Network slice admission control (NSAC) discovery and roaming enhancements

Abstract

An access and mobility management function (AMF) of a 5G core network is configured to transmit a network function registration request to a network resource function (NRF), receive a response to the network function registration request from the NRF, transmit a network function discovery request to the NRF, the network function discovery request including one or more single network slice selection assistance information (S-NSSAI) and an indication that the discovery request is for a network slice admission control function (NSACF), and receive a network function discovery response from the NRF, wherein the network function discovery response includes a NSACF address.

Description

[0001] Priority Information / Incorporation by Reference

[0002] This patent application claims priority to U.S. Provisional Application Serial No. 63 / 201,705, filed May 10, 2021, entitled “Network Slice Admission Control (NSAC) Discovery and Roaming Enhancements,” which is incorporated by reference herein in its entirety. BACKGROUND

[0003] A network can deploy multiple network slices. Generally, a network slice refers to an end-to-end logical network configured to provide specific services and / or have specific network characteristics. Each network slice can be isolated from one another, but run on a shared network infrastructure. Thus, each network slice can share network resources, but facilitate different functionality.

[0004] A network operator can want to limit the number of devices registered to a particular network slice. The network can be equipped with a network slice admission control function (NSACF) to perform this task. For example, the NSACF can perform various operations related to managing the number of UEs and / or sessions registered to individual network slices. SUMMARY

[0005] Some example embodiments relate to an access and mobility management function (AMF) of a 5G core network, the LMF configured to perform operations. The operations include transmitting a network function registration request to a network repository function (NRF), receiving a response to the network function registration request from the NRF, transmitting a network function discovery request to the NRF, the network function discovery request including one or more single network slice selection assistance information (S-NSSAI) and an indication that the discovery request is for a network slice admission control function (NSACF), and receiving a network function discovery response from the NRF, where the network function discovery response includes a NSACF address.

[0006] Other example embodiments relate to a network slice admission control function (NSACF) of a 5G core network, the NSACF configured to perform operations. The operations include transmitting a network function registration request to a network repository function (NRF), receiving a response to the network function registration request from the NRF, transmitting a network function discovery request to the NRF, the network function discovery request including one or more single network slice selection assistance information (S-NSSAI) and an indication that the discovery request is for an access and mobility management function (AMF), and receiving a network function discovery response from the NRF.

[0007] Further example embodiments relate to a network slice admission control function (NSACF) of a 5G core network, the NSACF configured to perform operations. The operations include maintaining network slice quotas for one or more network slices, wherein the NSACF is configured to perform network slice admission control (NSAC) for both a visited public land mobile network (VPLMN) and a home public land mobile network (HPLMN); receiving, from an access and mobility management function (AMF), a registered user equipment (UE) quantity availability check and update request for each network slice, and sending, to the AMF, a response indicating that a maximum number of registered UEs or sessions for an S-NSSAI has been reached. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 An example network arrangement is shown in accordance with various example embodiments.

[0009] Figure 2 An example network architecture is shown in accordance with various example embodiments.

[0010] Figure 3 A signaling diagram of a network slice admission control function (NSACF) discovery procedure is shown in accordance with various example embodiments.

[0011] Figure 4 A signaling diagram of an access and mobility management function (AMF) discovery procedure is shown in accordance with various example embodiments.

[0012] Figure 5 A table is shown in accordance with various example embodiments, showing examples of example information that can be included by a network resource function (NRF) in a discovery response to a NSACF during an AMF discovery procedure.

[0013] Figure 6 A signaling diagram of an early admission control (EAC) update procedure is shown in accordance with various example embodiments.

[0014] Figure 7 An example of a local breakout (LBO) roaming scenario is shown in accordance with various example embodiments.

[0015] Figure 8 An example of a home routed roaming scenario is shown in accordance with various example embodiments.

[0016] Figure 9 A signaling diagram of a per network slice user equipment (UE) quantity availability check and update procedure is shown in accordance with various example embodiments.

[0017] Figure 10An exemplary UE is shown in accordance with various exemplary embodiments.

[0018] Figure 11 An exemplary base station is shown in accordance with various exemplary embodiments. DETAILED DESCRIPTION

[0019] Exemplary embodiments can be further understood with reference to the following description and related drawings in which like elements are referred to with the same reference numerals. The exemplary embodiments relate to network slice admission control (NSAC). Those skilled in the art will appreciate that NSAC generally refers to a Third Generation Partnership (3GPP) protocol and policy that allows a network operator to control the number of devices and / or sessions registered to a particular network slice.

[0020] Exemplary embodiments are described with reference to a fifth generation (5G) network that supports network slicing. Generally, network slicing refers to a network architecture in which multiple end-to-end logical networks operate on a shared physical network infrastructure. Each network slice can be configured to provide a specific set of capabilities and / or characteristics. Thus, the physical infrastructure of a 5G network can be sliced into multiple virtual networks, each configured for a different purpose. Throughout this specification, a reference to a network slice can mean any type of end-to-end logical network that is configured for a particular purpose and implemented on a 5G physical infrastructure.

[0021] Those skilled in the art will appreciate that 5G can support a variety of different use cases, such as enhanced mobile broadband (eMBB), enhanced machine type communication (eMTC), industrial internet of things (IIoT), etc. Each type of use case can involve various different types of applications and / or services. A network slice can be characterized by the type of use case, the type of application and / or service, or the entity that provides the application and / or service via the network slice. However, any example in this specification that characterizes a network slice in a particular way is provided for illustrative purposes only. Throughout this specification, a reference to a network slice can mean any type of end-to-end logical network that is configured for a particular purpose and implemented on a 5G physical infrastructure.

[0022] A network slice can be identified by a single network slice selection assistance information (S-NSSAI). Each S-NSSAI instance can be associated with a public land mobile network (PLMN) and can include a slice service type (SST) and a slice descriptor (SD). The SST can identify the intended behavior of the corresponding network slice in terms of services, functions, and characteristics. Those skilled in the art will appreciate that the SST can be associated with a standardized SST value. The SD can identify any one or more entities associated with the network slice. For example, the SD can indicate an owner or entity (e.g., an operator) that manages the network slice and / or an entity (e.g., a third party, an entity that provides an application or service, etc.) that provides an application / service via the network slice. In some embodiments, the same entity can own the slice and provide the service (e.g., an operator service). Throughout the specification, S-NSSAI refers to a single network slice, and the terms “NSSAI” or “S-NSSAI” can be used to refer to one or more network slices interchangeably.

[0023] A user equipment (UE) can be configured to perform any one of a number of different tasks. Accordingly, the UE can be configured to utilize one or more network slices. To provide an example, the UE can utilize different second network slices for one or more operator services (e.g., voice, multimedia messaging service (MMS), the Internet, etc.) and for third party services. However, the configuration of network slices is beyond the scope of the example embodiments. The example embodiments are not limited to any particular type of network slice. Rather, the example embodiments introduce enhancements related to NSAC.

[0024] The example embodiments are also described with reference to a network slice admission control function (NSACF). The NSACF refers to a network function configured to control and limit the number of UEs and / or packet data unit (PDU) sessions registered to a particular network slice. To provide an example, the NSACF can perform various operations related to enforcing a quota for a maximum number of UEs registered to a particular network slice (e.g., S-NSSAI). The NSACF service area is related to the location of a network function user. However, references to the term “NSACF” are provided for illustrative purposes only. Different networks can refer to similar concepts by different names, for example, 3GPP networks can use the terms “NSACF” and “network slice quota function” (NSQ) interchangeably.

[0025] In one aspect, example embodiments relate to NSAC discovery and early admission control (EAC). As will be described in greater detail below, example embodiments include enhancements to NSACF discovery procedures initiated by an access and mobility management function (AMF), enhancements to AMF discovery procedures initiated by a NSACF, and enhancements to EAC update procedures between an AMF and a NSACF. In another aspect, example embodiments relate to NSAC in the context of roaming scenarios. As will be described in greater detail below, example embodiments include enhancements to NSACFs deployed by a visited public land mobile network (VPLMN) and NSACFs deployed by a home public land mobile network (HPLMN). The example enhancements described herein can be used in conjunction with currently implemented NSAC protocols and policies or future NSAC protocols and policies implementations.

[0026] Figure 1 An example network arrangement 100 is shown in accordance with various example embodiments. The example network arrangement 100 includes a UE 110. Those skilled in the art will appreciate that the UE 110 can be any type of electronic component configured to communicate via a network, such as a mobile phone, a tablet, a desktop computer, a smart phone, a phablet, an embedded device, a wearable device, an Internet of Things (IoT) device, etc. It will also be appreciated that a practical network arrangement can include any number of UEs used by any number of users. Thus, only an example with a single UE 110 is provided for purposes of illustration.

[0027] The UE 110 can be configured to communicate with one or more networks. In the example of the network arrangement 100, the network with which the UE 110 can wirelessly communicate is a 5G New Radio (NR) Radio Access Network (RAN) 120. However, the UE 110 can also communicate with other types of networks (e.g., a 5G cloud RAN, a Next Generation RAN (NG-RAN), a Long Term Evolution (LTE) RAN, a traditional cellular network, a Wireless Local Area Network (WLAN), etc.), and the UE 110 can also communicate with networks through a wired connection. Thus, in this example, the UE 110 can have a 5G NR chipset to communicate with the 5G NR RAN 120.

[0028] 5G NR RAN 120 can be part of a cellular network that can be deployed by a cellular provider (e.g., Verizon, AT&T, T-Mobile, etc.). 5G NR RAN 120 may, for example, include a cell or base station (node B, eNodeB, HeNB, eNBS, gNB, gNodeB, macrocell base station, microcell base station, picocell base station, femtocell base station, etc.) configured to send and receive communication traffic from UEs equipped with the appropriate cellular chipset. In network arrangement 100, 5G NR RAN 120 is shown with a gNB 120A. However, a practical network arrangement can include any number of different types of base stations or cells deployed by any number of RANs. Thus, the example of a single 5G NR RAN 120 and a single gNB 120A is provided for illustrative purposes only.

[0029] Those skilled in the art will appreciate that any relevant procedures can be performed for UE 110 to connect to 5G NR RAN 120. For example, as described above, 5G NR RAN 120 can be associated with a particular network operator at which UE 110 and / or its user has agreement and credential information (e.g., stored on a SIM card). Upon detecting the presence of 5G NR RAN 120, UE 110 can transmit the corresponding credential information in order to associate with 5G NR RAN 120. More specifically, UE 110 can associate with a particular base station or cell (e.g., gNB 120A).

[0030] Network arrangement 100 also includes a cellular core network 130, the Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network services backbone 160. Cellular core network 130 can be viewed as an interconnected set of components that manage the operation and traffic of a cellular network. It can include an Evolved Packet Core (EPC) and / or a 5G Core (5GC). Cellular core network 130 also manages traffic that flows between the cellular network and the Internet 140. IMS 150 can generally be described as an architecture for delivering multimedia services to UE 110 using IP protocols. IMS 150 can communicate with cellular core network 130 and the Internet 140 to provide multimedia services to UE 110. Network services backbone 160 communicates with the Internet 140 and cellular core network 130, either directly or indirectly. Network services backbone 160 can generally be described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that can be used to extend the functionality of UEs 110 in communicating with various networks.

[0031] Figure 2An exemplary network architecture 200 is shown in accordance with various exemplary embodiments. The following description will provide a general overview of the various components of the exemplary architecture 200. The description of the architecture 200 will be followed by a more detailed description of specific operations performed by the components with respect to the exemplary embodiments.

[0032] Those skilled in the art will appreciate that the components of the exemplary architecture 200 may be arranged with respect to Figure 1 The network arrangement 100 resides in various physical and / or virtual locations. These locations may include: within an access network (e.g., RAN 120), within a core network 130, as part of a Figure 1 Separate components outside the described positions, etc.

[0033] exist Figure 2 In the example embodiment, various components are shown as being connected via connections labeled Nx (e.g., N1, N2, N11, Nsmf, Namf, Nnssf, Nnrf, Nnsacf, etc.). Those skilled in the art will appreciate that each of these connections (or interfaces) is defined in the 3GPP specifications. The exemplary architecture 200 uses these connections in the manner defined in the 3GPP specifications. Furthermore, while these interfaces are referred to as connections throughout the specification, it should be understood that these interfaces need not be direct wired or wireless connections. For example, these interfaces may communicate via intermediary hardware and / or software components. To provide an example, the UE 110 may exchange signals with the cell 120A via radio. However, in the architecture 200, the UE 110 is shown as having a connection to the AMF 205. This connection or interface is not a direct communication link between the UE 110 and the AMF 205, but rather a connection facilitated by intermediary hardware and software components. Therefore, throughout this specification, the terms "connection" and "interface" may be used interchangeably to describe the Nx interface between various components.

[0034] Architecture 200 includes UE 110 and 5G NR RAN 120. UE 110 and 5G NR RAN 120 may be connected to AMF 205. AMF 205 is generally responsible for connection and mobility management in 5G NR RAN 120. For example, AMF 205 may perform operations related to management of registration procedures between UE 110 and core network 130. Example embodiments are not limited to an AMF performing the above-referenced operations. Those skilled in the art will appreciate the various different types of operations that an AMF may perform. Furthermore, reference to a single AMF 205 is for illustrative purposes only, and an actual network arrangement may include any appropriate number of AMFs.

[0035] The AMF 205 is connected to a session management function (SMF) 210. The SMF 210 can perform operations related to session management, such as, but not limited to, session establishment, session release, IP address allocation, policy and quality of service (QoS) enforcement, etc. The example embodiments are not limited to an SMF performing the above- referenced operations. Persons skilled in the art will understand that various different types of operations can be performed by an SMF. Moreover, reference to a single SMF 210 is merely for illustrative purposes, as a practical network arrangement can include any suitable number of SMFs.

[0036] The AMF 205 and the SMF 210 are also connected to a network slice selection function (NSSF) 215, a network resource function (NRF) 220, and a NSACF 225. The NSSF 215 performs operations related to network slicing. For example, the NSSF 215 can select a set of network slice instances to serve the UE 110. The NSSF 215 can also manage one or more databases that include a mapping table of S-NSSAI and frequency bands that the S-NSSAI is allowed to work with. The NRF 220 can perform operations related to a network service discovery function for determining where and how to access other network functions. However, reference to the term “network resource function” is provided for illustrative purposes only. Different networks can refer to similar entities by different names, for example, 3GPP networks can interchangeably use the terms “network resource function” and “network repository function.”

[0037] The NSACF 225 can be configured to perform operations related to controlling the number of registered UEs and / or sessions for each network slice that is subject to NSAC. During operation, the NSACF 225 can check the count of registered UEs and / or PDU sessions for an S-NSSAI and determine whether a network slice quota has been reached. The NSACF 225 can then accept or reject a registration request based on the count and the quota. However, reference to the concept of a quota is provided for illustrative purposes only. Persons skilled in the art will understand that different entities can refer to similar concepts by different names. For example, 3GPP networks can use the terms “quota” and “admission control” to refer to the same concept. Moreover, reference to a single NSACF 225 is merely for illustrative purposes, as a practical network arrangement can include any suitable number of NSACFs.

[0038] To provide a more specific example, the NSACF 225 can be configured with a maximum number of PDU sessions per network slice that are allowed to be served by the multiple network slices subject to NSAC. During operation, the SMF 210 can be triggered to send a request to the NSACF 225 for maximum number admission control of PDU sessions per network slice during a PDU session establishment / release procedure. The NSACF 225 can control (e.g., increase, decrease, etc.) the current number of PDU sessions per network slice so that the number does not exceed the maximum number of PDU sessions allowed to be served by the network slice. When the current number of PDU sessions utilizing the network slice is to be increased, the NSACF 225 can check whether the maximum number of PDU sessions per network slice has been reached for the network slice. The NSACF 225 can then accept or reject the request based on the count and quota.

[0039] To provide another example, the NSACF 225 can be configured with a maximum number of UEs per network slice that are allowed to be served by each network slice subject to NSAC. During operation, the AMF 205 can be triggered to send a request to the NSACF 225 for maximum number admission control of UEs per network slice when the registration status of a UE can change for a network slice subject to NSAC. The registration status can change during procedures such as, but not limited to, a UE registration procedure, a UE deregistration procedure, a network slice specific authentication and authorization procedure, an authentication, authorization, and accounting (AAA) server triggered network slice specific re-authentication and re-authorization procedure, and an AAA server triggered slice specific authorization revocation procedure. As described above, the NSACF 225 can control (e.g., increase, decrease, etc.) the current number of UEs registered to a network slice so that the number does not exceed the maximum number of UEs allowed to be registered to the slice. The NSACF 225 can also maintain a list of UE IDs registered to network slices subject to NSAC. When the current number of UEs registered to a network slice is to be increased, the NSACF 225 can first check whether the UE identity is already in the list of UEs registered to the network slice. If not, the NSACF 225 can check whether the maximum number of UEs per network slice has been reached for the network slice. The NSACF 225 can then accept or reject the request based on the count and quota.

[0040] Various example enhancements related to NSAC discovery will be described in detail below. Initially, enhancements to the NSACF discovery procedure initiated by the AMF 205 will be described with reference to the signaling diagram 300 of Figure 3 Thereafter, an example AMF discovery procedure initiated by the NSACF 225 will be described with reference to the signaling diagram 400 of Figure 4 Subsequently, an example NSACF discovery procedure initiated by the AMF 205 will be described with reference to the signaling diagram 500 of Figure 6The signaling diagram 600 depicts an exemplary EAC update procedure between the AMF 205 and the NSACF 225. The exemplary AMF discovery procedure may provide a basis for the enhancements introduced for the exemplary EAC update procedure.

[0041] Figure 3 A signaling diagram 300 for the NSACF discovery procedure is shown in accordance with various exemplary embodiments. The signaling diagram 300 will be described with reference to the network architecture 200 and includes the AMF 205 and the NRF 220.

[0042] The NSACF discovery procedure may be initiated by the AMF 205. In 305, the AMF 205 may transmit a network function registration request to the NRF 220. For example, the network function registration request may be sent via Figure 2 The Namf and / or Nnrf interfaces shown are transmitted by the AMF 205 to the NRF 220. The request may be referred to as "Nnrf_NFManagement_NFRegister_Request" and may include one or more globally unique AMF IDs (GUAMIs) and a list of S-NSSAIs supported by the AMF 205. Therefore, when the user of the Nnrf_NFManagement_NFRegister service is the AMF 205, the AMF 205 may include a list of S-NSSAIs supported by the AMF 205 in the Nnrf_NFManagement_NFRegister operation.

[0043] Normally, the list of S-NSSAIs supported by the AMF 205 is not provided to the NRF 220. Figure 4 Described in more detail, this exemplary enhancement allows the NRF 220 to learn the S-NSSAIs supported by that particular AMF 205. Thus, the NRF 220 is able to provide the NSACF 225 with a list of S-NSSAIs supported by the AMF 205 in the AMF discovery procedure.

[0044] In 310, NRF 220 may transmit a response to the network function registration request to AMF 205. The response may indicate whether the registration request is successful. For example, the response may be transmitted by NRF 220 via Figure 2 The Nnrf and / or Namf interface shown is transmitted to the AMF 205. The request may be referred to as "Nnrf_NFManagement_NFRegister_Response" and includes a result (e.g., success, failure, etc.). In this example, it is assumed that the registration attempt is successful.

[0045] In 315, the AMF 205 can transmit a discovery request to the NRF 220. For example, the discovery request can be transmitted by the AMF 205 to the NRF 220 through the Nnrf and / or Namf interface as illustrated. The request can be referred to as a “Nnrf_NFDiscovery_Request” and can include the S-NSSAI and an indication that the discovery request is for a NSACF. Thus, if the target network function of the Nnrf_NFDiscovery service is a NSACF, the discovery request can include the S-NSSAI. Figure 2 The Nnrf and / or Namf interface as illustrated by the AMF 205 to the NRF 220. The request can be referred to as a “Nnrf_NFDiscovery_Request” and can include the S-NSSAI and an indication that the discovery request is for a NSACF. Thus, if the target network function of the Nnrf_NFDiscovery service is a NSACF, the discovery request can include the S-NSSAI.

[0046] In 320, the NRF 220 can transmit a discovery response to the AMF 205. For example, the discovery response can be transmitted by the NRF 220 to the AMF 205 through the Nnrf and / or Namf interface as illustrated. The response can be referred to as a “Nnrf_NFDiscovery_Response” and can include the address for the NSACF 225. Additionally, the response can include other S-NSSAIs supported by the NSACF 225. Thus, if the target network function of the Nnrf_NFDiscovery service is the NSACF 225, the discovery response can include a list of S-NSSAIs for which the NSACF 225 manages admission control. Figure 2 The Nnrf and / or Namf interface as illustrated by the AMF 205 to the NRF 220. The request can be referred to as a “Nnrf_NFDiscovery_Request” and can include the S-NSSAI and an indication that the discovery request is for a NSACF. Thus, if the target network function of the Nnrf_NFDiscovery service is a NSACF, the discovery request can include the S-NSSAI.

[0047] In a regular case, other S-NSSAIs supported by the NSACF 225 are not provided to the AMF 205 during the discovery procedure. Thus, only when a specific S-NSSAI is provided in the discovery request to the NRF 220 and the corresponding NSACF address is provided in the response, the AMF 205 can know the NSACF corresponding to the specific S-NSSAI.

[0048] Exemplary embodiments incorporate other S-NSSAIs supported by the NSACF 225 into the discovery response in an attempt to reduce the number of subsequent discovery requests that can be transmitted by the AMF 205. For example, the AMF 205 can use the information received in 320 of other S-NSSAIs supported by the NSACF 225 to determine that the requested NSSAI in a registration request from the UE 110 contains an S-NSSAI subject to access control for which the AMF 205 has not previously performed a NSACF discovery procedure. In other words, since the AMF 205 knows of other S-NSSAIs supported by the NSACF 225, the AMF 205 can use the information received in 320 to instead of transmitting a subsequent discovery request to the NRF 220. This allows the AMF 205 to proceed to the next step of the registration procedure (e.g., request the NSACF 225 check if a quota is available for another UE / session, transmit a context request to the SMF 210, or any other appropriate action) without having to transmit a discovery request to the NRF 220.

[0049] Figure 4 A signaling diagram 400 for an AMF discovery procedure is shown in accordance with various exemplary embodiments. The signaling diagram 400 will be described with reference to the network architecture 200, and includes the NSACF 225 and the NRF 220.

[0050] The AMF discovery procedure can be initiated by the NSACF 225. In 405, the NSACF 225 can transmit a network function registration request to the NRF 220. For example, the network function registration request can be transmitted by the NSACF 225 via the Nnsacf and / or Nnrf interfaces shown. The request can be referred to as an “Nnrf NFManagement NFRegister Request,” and can include a list of S-NSSAIs supported by the NSACF 225. Thus, when the user of the Nnrf NFManagement NFRegister service is the NSACF 335, the NSACF 225 can include in the Nnrf NFManagement NFRegister operation a list of S-NSSAIs that the NSACF 225 manages access control for. Figure 2

[0051] ​Under normal circumstances, the NRF 220 is not provided with a list of S-NSSAIs supported by the NSACF 225. This exemplary enhancement allows the NRF 220 to know the S-NSSAIs supported by that particular NSACF 225. Thus, as shown in the signaling diagram 300, the NRF 220 is able to provide the AMF 205 with a list of S-NSSAIs supported by the NSACF 225 in the NSACF discovery procedure. Thus, in some embodiments, the exemplary enhancement referenced above with reference to 320 of the signaling diagram 300 may be enabled by this message in 405.

[0052] In 410, NRF 220 may transmit a response to the network function registration request to NSACF 225. The response may indicate whether the registration request was successful. For example, the response may be transmitted by NRF 220 via Figure 2 The Nnrf and / or Nnsacf interfaces shown are transmitted to the NSACF 225. The request may be referred to as "Nnrf_NFManagement_NFRegister_Response" and includes a result (eg, success, failure, etc.). In this example, it is assumed that the registration attempt was successful.

[0053] In 415, NSACF 225 may transmit a discovery request to NRF 220. For example, the discovery request may be sent via Figure 2 The Nnrf and / or Nnsacf interfaces shown are transmitted by the NSACF 225 to the NRF 220. The request may be referred to as "Nnrf_NFDiscovery_Request" and may include an S-NSSAI and an indication that the discovery request is for the AMF 205.

[0054] In 420, NRF 220 may transmit a discovery response to NSACF 225. For example, the discovery response may be transmitted by NRF 220 via Figure 2 The Nnrf and / or Nnsacf interfaces shown are transmitted to the NSACF 225. The response may be referred to as "Nnrf_NFDiscovery_Response" and may include a list of one or more AMFs, their corresponding GUAMIs, and the S-NSSAIs supported by each AMF. Thus, if the target network function of the Nnrf_NFDiscovery service is the AMF 205, the discovery response may include a list of GUAMIs, a list of GUAMIs that may be used as backups, and the S-NSSAIs supported by the AMF 205.

[0055] It should be understood that Figure 3 Method 300 and Figure 4Methods 400 can be related to each other, and the various operations of these methods can be performed in any order. For example, in some example embodiments, NSACF registration operations 405 and 410 of method 400 can be performed. After NSACF registration is complete, method 300 can be performed by the AMF. Thus, in this example, the NSACF registration operations are Figure 3 an initial form of the AMF operations. In other example embodiments, other orders of the operations of methods 300 and 400 can be used.

[0056] Figure 5 Table 500 is shown, which shows an example of example information that can be included by the NRF in a discovery response sent to the NSACF during the AMF discovery procedure. In this example, the table includes a column 505 for AMF details, a column 510 for the corresponding GUAMI, and a column 515 for a list of S-NSSAIs supported by the corresponding GUAMI. This column can be used as a lookup table by the NSACF 225 to look up the appropriate AMF for the EAC update procedure.

[0057] In a regular case, the NSACF 225 is not provided with a list of one or more AMFs, the corresponding GUAMIs for these AMFs, and the list of S-NSSAIs supported by each AMF. In some embodiments, this example enhancement can be enabled by the example enhancements introduced in 305 of signaling diagram 300, where the AMF 205 provides the GUAMI, and the list of S-NSSAIs supported by the AMF 205 during the NSACF discovery procedure.

[0058] Signaling diagram 400 introduces the NSACF as a consumer of some NRF services and operations. Specifically, the NSACF 225 is shown as a consumer of the Nnrf_NFmanagement service (e.g., the NFRegister request and response operations). Additionally, the NSACF 225 is shown as a consumer of the Nnrf_NFDiscovery service (e.g., the NFDiscovery request and response operations). Thus, although not shown in signaling diagram 400, the NSACF 225 can also be a consumer of the Nnrf_NFmanagement service “NFupdate” request / response operations and a consumer of the “NFDeregister” request / response operations.

[0059] Additionally, the example enhancements shown in 420 can provide a basis for example enhancements introduced by an EAC update procedure. The EAC update procedure indicates to the AMF 204 activation or deactivation of the EAC mode for S-NSSAIs subject to NSAC. Those skilled in the art will appreciate that the EAC mode for S-NSSAIs can control whether a network slice availability check and update procedure needs to be performed on the AMF 205 before the S-NSSAI is considered as an allowed S-NSSAI for the UE 110.

[0060] Figure 6 A signaling diagram 600 for example EAC update procedures is shown in accordance with various example embodiments. The signaling diagram 600 will be described with reference to the network architecture 200, and includes the NSACF 225 and the AMF 205.

[0061] In 605, the NSACF 225 determines that the number of UEs (or sessions) registered to a network slice subject to NSAC exceeds a threshold. The threshold indicates whether the EAC mode for the S-NSSAI is to be activated or deactivated.

[0062] In 610, the NSACF 225 sends an EAC mode activation or deactivation command to the AMF 205. For example, the determination in 605 can trigger the NSACF 225 to transmit a message including one or more S-NSSAIs and an EAC flag for each S-NSSAI. If the number of UEs registered to the network slice is above the threshold, the EAC flag for the S-NSSAI can be set to activated. Alternatively, if the number of UEs registered to the network slice is below the threshold, the EAC flag for the S-NSSAI can be set to deactivated. The message can be referred to as a “Nnsacf_NumberOfUEsPerSliceEACnotify” command.

[0063] It has been identified that, in regular cases, the NSACF 225 can not be able to determine which one of the network deployed AMFs will be notified when the threshold is reached. The example enhancements described above with reference to the signaling diagrams 300-400 can provide a solution to this problem. For example, one of the example enhancements introduced in the signaling diagram 300 is that the AMF 205 provides the GUAMI and the list of S-NSSAIs supported by the AMF 205 in the registration request 405 to the NRF 220. According to another example enhancement introduced in the signaling diagram 400, the information obtained by the NRF 220 (e.g., the list of S-NSSAIs supported by the AMF 205) can be provided to the NSACF 225 in the AMF discovery response. Since the NSACF 225 has this information, the NSACF can trigger the Nnsacf_NumberOfUEsPerSliceEACnotify operation to notify only the AMF(s) that support the corresponding S-NSSAI.

[0064] In 615, the AMF 205 uses the EAC flag to decide when to trigger the UE number per slice availability check and update procedure. This can reduce the delay of the registration procedure and avoid negative impact on the network slices that have already been allowed.

[0065] When the EAC flag indicates that the EAC mode is to be activated, the AMF 205 can trigger the UE number per slice availability check and update procedure before the registration accept step of the registration procedure or before the UE configuration update message. In other words, if the quota of a network slice has been reached, the AMF 205 can perform the availability check before these messages are provided to the UE 110. When the EAC flag indicates that the EAC mode is to be deactivated, the AMF 205 triggers the UE number per slice availability check and update procedure after the registration accept step of the registration procedure or after the UE configuration update message.

[0066] In another aspect, example embodiments relate to the behavior of the NSACF in the context of roaming scenarios. Before discussing example embodiments, examples of two different roaming scenarios are described below.

[0067] Figure 7An example of a local breakout (LBO) roaming scenario 700 is shown. The example 700 includes a UE 110, a VPLMN 710, a HPLMN 750, a data network 715, a NSACF deployed by the VPLMN (vNSACF) 712, a NSACF deployed by the HPLMN (hNSACF) 852, a Security Edge Protection Proxy (SEPP) on the VPLMN side 714, and a SEPP on the HPLMN side 754. Those skilled in the art will appreciate that the SEPPs 714, 754 can act as a service relay between the VPLMN 710 and the HPLMN 750 to provide a secure connection and hide the network topology.

[0068] In LBO, data traffic can be routed directly from the VPLMN 710 to the data network 715, while authentication and handling of subscription data is handled in the HPLMN 750. Here, the Internet Protocol (IP) address of the data network 715 can be obtained by the UE 110 from the VPLMN 710.

[0069] Figure 8 An example of a home routed roaming scenario 800 is shown. The example 800 includes a UE 110, a VPLMN 810, a HPLMN 850, a data network 855, a NSACF deployed by the VPLMN (vNSACF) 812, a NSACF deployed by the HPLMN (hNSACF) 852. A SEPP on the VPLMN side 814 and a SEPP on the HPLMN side 854. Those skilled in the art will appreciate that the SEPPs 814, 854 can act as a service relay between the VPLMN 810 and the HPLMN 850 to provide a secure connection and hide the network topology.

[0070] In a home routed scenario, VPLMN 810 data traffic is routed to the data network 855 via the HPLMN 850. This scenario provides operators more control in providing roaming services, policies, and subscriber charging. Here, the IP address of the data network 855 can be obtained from the HPLMN 850.

[0071] In roaming scenarios, the NSAC for roaming UEs can be performed by both the VPLMN and the HPLMN, depending on the operator's policies, roaming agreements, or service level agreements (SLAs) between the VPLMN and the HPLMN. For example, a NSACF in the VPLMN can be configured by both the HPLMN and the VPLMN with a maximum number of roaming UEs per network slice that are allowed to be served by each network slice subject to NSAC. A NSACF in the VPLMN can perform NSAC for both S-NSSAIs in the VPLMN and the corresponding mapped S-NSAAIs in the HPLMN.

[0072] To provide an example, within the context of the LBO roaming scenario 700, for NSAC of a roaming UE (e.g., UE 110) managed by the VPLMN 710, the NSACF (e.g., vNSACF 712) can be configured with a maximum number of PDU sessions per network slice allowed to be served by each network slice subject to NSAC in the LBO mode.

[0073] In the LBO roaming scenario 700, for maximum number of UE per network slice admission control, the AMF can trigger a request to perform network slice admission control for the NSACF (e.g., vNSACF 712) in the serving PLMN. In this example, the NSACF in the HPLMN (e.g., hNSACF 752) can not be included.

[0074] To provide an example, within the context of the home routed roaming scenario 800, the NSACF in the HPLMN 850 (e.g., hNSACF 852) can be configured with a maximum number of PDU sessions per network slice, and the NSACF in the VPLMN 810 (e.g., vNSACF 812) can be configured with a maximum number of PDU sessions per network slice allowed to be served by each network slice subject to NSAC in the home routed mode. Both NSACFs (e.g., hNSACF 852, vNSACF 812) can perform NSAC, with the vNSACF 812 performing NSAC for S-NSSAIs in the VPLMN 810, and the hNSACF 852 in the HPLMN 850 performing NSAC for corresponding mapped S-NSSAIs in that HPLMN.

[0075] In the home routed roaming scenario 800, for maximum number of PDU sessions per network slice admission control, the SMF of the VPLMN can trigger a request to the vNSACF 812 in the VPLMN 810. Additionally, the SMF of the HPLMN 850 can trigger a request to perform maximum number of PDU sessions admission control for the hNSACF 852 in the HPLMN 850.

[0076] Figure 9 A signaling diagram 900 of a UE number per network slice availability check and update procedure is shown in accordance with various example embodiments. Initially, an overview of the signaling diagram 900 will be provided with reference to the network architecture of Figure 2 Thus, the signaling diagram 900 includes the AMF 205 and the NSACF 225. Subsequently, enhancements to network slice admission control support for roaming will be described with reference to the signaling diagram 900, the LBO roaming scenario 700, and the home routed roaming scenario 800.

[0077] The per network slice UE number availability check and update procedure is to update (e.g., increase or decrease) the number of UEs registered to an S-NSSAI subject to NSAC. The AMF 205 can be configured with information indicating which network slices are subject to NSAC.

[0078] In 905, the AMF 205 triggers the per network slice UE number availability check and update procedure to update the number of UEs registered to a network slice when including a network slice subject to NSAC or removing that network slice from the allowed NSSAI for the UE.

[0079] In 910, the AMF 205 transmits a per network slice UE number availability check and update request to the NSACF 225. For example, the message can be referred to as “Nnsacf_NumberOfUEsPerSliceAvailabilityCheckandUpdate_Request” and includes information such as, but not limited to, UE ID, S-NSSAI for which the registered UE number per network slice is needed to be updated, and an update flag indicating whether the registered UE number per network slice is to be increased or decreased.

[0080] In 915, the NSACF 225 updates the current number of registered UEs for the S-NSSAI. For example, the NSCAF 225 can increase or decrease the registered UE number per network slice based on the information provided by the AMF 205 in the update flag parameter.

[0081] In 920, the NSACF 225 transmits a response to the request to the AMF 205. For example, the message can be referred to as “Nnsacf_NumberOfUEsPerSliceAvailabilityCheckandUpdate_Response” and includes information such as, but not limited to, S-NSSAI for which the maximum number of UEs has been reached, and a result parameter indicating that the maximum number of UEs registered to that network slice has been reached. If all S-NSSAI returned by the NSACF 225 to the AMF 205 have been reached, the AMF 205 can reject the request from the UE 110. Otherwise, the AMF 205 returns a registration accept message, where the AMF 205 includes the rejected S-NSSAI in the list of rejected NSSAI.

[0082] For NSAC of roaming UEs, the maximum number of roaming UEs per network slice, or the maximum number of PDU sessions per network slice in LBO mode, or the maximum number of PDU sessions per network slice in home routing mode, is assigned to the VPLMN according to the SLA agreement and stored in the responsible vNSACF for the S-NSSAI. The vNSACF monitors and enforces the maximum number of UEs registered to the network slice in the VPLMN. However, in signaling diagram 900, the "Nnsacf_NumberOfUEsPerSliceAvailabilityCheckandUpdat_Request" service operation of the AMF 205 provides the vNSACF with both the S-NSSAI in the VPLMN and the corresponding mapped S-NSSAI in the HPLMN. At 915, the vNSACF performs NSAC for the S-NSAAI in the VPLMN based on the SLA with the UE's HPLMN.

[0083] In the home-routed roaming scenario 800 , maximum number of PDU sessions per network slice monitoring and enforcement is done in the VPLMN 810 by the vNSACF 812 and in the HPLMN 850 by the hNSACF 852 .

[0084] Figure 10 An exemplary UE 110 is shown according to various exemplary embodiments. Figure 1 10. The UE 110 may include a processor 1005, a memory arrangement 1010, a display device 1015, an input / output (I / O) device 1020, a transceiver 1025, and other components 130. The other components 1030 may include, for example, an audio input device, an audio output device, a power source, a data acquisition device, a port for electrically connecting the UE 110 to other electronic devices, and the like.

[0085] The processor 1005 may be configured to execute multiple engines of the UE 110. For example, the engines may include a session management engine 1035. The session management engine 1035 may perform various operations related to establishing and maintaining a PDU session.

[0086] The engine 1035 described above is provided for illustrative purposes as an application (e.g., program) executed by the processor 205. The functionality associated with the engine 235 can also be represented as a standalone component of the UE 110, or can be a modular component coupled to the UE 110, e.g., an integrated circuit with or without firmware. For example, the integrated circuit can include input circuitry to receive signals and processing circuitry to process signals and other information. The engine can also be embodied as one application or multiple applications separate from each other. Moreover, in some UEs, the functionality described with respect to the processor 1005 is shared among two or more processors, such as a baseband processor and an application processor. The example embodiments can be implemented in any of these or other configurations of the UE.

[0087] The memory arrangement 1010 can be a hardware component configured to store data related to operations performed by the UE 110. The display device 1015 can be a hardware component configured to display data to a user, while the I / O device 1020 can be a hardware component that enables a user to make inputs. The display device 1015 and the I / O device 1020 can be separate components or can be integrated together, such as a touchscreen. The transceiver 1025 can be a hardware component configured to establish a connection with the 5G NR-RAN 120 and / or any other appropriate type of network. Thus, the transceiver 1025 can operate on various different frequencies or channels (e.g., a set of contiguous frequencies).

[0088] Figure 11 An example base station 1100 according to various example embodiments is shown. The base station 1100 can represent any access node (e.g., gNB 120A, etc.) with which the UE 110 can establish a connection and manage network operations.

[0089] The base station 1100 can include a processor 1105, a memory arrangement 1110, an input / output (I / O) device 1115, a transceiver 1120, and other components 1125. The other components 1125 can include, for example, a battery, a data acquisition device, a port that electrically connects the base station 1100 to other electronic devices, etc.

[0090] The processor 1105 can be configured to execute a number of engines of the base station 1100. However, references to the processor 1105 are exemplary only. The functionality associated with these engines can also be represented as combined components of the base station 1100, or can be modular components coupled to the base station 1100, e.g., integrated circuits with or without firmware. For example, the integrated circuits can include input circuitry to receive signals and processing circuitry to process the signals and other information. Further, in some base stations, the functionality described with respect to the processor 305 is split among multiple processors (e.g., a baseband processor, an application processor, etc.). The example embodiments can be implemented in accordance with any of these or other configurations of the base station.

[0091] The memory 1110 can be a hardware component configured to store data related to the operations performed by the base station 1100. The I / O device 1115 can be a hardware component or port that enables a user to interact with the base station 1100. The transceiver 1120 can be a hardware component configured to exchange data with the UE 110 and any other UEs in the system 100. The transceiver 1120 can operate on a variety of different frequencies or channels (e.g., a set of contiguous frequencies). Thus, the transceiver 1120 can include one or more components (e.g., radio components) capable of data exchange with a variety of networks and UEs.

[0092] Example

[0093] In a first embodiment, a network slice admission control function (NSACF) of a 5G core network is configured to perform operations comprising: maintaining network slice quotas for one or more network slices, wherein the network function is a network slice admission control function (NSACF) configured to perform network slice admission control (NSAC) for both a visited public land mobile network (VPLMN) and a home public land mobile network (HPLMN); receiving, from an access and mobility management function (AMF), a registered user equipment (UE) quantity availability check and update request per network slice; and sending, to the AMF, a response indicating that a maximum number of registered UEs or sessions for an S-NSSAI has been reached.

[0094] In a second embodiment, the NSACF of the first embodiment, wherein the operations further comprise receiving a maximum number of roaming UEs per network slice for a single network slice selection assistance information (S-NSSAI) in a visited public land mobile network (VPLMN), and receiving a maximum number of roaming UEs per network slice for a corresponding mapped S-NSAAI in a home public land mobile network (HPLMN).

[0095] In a third embodiment, the NSACF of the first embodiment, wherein the network function is a Network Slice Admission Control Function (NSACF) deployed by a Visited Public Land Mobile Network (VPLMN), the NSACF configured with a maximum number of Packet Data Unit (PDU) sessions per network slice in a Local Breakout (LBO) mode.

[0096] In a fourth embodiment, the NSACF of the third embodiment, wherein the network function is a Network Slice Admission Control Function (NSACF) deployed by a Visited Public Land Mobile Network (VPLMN), the NSACF configured with a maximum number of Packet Data Unit (PDU) sessions per network slice in a Home Routing mode.

[0097] In a fifth embodiment, the NSACF of the fourth embodiment, wherein the NSACF deployed by the VPLMN is configured to perform Network Slice Admission Control (NSAC) for a single Network Slice Selection Assistance Information (S-NSSAI), and the NSACF deployed by a Home Public Land Mobile Network (HPLMN) is configured to perform NSAC for a corresponding mapped S-NSSAI.

[0098] In a sixth embodiment, the NSACF of the first embodiment, wherein the network function is a Network Slice Admission Control Function (NSACF) deployed by a Visited Public Land Mobile Network (VPLMN), and the request is received from a Session Management Function (SMF) deployed by the VPLMN.

[0099] In a seventh embodiment, the NSACF of the first embodiment, wherein the quota comprises a maximum number of Packet Data Unit (PDU) sessions per network slice in a Local Breakout (LBO) mode.

[0100] In an eighth embodiment, the NSACF of the first embodiment, wherein the quota comprises a maximum number of Packet Data Unit (PDU) sessions per network slice in a Home Routing mode.

[0101] In a ninth embodiment, the NSACF of the first embodiment, wherein the network function is a Network Slice Admission Control Function (NSACF) deployed by a Visited Public Land Mobile Network (VPLMN).

[0102] In a tenth embodiment, the NSACF of the ninth embodiment, wherein the request comprises a single Network Slice Selection Assistance Information (S-NSSAI) in the VPLMN and a corresponding mapped S-NSSAI in a Home Public Land Mobile Network (HPLMN).

[0103] In an eleventh embodiment, the NSACF of the tenth embodiment, wherein the NSACF is configured to perform network slice admission control (NSAC) for a single network slice selection assistance information (S-NSSAI) in the VPLMN based on an agreement between the VPLMN and a home public land mobile network (HPLMN).

[0104] In a twelfth embodiment, a method performed by a network slice admission control function (NSACF) of a 5G core network includes maintaining network slice quotas for one or more network slices, wherein the network slice admission control function (NSACF) is configured to perform network slice admission control (NSAC) for a visited public land mobile network (VPLMN) and a home public land mobile network (HPLMN); receiving, from an access and mobility management function (AMF), a registered user equipment (UE) quantity availability check and update request per network slice; and sending a response to the AMF indicating that a maximum number of registered UEs or sessions for an S-NSSAI has been reached.

[0105] In a thirteenth embodiment, the method of the twelfth embodiment, wherein the operations further comprise receiving a maximum number of roaming UEs per network slice for a single network slice selection assistance information (S-NSSAI) in a visited public land mobile network (VPLMN) and receiving a maximum number of roaming UEs per network slice for a corresponding mapped S-NSAAI in a home public land mobile network (HPLMN).

[0106] In a fourteenth embodiment, the method of the twelfth embodiment, wherein the network function is a network slice admission control function (NSACF) deployed by a visited public land mobile network (VPLMN) configured with a maximum number of packet data unit (PDU) sessions per network slice in a local breakout mode (LBO).

[0107] In a fifteenth embodiment, the method of the twelfth embodiment, wherein the network function is a network slice admission control function (NSACF) deployed by a visited public land mobile network (VPLMN) configured with a maximum number of packet data unit (PDU) sessions per network slice in a home routed mode.

[0108] In a sixteenth embodiment, the method of the fifteenth embodiment, wherein the NSACF deployed by the VPLMN is configured to perform network slice admission control (NSAC) for a single network slice selection assistance information (S-NSSAI), and a NSACF deployed by a home public land mobile network (HPLMN) is configured to perform NSAC for a corresponding mapped S-NSSAI.

[0109] In a seventeenth embodiment, the method of the twelfth embodiment, wherein the network function is a network slice admission control function (NSACF) deployed by a visited public land mobile network (VPLMN), and the request is received from a session management function (SMF) deployed by the VPLMN.

[0110] In an eighteenth embodiment, the method of the twelfth embodiment, wherein the quota comprises a maximum number of packet data unit (PDU) sessions per network slice in a local breakout (LBO) mode.

[0111] In a nineteenth embodiment, the method of the twelfth embodiment, wherein the quota comprises a maximum number of packet data unit (PDU) sessions per network slice in a home routed mode.

[0112] In a twentieth embodiment, the method of the twelfth embodiment, wherein the network function is a network slice admission control function (NSACF) deployed by a visited public land mobile network (VPLMN).

[0113] In a twenty-first embodiment, the method of the twentieth embodiment, wherein the request comprises a single network slice selection assistance information (S-NSSAI) in the VPLMN and a corresponding mapped S-NSSAI in a home public land mobile network (HPLMN).

[0114] In a twenty-second embodiment, the method of the twenty-first embodiment, wherein the NSACF is configured to perform network slice admission control (NSAC) for the single network slice selection assistance information (S-NSSAI) in the VPLMN based on a protocol between the VPLMN and a home public land mobile network (HPLMN).

[0115] In a twenty-third embodiment, a method performed by a network slice admission control function (NSACF) of a 5G core network, the method comprising: transmitting a network function registration request to a network resource function (NRF), wherein the network function registration request includes a list of single network slice selection assistance information (S-NSSAI) for which the NSACF manages its admission control; and receiving a response to the network function registration request from the NRF, wherein the NSACF is a consumer of the Nnrf_NFManagement service.

[0116] In a twenty-fourth embodiment, the method of the twenty-third embodiment, wherein the network function registration request further includes a number of registered user equipment (UE) supported by a first one of the S-NSSAI.

[0117] In a twenty-fifth embodiment, the method of the twenty-third embodiment, wherein the network function registration request further includes a number of protocol data unit (PDU) sessions supported by a first one of the S-NSSAI.

[0118] In a twenty-sixth embodiment, the method of the twenty-third embodiment, wherein the network function registration request further includes a service area for the NSACF.

[0119] In a twenty-seventh embodiment, the method of the twenty-third embodiment, further comprising identifying that a number of registered user equipment (UE) for an S-NSSAI exceeds a threshold, identifying one or more AMFs associated with the S-NSSAI based on the discovery response, and transmitting an early admission control (EAC) flag to only the identified AMFs in response to the number of registered UEs for the S-NSSAI exceeding the threshold.

[0120] Those skilled in the art will understand that the exemplary embodiments described above can be implemented in any suitable software configuration or hardware configuration, or a combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments can include, for example, an Intel x86-based platform with a compatible operating system, Windows OS, Mac platform and MAC OS, mobile devices with operating systems such as iOS, Android, and the like. Exemplary embodiments of the above-described methods can be embodied as a program including code lines stored on a non-transitory computer-readable storage medium, which, when executed, can be executed on a processor or microprocessor.

[0121] While various combinations of various embodiments, each having various features, are described herein, one of skill in the art will understand that any feature of one embodiment can be combined with features of other embodiments, or features that are not inconsistent with the operation or functioning of the devices disclosed herein, in any combination, in any embodiment, without departing from the disclosure.

[0122] It is well understood that, as a matter of good practice and assuming compliance with applicable laws and regulations, use of personal identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personal identifiable information data should be managed and handled in a manner that minimizes risk of unauthorized or unintended access or use of data and that is consistent with privacy ethics and principles regarding authorized use.

[0123] It will be apparent to those skilled in the art that various modifications can be made to the disclosure without departing from the spirit or scope of it. Thus, it is intended that the disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims

1. A processor of an Access and Mobility Management Function (AMF) of a 5G core network, the processor configured to perform operations comprising: generating a network function registration request for transmission to a Network Resource Function (NRF), wherein the network function registration request includes a list of single network slice selection assistance information (S-NSSAI) supported by the AMF; receiving a response to the network function registration request from the NRF; generating a network function discovery request for transmission to the NRF, the network function discovery request including one or more S-NSSAI and an indication that the discovery request is for a Network Slice Admission Control Function (NSACF); and receiving a network function discovery response from the NRF, wherein the network function discovery response includes an NSACF address and a list of S-NSSAI for which the NSACF manages admission control.

2. The processor of claim 1, the operations further comprising: receiving a registration request from a user equipment (UE), wherein the registration request is received after the network function discovery response and corresponds to one or more S-NSSAI not included in the network function discovery request transmitted to the NRF; and determining, based on the list of S-NSSAI included in the network function discovery response, that the NSACF manages admission control for the one or more S-NSSAI.

3. The processor of claim 2, the operations further comprising: sending an update request to the NSACF to indicate that the NSACF should increment a count of UEs corresponding to each of the one or more S-NSSAI corresponding to the registration request of the UE; and receiving an update response to the update request from the NSACF.

4. The processor of claim 3, the operations further comprising: when the update response indicates that the one or more S-NSSAI corresponding to the registration request of the UE have all reached a maximum number of UEs, sending a registration reject message to the UE.

5. The processor of claim 3, the operations further comprising: when the update response indicates that a first one of the one or more S-NSSAI corresponding to the registration request of the UE has reached a maximum number of UEs and a second one of the one or more S-NSSAI corresponding to the registration request has not reached a maximum number of UEs, sending a registration accept message to the UE, wherein the registration accept message includes an identification of the first one of the one or more S-NSSAI that has reached the maximum number of UEs.

6. A processor of a Network Slice Admission Control Function (NSACF) of a 5G core network, the processor configured to perform operations comprising: ​ generating a network function registration request for transmission to a network resource function, NRF, the network function registration request including a list of single network slice selection assistance information, S-NSSAI, for which the NSACF manages its admission control; and receiving a response to the network function registration request from the NRF, wherein the NSACF is a consumer of the Nnrf_NFManagement service.

7. The processor of claim 6, wherein the network function registration request further includes a number of registered user equipment, UEs, supported by a first one of the S-NSSAIs.

8. The processor of claim 6, wherein the network function registration request further includes a number of protocol data unit, PDU, sessions supported by a first one of the S-NSSAIs.

9. The processor of claim 6, wherein the network function registration request further includes a service area for the NSACF.

10. The processor of claim 6, the operations further comprising: identifying that a number of registered user equipment, UEs, for a S-NSSAI exceeds a threshold; identifying one or more AMFs associated with the S-NSSAI based on the network function discovery response; and responsive to the number of registered UEs for the S-NSSAI exceeding the threshold, transmitting an early admission control, EAC, flag to only the identified AMFs.

11. A method performed by an access and mobility management function, AMF, of a 5G core network, the method comprising: transmitting a network function registration request to a network resource function, NRF; receiving a response to the network function registration request from the NRF, wherein the network function registration request includes a list of single network slice selection assistance information, S-NSSAI, supported by the AMF; transmitting a network function discovery request to the NRF, the network function discovery request including one or more S-NSSAIs and an indication that the discovery request is for a network slice admission control function, NSACF; and receiving a network function discovery response from the NRF, wherein the network function discovery response includes a NSACF address and a list of S-NSSAIs for which the NSACF manages its admission control.

12. The method of claim 11, further comprising: receiving a registration request from a user equipment, UE, wherein the registration request is received after the network function discovery response and corresponds to one or more S-NSSAIs not included in the network function discovery request transmitted to the NRF; and determining that the NSACF manages admission control for the one or more S-NSSAIs based on the list of S-NSSAIs included in the network function discovery response.

13. The method of claim 12, further comprising: sending, to the NSACF, an update request to indicate that the NSACF should increment a count of UEs corresponding to each of the one or more S-NSSAIs corresponding to the registration request of the UE; and receiving, from the NSACF, an update response to the update request.

14. The method of claim 13, further comprising: when the update response indicates that a maximum number of UEs has been reached for all of the one or more S-NSSAIs corresponding to the registration request of the UE, sending, to the UE, a registration reject message.

15. The method of claim 13, further comprising: when the update response indicates that a maximum number of UEs has been reached for a first one of the one or more S-NSSAIs corresponding to the registration request of the UE and a maximum number of UEs has not been reached for a second one of the one or more S-NSSAIs corresponding to the registration request, sending, to the UE, a registration accept message, wherein the registration accept message includes an identification of the first one of the one or more S-NSSAIs for which the maximum number of UEs has been reached.

Images