VPLMN policy control

Abstract

The present invention discloses a method performed by an AMF entity 1100 in a visited public land mobile network VPLMN entity serving a roaming UE 112, the method comprising: obtaining, by the AMF entity, a subscribed UE‑AMBR of NN102 for the UE; sending, by the AMF entity, an access management AM policy request message XX102, XX200, XX304 to a visited policy control function V‑PCF entity 1200 in the VPLMN to establish or update an AM policy for the roaming UE; receiving, by the AMF entity in response to sending the AM policy request message, an XX104, XX204, XX306 AM policy response message, the AM policy response message being sent by the V‑PCF entity and including access and mobility related policy information, the access and mobility related policy information including a serving network UE‑AMBR for the UE determined by the V‑PCF entity; and deploying, by sending policy control information including the determined UE‑AMBR to a RAN node in the serving network, an XX106, XX206, XX308 serving network UE‑AMBR to replace the subscribed UE‑AMBR.

Description

Background Art

[0001] Generally, unless different meanings are clearly given and / or different meanings are implied in the context of using the term, all terms used in this article will be interpreted according to their common meanings in the relevant technical field. Unless clearly stated, all references to one / an / the element, device, assembly, part, step, etc. should be publicly interpreted as referring to at least one instance of the element, device, assembly, part, step, etc. Unless a step is explicitly described as being after or before another step and / or a step must be after or before another step implicitly, the steps of any method disclosed herein do not have to be performed in the exact order disclosed. Where appropriate, any feature of any embodiment disclosed herein may be applied to any other embodiment. Similarly, any advantage of any embodiment may be applicable to any other embodiment, and vice versa. By the following description, other purposes, features and advantages of the attached embodiments will be apparent.

[0002] The fifth generation system (5GS) introduces the separation of mobility management (based on user equipment (UE)) and session management (based on protocol data unit (PDU) session). As a result, some UE-based session management becomes transparent to the access and mobility management function (AMF) and is implemented by the radio access network (RAN).

[0003] The UE aggregate maximum bit rate (UE-AMBR) relates to all Quality of Service (QoS) flows in all Protocol Data Unit (PDU) sessions of the UE, not just the QoS flows in one PDU session - unless the UE has only one PDU session established. Figure 1 It is a schematic diagram of the principles for classification and user plane marking of QoS flows and mapping to AN resources, which is copied from 3GPP TS 23.501.

[0004] Below is some text from TS23.501 related to UE-AMBR (which is conceptually a session management control). Currently, the RAN may only enforce the implementation of UE-AMBR at the UE level.

[0005]

[0006]

[0007] Summary of the invention

[0008] There are currently specific challenges in controlling UE-AMBR in a serving network.

[0009] From the existing text in TS23.501 above, it can be seen that the upper limit of the AMBR at the UE level depends only on the subscribed UE-AMBR. In case of roaming scenarios, there is no logic to let the Visited Public Land Mobile Network (VPLMN) steer the policy.

[0010] Furthermore, in a VPLMN, the AMF has control over mobility, which is at the UE level, but is transparent to session related policies / controls and is therefore not suitable for UE level session policy control. The Visited Session Management Function (V-SMF) only sees the PDU session level and has no overview of the UE.

[0011] Certain aspects of the present disclosure and embodiments thereof can provide solutions to the above-mentioned or other challenges.

[0012] Embodiments of the present disclosure provide UE-level session-related policy control through a policy control function (PCF) used for access and mobility in the current 5GS architecture.

[0013] In some embodiments, UE-level session-related policy control may be used as a trigger for the AMF to initiate communication with the access and mobility PCF (i.e., amPCF). The AMF may indicate support for obtaining the UE-AMBR from the PCF a) based on a specific indication or b) by providing the subscribed UE-AMBR from the UDM.

[0014] In some embodiments, the amPCF may provide UE-level session policies (e.g., UE-AMBR) to the AMF as part of the UE access and mobility policy.

[0015] In some embodiments, the amPCF supports optional UE-level session policy control as part of the access and mobility policy based on the configuration for roaming subscribers.

[0016] In some embodiments, even for home subscribers, the amPCF can provide more dynamic UE level session control (eg, UE-AMBR), while the UDM can provide more static UE-AMBR control.

[0017] Various embodiments are presented herein that address one or more of the issues disclosed herein.

[0018] Certain embodiments can provide one or more of the following technical advantages. Embodiments of the solution described herein provide control logic in the serving network through the access and mobility PCF for UE level session management in general and UE-AMBR parameter control in particular.

[0019] Another embodiment relates to a method performed by an AMF entity in a VPLMN serving a roaming UE. The method includes: obtaining, by the AMF entity, a subscribed UE-AMBR for the UE; sending, by the AMF entity, an AM policy request message to a V-PCF entity in the VPLMN to establish or update an AM policy for the roaming UE; receiving, by the AMF entity in response to sending the AM policy request message, an AM policy response message, the AM policy response message being sent by the V-PCF entity and including access and mobility related policy information, the access and mobility related policy information including a service network UE-AMBR for the UE determined by the V-PCF entity; deploying the service network UE-AMBR to replace the subscribed UE-AMBR by sending policy control information including the service network UE-AMBR to a RAN node in the service network.

[0020] Another embodiment relates to a method performed by a V-PCF entity in a VPLMN serving a roaming UE. The method includes: receiving, by the V-PCF entity, an AM policy request message sent by an AMF entity in the VPLMN to establish or update an AM policy for the roaming UE, the AM policy request message including at least one of the following: a UE-AMBR acquisition indication or a subscribed UE-AMBR; determining, by the V-PCF entity, a serving network UE-AMBR for the UE based on at least one of the following: the UE-AMBR acquisition indication or the subscribed UE-AMBR; and sending, by the V-PCF entity in response to receiving the AM policy request message, an AM policy response message to the AMF entity, the AM policy response message including access and mobility related policy information, the access and mobility related policy information including the serving network UE-AMBR for the UE.

[0021] Another embodiment relates to an AMF entity configured to operate in a VPLMN serving a roaming UE, the AMF entity comprising one or more processors (QQ204), the one or more processors (QQ204) being used to provide the functionality of the AMF entity so that the AMF entity can operationally: obtain a subscribed UE-AMBR for the UE; send an AM policy request message to a V-PCF entity in the VPLMN to establish or update an AM policy for the roaming UE; receive an AM policy response message in response to sending the AM policy request message, the AM policy response message being sent by the V-PCF entity and including access and mobility-related policy information, the access and mobility-related policy information including a service network UE-AMBR for the UE determined by the V-PCF entity; and deploy the service network UE-AMBR to replace the subscribed UE-AMBR by sending policy control information including the service network UE-AMBR to a RAN node in the service network.

[0022] Another embodiment relates to a V-PCF entity configured to operate in a VPLMN serving a roaming UE, the V PCF entity comprising one or more processors for providing functionality of the V PCF entity so that the V-PCF entity can operationally: receive an AM policy request message sent by an AMF entity in the VPLMN to establish or update an AM policy for the roaming UE, the AM policy request message comprising at least one of the following: a UE-AMBR acquisition indication or a subscribed UE-AMBR; determine a serving network UE-AMBR for the UE based on at least one of the following: the UE-AMBR acquisition indication or the subscribed UE-AMBR; and send an AM policy response message to the AMF entity in response to receiving the AM policy request message, the AM policy response message comprising access and mobility related policy information, the access and mobility related policy information comprising the serving network UE-AMBR for the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0024] Figure 1 is a schematic diagram of the principles for classification and user plane marking of QoS flows and mapping to AN resources;

[0025] Figure 2 An example of a cellular communication system in which embodiments of the present disclosure may be implemented is shown;

[0026] Figure 3 A wireless communication system represented as a 5G network architecture including core NFs is shown, wherein the interaction between any two NFs is represented by point-to-point reference points / interfaces;

[0027] Figure 4a Shows the use of service-based interfaces between NFs in the control plane instead of Figure 3 5G network architecture of point-to-point reference points / interfaces used in the 5G network architecture;

[0028] Figure 4b shows the roaming 5G network architecture in a home routing scenario using a service-based interface representation;

[0029] Figure 5 An embodiment of the present disclosure is shown;

[0030] Figure 6 An access and mobility (AM) policy establishment process according to an example embodiment of the present disclosure is shown;

[0031] Figure 7 shows an AM policy association modification initiated by an AMF entity according to some example embodiments of the present disclosure;

[0032] Figure 8 shows AM policy association modification of old PCF during AMF relocation according to some embodiments of the present disclosure;

[0033] Fig. 9 The process of AM policy association modification initiated by a PCF entity according to some embodiments of the present disclosure is shown;

[0034] Fig.10 is a schematic block diagram of a network node QQ200 according to some embodiments of the present disclosure;

[0035] Fig.11 is a schematic block diagram showing a virtualized embodiment of a network node QQ200 according to some embodiments of the present disclosure;

[0036] Fig.12 is a schematic block diagram of a network node QQ200 according to some other embodiments of the present disclosure;

[0037] Fig.13 is a schematic block diagram of a UE QQ500 according to some embodiments of the present disclosure;

[0038] Fig.14 is a schematic block diagram of a UE QQ500 according to some other embodiments of the present disclosure. DETAILED DESCRIPTION

[0039] Some embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. However, other embodiments are included within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be construed as being limited to only the embodiments set forth herein; rather, these embodiments are provided merely as examples to convey the scope of the subject matter to those skilled in the art. Additional information may also be found in the documents provided in the appendix.

[0040] Radio Node: As used herein, a "radio node" is a radio access (RAN) node or a wireless device.

[0041] Radio access node: As used herein, a "radio access node" or "radio network node" or RAN node is any node in a radio access network of a cellular communication network for wirelessly sending and / or receiving signals. Some examples of radio access nodes include, but are not limited to, base stations (e.g., new radio (NR) base stations (gNBs) in third generation partnership project (3GPP) fifth generation (5G) NR networks or enhanced or evolved node Bs (eNBs) in 3GPP long term evolution (LTE) networks), high power or macro base stations, low power base stations (e.g., micro base stations, pico base stations, home eNBs, etc.), and relay nodes.

[0042] Core network node: As used herein, a "core network entity" is any type of node in a core network. Some examples of core network entities include, for example, a mobility management entity (MME) in an evolved packet core (EPC), a packet data network gateway (P-GW), a service capability exposure function (SCEF), etc. Some other examples of core network entities include, for example, an access and mobility management function (AMF) in a 5G core (5GC), a network slice selection function (NSSF), an authentication server function (AUSF), UDM, a session management function (SMF), a policy control function (PCF), an AF, a NEF, a user plane function (UPF), etc. The core network entity may be implemented as a physical network node (e.g., including hardware or a combination of hardware and software) or as a functional entity (e.g., implemented as software), which is implemented, for example, on a physical network node or distributed across two or more physical network nodes.

[0043] Wireless Device: As used herein, a "wireless device" is any type of device that accesses (i.e., is served by) a cellular communication network by wirelessly sending and / or receiving signals to a radio access node. Some examples of wireless devices include, but are not limited to, user equipment devices (UE) and machine type communication (MTC) devices in 3GPP networks.

[0044] Network node: As used herein, a "network node" is any node that is any part of the radio access network or the core network of a cellular communication network / system.

[0045] Note that the description given herein focuses on a 3GPP cellular communication system and, therefore, 3GPP terminology or terminology similar to 3GPP terminology is often used. However, the concepts disclosed herein are not limited to 3GPP systems.

[0046] Note that in the description of this document, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells, and therefore, it is important to note that the concepts described herein apply equally to both cells and beams.

[0047] Figure 2

[0048] Figure 2 An example of a cellular communication system QQ100 in which embodiments of the present disclosure may be implemented is shown. In the embodiments described herein, the cellular communication system QQ100 is a 5GS including a 5G NR RAN. In this example, the 5G RAN includes base stations QQ102-1 and QQ102-2, which are referred to as gNBs in 5G NR, and which control corresponding (macro) cells QQ104-1 and QQ104-2. Base stations QQ102-1 and QQ102-2 are generally referred to herein as base stations QQ102 and individually as base stations QQ102. Similarly, (macro) cells QQ104-1 and QQ104-2 are generally referred to herein as (macro) cells QQ104 and individually as (macro) cells QQ104. The RAN may also include a plurality of low power nodes QQ106-1 to QQ106-4, which control corresponding small cells QQ108-1 to QQ108-4. The low power nodes QQ106-1 to QQ106-4 can be small base stations (e.g., pico base stations or femto base stations) or remote radio heads (RRHs), etc. It is worth noting that, although not shown, one or more of the small cells QQ108-1 to QQ108-4 can be provided alternatively by the base station QQ102. The low power nodes QQ106-1 to QQ106-4 are generally referred to herein as low power nodes QQ106 and individually as low power nodes QQ106. Similarly, the small cells QQ108-1 to QQ108-4 are generally referred to herein as small cells QQ108 and individually as small cells QQ108. The cellular communication system QQ100 also includes a core network QQ110 (e.g., a 5G core in a 5GS), to which the base station QQ102 (and optionally the low power node QQ106) is connected.

[0049] Base station QQ 102 and low power node QQ 106 provide services to wireless devices QQ 112-1 through QQ 112-5 in corresponding cells QQ 104 and QQ 108. Wireless devices QQ 112-1 through QQ 112-5 are generally referred to herein collectively and individually as wireless devices QQ 112. Wireless devices QQ 112 are also sometimes referred to herein as UEs.

[0050] Figure 3

[0051] Figure 3 A wireless communication system is shown represented as a 5G network architecture including core network functions (NFs), where the interaction between any two NFs is represented by point-to-point reference points / interfaces. Figure 3 Can be considered as Figure 2 A specific implementation of system QQ100.

[0052] From the access side, Figure 3 The 5G network architecture shown includes multiple user equipment (UE) connected to the radio access network (RAN) or access network (AN) and access and mobility management function (AMF). Typically, R (AN) includes base stations, such as evolved node B (eNB) or 5G base station (gNB). From the core network side, Figure 3 The 5G core NF shown includes a network slice selection function (NSSF), an authentication server function (AUSF), a unified data management (UDM), an AMF, a session management function (SMF), a policy control function (PCF), and an application function (AF).

[0053] The reference point representation of the 5G network architecture is used to develop detailed call flows in specification standardization. The N1 reference point is defined to carry signaling between the UE and the AMF. The reference points for connecting between the AN and the AMF and between the AN and the UPF are defined as N2 and N3, respectively. There is a reference point N11 between the AMF and the SMF, which means that the SMF is at least partially controlled by the AMF. N4 is used by the SMF and the UPF so that the UPF can be set using control signals generated by the SMF, and the UPF can report its status to the SMF. Respectively, N9 is a reference point for connections between different UPFs, and N14 is a reference point for connections between different AMFs. N15 and N7 are defined because the PCF applies policies to the AMF and SMP, respectively. The AMF requires N12 to perform authentication of the UE. N8 and N10 are defined because the AMF and the SMF require subscription data for the UE.

[0054] The 5G core network is designed to separate the user plane and the control plane. The user plane carries user services, while the control plane carries signaling in the network. Figure 3 In the NF, UPF is located in the user plane, while all other NFs (i.e., AMF, SMF, PCF, AF, AUSF, and UDM) are located in the control plane. Separating the user plane from the control plane ensures that each plane resource is scaled independently. It also allows the UPF to be deployed in a distributed manner separate from the control plane functions. In this architecture, for some applications that require low latency, the UPF can be deployed very close to the UE to shorten the round-trip time (RTT) between the UE and the data network.

[0055] The core 5G network architecture includes modular functions. For example, AMF and SMF are independent functions in the control plane. Separation of AMF and SMF allows independent evolution and scaling. Other control plane functions (such as PCF and AUSF) can be Figure 3 The modular functional design enables the 5G core network to flexibly support various services.

[0056] Each NF interacts directly with another NF. An intermediate function can be used to route messages from one NF to another. In the control plane, a set of interactions between two NFs is defined as a service, so its reuse is possible. This service implementation supports modularity. The user plane supports interactions such as forwarding operations between different UPFs.

[0057] Figure 4a

[0058] Figure 4a Shows the use of service-based interfaces between NFs in the control plane instead of Figure 3 The 5G network architecture uses point-to-point reference points / interfaces in the 5G network architecture. However, the above reference Figure 3 The NF described corresponds to Figure 4a The services provided by the NF to other authorized NFs can be opened to the authorized NF through a service-based interface. Figure 4a In the NF, the service-based interface is indicated by the letter "N" followed by the name of the NF, such as Namf for the service-based interface of AMF, Nsmf for the service-based interface of SMF, and so on. Figure 4a The Network Open Function (NEF) and Network Repository Function (NRF) in Figure 3 However, it should be clarified that Figure 3 All NFs depicted in Figure 4a The NEF and NRF interact, although in Figure 3 Not explicitly stated.

[0059] Figure 3 and Figure 4a Some of the characteristics of the NFs shown in can be described as follows. AMF provides UE-based authentication, authorization, mobility management, etc. Even UEs using multiple access technologies are basically connected to a single AMF because the AMF is independent of the access technology. SMF is responsible for session management and assigns an Internet Protocol (IP) address to the UE. It also selects and controls the UPF for data transmission. If the UE has multiple sessions, a different SMF can be assigned to each session to manage the session separately and possibly provide different functions per session. AF provides information about packet flows to the PCF responsible for policy control in order to support quality of service (QoS). Based on this information, the PCF determines policies on mobility and session management so that the AMF and SMF work correctly. AUSF supports authentication functions for UEs, etc., and therefore stores data for authenticating UEs, etc., while UDM stores subscription data for UEs. The data network (DN) (which is not part of the 5G core network) provides Internet access or operator services, etc.

[0060] NFs may be implemented as network elements on dedicated hardware, as software instances running on dedicated hardware, or as virtualized functions instantiated on a suitable platform (e.g., cloud infrastructure).

[0061] As mentioned above, currently, the upper limit of the AMBR at the UE level depends only on the subscribed UE-AMBR. In the case of UE roaming, there is no logic for the VPLMN to manipulate the policy to adjust or limit the UE-AMBR.

[0062] Figure 4b

[0063] Figure 4b The roaming 5G network architecture in the home routing scenario with service-based interface representation in the control plane is shown. Here, the PCF in the VPLMN is a visited PCF (V-PCF).

[0064] Figure 5

[0065] exist Figure 5 In the illustrated embodiment, a method performed by a core NF (e.g., an AMF entity) in a service network serving a UE includes: obtaining a first UE-AMBR (NN102), such as a subscribed UE-AMBR, in the core NF; obtaining a second UE-AMBR (NN104); determining a UE-AMBR (NN106) for a UE in the service network based on the first UE-AMBR and the second UE-AMBR; and deploying policy control information (NN108) including the determined UE-AMBR to the service network serving the UE.

[0066] In one embodiment, the first UE-AMBR is the subscribed UE-AMBR of the UE, which may be obtained from a UDM entity (wherein (among other things) the subscription data of the UE is stored), or from an old AMF in the case of AMF relocation, and the second UE-AMBR is a policy parameter of the serving network (e.g. obtained from the corresponding PCF), such as a policy-based serving network UE-AMBR generated by a V-PCF entity. In one embodiment, the serving network is a visited network (VPLMN). In one embodiment, deploying the policy control information in step NN108 may include sending policy control information including the determined UE-AMBR to a serving RAN in the serving PLMN (e.g. to a serving base station or a serving gNB). In one embodiment, determining the UE-AMBR for the UE in the serving network may include selecting one of the first UE-AMBR and the second UE-AMBR. In another embodiment, selecting one of the first UE-AMBR and the second UE-AMBR includes selecting one of the first UE-AMBR and the second UE-AMBR having a smaller size (i.e. selecting the smaller of the first UE-AMBR and the second UE-AMBR).

[0067] In other words, the AMF in the UE's serving network (which may be the UE's home network or the UE's visited network (when the UE is roaming)) obtains the subscribed UE-AMBR from the UDM, and the policy-based UE-AMBR from the PCF in the serving network. Therefore, in a roaming scenario, the VPLMN is able to manipulate the UE-AMBR via the policy-based UE-AMBR provided by the (V-)PCF. The AMF may determine the UE-AMBR for the UE by selecting one of the first UE-AMBR from the UDM and the second UE-AMBR from the PCF. In one example, the AMF may determine that the smaller of the first UE-AMBR and the second UE-AMBR is the UE-AMBR for the UE. For example, if the subscribed UE-AMBR in the UE's home network is greater than the UE-AMBR set by the PCF in the visiting network, the AMF limits the UE-AMBR of the UE to the UE-AMBR of the visiting network.

[0068] Now, we will describe Figure 5 Details of some example implementations of the process.

[0069] Figure 6

[0070] Figure 6 The access and mobility (AM) policy establishment process according to an exemplary embodiment of the present disclosure is shown. Figure 5In the embodiment of FIG. 1 , it is assumed that the first UE-AMBR for the UE (e.g., the subscribed UE-AMBR) has been obtained by the AMF entity, e.g., from a UDM entity, etc., or from another AMF entity (e.g., by a new AMF entity from an old AMF entity in case of AMF relocation). For AM policy association establishment, three cases are considered, namely:

[0071] 1. UE initially registers with the network.

[0072] 2. During the switching process and registration process, the AMF entity is reallocated and the PCF entity is changed.

[0073] 3. EPS to 5GS mobility when there is no existing AM policy association between the AMF entity and the PCF entity for the UE.

[0074] In particular, Figure 6 The AM policy association establishment with a new selected PCF process according to some embodiments of the present disclosure is shown. The process involves both roaming and non-roaming scenarios. In the non-roaming case, the role of the V-PCF entity is completed by the PCF entity. For the roaming scenario, the V-PCF entity interacts with the AMF entity. Figure 6 The steps of the process are as follows:

[0075] Step XX100: Based on the local policy, the AMF entity determines to establish an AM policy association with the (V-)PCF entity, and then performs steps XX102 and XX104 under the conditions described below.

[0076] Step XX102 [Conditional]: If the AMF entity has not obtained the access and mobility policy for the UE or if the access and mobility policy in the AMF entity is no longer valid, the AMF requests the PCF entity to apply the operator policy for the UE from the PCF entity. The AMF sends an AM policy request message (e.g. an AM policy create request message such as Npcf_AMPolicyControl_Create) to the (V-)PCF entity to establish an AM policy control association with the (V-)PCF. The request includes at least one of the following information: SUPI, internal group (see clause 5.9.7 of TS23.501 [2]), subscription notification indication and (if available) service area restriction, RFSP index, UE-AMBR acquisition indication (or alternatively subscribed UE-AMBR), allowed NSSAI, GPSI (which are obtained from UDM during the update location procedure), and may include access type and RAT, PEI, ULI, UE time zone and serving network. Note that the UE-AMBR fetch indication (or alternatively including the subscribed UE-AMBR in the create request) may be viewed as a request for the serving network UE-AMBR (ie the UE-AMBR set by the serving network's policy).

[0077] Step XX104: (V)-PCF responds to the Npcf_AMPolicyControl_Create service operation. The (V)-PCF provides access and mobility related policy information (e.g., service area restrictions) as defined in clause 6.5 of TS23.503

[20] . In addition, the (V)-PCF may provide a policy control request trigger associated with the AM policy to the AMF. The AMF is implicitly subscribed in the (V-)PCF to be notified of policy changes. According to an embodiment of the present disclosure, the access and mobility related policy information returned to the AMF in step XX104 includes a serving network UE-AMBR for the UE (e.g., a serving network UE-AMBR generated by the (V-)PCF, e.g., a policy-based UE-AMBR preferably defined by the policy of the serving PLMN). Preferably, the serving network UE-AMBR is determined (i.e., generated) by the (V-)PCF based on at least one of the following: a UE-AMBR acquisition indication or a subscribed UE-AMBR provided in the request in step XX102.

[0078] Step XX106 [Conditional]: The AMF deploys access and mobility related policy information, which includes policy control request triggers for storage area restrictions and AM policy association, provision of service area restrictions to the UE, and provision of RFSP index and service area restrictions to the NG-RAN, as defined in TS 23.501 [2].

[0079] Note that in some embodiments, before the access and mobility related policy information is deployed in the RAN, the AMF determines the UE-AMBR to be included in the policy information based on the subscribed UE-AMBR and the serving network UE-AMBR (e.g., selecting the smallest of the two). The determined UE-AMBR is then the UE-AMBR included in the access and mobility related policy information deployed to the RAN. The RAN can then implement the provided UE-AMBR, for example, using conventional methods.

[0080] Figures 6 to 9 A variation of the AM policy association modification process according to some embodiments of the present disclosure is shown. Generally speaking, three situations are considered for AM policy association modification:

[0081] Case A: Policy control request triggering conditions are met: This process is initiated by AMF.

[0082] Case B: PCF local decision or trigger from other peers of PCF (ie UDR): The process is initiated by PCF.

[0083] Case C: AM policy association modification to old PCF during AMF relocation: This procedure is initiated by the AMF.

[0084] Figure 7

[0085] Figure 7 FIG. 4 shows an AM policy association modification initiated by an AMF entity without AMF relocation according to some embodiments of the present disclosure. Figure 5 In the embodiment of the present invention, it is assumed that the first UE-AMBR (e.g., the subscribed UE-AMBR) for the UE has been obtained by the AMF entity, for example, from the UDM entity, etc. The process involves both roaming scenarios and non-roaming scenarios. In the non-roaming case, the role of the V-PCF is completed by the PCF. For the roaming scenario, the V-PCF interacts with the AMF. Figure 7 The steps are as follows.

[0086] Step XX200: When the policy control request trigger condition is met, the AMF entity updates the AM policy association by calling Npcf_AMPolicyControl_Update and provides information about the changed condition to the PCF entity. Therefore, the AMF entity sends an AM policy request message (e.g., an AM policy update request message such as Npcf_AMPolicyControl_Update) to the (V-)PCF entity to update the AM policy control association with the (V-)PCF entity. The request may include at least one of the following information: SUPI, AM policy association ID, the policy control request trigger that has been met, the subscribed service area restriction (if updated), the subscribed RFSP index obtained from the UDM during the update location procedure (if updated), and may include the access type and RAT, PEI, ULI, UE time zone, serving network, and UE-AMBR acquisition indication (or alternatively the subscribed UE-AMBR).

[0087] Step XX202: (V-)PCF stores the information received in step XX200 and makes a policy decision.

[0088] Step XX204: The (V-)PCF responds to the AMF with the updated access and mobility related policy control information and the updated policy control request trigger parameters as defined in clause 6.5 of TS23.503

[20] . According to an embodiment of the present disclosure, the updated access and mobility related policy information returned to the AMF in step XX204 includes the serving network UE-AMBR for the UE (e.g., the serving network UE-AMBR generated by the (V-)PCF, such as the UE-AMBR defined by the policy of the serving PLMN).

[0089] Step XX206: The AMF deploys the access and mobility control policy, which includes storing the service area restriction and policy control request trigger associated with the AM policy, providing the service area restriction to the UE and providing the RFSP index, UE-AMBR and service area restriction to the NG-RAN, as defined in TS 23.501 [2].

[0090] Note that in some embodiments, before the access and mobility related policy information is deployed in the RAN in step XX206, the AMF determines the UE-AMBR to be included in the policy information based on the subscribed UE-AMBR and the serving network UE-AMBR (e.g., selecting the smallest of the two). The determined UE-AMBR is then the UE-AMBR included in the access and mobility related policy information deployed to the RAN. The RAN can then implement the provided UE-AMBR, for example, using conventional methods.

[0091] Figure 8

[0092] Figure 8 FIG. 4 shows the AM policy association modification of the old PCF during AMF relocation according to some embodiments of the present disclosure. Figure 5 In the embodiment of , it is assumed that the first UE-AMBR for the UE (e.g., the subscribed UE-AMBR) is obtained by the new AMF entity from the old AMF entity, for example, in the case of such AMF relocation. This procedure is applicable to case C. In this case, AMF relocation is performed without PCF change during the handover procedure and registration procedure. The procedure involves both roaming scenarios and non-roaming scenarios. In the non-roaming scenario, the role of V-PCF is completed by the PCF. For the roaming scenario, the V-PCF entity interacts with the AMF entity. Figure 8 The steps of the process are as follows.

[0093] Step XX300 [Conditional]: When the old AMF entity and the new AMF entity belong to the same PLMN, the old AMF transmits AM policy association information to the new AMF, including the policy control request trigger and PCF ID and the subscribed UE-AMBR. For roaming cases, the new AMF receives the V-PCF ID.

[0094] Step XX302: Based on local policy, the new AMF entity determines to establish a UE context with the (V-)PCF entity and contacts the (V)PCF identified by the PCF ID received in step XX300.

[0095] Step XX304: The new AMF sends an AM policy request message (e.g., an AM policy update request message such as Npcf_AMPolicyControl_Update) to the (V-)PCF to update the AM policy association with the (V-)PCF. The request may include the following information: the policy control request trigger that has been satisfied, the subscribed service area limit (if updated), the subscribed RFSP index obtained from the UDM during the update location procedure (if updated), and may include the access type and RAT, PEI, ULI, UE time zone, serving network. The (V-)PCF updates the stored information provided by the old AMF with the information provided by the new AMF.

[0096] Step XX306: (V-)PCF may update policy decisions based on the information provided by the new AMF.

[0097] According to an embodiment of the present disclosure, the access and mobility related policy information returned to the new AMF in step XX306 includes a serving network UE-AMBR for the UE (e.g., a serving network UE-AMBR generated by a (V-)PCF, such as a UE-AMBR defined by a policy of the serving PLMN).

[0098] Step XX308: AMF deploys access and mobility control policies, which include storing service area restrictions, providing service area restrictions to UE, and providing RFSP index, UE-AMBR and service area restrictions to NG-RAN.

[0099] Note that in some embodiments, before the access and mobility related policy information is deployed in the RAN in step XX308, the new AMF determines the UE-AMBR to be included in the policy information based on the subscribed UE-AMBR and the serving network UE-AMBR (e.g., selecting the smallest of the two). The determined UE-AMBR is then the UE-AMBR included in the access and mobility related policy information deployed to the RAN. The RAN can then implement the provided UE-AMBR, for example, using conventional methods.

[0100] Fig. 9

[0101] Fig. 9 The process of AM policy association modification initiated by PCF according to some embodiments of the present disclosure is shown. The process is applicable to AM policy association modification due to situation B. The process involves both roaming scenarios and non-roaming scenarios. In non-roaming scenarios, the role of V-PCF is completed by PCF. For roaming scenarios, V-PCF interacts with AMF. Note: V-PCF stores access and mobility control policy information provided to AMF. Fig. 9 The steps of the process are as follows.

[0102] Step XX400 [Conditional]: The PCF determines locally that the new state of the UE context requires a new policy.

[0103] Step XX402: (V-)PCF makes a policy decision.

[0104] Step XX404: (V-)PCF sends Npcf_UpdateNotify, which includes SUPI, service area restriction, UE-AMBR or RFSP index.

[0105] According to an embodiment of the present disclosure, the UE-AMBR provided to the AMF in step XX404 is the serving network UE-AMBR (i.e., the UE-AMBR defined by the policy of the serving PLMN).

[0106] Step XX406: AMF deploys access and mobility related policy information, which includes storing the service area restrictions and policy control request triggers associated with the AM policy, providing the service area restrictions to the UE, and providing the RFSP index, UE-AMBR and service area restrictions to the NG-RAN.

[0107] Note that in some embodiments, before the access and mobility related policy information is deployed in the RAN in step XX406, the new AMF determines the UE-AMBR to be included in the policy information based on the subscribed UE-AMBR and the serving network UE-AMBR (e.g., selecting the smallest of the two). The determined UE-AMBR is then the UE-AMBR included in the access and mobility related policy information deployed to the RAN. The RAN can then implement the provided UE-AMBR, for example, using conventional methods.

[0108] Note that the changes to TS23.501, TS23.502 and TS23.503 can be found in the attached appendix in the form of change requests to TS23.501, TS23.502 and TS23.503. Figures 6 to 9 Additional details regarding example embodiments of the present invention are provided.

[0109] Fig.10

[0110] Fig.10 200 is a schematic block diagram of a network node QQ200 according to some embodiments of the present disclosure. The network node QQ200 may be, for example, a NF (e.g., AMF, PCF, V-PCF, etc.) in the core network QQ110 or a network node that implements a NF in the core network QQ110. As shown in the figure, the network node QQ200 includes one or more processors QQ204 (e.g., a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.), a memory QQ206, and a network interface QQ208. The one or more processors QQ204 are also referred to as processing circuits in this article. The one or more processors QQ204 operate to provide one or more functions of the network node QQ200 as described herein (e.g., one or more functions of AMF, PCF, or V-PCF). In some embodiments, these functions are implemented with software stored in, for example, the memory QQ206 and executed by one or more processors QQ204.

[0111] Fig.11

[0112] Fig.112 is a schematic block diagram showing a virtualized embodiment of a network node QQ200 according to some embodiments of the present disclosure. As used herein, a "virtualized" network node is an implementation of a network node QQ200, wherein at least a portion of the functions of the network node QQ200 is implemented as a virtual component (e.g., via a virtual machine executed on a physical processing node in the network). As shown in the figure, in this example, the network node QQ200 includes one or more processors QQ304 (e.g., CPU, ASIC, FPGA, etc.), a memory QQ306, and a network interface QQ308. In this example, the functions QQ310 of the network node QQ200 described herein (e.g., one or more functions of a NF service user, a NF service producer, SMF, or H-SMF) are implemented at one or more processing nodes QQ300. In some specific embodiments, some or all of the functions QQ310 of the network node QQ200 described herein (e.g., one or more functions of AMF, PCF, V-PCF) are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment hosted by the processing node QQ300.

[0113] In some embodiments, a computer program including instructions is provided, which, when executed by at least one processor, causes the at least one processor to perform the functions of a node (e.g., processing node QQ300) of a network node QQ200 or a node that implements one or more functions QQ310 of a network node QQ200 in a virtual environment according to any embodiment described herein. In some embodiments, a carrier including the aforementioned computer program product is provided. The carrier is one of an electrical signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium such as a memory).

[0114] Fig.12

[0115] Fig.12 is a schematic block diagram of a network node QQ200 according to some other embodiments of the present disclosure. The network node QQ200 includes one or more modules QQ400, each of which is implemented in software. The module QQ400 provides the functions of the network node QQ200 described herein (e.g., one or more functions of AMF, PCF, V-PCF). The discussion also applies to Fig.11 The processing node QQ300 of FIG. 1 , wherein the module QQ400 may be implemented at one of the processing nodes QQ300 or distributed across multiple processing nodes QQ300 and / or distributed across the processing node QQ300 and the control system.

[0116] Fig.13

[0117] Fig.13is a schematic block diagram of a UE QQ500 according to some embodiments of the present disclosure. As shown in the figure, the UE QQ500 includes one or more processors QQ502 (e.g., CPU, ASIC, FPGA, etc.), a memory QQ504, and one or more transceivers QQ506, each transceiver including one or more transmitters QQ508 and one or more receivers QQ510 coupled to one or more antennas QQ512. The transceiver QQ506 includes a radio front-end circuit connected to the antenna QQ512, which is configured to adjust the signal transmitted between the antenna QQ512 and the processor QQ502, as will be understood by a person of ordinary skill in the art. The processor QQ502 is also referred to as a processing circuit in this article. The transceiver QQ506 is also referred to as a radio circuit in this article. In some embodiments, the functions of the above-mentioned UE QQ500 can be implemented in whole or in part, for example, in software stored in the memory QQ504 and executed by the processor QQ502. Note that the UE QQ500 may include software not in Fig.13 Additional components shown in the figure, such as one or more user interface components (e.g., input / output interfaces including displays, buttons, touch screens, microphones, speakers, and / or the like and / or any other components for allowing information to be input into the UE QQ500 and / or allowing information to be output from the UE QQ500), a power source (e.g., a battery and associated power circuitry), etc.

[0118] In some embodiments, a computer program including instructions is provided, which, when executed by at least one processor, causes the at least one processor to perform the functions of the UE QQ 500 according to any embodiment described herein. In some embodiments, a carrier including the aforementioned computer program product is provided. The carrier is one of an electric signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium such as a memory).

[0119] Fig.14

[0120] Fig.14 is a schematic block diagram of UE QQ500 according to some other embodiments of the present disclosure. UE QQ500 includes one or more modules QQ600, each of which is implemented in software. Module QQ600 provides the functions of UE QQ500 described herein.

[0121] Any suitable steps, methods, features, functions or benefits disclosed herein may be performed by one or more functional units or modules of one or more virtual devices. Each virtual device may include a plurality of these functional units. These functional units may be implemented via processing circuits that may include one or more microprocessors or microcontrollers and other digital hardware that may include digital signal processors (DSPs), dedicated digital logic, etc. The processing circuit may be configured to execute program codes stored in a memory, and the memory may include one or more types of memory, such as a read-only memory (ROM), a random access memory (RAM), a cache memory, a flash memory device, an optical storage device, etc. The program code stored in the memory includes program instructions for executing one or more telecommunications and / or data communication protocols and instructions for executing one or more technologies described herein. In some embodiments, the processing circuit may be used to cause the corresponding functional unit to perform the corresponding functions according to one or more embodiments of the present disclosure.

[0122] Although the processes in the figures may show a particular order of operations performed by a particular embodiment of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform operations in a different order, combine particular operations, overlap particular operations, etc.).

[0123] Some of the embodiments described above can be summarized as follows:

[0124] 1. A method performed by a core network function (e.g., AMF) in a serving network serving a UE, comprising:

[0125] Obtaining (NN102) a first UE aggregate maximum bit rate UE-AMBR in the core network function;

[0126] Obtain (NN104, XX104, XX204, XX306, XX404) the second UE-AMBR in the core network function;

[0127] Based on the first UE-AMBR and the second UE-AMBR, determining (NN106, XX106, XX206, XX308, XX406) a UE-AMBR for a UE in the serving network; and

[0128] The policy control information including the determined UE-AMBR is deployed to the serving network (NN108, XX106, XX206, XX308, XX406) serving the UE.

[0129] 2. The method of embodiment 1, wherein:

[0130] The first UE-AMBR is a subscribed UE-AMBR; and

[0131] The second UE-AMBR is a policy parameter of the serving network.

[0132] 3. The method according to embodiment 1 or 2, wherein the serving network is a visited network.

[0133] 4. The method according to any one of embodiments 1 to 3, wherein deploying policy control information includes sending policy control information including the determined UE-AMBR to a RAN node in a service network.

[0134] 5. The method of any one of embodiments 1 to 4, wherein determining the UE-AMBR for the UE in the serving network comprises selecting one of a first UE-AMBR and a second UE-AMBR.

[0135] 6. The method of embodiment 5, wherein selecting one of the first UE-AMBR and the second UE-AMBR comprises selecting a UE-AMBR having a smaller size among the first UE-AMBR and the second UE-AMBR.

[0136] 7. The method of any one of embodiments 1 to 6, wherein obtaining the first UE-AMBR comprises obtaining the first UE-AMBR from a UDM.

[0137] 8. The method of any one of embodiments 1 to 7, wherein obtaining the first UE-AMBR comprises obtaining the first UE-AMBR from another core network function (eg, UDM).

[0138] 9. The method according to any one of embodiments 1 to 7, wherein obtaining the second UE-AMBR includes obtaining the second UE-AMBR from a PCF.

[0139] 10. The method of any one of embodiments 1 to 7, wherein obtaining the second UE-AMBR comprises obtaining the second UE-AMBR from the PCF in response to sending a message to the PCF (eg, including a request for the second UE-AMBR).

[0140] 11. The method of embodiment 10, wherein:

[0141] This message is a request to establish an AM policy association with the PCF.

[0142] 12. The method according to embodiment 11, further comprising:

[0143] Establishing an association with the PCF is determined in the core network functions.

[0144] 13. The method of embodiment 10, wherein:

[0145] This message is a policy update.

[0146] 14. The method according to embodiment 11, further comprising:

[0147] Sending the request further includes sending the request in response to determining that a policy control request triggering condition is satisfied.

[0148] 15. The method of any one of embodiments 1 to 7, wherein obtaining the second UE-AMBR comprises obtaining the second UE-AMBR from the PCF without sending a request for the second UE-AMBR to the PCF.

[0149] 16. The method of embodiment 10, wherein the request includes an indication related to UE-AMBR acquisition.

[0150] 17. The method according to embodiment 16, wherein the indication is a specific indication obtained by UE-AMBR.

[0151] 18. The method of embodiment 16, wherein the indication is including the first UE-AMBR in the message.

[0152] 19. A method performed by a policy control function (e.g., PCF) in a serving network serving a UE, comprising:

[0153] receiving, in a policy control function, a request for policy control information from a core network function;

[0154] In response to receiving the request, determining to send a UE aggregate maximum bit rate UE-AMBR to the core network function; and

[0155] Send UE-AMBR to the core network function.

[0156] 20. The method of embodiment 19, wherein determining to send the UE-AMBR comprises determining to send the UE-AMBR in response to an indication of UE-AMBR support in the request.

[0157] 21. A core network function, suitable for executing the method according to any one of embodiments 1 to 20.

[0158] Some other embodiments described above can be summarized as follows:

[0159] 1. A method performed by an access management (AM) function entity (1100) in a visited public land mobile network (VPLMN) serving a roaming user equipment (UE) (112), the method comprising:

[0160] The AMF entity obtains (NN102) the subscribed UE aggregate maximum bit rate UE-AMBR for the UE;

[0161] The AMF entity sends (XX102, XX200, XX304) an access management AM policy request message to a visiting policy control function V-PCF entity (1200) in the VPLMN to establish or update an AM policy for a roaming UE;

[0162] receiving (XX104, XX204, XX306) by the AMF entity an AM policy response message sent by the V-PCF entity in response to sending the AM policy request message, the AM policy response message including access and mobility related policy information, the access and mobility related policy information including a serving network UE-AMBR for the UE determined by the V-PCF entity;

[0163] The serving network UE-AMBR is deployed (NN108, XX106, XX206, XX308, XX406) to replace the subscribed UE-AMBR by sending policy control information including the serving network UE-AMBR to the RAN node (QQ102) in the serving network.

[0164] 2. According to the method described in embodiment 1, before sending the AM policy request message, the AMF entity determines (XX100, XX302) to establish an AM policy association with the V-PCF entity in the VPLMN.

[0165] 3. The method according to any one of embodiments 1 or 2, further comprising:

[0166] In response to determining that the policy control request triggering condition is met, an AM policy request message is sent.

[0167] 4. A method according to any one of embodiments 1 to 3, wherein obtaining the subscribed UE-AMBR includes: obtaining the subscribed UE-AMBR from a unified data management (UDM) entity (1300) or from another AMF entity (1120).

[0168] 5. The method of any one of embodiments 1 to 4, wherein:

[0169] The AM policy request message is an AM policy creation request message (eg, Npcf_AMPolicyControl_Create request) used to establish an AM policy association with a PCF entity, or an AM policy update request message (eg, Npcf_AMPolicyControl_Update request) used to update an AM policy association with a V-PCF entity.

[0170] 6. The method of any one of embodiments 1 to 5, wherein:

[0171] The AM policy request message includes at least one of the following: a UE-AMBR acquisition indication or a subscribed UE-AMBR.

[0172] 7. A method performed by a Visiting Policy Control Function (V-PCF) entity in a Visited Public Land Mobile Network (VPLMN) serving a roaming user equipment (UE), the method comprising:

[0173] The V-PCF entity receives (XX102, XX200, XX304) an access management AM policy request message sent by an AMF entity in the VPLMN to establish or update an AM policy for a roaming UE, the AM policy request message including at least one of the following: a UE aggregate maximum bit rate UE-AMBR acquisition indication or a subscribed UE-AMBR;

[0174] Determining (XX202, XX402) a serving network UE-AMBR for the UE by the V-PCF entity based on at least one of: a UE-AMBR acquisition indication or a subscribed UE-AMBR; and

[0175] In response to receiving the AM policy request message, the V-PCF entity sends an AM policy response message (XX104, XX204, XX306) to the AMF entity, where the AM policy response message includes access and mobility related policy information, where the access and mobility related policy information includes the service network UE-AMBR for the UE.

[0176] 8. An access management AM function entity, configured to operate in a visited public land mobile network VPLMN serving a roaming user equipment UE, the AMF entity comprising one or more processors (QQ204), the one or more processors (QQ204) being used to provide the functions of the AMF entity so that the AMF entity can be operated:

[0177] obtaining (NN102) a subscribed UE aggregate maximum bit rate UE-AMBR for the UE;

[0178] Sending (XX102, XX200, XX304) an access management AM policy request message to a visiting policy control function V-PCF entity in the VPLMN to establish or update an AM policy for roaming UEs;

[0179] receiving (XX104, XX204, XX306) an AM policy response message in response to sending the AM policy request message, the AM policy response message being sent by the V-PCF entity and including access and mobility related policy information, the access and mobility related policy information including a serving network UE-AMBR for the UE determined by the V-PCF entity; and

[0180] The serving network UE-AMBR is deployed (NN108, XX106, XX206, XX308, XX406) to replace the subscribed UE-AMBR by sending policy control information including the serving network UE-AMBR to the RAN node in the serving network.

[0181] 9. A visiting policy control function V-PCF entity, configured to operate in a visited public land mobile network VPLMN serving a roaming user equipment UE, the V-PCF entity comprising one or more processors (QQ204), the one or more processors (QQ204) being used to provide the functions of the V-PCF entity so that the V-PCF entity can be operated:

[0182] receiving (XX102, XX200, XX304) an access management AM policy request message sent by an AMF entity in a VPLMN to establish or update an AM policy for a roaming UE, the AM policy request message comprising at least one of the following: a UE aggregate maximum bit rate UE-AMBR acquisition indication or a subscribed UE-AMBR;

[0183] Determine (XX202, XX402) a serving network UE-AMBR for the UE based on at least one of: a UE-AMBR acquisition indication or a subscribed UE-AMBR; and

[0184] In response to receiving the AM policy request message, an AM policy response message (XX104, XX204, XX306) is sent to the AMF entity, wherein the AM policy response message includes access and mobility related policy information, and the access and mobility related policy information includes the service network UE-AMBR for the UE.

[0185] abbreviation

[0186] At least some of the following abbreviations may be used in the present disclosure. If there is an inconsistency between the abbreviations, the above usage should be preferred. If listed multiple times below, the first listing should take precedence over subsequent listings.

[0187] 3G Third Generation

[0188] 3GPP Third Generation Partnership Project

[0189] 4G Fourth Generation

[0190] 5G fifth generation

[0191] AF application function

[0192] AMF access and mobility management function

[0193] amPCF access and mobility policy control function

[0194] AN Access Network

[0195] AUSF authentication server function

[0196] BS Base Station

[0197] BSC Base Station Controller

[0198] BTS Base Transceiver Station

[0199] DL Downlink

[0200] DN Data Network

[0201] eNB Enhanced or evolved Node B

[0202] E-UTRA Evolved Universal Terrestrial Radio Access

[0203] E-UTRAN Evolved Universal Terrestrial Radio Access Network

[0204] GERAN Global System for Mobile Communications (GSM) Enhanced Data Rates GSM Evolved Radio Access Network

[0205] gNB New Radio Base Station

[0206] GSM Global System for Mobile Communications

[0207] HO Handover

[0208] IP Internet Protocol

[0209] LAN

[0210] LPP Long Term Evolution Positioning Protocol

[0211] LTE Long Term Evolution

[0212] MME Mobility Management Entity

[0213] MSC Mobile Switching Center

[0214] NEF network open function

[0215] NF Network Function

[0216] NFV Network Function Virtualization

[0217] NR New Radio

[0218] NRF network repository function

[0219] NSSF network slice selection function

[0220] OSS Operation Support System

[0221] PCF policy control function

[0222] P-GW Packet Data Network Gateway

[0223] PLMN Public Land Mobile Network

[0224] QoS Quality of Service

[0225] RAN Radio Access Network

[0226] RNC Radio Network Controller

[0227] SCEF service capability exposure function

[0228] SDU Service Data Unit

[0229] S-GW Service Gateway

[0230] SIM Subscriber Identity Module

[0231] SMF session management function

[0232] UDM unified data management

[0233] UE User Equipment

[0234] UL Uplink

[0235] UMTS Universal Mobile Telecommunications System

[0236] USIM Universal Subscriber Identity Module

[0237] UTRA Universal Terrestrial Radio Access

[0238] UTRAN Universal Terrestrial Radio Access Network ·WCDMA Wideband Code Division Multiple Access

[0239] WD Wireless Devices

[0240] WLAN Wireless Local Area Network

Claims

1. A method performed by an access management function (AMF) entity (1100) in a visited public land mobile network (VPLMN) serving a roaming user equipment (UE) (112), the method comprising: obtaining (NN102) by the AMF entity a subscribed UE aggregate maximum bit rate UE-AMBR for the roaming UE; The AMF entity sends (XX102, XX200, XX304) an access management AM policy request message to a visiting policy control function V-PCF entity (1200) in the VPLMN to establish or update an AM policy for the roaming UE; receiving (XX104, XX204, XX306) an AM policy response message by the AMF entity in response to sending the AM policy request message, the AM policy response message being sent by the V-PCF entity and including access and mobility related policy information, the access and mobility related policy information including a serving network UE-AMBR for the roaming UE determined by the V-PCF entity; The serving network UE-AMBR is deployed (NN108, XX106, XX206, XX308, XX406) to replace the subscribed UE-AMBR by sending policy control information including the serving network UE-AMBR to a RAN node (QQ102) in the serving network.

2. The method according to claim 1, wherein: Before sending the AM policy request message, the AMF entity determines (XX100, XX302) to establish an AM policy association with the V-PCF entity in the VPLMN.

3. The method according to claim 1, further comprising: In response to determining that the policy control request triggering condition is met, sending the AM policy request message.

4. The method according to claim 1, wherein: Obtaining the subscribed UE-AMBR includes: obtaining the subscribed UE-AMBR from a unified data management UDM entity (1300) or from another AMF entity (1120).

5. The method according to claim 1, wherein: The AM policy request message is an AM policy creation request message used to establish an AM policy association with the PCF entity, or an AM policy update request message used to update an AM policy association with the V-PCF entity.

6. The method according to any one of claims 1 to 5, wherein: The AM policy request message includes at least one of the following: a UE-AMBR acquisition indication or the subscribed UE-AMBR.

7. A method performed by a Visiting Policy Control Function (V-PCF) entity in a Visited Public Land Mobile Network (VPLMN) serving a roaming user equipment (UE), the method comprising: The V-PCF entity receives (XX102, XX200, XX304) an access management AM policy request message sent by an access management function AMF entity in the VPLMN to establish or update an AM policy for the roaming UE, wherein the AM policy request message includes at least one of the following: a UE aggregate maximum bit rate UE-AMBR acquisition indication or a subscribed UE-AMBR; Determining (XX202, XX402) a serving network UE-AMBR for the roaming UE by the V-PCF entity based on at least one of: the UE-AMBR acquisition indication or the subscribed UE-AMBR; as well as In response to receiving the AM policy request message, the V-PCF entity sends an AM policy response message (XX104, XX204, XX306) to the AMF entity, wherein the AM policy response message includes access and mobility related policy information, and the access and mobility related policy information includes the service network UE-AMBR for the roaming UE.

8. An access management function AMF entity, configured to operate in a visited public land mobile network VPLMN serving a roaming user equipment UE, the AMF entity comprising one or more processors (QQ204), the one or more processors (QQ204) being used to provide the functions of the AMF entity so that the AMF entity can be operated: obtaining (NN102) a subscribed UE aggregate maximum bit rate UE-AMBR for the roaming UE; Sending (XX102, XX200, XX304) an access management AM policy request message to a visiting policy control function V-PCF entity in the VPLMN to establish or update an AM policy for the roaming UE; receiving (XX104, XX204, XX306) an AM policy response message sent by the V-PCF entity in response to sending the AM policy request message, the AM policy response message including access and mobility related policy information, the access and mobility related policy information including a serving network UE-AMBR for the roaming UE determined by the V-PCF entity; and The serving network UE-AMBR is deployed (NN108, XX106, XX206, XX308, XX406) to replace the subscribed UE-AMBR by sending policy control information including the serving network UE-AMBR to a RAN node in the serving network.

9. A visiting policy control function V-PCF entity, configured to operate in a visited public land mobile network VPLMN serving a roaming user equipment UE, the V-PCF entity comprising one or more processors (QQ204), the one or more processors (QQ204) being used to provide the functions of the V-PCF entity so that the V-PCF entity can be operated: receiving (XX102, XX200, XX304) an access management AM policy request message sent by an access management function AMF entity in the VPLMN to establish or update an AM policy for the roaming UE, the AM policy request message comprising at least one of the following: a UE aggregate maximum bit rate UE-AMBR acquisition indication or a subscribed UE-AMBR; determining (XX202, XX402) a serving network UE-AMBR for the roaming UE based on at least one of: the UE-AMBR acquisition indication or the subscribed UE-AMBR; as well as In response to receiving the AM policy request message, an AM policy response message (XX104, XX204, XX306) is sent to the AMF entity, wherein the AM policy response message includes access and mobility related policy information, and the access and mobility related policy information includes the service network UE-AMBR for the roaming UE.

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