AF initiated request for network slice replacement

Abstract

Disclosed herein is a method performed by a first network function (e.g., PCF 210) in a core network of a cellular communications system. The method comprises: receiving (400-1 or 400-2C) an Application Function (AF) initiated request for replacement of a network slice for a User Equipment (UE) with an alternative network slice; and initiating (404) replacement of the network slice for the UE with the alternative network slice.

Description

Applicant's Ref. P112353WO01 1AF INITIATED REQUEST FOR NETWORK SLICE REPLACEMENTTechnical Field

[0001] The present disclosure relates to a wireless communication system that utilizes network slicing and, more specifically, to network slice replacement.Background

[0002] Release 18 of the 3rdGeneration Partnership Project (3GPP) specification supports network-initiated slice replacement for scenarios related to slice congestion. Details are included in the following excerpt from Section 5.15.19 of 3GPP Technical Specification (TS) 23.501 V18.7.0.***** START EXCERPT FROM 3GPP TS 23.501 *****5.15.19 Support of Network Slice ReplacementThe Network Slice Replacement feature is used to temporarily replace an S -NS SAI with an Alternative S -NS SAI when an S-NSSAI becomes unavailable or congested in the 5GC. The Network Slice Replacement may be triggered in the following cases:- If the NSSF detects that an S-NSSAI becomes unavailable or congested (e.g. based on 0AM or NWDAF analytics output), the NSSF sends network slice availability notification for the S-NSSAI to the AMF. The notification may include an Alternative S-NSSAI which can be used by the AMF to replace the S-NSSAI and congestion mitigation information if the S-NSSAI is congested. The NSSF notifies the AMF when the S- NSSAI is available again.- If the PCF detects that an S-NSSAI becomes unavailable or congested for a UE (e.g. based on 0AM or NWDAF analytics output), the PCF sends access and mobility related policy notification to the AMF. The notification may include an Alternative S-NSSAI which can be used by the AMF to replace the S-NSSAI. The PCF notifies the AMF when the S-NSSAI is available again for the UE.- The 0AM sends notification to AMF when an S-NSSAI becomes unavailable or congested (and also when this S-NSSAI becomes available again) and provides the Alternative S-NSSAI to AMF and the 0AM may provide congestion mitigation information if the S-NSSAI is congested.The network slice associated with the Alternative S-NSSAI is assumed in this specification to have NS-AoS to be covering at least the NS-AoS of the replaced network slice. If the UE moves to a cell where the replaced S-NSSAI is not supported, but still within the NS-AoS of the Alternative S-NSSAI, the AMF removes the replaced S-NSSAI from the Allowed NSSAI (if the S-NSSAI was in the Allowed NSSAI) and from the Partially Allowed NSSAI (if the UE moves out of the RA also).If the replaced S-NSSAI is subject to area restrictions, the AMF indicates to the SMF that the PDU Session is subject to area restrictions for the replaced S-NSSAI and the AMF and the SMF then apply the area restriction for the replaced S-NSSAI as described in clause 5.15.17 or clause 5.15.18 and the SMF additionally deactivates the PDU Session when the UE is OUT of Aol.NOTE 1 : It is recommended to use a network slice associated with the Alternative S-NSSAI that is able to support requirements for the services that the replaced network slice supports. It is further recommended in particular that the Alternative S-NSSAI supports at least the DNNs supported in the replaced S-NSSAI.NOTE 2: The AMF can, by using the UE’s presence in the Aol for the replaced S-NSSAI, prevent the UE from obtaining service in the Alternative network slice in cells outside the NS-AoS of the replaced network slice but within the NS-AoS of the Alternative network slice if the Alternative network slice NS-AoS exceeds the NS-AoS of the replaced network slice.Applicant's Ref. P112353WO01 2Based on the notification above from NSSF or PCF or OAM, the AMF may determine that an S-NSSAI is to be replaced with Alternative S-NSSAI. For roaming case, the AMF subscribes the network slice availability notification of the HPLMN S-NSSAI from the NSSF in VPLMN and the NSSF in VPLMN subscribes the notification from NSSF in the HPLMN as described in clause 5.15.6.If the notification is from NSSF or OAM, and reason for the replacement is due to congestion, the notification includes additional congestion mitigation information. The details of the congestion mitigation information from NSSF and how the congestion mitigation information is used by the AMF is described in clause 5.2.16.3.3 of TS 23.502 [3],NOTE 3 : It is recommended that, the operator configures to use only one option, i.e. OAM, PCF or NSSF, for determining an Alternative S-NSSAI and triggering the Network Slice Replacement for S-NSSAI.The AMF uses the Alternative S-NSSAI received in the notification from the NSSF, or from OAM or from the PCF. If the NSSF or PCF or OAM do not provide an Alternative S-NSSAI in the notification, the AMF uses an Alternative S-NSSAI based on local configuration. The Alternative S-NSSAI shall be supported in the UE Registration Area. If AMF cannot determine the Alternative S-NSSAI for the S-NSSAI, e.g. OAM or NSSF doesn't provide Alternative S-NSSAI and there is no Alternative S-NSSAI in the AMF local configuration, the AMF may further interact with the PCF to determine the Alternative S-NSSAI. The event trigger in AMF for interacting with PCF is described in clause 6.1.2.5 of TS 23.503

[0045] ,If the Alternative S-NSSAI is subject to NSSAA, the Alternative S-NSSAI shall only be used for UEs for which the Alternative S-NSSAI is included in the Subscribed S-NSSAIs. In this case, the AMF performs the NSSAA procedure for the Alternative S-NSSAI as described in clause 5.15.10 before the AMF triggers Network Slice Replacement as specified below.The UE indicates the support of Network Slice Replacement feature during the UE Registration procedure. For supporting UE in CM-CONNECTED state and if there is a PDU Sessions in the UE context associated with the S- NSSAI that needs to be replaced over an Access Type, the AMF additionally provides the Alternative S-NSSAI for this S-NSSAI in the Allowed NSSAI over the same Access Type and in the Configured NSSAI, if not included yet, and the mapping between S-NSSAI(s) to Alternative S-NSSAI(s) to the UE in UE Configuration Update message as follows:- for non-roaming UEs, the AMF provides the mapping of the S-NSSAI to the Alternative S-NSSAI to the UE.NOTE 4: In the non-roaming case, the Alternative S-NSSAI does not have to be a Subscribed S-NSSAIs, as the replaced S-NSSAI is always a subscribed S-NSSAI.- for roaming UEs when the VPLMN S-NSSAI has to be replaced by a VPLMN Alternative S-NSSAI, the AMF provides the mapping of the VPLMN S-NSSAI to the Alternative VPLMN S-NSSAI to the UE.- for roaming UEs when the HPLMN S-NSSAI has to be replaced by an Alternative HPLMN S-NSSAI, the AMF provides the mapping of the HPLMN S-NSSAI to the Alternative HPLMN S-NSSAI to the UE.NOTE 5: In the roaming cases, the Alternative HPLMN S-NSSAI does not have to be one of the Subscribed S- NSSAIs as the replaced HPLMN S-NSSAI is always part of the Subscribed S-NSSAIs.The AMF provides the mapping of the S-NSSAI to the Alternative S-NSSAI over the access the AMF wants to trigger Network Slice Replacement. The UE stores the received mapping information together with the received Access Type and only uses it over that access.Since Network Slice Replacement applies independent of Access Type, when the replacement occurs, the same Alternative S-NSSAI mapping to the replaced S-NSSAI is provided over the Access Types where the replaced S- NSSAI is in the Allowed NSSAI.If the replaced S-NSSAI cannot be kept in the Allowed NSSAI or Partially Allowed NSSAI, the AMF additionally removes the Alternative S-NSSAI from the Allowed NSSAI or Partially Allowed NSSAI if the Alternative S-NSSAI is only used for Network Slice Replacement.At mobility between AMFs, the source AMF provides, to the new AMF, the Alternative S-NSSAI and the mapping of the replaced S-NSSAI to the Alternative S-NSSAI in the UE context. When an S-NSSAI is subject to Network Slice Replacement, the new AMF compares the Requested NSSAI with the received UE context and updates the UE which misses the mapping of the replaced S-NSSAI to the Alternative S-NSSAI.Applicant's Ref. P112353WO01 3For the supporting UE when the UE has a NAS signalling connection, i.e. it is CM-CONNECTED or it has become CM-CONNECTED, e.g. through a Service Request procedure or through a UE registration procedure, if the AMF determines that the S-NSSAI is to be replaced and there is a PDU Session associated with the S-NSSAI in the UE context (see also NOTE 3), the AMF sends the mapping of the S-NSSAI to the Alternative S-NSSAI to the UE in the UE Configuration Update message or in the Registration Accept message.NOTE 6: It is left to AMF local policy whether to send the mapping of the S-NSSAI to the Alternative S-NSSAI to the UE when there is no PDU session associated with the S-NSSAI or wait and send the mapping of the S-NSSAI to the Alternative S-NSSAI to the UE when the UE establishes a PDU Session associated with the S-NSSAI.When the S-NSSAI is replaced by the Alternative S-NSSAI, the UE associates both of the replaced S-NSSAI and the Alternative S-NSSAI with the PDU session. The UE procedure for associating applications to PDU session based on URSP described in clause 6.6.2.3 of TS 23.503

[0045] and establishing a PDU session described in clause 5.15.5.3 is based on the replaced S-NSSAI (not based on Alternative S-NSSAI).During a new PDU Session establishment procedure for a S-NSSAI,- if the UE has received together with the Allowed NS SAI a mapping of the S-NSSAI to an Alternative S- NSSAI, the UE shall provide both the Alternative S-NSSAI and the S-NSSAI in the PDU Session Establishment message. When the AMF receives the Alternative S-NSSAI and the S-NSSAI in the PDU Session Establishment message, the AMF uses SMF Selection Subscription data of the replaced S-NSSAI and selects a suitable SMF supporting Network Slice Replacement and the Alternative S-NSSAI and verifies the Alternative S-NSSAI and the S-NSSAI based on the UE context and includes both the Alternative S-NSSAI and the S-NSSAI to the SMF in Nsmf PDUSession CreateSMContext service operation.- if the UE has not yet received with the Allowed NSSAI a mapping of the S-NSSAI to the Alternative S- NSSAI, the UE provides only the S-NSSAI in the PDU Session Establishment message. If the AMF determines that the requested S-NSSAI is to be replaced with the Alternative S-NSSAI and if the UE supports Network Slice Replacement, the AMF performs UE Configuration Update procedure to reconfigure the UE with the Alternative S-NSSAI. The AMF continues the PDU Session establishment procedure with the Alternative S-NSSAI and uses SMF Selection Subscription data of the replaced S-NSSAI and selects a suitable SMF supporting Network Slice Replacement and the Alternative S-NSSAI. The AMF provides both the Alternative S-NSSAI and the S-NSSAI to the SMF in Nsmf PDUSession CreateSMContext service operation.The SMF proceeds with the PDU Session establishment using the Alternative S-NSSAI and the received DNN. The SMF retrieves subscription data by using the replaced S-NSSAI and the DNN. The SMF uses replaced S-NSSAI value when the SMF registers the PDU Session to the UDM. The SMF sends the Alternative S-NSSAI to NG-RAN in N2 SM information and to UE in PDU Session Establishment Accept message.NOTE 7: It is assumed that the operator configures their network so that the Alternative S-NSSAI is selected to ensure that the selected SMF by using the Alternative S-NSSAI supports necessary capabilities according to the replaced S-NSSAI subscription data.For existing PDU Session associated with an S-NSSAI that is replaced with the Alternative S-NSSAI, after the AMF sends mapping of the S-NSSAI to the Alternative S-NSSAI to the supporting UE in UE Configuration Update message, the AMF sends updates to the SMF of the PDU Session, e.g. triggeringNsmf PDUSession UpdateSMContext service operation, that the PDU Session is to be transferred to Alternative S- NSSAI and includes the Alternative S-NSSAI as follows (see details in clause 4.3.3 of TS 23.502 [3]):- If the SMF determines that the PDU Session is to be retained (e.g. if the anchor UPF can be reused with the alternative S-NSSAI and SSC mode 1), the SMF sends the Alternative S-NSSAI to the UPF in the N4 message, to the NG-RAN in N2 message and to the supporting UE in PDU Session Modification Command message. The S-NSSAI provided to the (R)AN and to the UPF is the Alternative S-NSSAI.- If the SMF determines that the PDU Session is to be re-established, the SMF sends the Alternative S-NSSAI to the supporting UE either in PDU Session Modification Command if the PDU Session is of SSC mode 3, or in PDU Session Release if the PDU Session is of SSC mode 2 or SSC mode 1, to trigger the re-establishment of the PDU Session. The UE includes both, the S-NSSAI and the Alternative S-NSSAI in the PDU Session Establishment message.During registration procedure, the Requested NSSAI may include Alternative S-NSSAI(s) that are not subscribed S- NSSAI(s). In addition to the behaviour described in clause 5.15.5.2.1, the AMF verifies if S-NSSAI(s) in theApplicant's Ref. P112353WO01 4Requested NSSAI are either subscribed S-NSSAI(s) or Alternative S-NSSAI(s) in UE context and based on the verification, the AMF determines whether to update the UE configuration.When the AMF is notified that the S-NSSAI is available again (e.g. the congestion of the S-NSSAI has been mitigated), if the AMF has configured the supporting UE with the Alternative S-NSSAI, and the AMF determines for the UE in CM-CONNECTED state to use the replaced S-NSSAI again, the AMF reconfigures the supporting UE (e.g. by using UE Configuration Update procedure or in the next registration procedure) to use the replaced S- NSSAI again by removing the mapping of the replaced S-NSSAI to Alternative S-NSSAI and removing the Alternative S-NSSAI from the Allowed NSSAI if the Alternative S-NSSAI is only used for the Network Slice Replacement. The AMF also removes the Alternative S-NSSAI from the Configured NSSAI if the Alternative S- NSSAI is not one of the Subscribed S-NSSAIs and the Alternative S-NSSAI is not used in any Access Type. If the UE is in CM-IDLE, the AMF can wait until the UE in CM-CONNECTED state as described in clause 5.23. When the UE establishes a NAS signalling connection, e.g. through a Service Request procedure or through a UE registration procedure, the AMF reconfigures the UE.If there is an existing PDU Session associated with the Alternative S-NSSAI for the S-NSSAI being available again or not congested anymore, the AMF updates the SMF(s) of the PDU Session(s), byNsmf PDUSession UpdateSMContext service operation, causing the PDU Session to be transferred to the replaced S-NSSAI. The event trigger in SMF for interacting with PCF is described in clause 6.1.3.5 of TS 23.503

[0045] ,- If the SMF determines that the PDU Session is to be retained (e.g. if the anchor UPF can be reused with the replaced S-NSSAI and SSC mode 1), the SMF sends the replaced S-NSSAI i.e. does not include Alternative S-NSSAI to the UPF in the N4 message, to the NG-RAN in N2 message and to the supporting UE in PDU Session Modification Command message. The S-NSSAI provided to the (R)AN and to the UPF is the replaced S-NSSAI.- If the SMF determines that the PDU Session is to be re-established, the SMF sends the replaced S-NSSAI (i.e. does not include Alternative S-NSSAI) to the supporting UE either in PDU Session Modification Command if the PDU Session is of SSC mode 3, or in PDU Session Release if the PDU Session is of SSC mode 2 or SSC mode 1, to trigger the re-establishment of the PDU Session. The UE includes the replaced S- NSSAI in the PDU Session Establishment message.During a handover procedure, if an S-NSSAI has to be replaced with an Alternative S-NSSAI, the handover procedure (including any PDU session associated with the S-NSSAI to be replaced) shall continue unaffected by the Network Slice Replacement. Any Network Slice Replacement for the S-NSSAI shall not take place during the handover.During NSSAA re-authentication procedure for an S-NSSAI, if the S-NSSAI has to be replaced with Alternative S- NSSAI, the AMF shall continue with the NSSAA procedure unaffected by the Network Slice Replacement and the AMF executes the Network Slice Replacement after the NSSAA procedure is completed.If NS AC for maximum number of PDU sessions is configured for the replaced S-NSSAI and / or the Alternative S- NSSAI, the SMF performs NS AC by interacting with the NSACF of the replaced S-NSSAI and / or the NSACF of the Alternative S-NSSAI based on operator determined policies configured in the SMF (e.g. for the increase of Alternative S-NSSAI and the decrease of replaced S-NSSAI).*****EN DEXCERPT FROM 3GPP TS 23.501 *****Summary

[0003] Systems and methods enabling Application Function (AF)-initiated network slice replacement are disclosed. In one embodiment, a method performed by a first network function (e.g., a Policy and Control Function (PCF)) in a core network of a cellular communications system comprises receiving an AF-initiated request for replacement of a network slice for a User Equipment (UE) with an alternative network slice and, in response thereto, initiating replacement of the network slice for the UE with the alternative network slice. In this manner, AF-initiated network slice replacement is provided. Corresponding embodiments of a network node are also disclosed.Applicant's Ref. P112353WO01 5

[0004] In one embodiment, a method performed by first network function (e.g., a Network Exposure Function (NEF)) in a core network of a cellular communications system comprises receiving, from an AF, a request for replacement of a network slice for a UE with an alternative network slice and sending, to a second network function (e.g., PCF) in the core network, a request for replacement of the network slice for the UE with the alternative network slice. Corresponding embodiments of a network node are also disclosed.

[0005] In one embodiment, a method performed by an AF comprises sending, to a network function (e.g., PCF 210 or NEF) in a core network of a cellular communications system, an explicit or implicit request for replacement of a network slice for a UE with an alternative network slice. In one embodiment, the method further comprises receiving a notification that indicates an outcome (e.g., success or failure) of the requested replacement of a network slice for a User Equipment, UE, with an alternative network slice.Brief Description of the Drawings

[0006] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0007] Figure 1 illustrates one example of a cellular communications system in which embodiments of the present disclosure may be implemented;

[0008] Figure 2 illustrates a wireless communication system represented as a 5thGeneration (5G) network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point / interface

[0009] Figure 3 illustrates a 5G network architecture using service-based interfaces between the NFs in the control plane, instead of the point-to-point reference points / interfaces used in the 5G network architecture of Figure 2;

[0010] Figures 4A and 4B illustrate an Application Function (AF)-initiated network slice replacement procedure, in accordance with embodiments of the present disclosure;

[0011] Figures 5A and 5B correspond to Figure 4.3.4.2-1 of 3rdGeneration Partnership Project (3GPP) Technical Specification (TS) 23.502 V19.1.0;

[0012] Figure 6 corresponds to Figure 4.15.6.9.2-1 of 3GPP TS 23.503 V19.1.0;

[0013] Figure 7 corresponds to Figure 4.15.6.9.2-2 of 3GPP TS 23.503 V19.1.0;

[0014] Figure 8 corresponds to Figure 4.16.2.2-1 of 3GPP TS 23.503 V19.1 .0;

[0015] Figures 9A to 9F correspond to an enhanced version of Table 6.1.3.18-1 of 3GPP TS 23.503 V19.1.0, in accordance with an example embodiment of the present disclosure;

[0016] Figures 10A to 10C correspond to an enhanced version of Table 6.5-1 of 3GPP TS 23.503 V19.1.0, in accordance with an example embodiment of the present disclosure; and

[0017] Figures 11 and 12 are schematic block diagrams of example embodiments of a network node that implements all or part of the functionality of a network function, in accordance with embodiments of the present disclosure.Applicant's Ref. P112353WO01 6Detailed Description

[0018] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0019] Radio Node: As used herein, a "radio node” is either a radio access node or a User Equipment (UE).

[0020] Radio Access Network (RAN) Node: As used herein, a "RAN node” or "radio access node” or "radio network node” is any node in a RAN of a cellular communications network. Some examples of a RAN node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of RAN node.

[0021] Core Network Node: As used herein, a "core network node” is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0022] Communication Device: As used herein, a "communication device” is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer- comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data via a wireless or wireline connection.

[0023] User Equipment (UE): One type of communication device is a UE, which as used herein may be any type of wireless communication device that has access to (i.e. , is served by) a wireless network (e.g., a cellular network). Some examples of a UE include, but are not limited to: a UE in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (loT) device. Such UEs may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement,Applicant's Ref. P112353WO01 7 tablet computer, laptop, or PC. The UE may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data via a wireless connection.

[0024] Network Node: As used herein, a "network node” is any node that is either part of the RAN or the core network of a cellular communications network / system.

[0025] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0026] Note that, in the description herein, reference may be made to the term "cell”; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0027] There currently exist certain challenge(s). The existing network slice replacement feature supported in 3GPP Release 18 does not enable an Application Function (AF) to initiate network slice replacement.

[0028] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. Systems and methods are disclosed herein that enable AF-initiated network slice replacement.

[0029] In embodiments of the present disclosure, an AF explicitly or implicitly requests a network slice (i.e., a Single Network Slice Selection Assistance Information (S-NSSAI) using 3GPP terminology), for a UE to be replaced by an alternative network slice (i.e., an Alternative S-NSSAI in 3GPP terminology). In some embodiments, the AF is a trusted AF, and the request is an explicit request for the S-NSSAI for the UE to be replaced by the Alternative S- NSSAI. In this case, the AF sends the request directly to a Policy and Control Function (PCF) for the UE. In some other embodiments, the AF is an untrusted AF, and the request is an implicit request such as, for example, a request made by the untrusted AF, via a Network Exposure Function (NEF), for an enhanced performance to a service identifier for a UE that gets mapped to an Alternative S-NSSAI. In this case, the (implicit) request is sent, from the AF to the NEF and then from the NEF to the PCF for the UE.

[0030] In some embodiments, the AF-requested replacement is allowed if the Alternative S-NSSAI for the AF- initiated replacement is included in a UE subscription of the UE; otherwise, the AF-requested replacement is denied. In one embodiment, for the trusted AF, the PCF performs a validation for the Alternative S-NSSAI being in the subscribed network slices of the UE. In one embodiment, for the untrusted AF, the NEF performs the validation for the Alternative S-NSSAI being in the subscribed network slices of the UE.

[0031] At some later point in time, the AF (trusted or untrusted AF) can initiate a request to restore the replaced S-NSSAI.

[0032] Figure 1 illustrates one example of a cellular communications system 100 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 100 is a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC) or a similar 6thGeneration (6G) system. In this example, the RAN includes base stations 102-1 and 102-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), controlling corresponding (macro) cells 104-1 and 104-2. The base stations 102-1 and 102-2 are generally referred to herein collectively as base stations 102 and individually as base station 102. Likewise, the (macro) cellsApplicant's Ref. P112353WO01 8104-1 and 104-2 are generally referred to herein collectively as (macro) cells 104 and individually as (macro) cell 104. The RAN may also include a number of low power nodes 106-1 through 106-4 controlling corresponding small cells 108-1 through 108-4. The low power nodes 106-1 through 106-4 can be small base stations (such as pico or femto base stations) or RRHs, or the like. Notably, while not illustrated, one or more of the small cells 108-1 through 108-4 may alternatively be provided by the base stations 102. The low power nodes 106-1 through 106-4 are generally referred to herein collectively as low power nodes 106 and individually as low power node 106. Likewise, the small cells 108-1 through 108-4 are generally referred to herein collectively as small cells 108 and individually as small cell 108. The cellular communications system 100 also includes a core network 110, which in the 5G System (5GS) is referred to as the 5GC. The base stations 102 (and optionally the low power nodes 106) are connected to the core network 110.

[0033] The base stations 102 and the low power nodes 106 provide service to UEs 112-1 through 112-5 in the corresponding cells 104 and 108. The UEs 112-1 through 112-5 are generally referred to herein collectively as UEs 112 and individually as UE 112.

[0034] Figure 2 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to- point reference point / interface. Figure 2 can be viewed as one particular implementation of the system 100 of Figure 1.

[0035] Seen from the access side the 5G network architecture shown in Figure 2 comprises a plurality of UEs 112 connected to either a RAN 102 or an Access Network (AN) as well as an AMF 200. Typically, the R(AN) 102 comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 2 include a NSSF 202, an AUSF 204, a UDM 206, the AMF 200, a SMF 208, a PCF 210, and an Application Function (AF) 212.

[0036] Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 112 and AMF 200. The reference points for connecting between the AN 102 and AMF 200 and between the AN 102 and UPF 214 are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF 200 and SMF 208, which implies that the SMF 208 is at least partly controlled by the AMF 200. N4 is used by the SMF 208 and UPF 214 so that the UPF 214 can be set using the control signal generated by the SMF 208, and the UPF 214 can report its state to the SMF 208. N9 is the reference point for the connection between different UPFs 214, and N14 is the reference point connecting between different AMFs 200, respectively. N15 and N7 are defined since the PCF 210 applies policy to the AMF 200 and SMF 208, respectively. N12 is required for the AMF 200 to perform authentication of the UE 112. N8 and N10 are defined because the subscription data of the UE 112 is required for the AMF 200 and SMF 208.

[0037] The 5GC network aims at separating UP and CP. The UP carries user traffic while the CP carries signaling in the network. In Figure 2, the UPF 214 is in the UP and all other NFs, i.e., the AMF 200, SMF 208, PCF 210, AF 212, NSSF 202, AUSF 204, and UDM 206, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CP functions in aApplicant's Ref. P112353WO01 9 distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

[0038] The core 5G network architecture is composed of modularized functions. For example, the AMF 200 and SMF 208 are independent functions in the CP. Separated AMF 200 and SMF 208 allow independent evolution and scaling. Other CP functions like the PCF 210 and AUSF 204 can be separated as shown in Figure 2. Modularized function design enables the 5GC network to support various services flexibly.

[0039] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

[0040] Figure 3 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points / interfaces used in the 5G network architecture of Figure 2. However, the NFs described above with reference to Figure 2 correspond to the NFs shown in Figure 3. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the servicebased interface. In Figure 3 the service based interfaces are indicated by the letter “N” followed by the name of the NF, e.g. Namf for the service based interface of the AMF 200 and Nsmf for the service based interface of the SMF 208, etc. The NEF 300 and the NRF 302 in Figure 3 are not shown in Figure 2 discussed above. However, it should be clarified that all NFs depicted in Figure 2 can interact with the NEF 300 and the NRF 302 of Figure 3 as necessary, though not explicitly indicated in Figure 2.

[0041] Some properties of the NFs shown in Figures 2 and 3 may be described in the following manner. The AMF 200 provides UE-based authentication, authorization, mobility management, etc. A UE 112, even using multiple access technologies, is basically connected to a single AMF 200 because the AMF 200 is independent of the access technologies. The SMF 208 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 214 for data transfer. If a UE 112 has multiple sessions, different SMFs 208 may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF 212 provides information on the packet flow to the PCF 210 responsible for policy control in order to support QoS. Based on the information, the PCF 210 determines policies about mobility and session management to make the AMF 200 and SMF 208 operate properly. The AUSF 204 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 206 stores subscription data of the UE 112. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0042] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0043] Figures 4A and 4B illustrate the operation of the AF 212, the PCF 210, the AMF 200, and optionally the NEF 300 in accordance with embodiments of the present disclosure. Note that the AF 212 may be a trusted AF (i.e., an AF which is allowed to directly communicate with other NFs such as the PCF 210) or an untrusted AF (i.e., an AF that interacts with the core network via the NEF 300). In Figures 4A and 4B, optional elements and steps are represented by dashed lines / boxes.Applicant's Ref. P112353WO01 10

[0044] As illustrated, in a first option (i.e., option 1) where the AF 212 is a trusted AF, the AF 212 sends, to the PCF 210, a request (e.g., an explicit request) for network slice replacement (step 400-1). This request is a request for replacement of a network slice of a UE with an alternative network slice. The alternative network slice is, in some embodiments, indicated in the request. In a 3GPP system, network slices correspond to S-NSSAIs. Thus, in other words, the request is a request for replacement of a S-NSSAI of the UE with an Alternative S-NSSAI. For the description herein, the network slices are generally referred to as S-NSSAIs; however, the present disclosure is not limited thereto.

[0045] In a second option (i.e., option 2) where the AF 212 is an untrusted AF, the AF 212 sends, to the NEF 300, an implicit request for network slice replacement (i.e., a request that implicitly requests network slice replacement) (step 400-2A). For example, the implicit request for network slice replacement may be a request for a change of network service of the UE to an indicated network service, which is mapped within the core network (e.g., at the NEF 300) to an Alternative S-NSSAI. The requested network service may, for example, map to an AF-Service identifier used to reference an S-NSSAI in Nnsacf_SliceEventExposureSubscribe Request), which enables the NEF 300 to map the AF-Service identifier to the Alternative S-NSSAI in the target UE subscribed S-NSSAIs. Optionally, the NEF 300 validates whether the Alternative S-NSSAI is include in a UE subscription of the UE (step 400-2B). If not, the NEF 300 rejects the request (e.g., sends a response that rejects the request to the AF 212); otherwise, the NEF 300 accepts the request (i.e., continues with the procedure illustrated in Figures 4A and 4B). The NEF 300 sends, to the PCF 210, a request for the network slice replacement implicitly indicated by the request of step 400-2A (step 400-2C).

[0046] At the PCF 210, whether the AF-initiated network slice replacement request is received from the AF 212 in step 400-1 or from the NEF 300 in step 400-2C, the PCF 210 optionally validates that the Alternative S-NSSAI is part of the UE subscription of the UE (step 402). The PCF may obtain UE policy data for the UE from a UDR, where this UE policy data includes the subscribed S-NSSAIs of the UE. This validation may alternatively be performed by the NEF 300 in the case of the AF 212 is an untrusted AF or performed by the AMF 210. If the Alternative S-NSSAI is not part of the UE subscription, the PCF 210 rejects the request (e.g., sends a response that rejects the request to the AF 212 directly or via the NEF 300); otherwise, the PCF 210 accepts the request (i.e., continues with the procedure illustrated in Figures 4A and 4B).

[0047] The PCF 210 triggers (i.e., initiates or requests) the requested network slice replacement at the AMF 200 (step 404). More specifically, in one embodiment, the PCF 210 sends, to the AMF 200, information (e.g., Access and Mobility (AM) policy information) including the S-NSSAI to be replaced (referred to herein as the "Replaced S- NSSAI”) and the Alternative S-NSSAI (step 404A). This information sent the AMF 200 in step 404A may also include an indication for the AMF 200 to terminate all Protocol Data Unit (PDU) sessions of the UE associated with the replaced S-NSSAI and start using the Alternative S-NSSAI (e.g., trigger re-establishment of those PDU sessions with the Alternative S-NSSAI and / or establishment of any new PDU session(s) of the UE with the Alternative S-NSSAI).

[0048] At the AMF 200, the AMF 200 may optionally validate that the Alternative S-NSSAI is part of the UE subscription of the UE (step 406). This validation may alternatively be performed by the NEF 300 in the case of the AF 212 is an untrusted AF or performed by the PCF 210, as described above. If the Alternative S-NSSAI is not part of the UE subscription, the AMF 200 rejects the request (e.g., sends a response that rejects the request to the PCFApplicant's Ref. P112353WO01 11210); otherwise, the AMF 200 accepts the request (i.e., continues with the procedure illustrated in Figures 4A and 4B).

[0049] The AMF 200 performs the requested network slice replacement for the UE (step 408). More specifically, the AMF 200 terminates all PDU sessions of the UE associated with the replaced S-NSSAI and starts using the Alternative S-NSSAI (e.g., triggers re-establishment of the terminated PDU sessions with the Alternative S- NSSAI and / or starts establishing any new PDU session(s) of the UE with the Alternative S-NSSAI).

[0050] The AMF 200 may send a response to the PCF 210 that, for example, indicates an outcome of the requested network slice replacement (e.g., success or failure, where for failure the response may optionally include an indication of a cause of the failure) (step 410). The AF 212 can be informed about the outcome of the S-NSSAI replacement through a Notification sent to the AF either through explicit or implicit subscriptions.

[0051] In some embodiments, the AF 212 may terminate the network slice replacement, e.g., by sending a request to replace the Alternative S-NSSAI with the Replaced S-NSSAI. The procedure for terminating the network slice replacement may be the same as or similar to the AF-initiated network slice replacement procedure of Figures 4A and 4B where the Alternative S-NSSAI is replaced with the Replaced S-NSSAI. Alternatively, the network slice replacement may be terminated automatically (i.e., without a separate request from the AF 212) by, for example, including a timer with the network slice replacement request in step 400-1 or 400-2A. The PCT 210 may then store the timer and, upon expiry of the timer, trigger replacement of the Alternative S-NSSAI with the Replaced S-NSSAI, e.g., in a manner similar to step 404, where the AMF 200 then performs the replacement of the Alternative S-NSSAI with the Replaced S-NSSAI.

[0052] An example implementation of an embodiment of the solution described herein is shown below as changes to various 3GPP specifications where additions relative to V19.1.0 of these 3GPP specifications are indicated via underlined text:***** START CHANGES TO 3GPP TS 23.502 V19.1.0 *****4.3.4.2 UE or network requested PDU Session Release for Non-Roaming and Roaming with Local BreakoutFigure 4.3.4.2-1 captures both the UE Requested PDU Session Release procedure and the network requested PDU Session Release procedure. The procedure allows the UE to request the release of one PDU Session. The procedure also allows the AMF, the SMF or the PCF to initiate the release of a PDU Session. In the case of LBO, the procedure is as in the case of non-roaming with the difference that the AMF, the SMF, the UPF and the PCF are located in the visited network.[REPRODUCED HEREIN AS FIGURES 5A AND 5B]Figure 4.3.4.2-1 : UE or network requested PDU Session Release for non-roaming and roaming with local breakout1. The procedure is triggered by one of the following events: la. (UE requested) The UE initiates the UE Requested PDU Session Release procedure by the transmission of an NAS message (N1 SM container (PDU Session Release Request (PDU session ID)), PDU Session ID). The NAS message is forwarded by the (R)AN to the AMF with an indication of User Location Information. This message is relayed to the SMF corresponding to the PDU Session ID via N2 and the AMF. The AMF invokes the Nsmf PDUSession UpdateSMContext service operation andApplicant's Ref. P112353WO01 12 provides the N1 SM container to the SMF together with User Location Information (ULI) received from the (R)AN.NOTE 1 : Depending on the Access Type, when the UE is in CM-IDLE state, the UE can trigger a Service Request procedure before being able to release the PDU Session. lb. (PDU Session Release initiated by the PCF) The PCF may invoke an SM Policy Association Termination procedure as defined in clause 4.16.6 to request the release of the PDU Session. lc. The AMF may invoke the Nsmf PDUSession ReleaseSMContext service operation to request the release of the PDU Session in the case of mismatch of PDU Session status between UE and AMF or other cases where neither N1 nor N2 SM signalling is needed before the releasing of SM context.NOTE 2: The AMF invokes the Nsmf PDUSession ReleaseSMContext service operation when the AMF determines to release the PDU Session due to S-NSSAI is removed from Allowed NSSAI and the AMF separately updates the UE with a PDU Session status without the PDU Session, in a Registration Accept as specified in clause 4.2.2.2.2. ld. (R)AN may decide to indicate to the SMF that the PDU Session related resource is released, e.g. when all the QoS Flow(s) of the PDU Session are released.NOTE 3 : In this case, if s up to SMF to decide whether to keep the PDU Session with user plane connection deactivated or release the PDU Session. le. (PDU Session Release initiated by the SMF).The SMF may decide to release a PDU Session under the following scenarios:- Based on a request from the DN (cancelling the UE authorization to access to the DN);- Based on a request from the UDM (subscription change) or from the CHF;If the SMF received an event notification from the AMF that the UE is out of LADN service area;- Based on locally configured policy (e.g. the release procedure may be related with the UPF reallocation for SSC mode 2 / mode 3);- If the SMF is notified by the (R)AN that the PDU Session resource establishment has failed during mobility procedure;- The SMF initiates release of an emergency PDU Session when the UPF reports detection of PDU Session inactivity for a specified period as specified in clause 4.4.2.2;- Based on PDU Session inactivity report from the UPF if the S-NSSAI of a PDU Session for nonroaming subscribers is subject to usage control as described in clause 5.15.15 of TS 23.501 [2]; or- If the SMF is notified by the AMF that the S-NSSAI of the PDU Session with SSC mode 1 or SSC mode 2 is to be replaced with Alternative S-NSSAI, and if the SMF determines that a new PDU Session is to be established on the Alternative S-NSSAI, the SMF initiates release of the PDU Session, as described in clause 5.15.19 of TS 23.501 [2], lf. The AMF may invoke the Nsmf PDUSession UpdateSMContext service operation with a release indication to request the release of the PDU Session where:- N1 signalling is needed and N2 SM signalling may be needed before releasing the SM context with appropriate cause value (e.g. due to a change of the set of network slices for a UE where a network slice instance is no longer available as described in clause 5.15.5.2.2 of TS 23.501 [2];- The AAA Server triggered Network Slice-Specific Re-authentication and Re-authorization procedure fails as specified in clause 4.2.9.2;- The AAA Server triggered Slice-Specific Authorization Revocation takes place as specified in clause 4.2.9.4;- AMF determines that Control Plane Only indication associated with PDU Session is not applicable any longer as described in clause 5.31.4.1 of TS 23.501 [2]);Applicant's Ref. P112353WO01 13- The MBSR authorization state is changed from "authorized" to "not authorized" as described in clause 5.35A.4 of TS 23.501 [2];- The Network Slice instance is congested or not available as described in clause 5.15.5.3 of TS 23.501 [2],There is no LADN service area for the DNN and S-NSSAI of the PDU session and the AMF determines to configure the LADN service area configured per LADN DNN and S-NSSAI for the associated DNN and S-NSSAI (e.g. due to notification from UDM or local configuration update);- The PDU session is subject to LADN per LADN DNN and S-NSSAI and the AMF determines the LADN service area for the DNN and S-NSSAI is removed (e.g. due to notification from UDM or local configuration update).The AMF received from AM-PCF, an Npcf AMPolicvControl Update Notify Request that includes an Alternative S-NSSAI for a Replaced S-NSSAI, and Network Slice Replacement with PDU re-establishment parameter.If the SMF receives one of the triggers in step la, lb, 1c, le, or If, the SMF starts PDU Session Release procedure. If the cause value in step If indicates the Network Slice instance is congested or not available, the SMF triggers the impacted UE(s) to establish new PDU session(s) associated with the same S-NSSAI by using the procedures for PDU Session(s) of SSC mode 2 or SSC mode 3 as defined in clause 4.3.5.If interworking with TSN deployed in the transport network is supported the SMF / CUC shall initiate the release of TN streams via UNI.2. The SMF releases the IP address / Prefix(es) that were allocated to the PDU Session and releases the corresponding User Plane resources:2a. The SMF sends an N4 Session Release Request (N4 Session ID) message to the UPF(s) of the PDU Session. The UPF(s) shall drop any remaining packets of the PDU Session and release all tunnel resource and contexts associated with the N4 Session.If interworking with TSN deployed in the transport network is supported and the UPF supports CN-TL and TN streams are associated with the PDU session, the SMF / CUC shall initiate to the CN-TL the deletion of TN stream configurations.2b. The UPF(s) acknowledges the N4 Session Release Request by the transmission of an N4 Session Release Response (N4 Session ID, [Small Data Rate Control Status], [APN Rate Control Status]) message to the SMF.If UPF / CN-TL has performed the deletion of TN stream based on the request received from the SMF / CUC in step 2a, the UPF / CN-TL shall confirm the deletion of TN stream configurations.The UPF includes Small Data Rate Control Status if the PDU Session used Small Data Rate Control.If a NEF has been selected as anchor of the Control Plane CIoT 5GS Optimisation enabled PDU session which is Unstructured PDU Session Type as described in clause 4.3.2.2 and the SMF-NEF Connection is released for this PDU Session.If interworking with TSN deployed in the transport network is supported and the NG-RAN supports AN-TL and TN streams are associated with the released PDU session, the SMF / CUC shall initiate to the AN-TL the deletion of TN stream configurations.NOTE 4: If there are multiple UPFs associated with the PDU Session (e.g. due to the insertion of UL CL or Branching Point, or redundant I-UPFs if the redundant I-UPFs are used for URLLC), the Session Release Request procedure (steps 2a and 2b) is done for each UPF. In order to avoid charging of PDUs that later get dropped, the SMF performs the N4 Session Release first with the UPF(s) performing usage reporting, before releasing the other UPF(s) that forward traffic for the same user plane resources.3 If the PDU Session Release is initiated by the PCF and SMF and the SMF has been notified by the AMF that UE is unreachable, e.g. due to the UE is in MICO mode or periodical registration failure, the procedureApplicant's Ref. P112353WO01 14 continues in step 11 by SMF notifying the AMF that the PDU Session is released by invoking the Nsmf PDUSession SMContextStatusNotify. The rest of step 3 and the steps 4-10 are skipped.If the PDU Session Release procedure was triggered by steps la, lb, Id or le above, the SMF creates an N1 SM including PDU Session Release Command message (PDU Session ID, Cause, Alternative S-NSSAI). The Cause may indicate a trigger to establish a new PDU Session with the same characteristics (e.g. when procedures related with SSC mode 2 are invoked). .If the cause value indicates that a PDU Session reestablishment on the Alternative S-NSSAI is required the PDU Session Release Command message also includes the Alternative S-NSSAI. The UE establishes a new PDU Session on the Alternative S-NSSAI, as described in clause 5.15.19 of TS 23.501 [2],If the User Plane connection of the PDU Session is activated, the message sent by the SMF to the AMF shall include N2 SM Resource Release request. If the User Plane connection of the PDU Session is not activated, the message sent by the SMF to the AMF shall not include N2 SM Resource Release request.NOTE 5: SSC modes are defined in clause 5.6.9 of TS 23.501 [2],3a. (If the PDU Session Release is initiated by the UE in step la or has been triggered by (R)AN in step Id) The SMF responds to the AMF with the Nsmf PDUSession UpdateSMContext response (N2 SM Resource Release request, Nl SM container (PDU Session Release Command)). N2 SM Resource Release request is included if the PDU Session Release is initiated by the UE and if the UP connection of the PDU Session is active. Neither N2 SM Resource Release request nor N1 SM container is included if the PDU Session Release is triggered by (R)AN and the SMF decides to keep the PDU session with user plane connection deactivated and the subsequent steps are skipped.3b. If the PDU Session Release is initiated by the SMF or the PCF, the SMF invokes the Namf_Communication_NlN2MessageTransfer service operation (N1 SM container (PDU Session Release Command), skip indicator).If the UP connection of the PDU Session is active, the SMF shall also include the N2 Resource Release request (PDU Session ID) in the Namf_Communication_NlN2MessageTransfer, to release the (R)AN resources associated with the PDU Session.The "skip indicator" tells the AMF whether it may skip sending the N1 SM container to the UE (e.g. when the UE is in CM-IDLE state). SMF includes the "skip indicator" in theNamf Communication N lN2MessageTransfer except when the procedure is triggered to change PDU Session Anchor of a PDU Session with SSC mode 2.If the UE is in CM-IDLE state and "skip indicator" is included in the Namf_Communication_NlN2MessageTransfer service operation or if the UE is in CM-IDLE state and "skip indicator" is not included in the Namf_Communication_NlN2MessageTransfer service operation but the AMF detects that the UE context contains Paging Restriction Information indicating that all paging is restricted, the AMF acknowledges the step 3b by sending an Namf_Communication_NlN2MessageTransfer Response message ("Nl SM Message Not Transferred") to SMF and steps 4 to 10 are skipped.3c. If the PDU Session Release is initiated by the AMF in step 1c, i.e. the SMF received the Nsmf PDUSession ReleaseSMContext Request from the AMF, the SMF responds to the AMF with the Nsmf PDUSession ReleaseSMContext response, optionally including the Small Data Rate Control Status and APN Rate Control Status.If the UPF included APN Rate Control Status and / or Small Data Rate Control Status in step 2 then the SMF includes APN Rate Control and / or Small Data Rate Control Status and the AMF stores the Small Data Rate Control Status and / or the APN Rate Control Status in the UE context in AMF.The AMF and SMF shall remove all contexts (including the PDU Session ID) associated with the PDU Session which are indicated as released at the UE. The SMF shall remove any event subscriptions on the AMF by the SMF that becomes no more needed due to the PDU Session Release. The steps 4 to 11 are skipped.3d. If the PDU Session Release is initiated by the AMF in step If, i.e. the SMF received theNsmf PDUSession UpdateSMContext Request from the AMF with a release indication to request the release of the PDU Session, the SMF responds to the AMF with the Nsmf PDUSession UpdateSMContext Response which may contain the Nl SM container (PDU Session Release Command) to release the PDU session at the UE.Applicant's Ref. P112353WO01 15If the UP connection of the PDU Session is active, the Nsmf PDUSession UpdateSMContext Response shall also include the N2 Resource Release request (PDU Session ID) to release the (R)AN resources associated with the PDU Session.4. If the UE is in CM-IDLE state and "N1 SM delivery can be skipped" is not indicated, the AMF initiates the network triggered Service Request procedure to transmit the NAS message (PDU Session ID, N1 SM container) to the UE and the steps 6, 7 are skipped.If the message received from the SMF in step 3 does not include N2 SM Resource Release request, the AMF transmits the NAS message (PDU Session ID, N1 SM container) to the UE and the steps 6, 7 are skipped.If the PDU Session is Control Plane CIoT 5GS Optimisation enabled, the SMF shall not include N2 SM Resource Release request in the message sent to the AMF, the AMF transmits the NAS message (PDU Session ID, N1 SM container) to the UE and the steps 6, 7 are skipped.If the UE is in CM-CONNECTED state and the received message from the SMF in step 3 includes N2 SM Resource Release request, the AMF transfers the SM information received from the SMF in step 4 (N2 SM Resource Release request, N1 SM container) to the (R)AN.If the message from the SMF includes Small Data Rate Control Status then the AMF stores it in the UE Context in AMF.5. When the (R)AN has received an N2 SM request to release the AN resources associated with the PDU Session it issues AN specific signalling exchange(s) with the UE to release the corresponding AN resources.In the case of a NG-RAN, the NAS message is sent to the UE in an RRC message which may take place with the UE releasing the NG-RAN resources related to the PDU Session. If NG-RAN resources do not need to be released (i.e. the User Plane of the PDU Session is deactivated), the NAS message is sent to the UE in an RRC message which does not release the NG-RAN resources related to the PDU Session.During this procedure, the (R)AN sends any NAS message (N1 SM container (PDU Session Release Command)) received from the AMF in step 4.For PDU Session for non-roaming subscribers, if the S-NSSAI of the released PDU Session is subject to network slice usage control as described in clause 5.15.15 of TS 23.501 [2] and there is no other PDU Session using the S-NSSAI over which the Access Type the PDU Session was released, the UE starts slice deregistration inactivity timer for the S-NSSAI over the Access Type if the UE received slice deregistration inactivity timer for the S-NSSAI for that the Access Type.6. [Conditional] If the (R)AN had received a N2 SM request to release the AN resources, the (R)AN acknowledges the N2 SM Resource Release Request by sending an N2 SM Resource Release Ack (User Location Information, Secondary RAT usage data) Message to the AMF.If the PLMN has configured secondary RAT usage reporting, the NG-RAN node may provide RAN Usage Data Report.If NG-RAN / AN-TL has performed the deletion of TN stream based on the request received from the SMF / CUC in step 3, the NG-RAN / AN-TL shall confirm the deletion of TN stream configurations.7a. The AMF invokes the Nsmf PDUSession UpdateSMContext (N2 SM Resource Release Ack (Secondary RAT usage data), User Location Information) to the SMF.7b. The SMF responds to the AMF with an Nsmf PDUSession UpdateSMContext response.8. The UE acknowledges the PDU Session Release Command by sending a NAS message (PDU Session ID, N1 SM container (PDU Session Release Ack)) over the (R)AN.9. [Conditional] The (R)AN forwards the NAS message from the UE by sending a N2 NAS uplink transport (NAS message (PDU Session ID, N1 SM container (PDU Session Release Ack)), User Location Information) to the AMF.10a. The AMF invokes the Nsmf PDUSession UpdateSMContext (N1 SM container (PDU Session Release Ack, User Location Information) to the SMF.10b. The SMF responds to the AMF with an Nsmf PDUSession UpdateSMContext response.Applicant's Ref. P112353WO01 16Steps 8-10 may happen before steps 6-7.11. If steps 3a, 3b or 3d were performed, the SMF waits until it has received replies to the N1 and N2 information provided in step 3, as needed.The SMF invokes Nsmf PDUSession SMContextStatusNotify to notify AMF that the SM context for this PDU Session is released. If the UPF included Small Data Rate Control Status and / or APN Rate Control Status in step 2 then the SMF includes Small Data Rate Control Status and / or APN Rate Control Status in its request to the AMF in this step. The AMF releases the association between the SMF ID and the PDU Session ID, DNN, as well as S-NSSAI and stores the Small Data Rate Control Status and / or the APN Rate Control Status in the UE context in AMF. The SMF shall remove any event subscriptions on the AMF that becomes no more needed due to the PDU Session Release.NOTE 6: The UE and the 5GC will get synchronized about the status of the (released) PDU Session at the next Service Request or Registration procedure.For PDU Session for non-roaming subscribers, if the S-NSSAI of the released PDU Session is subject to network slice usage control and if the SMF indicates cause of slice inactivity and there is no other PDU Session using the S-NSSAI over which the Access Type the PDU Session was released, then AMF may remove the S-NSSAI from the Allowed NSSAI or start slice deregistration inactivity timer for the S-NSSAI for that Access Type as described in clause 5.15.15.3 of TS 23.501 [2], If the AMF did not provide slice deregistration inactivity timer of the S-NSSAI to the UE for the Access Type and S-NSSAI is removed from Allowed NSSAI, the AMF triggers UE Configuration Update procedure to provide the new Allowed NSSAI to the UE.12. If Dynamic PCC applied to this session the SMF invokes an SM Policy Association Termination procedure as defined in clause 4.16.6 to delete the PDU Session.13. SMF notifies any entity that has subscribed to User Location Information related with PDU Session change.14. If it is the last PDU Session the SMF is handling for the UE for the associated (DNN, S-NSSAI), the SMF unsubscribes from Session Management Subscription data changes notification with the UDM by means of the Nudm SDM Unsubscribe (SUPI, DNN, S-NSSAI) service operation. The UDM may unsubscribe the subscription notification from UDR by Nudr DM Unsubscribe (SUPI, Subscription Data, Session Management Subscription data, DNN, S-NSSAI).15. The SMF invokes the Nudm UECM Deregistration service operation including the DNN and the PDU Session ID. The UDM removes the association it had stored between the SMF identity and the associated DNN and PDU Session ID. The UDM may update this information by Nudr DM Update (SUPI, Subscription Data, UE context in SMF data).***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****4.15.6.9.2 Processing AF requests to influence access and mobility management policies targeting an individual UEThis procedure is used for individual UEs when the request shall be applied independently of conditions related to the application traffic. Depending on the AF deployment (see clause 6.2.10 of TS 23.501 [2]), the AF may interact with NFs of the Core Network either directly or via the NEF. The procedure for the direct case is described in Figure 4.15.6.9.2-1, while the procedure for the NEF -mediated case is described in Figure 4.15.6.9.2-2.[REPRODUCED HEREIN AS FIGURE 6]Figure 4.15.6.9.2-1 : Handling an AF request targeting an individual UE without using NEFThis procedure concerns only non-roaming scenarios, i.e. to cases where the involved entities serving the UE (AF, PCF, BSF, AMF) belong to the home PLMN.1. An AM Policy Association is established for a UE as described in clause 4.16.1.Applicant's Ref. P112353WO01 172a. The AF searches the PCF for the UE using Nbsf Management Subscribe with SUPI or GPSI as input, indicating that it is searching for the PCF that handles the AM Policy Association of the UE.2b. The BSF provides to the AF the identity of the PCF for the UE for the requested SUPI or GPSI via an Nbsf Management Notify operation. If a matching entry already exists in the BSF when step 2a is performed, this shall be immediately reported to the AF.2c. The AF sends to the PCF for the UE its request for influencing the access and mobility management policy of the UE (identified by SUPI or GPSI) using Npcf AMPolicy Authorization (optionally providing a timer on how long this policy shall last, in which case the system behaviour upon expiration of this timer is as specified in TS 23.503

[0020] ). This may include information for network slice replacement i.e. an Alternative S-NSSAI for a Replaced S-NSSAI, (see clauses 5,15.5,2.2a of TS 23,501 [2]), The Alternative S-NSSAI is part of the UE subscription. As part of the Npcf AMPolicy Authorization request, the AF may subscribe (within the Create and Update operations) or unsubscribe (within the Delete operation) to relevant events specified in clause 6.1.3.18 of TS 23.503

[0020] , e.g. events related to change of service area coverage.3. The PCF takes a policy decision and then an AM Policy Association Modification procedure initiated by the PCF for the UE may be performed as described in clause 4.16.2.2. If the AF has subscribed to access and mobility management related events (i.e. request for service area coverage outcome) in step 2, the PCF reports the event (i.e. outcome of the request for service area coverage) to the AF.[REPRODUCED HEREIN AS FIGURE 7]Figure 4.15.6.9.2-2: Handling an AF request targeting an individual UE using NEFThis procedure concerns only non-roaming scenarios, i.e. to cases where the involved entities serving the UE (AF, NEF, PCF, BSF, AMF) belong to the home PLMN, or the AF belongs to a third party with which the home PLMN has an agreement.1. An AM Policy Association is established for a UE as described in clause 4.16.1.2a. The AF sends to NEF its request for influencing the access and mobility management policy of the UE (identified by GPSI) using Nnef AMPolicy Authorization (optionally providing a timer on how long this policy shall last, in which case the system behaviour upon expiration of this timer is as specified in TS 23.503

[0020] ). As part of the Nnef AMPolicy Authorization request, the AF may request to subscribe (within the Create and Update operations) or unsubscribe (within the Delete operation) for relevant events specified in clause 6.1.3.18 of TS 23.503

[0020] , e.g. events for request for service area coverage outcome. The NEF stores the request and sends a response to the AF. In this message it is possible to include information for a change of network service (which is mapped to an Alternative S-NSSAI at NEF), (see clauses 5,15.5,2.2a of TS 23,501 [2]), The Alternative S-NSSAI selected by the NEF is part of the UE subscription.2b. The NEF searches the PCF for the UE using Nbsf Management Subscribe with SUPI as input parameter, indicating that it is searching for the PCF that handles the AM Policy Association of the UE.2c. The BSF provides to the NEF the identity of the PCF for the UE for the requested SUPI via an Nbsf Management Notify operation. If a matching entry already exists in the BSF when step 2b is performed, this shall be immediately reported to the NEF.2d. The NEF sends to PCF for the UE the request for influencing the access and mobility management policy of the UE (identified by SUPI) using Npcf AMPolicy Authorization (having potentially translated GPSI to SUPI via UDM). This may include information for AF -requested network slice replacement i.e. an Alternative S- NSSAI for a Replaced S-NSSAI and indication that the replacement is AF -requested (see clause 5, 15,5,2,2a of TS 23,501 [2]), As part of the Npcf AMPolicy Authorization request, the NEF may subscribe or unsubscribe (according to what the AF requested in step 2a) for relevant events specified in clause 6.1.3.18 of TS 23.503

[0020] , e.g. events for change of service area coverage.2e. The NEF informs the AF about events to which the AF has potentially subscribed (i.e. events for change of service area coverage) using Nnef AMPolicyAuthorization Notify.3. The PCF takes a policy decision and then an AM Policy Association Modification procedure initiated by the PCF for the UE may be performed as described in clause 4.16.2.2. If the AF has subscribed to access and mobility management related events i.e. request for service area coverage outcome in step 2, then the PCFApplicant's Ref. P112353WO01 18 reports the event (i.e. outcome of the request for service area coverage) to the AF as described in clause 4.16.2.2.***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****4.16.2.2 AM Policy Association Modification initiated by the PCFThe AM Policy Association modification procedure may be initiated by an internal PCF event or by PCF obtaining pertinent analytics information from an NWDAF.The following procedure is applicable to AM Policy Association modification due to Case B.[REPRODUCED HEREIN AS FIGURE 8]Figure 4.16.2.2-1 : AM Policy Association Modification initiated by the PCFThe procedure driven by a PCF internal event applies to both roaming and non-roaming scenarios and when driven by NWDAF or CHF, applies only to non-roaming scenarios.An AM Policy Association is established, with the V-PCF in case of roaming or with the PCF in a non-roaming case as described in clause 4.16.1.2 before this procedure is triggered.In the non-roaming case the role of the V-PCF is performed by the PCF. For the roaming scenarios, the V-PCF interacts with the AMF.NOTE: The V-PCF / PCF stores the access and mobility related policy information provided to the AMF.1. [Conditional] The PCF determines internally that the new status of the UE context requires new policies, potentially triggered by an AF as described in clause 4.15.6.9 or by a notification from the UDR or optionally, the CHF provides a Spending Limit Report to the PCF as described in clause 4.16.8. This may be triggered by obtaining pertinent analytics information from an NWDAF as described in clause 6.1.1.3 of TS 23.503

[0020] ,2. The (V-)PCF in case of roaming and PCF in a non-roaming case makes a policy decision. The PCF may also decide to subscribe to a new Analytics ID from NWDAF as described in clause 6.1.1.3 of TS 23.503

[0020] ,3. The (V-)PCF in the roaming case and the PCF in a non-roaming case sendsNpcf AMPolicyControl UpdateNotify including AM Policy Association ID associated with the SUPI defined in TS 29.507

[0032] , The policy update may include Service Area Restrictions, UE-AMBR, RFSP index value and RFSP Index in Use Validity Time, access stratum time distribution indication, Un time synchronization error budget, clock quality detail level and optionally clock quality acceptance criteria., information for network slice replacement i.e. an Alternative S-NSSAI for a Replaced S-NSSAI and a Network Slice Replacement with PDU re-establishment parameter (see clause 5,15.5,2.2a of TS 23,501 [2]), If an AF has previously subscribed to event request for allocation of service area coverage outcome in step 1, the (V-)PCF checks if the allocated service area coverage was changed and sends a respective notification to the AF using Npcf AMPolicyAuthorization Notify as defined in clause 6.1.3.18 of TS 23.503

[0020] ,4. The AMF deploys and stores the updated access and mobility related policy information, which includes storing the Service Area Restrictions and Policy Control Request Trigger of AM Policy Association, provisioning of the Service Area Restrictions to the UE, provisioning the RFSP index, UE-AMBR, Service Area Restrictions to the NG-RAN, optionally the access stratum time distribution indication, Un time synchronization error budget, clock quality detail level and optionally clock quality acceptance criteria to the NG-RAN and request for notification of SM Policy association establishment and termination to a list of (DNN, S-NSSAI)(s) together with PCF for the UE binding information.Applicant's Ref. P112353WO01 19***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****5.2.5.2.3 Npcf_AMPolicyControl_UpdateNotify service operationService operation name: Npcf AMPolicyControl UpdateNotifyDescription: Provides to the NF Service Consumer, e.g. AMF, updated AM related Policy information for the AM Policy Association as defined in clause 6.5 of TS 23.503 [201, including network slice replacement information and Network Slice Replacement with PDU re-establishment parameter (see clause 5,15.5,2.2a of TS 23,501 [21 ).NOTE: This notification corresponds to an implicit subscription.Inputs, Required: AM Policy Association ID.Inputs, Optional: Access and Mobility related information or indication of AM Policy Association termination.Outputs, Required: Success or failure.Outputs, Optional: None.See clause 4.16.2.2 for the usage of this service operation.***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****5.2.6.22.2 Nnef_AMPolicyAuthorization_Create service operationService operation name: Nnef AMPolicyAuthorization CreateDescription: Authorizes the request and triggers an Npcf AMPolicyAuthorization Create, potentially translating GPSI to SUPI.Inputs, Required: GPSI.Inputs, Optional: Throughput requirements, service coverage requirements, network service requirement, policy duration, subscribed event(s).The subscribed event includes Event ID as specified in Nnef AMPolicyAuthorization Notify service operation, Event Reporting Information defined in Table 4.15.1-1 (only the Event Reporting mode and the immediate reporting flag when applicable), Notification Target Address.The network service requirement is mapped into an Alternative Slice which is part of the UE subscription to fulfil the requirement.Editors Note: The exact nature of network service that maps to Alternative S-NSSAI is FFS.Outputs, Required: Success or Failure.Outputs, Optional: Identification of the created application context, the inputs that can be accepted by the PCF.***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****5.2.6.22.3 Nnef_AMPolicyAuthorization_Update service operationService operation name: Nnef AMPolicyAuthorization UpdateDescription: Provides updated information about an application context to the NEF and triggers an Npcf AMPolicy Authorization Update .Inputs, Required: Identification of the application context.Inputs, Optional: Throughput requirements, service coverage requirements, network service requirement, policy duration.Applicant's Ref. P112353WO01 20The network service requirement is mapped into an Alternative Slice which is part of the UE subscription to fulfil the requirement.Editors Note: The exact nature of network service that maps to Alternative S-NSSAI is FFS.Outputs, Required: Success or Failure.Outputs, Optional: The inputs that can be accepted by the PCF.*****ENDCHANGES TO 3GPP TS 23.503 V19.1.0 ********** START CHANGES TO 3GPP TS 23.503 V19.1.0 *****6.1.2 Non-session management related policy control6.1 .2.1 Access and mobility related policy control6.1.2.1.1 GeneralThe access and mobility related policy control encompasses the management of service area restrictions, the management of the RFSP Index, the management of the UE-AMBR, the management of the UE Slice-MBR, the slice replacement management and the management of the SMF selection. This clause defines the management of service area restrictions and RFSP Index for a UE registered over 3 GPP access. The management of service area restrictions for a 5G-RG or a FN-CRG using W-5GAN are specified in TS 23.316

[0027] ,The management of service area restrictions enables the PCF of the serving PLMN (e.g. V-PCF in roaming case) to modify the service area restrictions used by AMF as described in clause 5.3.4 of TS 23.501 [2],A UE’s subscription may contain service area restrictions, which may be further modified by PCF based on operator defined policies at any time, either by expanding a list of allowed TAIs or by reducing a non-allowed TAIs or by increasing the maximum number of allowed TAIs. Operator defined policies in the PCF may depend on input data such as UE location, time of day, information provided by other NFs such as an AF request to change the service coverage, network analytics from NWDAF, etc.The AMF may report the subscribed service area restrictions received from UDM during Registration procedure or when the AMF changed, the conditions for reporting are that local policies in the AMF indicate that access and mobility related policy control is enabled. The AMF reports the subscribed service area restrictions to the PCF also when the policy control request trigger for service area restrictions changes, as described in clause 6.1.2.5, is met. The AMF receives the modified service area restrictions from the PCF. The AMF stores them and then uses it to determine mobility restriction for a UE. The PCF may indicate to the AMF that there is an unlimited service area.The service area restrictions consist of a list of allowed TAI(s) or a list of non-allowed TAI(s) and optionally the maximum number of allowed TAIs.NOTE 1 : The enforcement of the service area restrictions is performed by the UE, when the UE is in CM-IDLE state or in CM-CONNECTED state when in RRC Inactive, and in the RAN / AMF when the UE is in CM-CONNECTED state.The management of the RFSP Index enables the PCF to modify the RFSP Index used by the AMF to perform radio resource management functionality as described in clause 5.3.4 of TS 23.501 [2], The PCF may determine to modify the RFSP Index at any time based on operator policies that take into consideration e.g. accumulated usage, load level information per network slice instance, the indication that high throughput is desired for a specific application traffic or independently of the application in use and other information described in clause 6.1.1.3. If the modified RFSP index value indicates that EPC / E-UTRAN access is prioritized over the 5G access for the UE, the PCF may, based on operator policy, include a RFSP Index in Use Validity Time of the RFSP Index.The determination of the RFSP Index value requires to configure the PCF with the mapping of RAT Type and / or Frequency value to the RFSP Index that will be sent to RAN.Applicant's Ref. P112353WO01 21Operator policies in the PCF may modify the RFSP index based on the Allowed NSSAI, Target NSSAI, Partially Allowed NSSAI, S-NSSAI(s) rejected partially in the RA, rejected S-NSSAI(s) for the RA, Alternative S-NSSAI(s) mapped to some Replaced S-NSSAI(s) or Pending NSSAI as defined in clause 5.15 of TS 23.501 [2],Operator policies in the PCF may determine that the access and mobility related policy information (e.g. RFSP index value or service area restrictions) can change at the start and stop of an application traffic detection, at the start and stop of a SM Policy Association to a DNN and S-NSSAI, or immediately. In the former case, the PCF subscribes to the SMF for application traffic detection as described in clause 6.2.2.5. In addition, when the PCF evaluates that the access and mobility related policy information need any changes, the PCF reports it to the AF if the AF has subscribed to the notification on outcome of service area coverage change as defined in clause 6.1.3.18.Operator policies in the PCF may determine that the access and mobility related policy information (e.g. RFSP index value or service area restrictions) can change based on the Spending Limits information from CHF as defined in clause 6.1.1.4.For radio resource management, the AMF may report the subscribed RFSP Index received from UDM during the Registration procedure or when the AMF changed. The conditions for reporting are that local policies in the AMF indicate that access and mobility related policy control is enabled. The AMF reports the subscribed RFSP Index to the PCF when the subscription to the RFSP Index change to the PCF is met. The AMF receives the modified RFSP Index from the PCF.NOTE 2: The enforcement of the RFSP Index is performed in the RAN.Upon change of AMF, the source AMF informs the PCF that the UE context was removed in the AMF in the case of inter-PLMN mobility.The management of UE-AMBR enables the PCF to provide the UE-AMBR information to the AMF based on serving network policy. The AMF may report the subscribed UE-AMBR received from UDM. The conditions for reporting are that the PCF provided Policy Control Request Triggers the AMF to report subscribed UE-AMBR. The AMF receives the modified UE-AMBR from the PCF. The AMF provides a UE-AMBR value of the serving network to the RAN as specified in clause 5.7.2.6 of TS 23.501 [2],The management of the SMF selection enables the PCF to instmct the AMF to contact the PCF during the PDU Session Establishment procedure to perform a DNN replacement, as specified in clause 5.6.1 of TS 23.501 [2], To indicate the conditions to check whether to contact the PCF at PDU Session establishment (as specified in clause 6.1.2.5), the PCF provides the Policy Control Request Triggers SMF selection management and, if necessary Change of the Allowed NSSAI, together with SMF selection management related policy information (see clause 6.5) during UE Registration procedure and at establishment of the AM Policy Association.The PCF may update the SMF selection management information based on a PCF local decision or upon being informed about a new Allowed NSSAI. The AMF applies the updated SMF selection management information to new PDU Sessions only, i.e. already established PDU Sessions are not affected.The management of the slice replacement enables the PCF to instruct the AMF to contact the PCF to provide the Alternative S-NSSAI for each S-NSSAI that requires slice replacement as specified in clause 5.15.19 of TS 23.501 [2], The AMF reports S-NSSAI(s) of the serving network that requires slice replacement. The conditions for reporting are defined in clause 6.1.2.5. The PCF returns the Alternative S-NSSAI for the S-NSSAI of the serving network received from the AMF. The AMF receives the Alternative S-NSSAI for each S-NSSAI that requires slice replacement for which it has provided to the PCF.If the AMF has indicated support of the Network Slice Replacement for the UE and the PCF detects the change in the availability of the S-NSSAI in the Allowed NSSAI (i.e. the S-NSSAI becomes unavailable or available) based on a PCF local decision (e.g. based on 0AM or NWDAF analytics output) or based on AF -requested network slice replacement requests received by the PCF and irrespective of UE support (see clauses 5,15.5,2.2a) the PCF notifies the S-NSSAI availability information (see clause 6.5) based on the implicit subscription from the AMF. The AMF may also interact with the PCF to determine the Alternative S-NSSAI for S-NSSAI to be replaced based on Policy Control Request Triggers as defined in clause 6.1.2.5.The optional management of UE-Slice-MBR enables the PCF to modify the value in the list of Subscribed UE-Slice- MBR assigned to a SUPI based on serving network policies, if the HPLMN permits based on roaming agreement. The AMF reports the Subscribed UE-Slice-MBR for each S-NSSAI of the serving network. The S-NSSAI of the VPLMN is derived from the Subscribed S-NSSAI by the AMF and provided to the PCF. The AMF may provide the Subscribed S-NSSAI together with the S-NSSAI of the VPLMN. The conditions for reporting are defined in clause 6.1.2.5. The PCF returns the authorized UE-Slice-MBR for the S-NSSAI of the serving network. The AMFApplicant's Ref. P112353WO01 22 receives the authorized list of UE-Slice-MBR value for each S-NSSAI for which it has provided the Subscribed UE- Slice-MBR from the PCF. Then the AMF provides the authorized list of UE-Slice-MBR for the S-NSSAIs in the Allowed S-NSSAI to the RAN as specified in clause 5.7.1.10 of TS 23.501 [2],The optional management of 5G access stratum time distribution enables the PCF for the UE to instruct the AMF about the 5G access stratum time distribution parameters, i.e. 5G access stratum time distribution indication (enable, disable). Optionally, when 5G access stratum time distribution or (g)PTP time synchronization is enabled, the PCF for the UE instructs the AMF about the Uu Time synchronization error budget. Optionally, when 5G access stratum time distribution is enabled, the PCF for UE instructs the AMF about the clock quality reporting control information (clock quality detail level, clock quality acceptance criteria).In the case that the PCF for the UE (providing the access and mobility related policy information) and the PCF for the PDU Session of this UE (providing the Session Management related policies) are separate PCF instances, the following applies:- If the PCF for the UE determines that the access and mobility related policy information can change at the start and stop of an application traffic detection, the following applies:The PCF for the UE may subscribes to be notified about the PCF binding information when a PCF for the PDU Session (of this UE) is registered in the BSF, including the SUPI, DNN, S-NSSAI. The DNN, S-NSSAI is either provided by the AF or locally configured in the PCF for certain Application Identifiers). An alternative mechanism for the PCF for the UE to be notified of the PCF for the PDU Session of this UE is to request the AMF to send to the PCF for the PDU Session of the DNN, S-NSSAI, via SMF, the request for notification of SM Policy Association establishment. In this case, the PCF for the PDU Session should subscribe Request for notification on SM Policy Association establishment or termination Policy Control Request Trigger as described in clause 6.1.3.5 to get the binding information of PCF for the UE (as defined in clause 6.1.1.2.2).When the PCF for the UE is notified that PCF for the PDU Session is registered, either via the BSF that provides the UE address, DNN and the PCF address, PCF instance Id and PCF set id if available or via PCF for the PDU Session when it received a request for notification from the SMF. The PCF for the UE may subscribe to the " start / stop of application traffic detection" event defined in clause 6.1.3.18 or trigger a policy decision if there is a SM Policy Association to the DNN, S-NSSAI.The reporting of "start / stop of application traffic detection" to the PCF for the UE is used as input for a policy decision to change the access and mobility related policy information.NOTE 3 : The PCF for the UE may subscribe to the notifications of newly registered PCF for the PDU Session and subscribe to the "start / stop of application traffic detection" events for multiple applications with different application identifiers. When PCF receives the notifications for multiple applications, the PCF for the UE can determine which access and mobility related policy information to apply based on local configuration and operator policy.- If the PCF for the UE determines that the access and mobility related policy information can change at the establishment and termination of a SM Policy Association to a DNN and S-NSSAI base on the notification sent by the BSF, the PCF may indicate to the BSF to report the registration of a PCF for the PDU Session when the first SM Policy Association is established and the deregistration of the PCF for the PDU Session when the last SM Policy Association is terminated for a DNN, S-NSSAI.- The PCF for the UE checks if an AF is subscribed to be notified on outcome of service area coverage change, using the related event defined in clause 6.1.3.18.***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****6.1.2.6.1 AF request Access and Mobility related Policy Control for a UEThis clause applies to non-roaming, i.e. cases where the PCF, AF, AMF and SMF belong to the serving PLMN, or the AF belongs to a third party with which the Serving PLMN has an agreement. AF influence on Access and Mobility related policy control does not apply in the case of Home Routed or Local breakout roaming cases.The AF may subscribe to notifications when a PCF for the UE is registered in the BSF for a certain SUPI or GPSI.Applicant's Ref. P112353WO01 23The AF may contact, either directly or via NEF, the PCF for the UE to request notifications on the outcome of a service area coverage change (represented as a geographical area or a list of TA(s)) or the indication that high throughput is desired for UE traffic or both, for a SUPI or a GPSI. The request applies until the AF requests to terminate the request, or the AF request expires (according to relevant input provided by the AF), or the AM Policy Association is terminated. The AF may subscribe to notifications on the outcome of the service area coverage change to the PCF, according to the events described in clause 6.1.3.18. At the time the AF request expires, the PCF removes the context provided by the AF and then checks if the Access and Mobility related policy information needs to be updated at the AMF.NOTE: The assumption is that the AF also removes the context at the time the AF request expires.When the AF contacts the NEF then the following mappings are performed by the NEF:1) The geographical area (e.g. a civic address or shapes) is mapped into a list of TAs determined by local configuration.2) The GPSI, if provided, is mapped to a SUPI according to the subscription information received from UDM.The PCF takes the list of TAs as input for policy decisions, considering the list of TAs provided by the AF as allowed TAIs for the UE when calculating the service area restrictions, then checking operator policies to determine whether the service area restrictions need to be updated.The PCF reports the outcome of a service area coverage change, including the list of allowed TAIs (that is mapped to a geographical area if the requests goes via NEF) and any changes to the AF, according to the events described in clause 6.1.3.18.The PCF checks if the RFSP value index for a UE needs to be changed, as described in clause 6.1.2.1, using the indication that high throughput is desired. The PCF reports to the AF that the request was executed, but without reporting anything related to actually applied RFSP or throughput changes.The PCF triggers the network slice replacement based on the slice replacement request initiated by an AF, as described in clause 6, 1,2.1.1.***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****6.1.3.18 Event reporting from the PCFThe AF may subscribe / unsubscribe to notifications of events from the PCF for the PDU Session to which the AF session is bound. The AF can either subscribe / unsubscribe directly at the PCF or indirectly via an NEF or a TSCTSF.The PCF for the UE may subscribe / unsubscribe to notifications of events from the PCF for the PDU Session. Other NFs may subscribe / unsubscribe to notifications of events from the PCF for the PDU Session or from the PCF for the UE.The events that can be subscribed by the AF and by other NFs are listed in Table 6.1.3.18-1.Table 6.1.3.18-1 : Events relevant for reporting from the PCF[REPRODUCED HEREIN AS FIGURES 9A TO 9F]If an AF requests the PCF to report the PLMN identifier where the UE is currently located, then the PCF shall provide the PLMN identifier or the SNPN identifier to the AF if available. Otherwise, the PCF shall provision the corresponding PCC rules, and the Policy Control Request Trigger to report PLMN change to the SMF. The PCF shall, upon receiving the PLMN identifier or the SNPN identifier from the SMF forward this information to the AF, including the PLMN Id and if available the NID. If the H-PCF requests to report the PLMN identifier where the UE is currently located, the V-PCF provisions the PCRT on "PLMN change" to the AMF as described in clause 6.1.2.5 and then forwards the PLMN ID received from the AMF to the H-PCF.If an AF requests the PCF to report on the change of Access Type, the PCF shall provide the corresponding Policy Control Request Trigger to the SMF to enable the report of the Change in Access Type to the PCF. The PCF shall,Applicant's Ref. P112353WO01 24 upon reception of information about the Access Type the user is currently using and upon indication of change of Access Type, notify the AF on changes of the Access Type and forward the information received from the SMF to the AF. The change of the RAT Type shall also be reported to the AF, even if the Access Type is unchanged. For MA PDU Session the Access Type information may include two Access Type information that the user is currently using.If an AF requests the PCF to report on the signalling path status, for the AF session, the PCF shall, upon indication of removal of PCC Rules identifying signalling traffic from the SMF report it to the AF.If an AF requests the PCF to report Access Network Charging Correlation Information, the PCF shall provide to the AF the Access Network Charging Correlation Information, which allows to identify the usage reports that include measurements for the Service Data Flow(s), once the Access Network Charging Correlation Information is known at the PCF.If an AF requests the PCF to report Access Network Information (i.e. the User Location Report and / or the UE Timezone Report) at AF session establishment, modification or termination, the PCF shall set the Access Network Information report parameters in the corresponding PCC rule(s) and provision them together with the corresponding Policy Control Request Trigger to the SMF. For those PCC rule(s) based on preliminary service information the PCF may assign the 5QI and ARP of the QoS Flow associated with the default QoS rule to avoid signalling to the UE.NOTE 1 : The PCF can also use the dynamic or pre-defined PCC Rules related to the IMS signalling to request Access Network Information reporting. This can be used to support e.g. regulatory requirements for SMS over IP, where the IMS network (i.e. P-CSCF) needs to retrieve the user location and / or UE Time Zone information. Note that due to regulatory requirements, the Access Network Information can be requested for SMS over IP, impacting a large number of PDU Sessions, that can lead to significant increase in signalling load when the Access Network Information is requested from AMF.The PCF shall, upon receiving an Access Network Information report corresponding to the AF session from the SMF, forward the Access Network Information as requested by the AF (if the SMF only reported the serving PLMN identifier or the SNPN identifier to the PCF, as described in clause 6.1.3.5, the PCF shall forward it to the AF). For AF session termination the communication between the AF and the PCF shall be kept alive until the PCF report is received.If an AF requests the PCF to report the Usage for Sponsored Data Connectivity, the PCF shall provision the corresponding PCC rules, and the Policy Control Request Trigger to the SMF. If the usage threshold provided by the AF has been reached or the AF session is terminated, the PCF forwards such information to the AF.If an AF or TSCTSF requests the PCF to report the Service Data Flow deactivation, the PCF shall report the release of resources corresponding to the AF session. The PCF shall, upon being notified of the removal of PCC Rules corresponding to the AF session from the SMF, forward this information to the AF. The PCF shall also forward, if available, the reason why the resources are released, the user location information and the UE Timezone.If an AF or TSCTSF requests the PCF to report the Resource allocation outcome, the PCF shall report the outcome of the resource allocation of the Service Data Flow(s) related to the AF session. The AF or TSCTSF may request to be notified about successful or failed resource allocation. In this case, the PCF shall instruct the SMF to report the successful resource allocation trigger (see clause 6.1.3.5). If the SMF has notified the PCF that the resource allocation of a Service Data Flow is successful and the currently fulfilled QoS matches an Alternative QoS parameter set (as described in clause 6.2.2.1), the PCF shall also provide to the AF the QoS Reference parameter or the Requested Alternative QoS Parameter Set which corresponds to the Alternative QoS parameter set referenced by the SMF. If the SMF has notified the PCF about resource allocation failure together with an Access Type (as described in clause 6.1.3.5), the PCF shall only notify the AF when the PCC rule is removed and without forwarding any Access Type information. If the SMF has notified the PCF about resource allocation failure due to UE temporary unreachable together with a maximum waiting time, if available, (as described in clause 6.1.3.5), the PCF shall notify the AF on resource allocation failure and provide the UE temporary unreachable and the maximum waiting time, if available.If an AF requests the PCF to report when the QoS targets can no longer (or can again) be fulfilled for a particular media flow, the PCF shall set the QNC indication in the corresponding PCC mle(s) that includes a GBR or delay critical GBR 5QI value and provision them together with the corresponding Policy Control Request Trigger to the SMF. At the time, the SMF notifies that GFBR can no longer (or can again) be guaranteed for a QoS Flow to which those PCC Rule(s) are bound, the PCF shall report to the AF the affected media flow and provides the indication that QoS targets can no longer (or can again) be fulfilled. If additional information is received with the notification from SMF (see clause 5.7.2.4 of TS 23.501 [2]), the PCF shall also provide to the AF the QoS Reference parameter or the Requested Alternative QoS Parameter Set which corresponds to the Alternative QoS parameter set referenced by theApplicant's Ref. P112353WO01 25SMF. If the SMF has indicated that the lowest priority Alternative QoS parameter set cannot be fulfilled, the PCF shall indicate to the AF that the lowest priority QoS Reference or the lowest priority set of Requested Alternative QoS Parameters of the Alternative Service Requirements cannot be fulfilled.If the AF subscribes to be notified of the QoS Monitoring reports, the PCF decides about the path for the QoS Monitoring reports and sets the QoS Monitoring Policy Control Request Trigger accordingly, as described in clause 6.1.3.21. The PCF sends the QoS Monitoring reports to AF based on the QoS Monitoring reports that it receives from the SMF, according to AF subscription and PCF selected notification path e.g. PCF does not report to AF if AF will receive the QoS Monitoring reports directly from the UPF.NOTE 2: The QoS Monitoring report received by the PCF and the information sent to the AF can be different. The QoS Monitoring report (e.g. packer delay) may be used by PCF to calculate the requested QoS parameter (e.g. packet delay variation).NOTE 3 : This event can only be subscribed as part of an AF session with required QoS (described in clause 6.1.3.22) and as part of AF requested QoS for a UE or group of UEs not identified by a UE address (described in clause 6.1.3.28).NOTE 4: If the service data flow is mapped to two QoS Flows (i.e. the UL traffic and DL traffic of the service data flow are separated into two QoS Flows respectively) in the same PDU Session, the PCF triggers QoS Monitoring for each direction packet delay of the individual QoS Flows respectively and generates the QoS Monitoring reports for the AF based on the packet delay monitored on the QoS Flow for each direction (as described in clause 5.37.4 of TS 23.501 [2]).If the AF subscribes to be notified of Packet Delay Variation reports (the variation of UL / DL packet delay between UE and PSA UPF), the PCF triggers the QoS monitoring procedure, derives the 5GS Packet Delay Variation and reports the value to the AF, as described in clause 6.1.3.26.NOTE 5: This event can only be subscribed as part of an AF session with required QoS (described in clause 6.1.3.22).If the AF subscribes to Round-trip delay measurement over two service data flows considering the UL direction of a service data flows and the DL direction of another service data flow, PCF triggers the QoS monitoring procedure to derive the Round-Trip delay measurement for delay measurements on the individual QoS Flows respectively (as described in clause 6.1.3.27.1 and in clause 5.37.4 of TS 23.501 [2], The PCF derives the Round-Trip delay based on the packet delay measurement reports of the QoS Flows of each direction and reports the results to the AF. PCF sets QoS Monitoring Policies for each of the individual service data flows and QoS Monitoring Policy Control Request Trigger as described in clause 6.1.3.21.NOTE 6: This event can only be subscribed as part of an AF session with required QoS (described in clause 6.1.3.22).If the AF subscribes to the event Network support for QoS Monitoring, the PCF sets the QoS Monitoring can no longer (or can again) be performed Policy Control Request Trigger in the SMF, if not done before. The PCF shall notify the AF that QoS Monitoring can no longer (or can again) be performed by the network whenever it receives from the SMF a notification that QoS Monitoring can no longer (or can again) be performed.If the AF indicates ECN marking for L4S support by the application, PCF authorizes the request and sets the ECN marking for L4S can no longer (or can again) be performed trigger accordingly. PCF shall further send the notification it receives from the SMF to AF on whether the network can not (or can again) perform ECN marking for L4S, for example, if due to user mobility neither target RAN nor UPF PSA support ECN marking for L4S.If an AF requests the PCF to report on the Out of credit event for the associated service data flow(s), the PCF shall inform the AF (when it gets informed by the SMF) that credit is no longer available for the services data flow(s) related to the AF session together with the applied termination action.If an AF requests the PCF to report on the Reallocation of credit event for the associated service data flow(s), the PCF shall inform the AF (when it gets informed by the SMF) that credit has been reallocated after credit was no longer available and the termination action was applied for the service data flow(s) related to the AF session.The PCF can arm the trigger of 5GS Bridge / Router information available to SMF based on local policy (i.e. without an AF request) or based on subscription request from TSCTSF. The PCF shall, upon reception of the 5GS Bridge / Router information (refer to clauses 6.1.3.23, 6.1.3.23a, 6.1.3.23b) from the SMF, forward this information to the TSN AF or the TSCTSF. When the PCF has received the User plane node Management Information Container or Port Management Information Container and related port number from SMF, the PCF also provides User plane nodeApplicant's Ref. P112353WO01 26Management Information Container or Port Management Information Container and related port number to the TSN AF or TSCTSF. When SMF has reported the 5GS Bridge / Router information and no AF session exists, the PCF forward this information to a pre-configured TSN AF, or to a pre-configured TSCTSF or a TSCTSF discovered and selected via NRF. In the case of private IPv4 address being used for IP type PDU Session, the PCF shall additionally report DNN and S-NSSAI of the PDU Session to TSCTSF.If the AF requests the PCF to report on the outcome of the service area coverage change, the PCF reports the outcome of the service area coverage change to the AF and notifies the current service area coverage to the AF. The outcome is the result of the execution of the request of service coverage change at the PCF; the outcome is successful if the request was executed, and includes the current service area coverage that may be the same or different from the service area coverage provided by the AF. The subscription may also be implicit. In this case there may be bulk subscription, either for an Intemal-Group-Id or for any UE. In order to prevent massive notifications to the AF, the request for any UE is associated to a specific Application Identifier or DNN, S-NSSAI. For bulk subscription, when the AF request includes an expiration time, the PCF stops reporting to the AF when the expiration time is reached.If the AF requests the (H-)PCF, via V-PCF when roaming, to report on the outcome of the UE Policies delivery due to service specific parameter provisioning procedure, the (H-)PCF reports the outcome of the related UE Policies provisioning procedure for the related traffic descriptor for the UE to the AF, via V-PCF when roaming. The outcome of the UE Policies provisioning procedure includes the success, the failure with an appropriate cause or the interim status report such as the UE is temporarily unreachable or that URSP Rules have not yet been delivered by the H-PCF (see clauses 4.15.6.7 and 5.2.5.7 of TS 23.502 [3]). The PCF reports the outcome of the UE Policy provisioning procedure for each of the UEs that were included as Target UEs in the service specific information Data Subset in UDR. When the AF requested the PCF for the UE to report on the outcome of the UE Policies delivery due to service specific parameter provisioning procedure targeting a single UE, the Result of UE Policy Container delivery via EPS event trigger shall be subscribed.NOTE 7: An example reason for sending an interim status report that indicates that "URSP Rules have not yet been delivered by the H-PCF" may be that the UE does not support the VPLMN Specific URSP Rules feature and is not registered in the PLMN where the service parameters apply.A request to report Start of application traffic detection and Stop of application traffic detection triggers the reporting when the PCF receives start of application traffic detection event or stop of application traffic detection event from SMF. The reception of a subscription to this event triggers the setting of the corresponding Policy Control Request Trigger to SMF, if not already subscribed.A request to forward UE reporting Connection Capabilities from an associated URSP mle triggers the reporting when the PCF receives UE reporting of URSP rule enforcement information from the SMF matching specific Connection Capabilities (see clause 6.6.2.4). The request may include SUPI(s), DNN(s) and / or S-NSSAI(s) to which the request applies. The PCF reports the received Connection Capabilities and PDU Session information including the SUPI, UE requested DNN, Selected DNN, S-NSSAI, SSC Mode, Request-Type. The reception of a subscription to this event triggers the setting of the corresponding Policy Control Request Trigger to SMF, if not already subscribed.If an AF requests the PCF to report Start of application traffic detection and Stop of application traffic detection via bulk subscription, the AF shall provide the application identifier together with the S-NSSAI and DNN. The PCF provides a PCC rule for the application identifier together with the corresponding Policy Control Request Trigger to the SMF for every PDU Session to this S-NSSAI and DNN. When the PCF receives start of application traffic detection event or stop of application traffic detection event for the PCC mle in a PDU Session, the PCF forwards the event to the AF together with the UE identifier and optionally the IP address of the PDU Session corresponding to this PCC rule. When the AF removes bulk subscription for this application identifier, then the PCF removes the Policy Control Request Trigger from the SMF for every PDU Session to this S-NSSAN and DNN, if it is not used for other purpose.NOTE 8: The restriction of the bulk subscription to a specific combination of S-NSSAI and DNN avoids excessive signalling load.If an AF requests the PCF to report on the change between different types of satellite backhaul or the change between satellite backhaul and non-satellite backhaul (as specified in clause 5.43.4 of TS 23.501 [2]), the PCF shall provide the corresponding Policy Control Request Trigger to the SMF to enable the report of satellite backhaul category change (see clause 6.1.3.5) to the PCF. The PCF shall, upon reception of information about the change of Satellite backhaul category, notify the AF on the Satellite backhaul category change event was met and forward the current Satellite backhaul category received from the SMF to the AF. When the satellite backhaul is no longer used, the Satellite backhaul category indicates that a non-satellite backhaul is used.Applicant's Ref. P112353WO01 27If 5G DDNMF requests the PCF to report on the Change of PDUID, the PCF shall notify whenever a new PDUID is allocated. Further details on how the 5G DDNMF retrieves and subscribes to notifications on Change of PDUID are defined in TS 23.304

[0034] ,A request to report SM Policy Association established or terminated triggers the reporting when the PCF receives the request for notification on the SM Policy Association from SMF. The PCF notifies on the EventID "SM Policy Association established / terminated", includes the PCF binding information of the PCF for the PDU Session of the UE, as described in clause 6.1.1.2.2.If the TSCTSF requests the PCF notifications for reporting of extra UE addresses, the PCF shall provide the extra UE addresses allocated to the PDU Session due to Framed Routes or IPv6 prefix delegation. The report shall include the actual list of IPv4 address masks or a list of IPv6 prefixes as currently allocated.If the AF provides the Capability for BAT adaptation or BAT Window and subscribes to PCF for Notification on BAT offset, the PCF will trigger the subscription to SMF for Notification on BAT offset defined in clause 6.1.3.5. When the Notification on BAT offset trigger is set and the PCF receives a BAT offset and optionally an adjusted periodicity from the SMF, the PCF identifies the affected AF session (based on the PCC rule indicated by the SMF) and forwards the BAT offset and optionally the adjusted periodicity for this AF session to the TSCTSF.A request to report Result of UE Policy Container delivery via EPS triggers the reporting when the PCF for the PDU Session receives the UE Policy Container from the UE during UE Policy Container delivery via EPS, or a delivery failure result for UE Policy Container delivery via EPS with appropriate reason from the SMF. The reception of a subscription to this event triggers the setting of the corresponding Policy Control Request Trigger to SMF, if not already subscribed.If an AF requests the PCF to report on the UE reachability status change, the PCF shall provide the corresponding Policy Control Request Trigger to the SMF to enable the report of the UE reachability status change to the PCF, if not already subscribed. The PCF shall, upon indication of change of reachability status, notify the AF and forward the information received from the SMF to the AF Jf an AF requests the PCF to report on the change between S- NSSAI and Alternative S-NSSAi, the PCF reports the outcome of the slice replacement to the AF, if the AF is trusted and authorized, the PCF notifies the S-NSSAi to the AF,***** NEXT CHANGE TO 3GPP TS 23.503 V19.1.0 *****6.5 Access and mobility related policy informationTo enable the enforcement in the 5GC system of the access and mobility policy decisions made by the PCF for the control as described in clause 6.1.2.1, the 5GC system may provide the Access and mobility related policy information from the PCF to the AMF.Table 6.5-1 lists the AMF access and mobility related policy information.Table 6.5-1 : Access and mobility related policy information[REPRODUCED HEREIN AS FIGURES 10A TO 10C]The list of allowed TAIs indicates the TAIs where the UE is allowed to be registered, see clause 5.3.4 of TS 23.501 [2] for the description on how AMF uses this information.The list of non-allowed TAIs indicates the TAIs where the UE is not allowed to be registered, see clause 5.3.4 of TS 23.501 [2] for the description on how AMF uses this information.The Maximum number of allowed TAs indicates the maximum number of allowed Tracking Areas, the list of TAI is defined in the AMF and not explicitly provided by the PCF.The RFSP Index for Allowed NSSAI and RFSP Index for Target NSSAI defines the RFSP Index for radio resource management functionality.RFSP Index in Use Validity Time defines the time for which the RFSP Index in use will be used in MME after 5GS to EPS mobility as specified in clause 5.17.2.2 of TS 23.501 [2],Applicant's Ref. P112353WO01 28The UE-AMBR limits the aggregated bit rate across all Non-GBR QoS Flows of a UE in the serving network.The list of UE-Slice-MBR defines the list of authorized UE-Slice-MBR allocated for a UE, how it is enforced is described in clause 5.7.1.10 of TS 23.501 [2],The DNN replacement of unsupported DNNs indicates that the AMF shall contact the PCF for replacement of an unsupported DNN requested by the UE.The List ofS-NSSAIs defines the S-NSSAIs, valid in the serving network, of the Allowed NSSAI that contain DNN candidates for replacement by PCF.The L ist of DNNs defines the DNN candidates for which the AMF shall contact the PCF for replacement if such a DNN is requested by a UE.The 5G access stratum time distribution indicates the 5G access stratum time distribution parameters to be indicated to the NG-RAN via AMF.The S-NSSAI availability information indicates whether the S-NSSAI is not available or is available, and / or an alternative S-NSSAI that the S-NSSAI can be replaced with.The Charging information includes CHF address(es) and if available, the associated CHF instance ID(s) and / or CHF set lD(s). This is described in detail in clause 6.3.11 of TS 23.501 [2] and in clause 6.1.1.4.*****ENDCHANGES TO 3GPP TS 23.503 V19.1.0 ********** START CHANGES TO 3GPP TS 23.501 V19.1.0 *****5.15.5.2.2a AF triggered modification of the Set of Network Slice(s) for a UEIn non-roaming cases, a trusted AF may request to replace a certain S-NSSAI (Replaced S-NSSAI) for a UE with another S-NSSAI (Alternative S-NSSAI) which is part of the UE subscription. Alternatively, an untrusted AF via the NEF, may request a change of network service (which is mapped at NEF to an Alternative S-NSSAI which is part of the UE subscription). In either case , the request is sent to the PCF for the UE handling the impacted subscriber. Similarly, a tmsted AF or an AF, subject to authorization via the NEF, may request to terminate Network Slice replacement.Editors Note: The exact nature of network service that maps to Alternative S-NSSAI is FFS.The PCF for the UE triggers the network slice replacement at the AMF as defined in TS 23,503 (451,NOTE 1: How the AF obtains the S-NSSAI to be replaced and the S-NSSAI replacing is out of scope of this specification.The PCF sends access and mobility related policies to the AMF, as described in TS 23,503 (451, including the Replaced S-NSSAI and an Alternative S-NSSAI to trigger the Network Slice replacement, together with an indication that instructs the AMF to terminate all PDU sessions associated with the Replaced S-NSSAI and start using the Alternative S-NSSAI. To that effect, the AMF performs the following:- If the Alternative S-NSSAI is not within the UE subscription, or is not supported in the UE Registration Area, the AMF notifies the PCF that the Network Slice Replacement is not triggered with a cause value. The PCF further informs the AF,- If the Alternative S-NSSAI is within the UE subscription and is supported in the UE Registration Area, the AMF includes the Alternative S-NSSAI in the Allowed NSSAI (if not present) and removes the Replaced S- NSSAI from the Allowed NSSAI and the Configured NSSAI. The PCF notifies the AF about the outcome of the network slice replacement.NOTE 2: It is assumed that the URSP rule is preconfigured to ensure that the UE will use the Alternative S- NSSAI to establish a new PDU Session. Otherwise the PCF sends the UE updated URSP rules.Applicant's Ref. P112353WO01 29When the trusted AF or a NEF sends request to PCF for the UE to terminate the Network Slice Replacement, the PCF for the UE sends access and mobility related policies to the AMF, as described in TS 23,503 [451, including the Replaced S-NSSAI and an Alternative S-NSSAI reversed from the initial procedure, together with an indication that instructs the AMF to perform same actions as in the initial procedure on the reversed S-NSSAIs to restore the original S-NSSAI.*****ENDCHANGES TO 3GPP TS 23.501 V19.1.0 *****

[0053] Note that the network functions mentioned can be implemented as physical bare metal, virtual, or cloud native such as Kubernetes environment in e.g., Hypercloud networks.

[0054] The solution disclosed herein is compatible with any version of Open RAN (O-RAN) implementation.

[0055] Figure 11 is a schematic block diagram of a network node 1100 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node 1100 may be, for example, a network node that implements all or part of the functionality of a network function (e.g., the AMF 200, the PCF 210, the NEF 300) as described herein or a network node that implements all or part of the functionality of an AF (e.g., the AF 212) as described herein. As illustrated, the network node 1100 includes one or more processors 1104 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory 1106, and a network interface 1108. The one or more processors 1104 are also referred to herein as processing circuitry. The one or more processors 1104 operate to provide one or more functions of the network node 1100 as described herein (e.g., one or more functions of an AMF, PCF, NEF, or AF, as described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 1106 and executed by the one or more processors 1104.

[0056] Figure 12 is a schematic block diagram that illustrates a virtualized embodiment of the network node 1100 according to some embodiments of the present disclosure. Again, optional features are represented by dashed boxes. As used herein, a "virtualized” network node is an implementation of the network node 1100 in which at least a portion of the functionality of the network node 1100 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, the network node 1100 includes one or more processing nodes 1200 coupled to or included as part of a network(s) 1202. Each processing node 1200 includes one or more processors 1204 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 1206, and a network interface 1208. In this example, functions 1210 of the network node 1100 described herein (e.g., one or more functions of an AMF, PCF, NEF, or AF, as described herein) are implemented at the one or more processing nodes 1200 or distributed across the one or more processing nodes 1200 in any desired manner. In some particular embodiments, some or all of the functions 1210 of the network node 1100 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 1200.

[0057] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the network node 1100 or a node (e.g., a processing node 1200) implementing one or more of the functions 1210 of the network node 1100 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrierApplicant's Ref. P112353WO01 30 comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0058] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0059] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).Applicant's Ref. P112353WO01 31EmbodimentsSome embodiments described herein may be summarized in the following manner:1. A method performed by a first network function (e.g., PCF 210) in a core network of a cellular communications system, the method comprising: receiving (400-1 or 400-2C) an Application Function, AF, -initiated request for replacement of a network slice for a User Equipment, UE, with an alternative network slice; and initiating (404) replacement of the network slice for the UE with the alternative network slice.2. The method of embodiment 1, wherein receiving (400-1) the AF-initiated request comprises receiving (400- 1) the AF-initiated request (e.g., directly) from an AF (212).3. The method of embodiment 1, wherein receiving (400-2C) the AF-initiated request comprises receiving (400- 2C) the AF-initiated request from a second network function (e.g., NEF 300) in the core network.4. The method of embodiment 2 or 3, wherein the AF (212) is notified of an outcome (e.g., success or failure) of the replacement of the network slice of the UE with the alternative network slice (e.g., via a notification sent to the AF (212) either through explicit or implicit subscription).5. The method of any of embodiments 1 to 4, further comprising: prior to initiating (404) replacement of the network slice for the UE with the alternative network slice, validating (402) that the alternative network slice is included in a UE subscription of the UE.6. The method of any of embodiments 1 to 5, wherein initiating (404) replacement of the network slice for the UE with the alternative network slice comprises sending (404A), to a third network function (e.g., AMF 200) information comprising an indication (e.g., S-NSSAI) of the network slice of the UE to be replaced and an indication (e.g., Alternative S-NSSI) of the alternative network slice that is to replace the network slice of the UE.7. The method of embodiment 6, wherein the information further comprises an indication to terminate all Protocol Data Unit, PDU, sessions of the UE that are associated with the network slice and re-establish those PDU sessions of the UE and establish any new PDU sessions of the UE using the alternative network slice.8. The method of embodiment 6 or 7, wherein the information is Access and Mobility, AM, policy information.9. The method of any of embodiments 6 to 8, wherein the AF-initiated request is an AM Policy Authorization request (e.g., a Npcf_AMPolicyAuthorization Request).Applicant's Ref. P112353WO01 3210. The method of any of embodiments 1 to 9, wherein the AF-initiated request comprises an indication of the alternative network slice (e.g., an Alternative S-NSSAI).11. A network node adapted to perform the method of any of embodiments 1 to 10.12. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to any of embodiments 1 to 10.13. A carrier containing the computer program of embodiment 12, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.14. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to any of embodiments 1 to 10.15. A method performed by a first network function (e.g., NEF 300) in a core network of a cellular communications system, the method comprising: receiving (400-2A), from an Application Function, AF, (212), a request for replacement of a network slice for a User Equipment, UE, with an alternative network slice; and sending (400-2C), to a second network function (e.g., PCF 210) in the core network, a request for replacement of the network slice for the UE with the alternative network slice.16. The method of embodiment 15, wherein the request received from the AF (212) is a request that implicitly requests replacement of the network slice for the UE with the alternative network slice.17. The method of embodiment 15, wherein the request received from the AF (212) is a request for a change of a network service of the UE to an indicated network slice that is mapped to the alternative network slice.18. The method of any of embodiments 15 to 17, wherein the request sent to the second network function (e.g., PCF 210) comprises an indication of the alternative network slice (e.g., an Alternative S-NSSAI).19. The method of embodiment 18, wherein the AF (212) is notified of an outcome (e.g., success or failure) of the replacement of the network slice of the UE with the alternative network slice (e.g., via a notification sent to the AF (212) either through explicit or implicit subscription for the AF):20. The method of any of embodiments 15 to 19, further comprising:Applicant's Ref. P112353WO01 33 prior to sending (400-2C) the request for replacement of the network slice for the UE with the alternative network slice to the second network function (e.g., PCF 210), validating (400-2B) that the alternative network slice is included in a UE subscription of the UE.21. The method of any of embodiments 15 to 20, wherein the request sent to the second network function (e.g., PCF 210) is an AM Policy Authorization request (e.g., a Npcf_AMPolicyAuthorization Request).22. A network node adapted to perform the method of any of embodiments 15 to 21 .23. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to any of embodiments 15 to 21 .24. A carrier containing the computer program of embodiment 23, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.25. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to any of embodiments 15 to 21.26. A method performed by an Application Function, AF, (212), the method comprising: sending (400-1 or 400-2C), to a network function (e.g., PCF 210 or NEF 300) in a core network of a cellular communications system, an explicit or implicit request for replacement of a network slice for a User Equipment, UE, with an alternative network slice.27. The method of embodiment 26, further comprising receiving a notification that indicates an outcome (e.g., success or failure) of the requested replacement of the network slice for the User Equipment, UE, with an alternative network slice.28. A network node adapted to perform the method of embodiment 26 or 27.29. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to embodiment 26.30. A carrier containing the computer program of embodiment 29, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.31. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to embodiment 26 or 27.

Claims

Applicant's Ref. P112353WO01 34Claims1 . A method performed by a first network function (e.g., PCF 210) in a core network of a cellular communications system, the method comprising: receiving (400-1 or 400-2C) an Application Function, AF, -initiated request for replacement of a network slice for a User Equipment, UE, with an alternative network slice; and initiating (404) replacement of the network slice for the UE with the alternative network slice.

2. The method of claim 1, wherein receiving (400-1) the AF-initiated request comprises receiving (400-1) the AF-initiated request (e.g., directly) from an AF (212).

3. The method of claim 1, wherein receiving (400-2C) the AF-initiated request comprises receiving (400-2C) the AF-initiated request from a second network function (e.g., NEF 300) in the core network.

4. The method of claim 2 or 3, wherein the AF (212) is notified of an outcome (e.g., success or failure) of the replacement of the network slice of the UE with the alternative network slice (e.g., via a notification sent to the AF (212) either through explicit or implicit subscription).

5. The method of any one of claim 1 to 4, further comprising: prior to initiating (404) replacement of the network slice for the UE with the alternative network slice, validating (402) that the alternative network slice is included in a UE subscription of the UE.

6. The method of any one of claim 1 to 5, wherein initiating (404) replacement of the network slice for the UE with the alternative network slice comprises sending (404A), to a third network function (e.g., AMF 200) information comprising an indication (e.g., S-NSSAI) of the network slice of the UE to be replaced and an indication (e.g., Alternative S-NSSI) of the alternative network slice that is to replace the network slice of the UE.

7. The method of claim 6, wherein the information further comprises an indication to terminate all Protocol Data Unit, PDU, sessions of the UE that are associated with the network slice and re-establish those PDU sessions of the UE and establish any new PDU sessions of the UE using the alternative network slice.

8. The method of claim 6 or 7, wherein the information is Access and Mobility, AM, policy information.

9. The method of any one of claim 6 to 8, wherein the AF-initiated request is an AM Policy Authorization request (e.g., a Npcf_AMPolicyAuthorization Request).Applicant's Ref. P112353WO01 3510. The method of any one of claim 1 to 9, wherein the AF-initiated request comprises an indication of the alternative network slice (e.g., an Alternative S-NSSAI).

11. A network node adapted to perform the method of any one of claim 1 to 10.

12. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to any one of claim 1 to 10.

13. A carrier containing the computer program of claim 12, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.

14. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to any one of claim 1 to 10.

15. A method performed by a first network function (e.g., NEF 300) in a core network of a cellular communications system, the method comprising: receiving (400-2A), from an Application Function, AF, (212), a request for replacement of a network slice for a User Equipment, UE, with an alternative network slice; and sending (400-2C), to a second network function (e.g., PCF 210) in the core network, a request for replacement of the network slice for the UE with the alternative network slice.

16. The method of claim 15, wherein the request received from the AF (212) is a request that implicitly requests replacement of the network slice for the UE with the alternative network slice.

17. The method of claim 15, wherein the request received from the AF (212) is a request for a change of a network service of the UE to an indicated network slice that is mapped to the alternative network slice.

18. The method of any one of claim 15 to 17, wherein the request sent to the second network function (e.g., PCF 210) comprises an indication of the alternative network slice (e.g., an Alternative S-NSSAI).

19. The method of claim 18, wherein the AF (212) is notified of an outcome (e.g., success or failure) of the replacement of the network slice of the UE with the alternative network slice (e.g., via a notification sent to the AF (212) either through explicit or implicit subscription for the AF):

20. The method of any one of claim 15 to 19, further comprising: prior to sending (400-2C) the request for replacement of the network slice for the UE with the alternative network slice to the second network function (e.g., PCF 210), validating (400-2B) that the alternative network slice is included in a UE subscription of the UE.Applicant's Ref. P112353WO01 3621. The method of any one of claim 15 to 20, wherein the request sent to the second network function (e.g., PCF 210) is an AM Policy Authorization request (e.g., a Npcf_AMPolicy Authorization Request).

22. A network node adapted to perform the method of any one of claim 15 to 21 .

23. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to any one of claim 15 to 21 .

24. A carrier containing the computer program of claim 23, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.

25. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to any one of claim 15 to 21.

26. A method performed by an Application Function, AF, (212), the method comprising: sending (400-1 or 400-2C), to a network function (e.g., PCF 210 or NEF 300) in a core network of a cellular communications system, an explicit or implicit request for replacement of a network slice for a User Equipment, UE, with an alternative network slice.

27. The method of claim 26, further comprising receiving a notification that indicates an outcome (e.g., success or failure) of the requested replacement of the network slice for the User Equipment, UE, with an alternative network slice.

28. A network node adapted to perform the method of claim 26 or 27.

29. A computer program comprising instructions which, when executed on at least one processor, cause the processor to carry out the method according to claim 28.

30. A carrier containing the computer program of claim 29, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium.

31. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a network node, whereby the network node is operable to perform the method according to claim 26 or 27.

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