal registration. Thus, the NSACF302may not increase counting of the number of terminals.

For example, in the case in which the number of terminal registrations is counted based on the number of terminals, when the terminal ID received in step746is included in the terminal ID list managed by the NSACF302(the terminal list is included in the terminal ID list in step718), the NSACF302may determine that the terminal is already included in the number of terminal registrations, and thus may not increase counting of the number of terminals. In this case, the terminal300is already registered, and thus a message in step750may include information indicating that a target slice is available.

Alternatively, in the case in which the number of terminal registrations is counted based on the number of registrations, when the terminal ID received in step746is included in the terminal ID list managed by the NSACF302(e.g., the terminal ID is included in step718), but when an access network (non-3gpp access) received in step746is not included in the terminal ID list managed by the NSACF302(e.g., 3GPP access is included in operation718), the NSACF302may determine that the terminal300is not included in the number of terminal registrations, and thus the NSACF302may include the access network in the terminal ID list, and may increase counting of the number of terminals. In this case, when the number of current terminals exceeds the maximum number of terminals, counting of the number of terminals may not be increased, the access network may be included in the terminal ID list. A message in step750may include information indicating that a target slice is unavailable.

In step750, the NSACF302may transmit a slice availability response message to the AMF702. The slice availability response message may include at least one of target slice information (e.g., S-NSSAI, requested NSSAI, allowed NSSAI, subscribed S-NSSAI, etc.) and information about whether target slice is available (e.g., an indication indicating availability or unavailability, a cause value, etc.).

The AMF702may determine an allowed slice, based on the information about whether the slice is available that is received from the NSACF302. For example, when the information indicating that a slice (S-NSSAI) is available has been received from the NSACF302, the AMF702may include the slice (S-NSSAI) in an allowed slice. As another example, when information indicating that a slice (S-NSSAI) is unavailable is received from the NSACF302has transmitted, the AMF702may include the slice (S-NSSAI) in a rejected slice (rejected NSSAI) without including the slice (S-NSSAI) in an allowed slice.

In step752, the AMF702transmits, to the terminal300, a response message (e.g., a registration accept or registration reject message) responding to the registration request message received in step744. The registration accept message may include at least one of an allowed slice (allowed NSSAI) and a rejected slice (rejected NSSAI). When there is no slice available by the terminal, the AMF702may transmit a registration reject message.

In step754, the second base station701transmits, to the terminal300, the registration accept or registration reject message received from the AMF702.

According to an embodiment of the disclosure, the NSACF302may determine slice availability for each terminal registration. Thus, even when the terminal300requests an identical slice (e.g., S-NSSAI A) in steps710and740, the availability of the corresponding slice may vary depending on a time point at which step718or748is performed, That is, the NSACF302in step718may determine that a corresponding slice (e.g., S-NSSAI A) is available, but the NSACF302in step748may determine that the corresponding slice (e.g., S-NSSAI A) is unavailable. Therefore, the AMF702may include corresponding slice (e.g., S-NSSAI A) as allowed NSSAI in the registration accept message transmitted in step722and then may transmit the message to the terminal300. However, the AMF702may include the corresponding slice (e.g., S-NSSAI A) as rejected NSSAI in the registration accept message transmitted in step752, and then may transmit the message to the terminal300.

AlthoughFIG.7sequentially illustrates a registration procedure of a 3GPP access network and a registration procedure of a non-3GPP access network, the registration procedure of a 3GPP access network may be performed after the registration procedure of a non-3GPP access network is performed.

FIG.8is a signal flow diagram illustrating a procedure of decreasing a number of terminal registrations according to an embodiment.

Referring toFIG.8, in step810, an AMF702determines to delete S-NSSAI provided to a terminal in the procedure inFIG.7) from allowed NSSAI.

In step812, the AMF702determines whether the S-NSSAI, determined to be deleted from the allowed NSSAI in step810is subject to counting the number of terminals (S-NSSAI subject to NSAC), When the S-NSSAI is subject to NSAC, the AMF702may determine to perform, with an NSACF302, a procedure of updating the number of terminal registrations.

In step814, the AMF702transmits a slice availability update request message to the NSACF302. The slice availability update request message may include S-NSSAI, a terminal ID, or current access network information (e.g., 3GPP, non-3GPP, etc.) of a terminal. Further, the slice availability update request message may include an indicator indicating that the number of terminal registrations should be decreased.

In step816, the NSACF302updates the number of currently accessed terminals in the received S-NSSAI. For example, when the number of terminal registrations is counted based on the number of registrations, the NSACF302may check whether the terminal ID and the access network, received in step814, are included in a terminal ID list managed by the NSACF302. When the terminal ID and the access network is included, the NSACF302may delete the corresponding terminal ID and the access network from the terminal ID list managed by the NSACF302, and may decrease the number of terminal registrations. That is, when access to a 3GPP access network and a non-3GPP access network is simultaneously made using an identical terminal ID, the NSACF302may delete the access network received in step814from the terminal ID list managed by the NSACF302.

Alternatively, when the number of terminal registrations is counted based on the number of terminals, the NSACF302may check whether the terminal ID and the access network received in step814are included in the terminal ID list managed by the NSACF302. When the terminal ID and the access network are included, the NSACF302may delete the corresponding access network from the terminal ID list managed by the NSACF302. However, when another access network is registered using an identical terminal ID, the NSACF302may maintain the number of terminal registrations as it is without decreasing the number of terminal registrations. That is, when access to a 3GPP access network and a non-3GPP access network is simultaneously made using an identical terminal ID, the NSACF302may delete the access network received in step814from the terminal ID list managed by the NSACF302. However, the terminal300is still connected to a network as another access network, and thus the NSACF302may not delete the terminal ID from the terminal ID list, and may maintain the number of terminal registrations as it is without decreasing the number of terminal registrations.

FIG.9is a signal flow diagram illustrating a bulk terminal registration update procedure according to an embodiment.

Referring toFIG.9, in step910, the NSACF302transmits, to the AMF702, an indicator indicating that slice availability checking may be performed late (e.g., need not be performed early). For example, when the number of currently accessed registered terminals is significantly smaller than the maximum number of registered terminals, the NSACF302may determine to transmit the indicator to the AMF702. The AMF702may store information received from the NSACF302.

In step912, the AMF702processes a registration procedure for a first terminal900. During the registration procedure, the AMF702may omit a slice availability check procedure, based on the indicator received in step910. That is, steps716to720inFIG.7may be determined to be performed after operation724.

In step914, the AMF702processes a registration procedure for a second terminal901. During the registration procedure, the AMF702may omit the slice availability check procedure, based in the indicator received in step910.

After steps912and914are completed, in step916, the AMF702transmits, to the NSACF302, a slice availability update request message in order to update the registered terminal. The slice availability update request message may include S-NSSAI, at least one registered terminal ID (a list of UE IDs), that is, a UE ID of the UE900and a UD ID of the UE901, or information about a network accessed by each terminal.

In step918, the NSACF302updates, based on the information received in step916, a terminal ID list managed by the NSACF302and the number of currently registered terminals. For example, the NSACF302may add the UE ID of the UE900and the UE ID of the UD901ID to the terminal ID list. Further, the NSACF302may add, to the terminal ID list, an access network of the UE900and an access network of the UE901. The NSACF302may increase the number of currently accessed terminals by the number of terminals, that is, twice.

According to another example, the message in step916may include S-NSSAI, a registered terminal ID, or multiple access networks assessed by the terminal. The NSACF302may update, based on the information received in step916, the terminal ID list managed by the NSACF302and the number of currently registered terminals. For example, the NSACF302may add a UE ID to the terminal ID list. Further, the NSACF302may add, to the terminal ID list, the multiple access networks (3GPP access and non-3GPP access) of the UE. The NSACF302may increase the number of currently accessed terminals by the number of terminals, that is, twice.

The embodiments of the disclosure described and shown in the specification and the drawings are merely specific examples that have been presented to easily explain the technical contents of the disclosure and help understanding of the disclosure, and are not intended to limit the scope of the disclosure. Therefore, the scope of the disclosure should be construed to include, in addition to the embodiments disclosed herein, all changes and modifications derived on the basis of the technical idea of the disclosure.

Methods based on the claims or the embodiments disclosed in the disclosure may be implemented in hardware, software, or a combination of both.

When implemented in software, a computer readable storage medium for storing one or more programs (software modules) may be provided. The one or more programs stored in the computer readable storage medium are configured for execution performed by one or more processors in an electronic device. The one or more programs include instructions for allowing the electronic device to execute the methods based on the claims or the embodiments disclosed in the disclosure.

The program (the software module or 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 read only memory (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage devices, and a magnetic cassette. Alternatively, the program may be stored in a memory configured in combination of all or some of these storage media. In addition, the configured memory may be plural in number.

Further, the program may be stored in an attachable storage device capable of accessing the electronic device through a communication network such as the Internet, an Intranet, a local area network (LAN), a wide LAN (WLAN), or a storage area network (SAN) or a communication network configured by combining the networks. The storage device may access via an external port to a device which performs the embodiments of the disclosure. In addition, an additional storage device on a communication network may access to a device which performs the embodiments of the disclosure.

In the above-described specific embodiments of the disclosure, elements included in the disclosure are expressed in singular or plural forms according to specific embodiments. However, singular or plural forms are appropriately selected according to suggested situations for convenience of explanation, and the disclosure is not limited to a single element or plural elements. An element which is expressed in a plural form may be configured in a singular form or an element which is expressed in a singular form may be configured in plural number.

While the disclosure has been shown and described with reference to certain 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 spirit and scope of the disclosure as defined by the appended claims and their equivalents.