CN110972090B - PCF + PCRF selection method, AMF, BSF and storage medium - Google Patents

Abstract

The embodiment of the invention discloses a PCF+PCRF selection method, AMF, BSF and storage medium, which belong to the field of communication. Wherein, the method includes: when the AMF detects that the UE switches from 4G to 5G, inquires the BSF for the PCF+PCRF selected by the SMF+PGW-C for the UE; requests the selected PCF+PCRF for access and mobility policy control . In the embodiment of the present invention, the SMF+PGW‑C in 4G access is inquired about the newly introduced 5G BSF to select the PCF+PCRF for the UE, and requests the selected PCF+PCRF for access and mobility policy control, so that the UE can switch from 4G to the PCF+PCRF. When switching to 5G, AMF can select the PCF+PCRF selected by SMF+PGW‑C during 4G access, so as to satisfy the association between PCF+PCRF policy control on AMF and policy control on SMF+PGW‑C. .

Description

PCF+PCRF selection method, AMF, BSF and storage medium

technical field

The present invention relates to the field of communication technologies, in particular to a PCF+PCRF selection method, AMF, BSF and storage medium based on a 4/5G mutual cut scenario.

Background technique

With the development of communication technology, mobile communication networks are evolving from the fourth generation (4G for short) to the fifth generation (5G for short). However, 5G access network (NG-RAN, Next Generation Radio Access Network, next generation radio access network) is still difficult to achieve full coverage, 5G access network and 4G access network E-UTRAN (Evolved Universal Terrestrial Radio Access Network, evolution The Universal Terrestrial Radio Access Network (Universal Terrestrial Radio Access Network) will coexist for a long time, and UE (User Equipment, user equipment) can support 5G and 4G access at the same time, and support smooth handover between these two access modes. In order to ensure the service continuity when the UE switches the access mode. Some network elements in the 4/5G core network need to be converged and deployed, such as the 4/5G architecture diagram in the non-roaming scenario shown in Figure 1, and the 4/5G architecture diagram in the local grooming roaming scenario as shown in Figure 2 , and the architecture diagram of 4/5G in the home routing roaming scenario shown in Figure 3, some of the network elements that need to be integrated and deployed in the three scenarios include:

The HSS (Home Subscriber Server, home subscriber server) of the 4G core network and the UDM (Unified Data Management) of the 5G core network are converged and deployed, called converged HSS+UDM, which provides all external standard interfaces of HSS and UDM. There is an internal interaction between the HSS part of the function and the UDM part.

The PCRF (Policy&Charging Control Function) of the 4G core network and the PCF (Policy Control Function) of the 5G core network are integrated and deployed, which is called PCF+PCRF (including V-PCF+V located in the visited network). - PCRF and H-PCF+H-PCRF in the home network).

The PGW-C (PDN Gateway Control Plane) of the 4G core network and the SMF (Session Management Function) of the 5G core network are integrated and deployed, which is called SMF+PGW-C.

The PGW-U (PDN Gateway User Plane, packet data network gateway user plane) of the 4G core network and the UPF (User Plan Function, user plane function) of the 5G core network are integrated and deployed, called UPF+PGW-U.

4G MME (Mobility Management Entity, Mobility Management Entity) and 5G AMF (Access and Mobility Management Function, Access and Mobility Management Function) have similar functions and are responsible for UE access and mobility management. The UE needs to register with the MME or AMF before establishing a session on the PGW-C or SMF.

The 5G AMF can request non-session management related control policies from the PCF when the UE registers or switches to the AMF, including AMRP (Access and Mobility related Policy) that needs to be executed by the AMF, and informs the AMF The URSP (UE Routing Selection Policy, UE routing selection policy) and the ANDDSP (Access Network Discovery and Selection Policy, access network discovery and selection policy) executed by the UE are transparently transmitted. In contrast, the MME of 4G does not have the function of obtaining the control strategy from the PCRF.

When the PGW-C or SMF receives a session establishment request from the UE, the PGW-C or SMF can request the PCRF or PCF for the control policy of the session, which is used to implement QoS (QoS Control, quality control), charging for the session Control (ChargingControl), traffic steering control (Traffic Steering Control), usage monitoring (Usage Monitoring), etc.

Multiple PCFs can be deployed in a 5G core network. AMF can configure each PCF address and selection method locally, or discover PCFs through NRF (Network Repository Function), which requires each PCF to first identify its own identity, The address and selection method are registered to the NRF.

In a 4G network, the PGW-C can locally configure the PCRF address and selection method, or send a request to a DRA (Diameter Routing Agent, Diameter Routing Agent). Among them, Diameter is an authentication, authorization and charging protocol. The interface between PCRF and PGW-C uses messages based on the Diameter protocol. The DRA can forward the messages based on the Diameter protocol, and the DRA selects the PCRF. In 5G network, SMF can configure PCRF address and selection method locally, or discover PCF through NRF, and AMF can also tell SMF that the AMF is the PCF selected by a certain UE, and then SMF selects the same PCF for the session.

In addition, the AMF can save the selected PCF identity in the local UE context. When the UE moves between 5G access networks, the AMF may be switched, and the new AMF obtains the UE context from the old AMF, so that the same PCF can be selected.

For a UE, if there is no correlation between its non-session management related policies and session management related policies, AMF and SMF can select different PCFs. However, if there is correlation, if AMF and SMF do not select the same PCF, it is difficult to realize the coordination of non-session management related policies and session management related policies. For example, the PCF requires the SMF to monitor the usage of the session, and notify the PCF when the usage reaches a set threshold, and the PCF adjusts the access and mobility-related policies delivered to the AMF accordingly. For another example, the PCF adjusts the session QoS control on the SMF according to the user location reported by the AMF, and there is a correlation between the non-session management related policies and the session management related policies.

In order to ensure that the AMF and the SMF select the same PCF, the prior art defines a method for the AMF to transmit the selected PCF identifier to the SMF during 5G access. In order to ensure that the old and new AMFs can select the same PCF during AMF switching, the prior art defines a method for the new AMF to obtain the selected PCF identifier from the old AMF during AMF switching. However, before the UE switches from 4G access to 5G handover, the SMF+PGW-C has selected a PCF+PCRF for the UE session. At this time, the switched AMF may be required to select the same PCF+PCRF. However, due to the MME There is no need to interact with PCF+PCRF, AMF cannot obtain the selected PCF+PCRF from the UE context provided by MME, which may cause AMF to select different PCF+PCRF, and further lead to PCF+PCRF's policy control and pairing of AMF. The policy control of SMF+PGW-C cannot be associated.

As shown in Figure 4, the 5G core network introduces BSF (Binding Support Function) for AF (Application Function) to address PCF. When the SMF requests the PCF for policy control for the session requested by the UE, it provides the UE's user ID, user IP address and other information to the PCF, and the PCF registers the binding information (user ID, user IP address, selected PCF ID) with the BSF . After that, the UE accesses the services on the AF through this session. The AF may need to request policy authorization from the PCF for the services accessed by the UE. The PCF selected by the AF for this policy authorization must be consistent with the PCF selected by the SMF for this session, because the policy authorization is generally The PCF will be triggered to adjust the policy control for the associated session of the SMF. The AF can query the BSF for the corresponding PCF according to the user IP address or user ID, and then directly request policy authorization from the AF through the N5 interface defined by 5G. In the 4G core network, similarly, the AF also addresses the PCRF, but different technologies are used. Both the PGW and the AF hand over the initial request message sent to the PCRF to the DRA, and the DRA addresses the same PCRF. In the 4G core network, the interface between the PCRF and the AF is the Rx interface, and the interface between the PCRF and the PGW is the Gx interface, both of which are based on the Diameter protocol; in the 5G core network, the interface between the PCF and the AF is the N5 interface, and The interface between SMFs is the N7 interface, both of which are HTTP-based service interfaces. In the converged core network supporting 4/5G interoperability, PCF+PCRF must support both Rx interface and N5 interface, because the UE may access the existing AF (only Rx interface is supported) or the new AF (support N5 interface) interface), the stock DRA can be upgraded so that when it receives the Rx interface request message of the stock AF, it can query the BSF and address the correct PCF+PCRF, or introduce BSF+DRA to replace the stock DRA. However, the prior art does not consider that the BSF provides the AMF with the addressing PCF function, so it still cannot solve the problem that the AMF may not be able to select the PCF+PCRF selected by the SMF+PGW-C when switching from 4G to 5G.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a PCF+PCRF selection method, AMF, BSF and storage medium, so as to solve the problem that the UE cannot access the same PCF+PCRF after switching from 4G access to 5G, resulting in PCF+ The technical problem that the policy control of PCRF to AMF and SMF+PGW-C cannot be related.

The technical solutions adopted by the embodiments of the present invention to solve the above-mentioned technical problems are as follows:

According to an aspect of the embodiments of the present invention, a PCF+PCRF selection method is provided, applied to AMF, and the method includes:

When the AMF detects that the UE switches from 4G to 5G, it queries the BSF for the PCF+PCRF selected by the SMF+PGW-C for the UE;

Access and mobility policy control is requested from the selected PCF+PCRF.

According to another aspect of the embodiments of the present invention, a method for selecting PCF+PCRF is provided, applied to BSF, and the method includes:

Receive the registration binding information request of PCF+PCRF, and store the binding information of the UE;

Receive a request from the AMF to query the PCF+PCRF selected by the UE, and feed back the PCF+PCRF selected by the UE to the AMF;

The binding information of the UE includes the user identity of the UE, the user IP address, and the identity of the PCF+PCRF selected for the UE.

According to yet another aspect of the embodiments of the present invention, an AMF is provided, the AMF includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the computer program is executed by the processor, realizes the above PCF + Steps of PCRF selection method.

According to yet another aspect of the embodiments of the present invention, a BSF is provided, the BSF includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor , to realize the steps of implementing the above PCF+PCRF selection method.

According to yet another aspect of the embodiments of the present invention, a storage medium is provided on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above-mentioned PCF+PCRF selection method applied to AMF are realized, and/ Or implement the steps of the above PCF+PCRF selection method applied to BSF.

The PCF+PCRF selection method, AMF, BSF, and storage medium provided by the embodiments of the present invention select PCF+PCRF for the UE by querying the BSF newly introduced in 5G by SMF+PGW-C in 4G access, and select PCF+PCRF for the selected PCF. +PCRF requests access and mobility policy control, so that when the UE switches from 4G to 5G, AMF can select the PCF+PCRF that has been selected by SMF+PGW-C during 4G access, so as to satisfy PCF+PCRF for AMF policy control and pairing The policy control of SMF+PGW-C needs to be associated with the associated application scenarios.

Description of drawings

FIG. 1 is an architecture diagram of 4/5G in a non-roaming scenario in a related art according to an embodiment of the present invention;

FIG. 2 is an architecture diagram of 4/5G in a local dredging roaming scenario in a related art according to an embodiment of the present invention;

3 is an architectural diagram of a home routing roaming scenario 4/5G in the related art according to an embodiment of the present invention;

FIG. 4 is an architecture diagram of interworking between BSF and DRA in 4/5G interoperation in the related art according to an embodiment of the present invention;

5 is a flowchart of a PCF+PCRF selection method applied to AMF provided by Embodiment 1 of the present invention;

6 is a flowchart of a PCF+PCRF selection method applied to BSF provided by Embodiment 2 of the present invention;

7 is a flowchart of a PCF+PCRF selection method applied in a non-roaming scenario provided by Embodiment 3 of the present invention;

8 is a flowchart of a PCF+PCRF selection method applied to a local grooming roaming scenario provided by Embodiment 4 of the present invention;

FIG. 9 is a flowchart of a PCF+PCRF selection method applied to a home route roaming scenario provided by Embodiment 5 of the present invention.

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more comprehensible, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention, but not for limiting the present invention.

Example 1

As shown in FIG. 5 , a PCF+PCRF selection method provided in an embodiment of the present invention is applied to AMF, and the method includes:

S501. When the AMF detects that the UE switches from 4G to 5G, it queries the BSF for the PCF+PCRF selected by the SMF+PGW-C for the UE.

S502. Request access and mobility policy control from the selected PCF+PCRF.

Specifically, please refer to FIG. 1 and FIG. 4. In a non-roaming scenario, the AMF queries the H-BSF located in the home network for the H-PCF+H-PCRF selected by the SMF+PGW-C for the UE, and asks the H-PCF+H-PCRF selected by the SMF+PGW-C for the UE. - Requested access and mobility policy control for PCF+H-PCRF.

Referring to Figure 2 and Figure 4, in the local roaming scenario, the AMF queries the V-BSF located in the visited network for the V-PCF+V-PCRF selected by the SMF+PGW-C for the UE, and asks the selected V-PCF to +V-PCRF request access and mobility policy control, H-PCRF+H-PCF is selected by the selected V-PCF+V-PCRF, and the H-PCRF+H-PCF is selected by the V-PCF+V-PCRF to the selected H- PCRF+H-PCF requests access and mobility policy control.

Referring to Figure 2 and Figure 4, in the home route roaming scenario, the AMF queries the H-BSF in the home network for the H-PCRF+H-PCF selected by the SMF+PGW-C for the UE, and selects V-PCF+V -PCRF, tell the selected H-PCRF+H-PCF to the selected V-PCF+V-PCRF, and the selected V-PCF+V-PCRF requests the selected H-PCRF+H-PCF for access and Mobility Policy Control.

Embodiment 2

As shown in FIG. 6 , a PCF+PCRF selection method provided in an embodiment of the present invention is applied to BSF, and the method includes:

S601. Receive a request for registration and binding information of the PCF+PCRF, and store the binding information of the UE.

The binding information of the UE includes the user identity of the UE, the user IP address, and the PCF+PCRF selected for the UE (including the H-PCF+H-PCRF located in the home network or the V-PCF+V located in the visited network). - PCRF) identification.

Specifically, please refer to FIG. 1 and FIG. 4. In non-roaming mode, SMF+PGW-C, PCF+PCRF (ie H-PCF+H-PCRF), and BSF (ie H-BSF) are all located in the home network. The H-BSF located in the home network receives the registration binding information request sent by the H-PCF+H-PCRF, and stores the UE's user identity, user IP address, and the identity of the H-PCF+H-PCRF selected for the UE.

Please refer to Figure 2 and Figure 4. In the local grooming roaming mode, SMF+PGW-C is in the visited network, SMF+PGW-C selects PCF+PCRF (ie V-PCF+V-PCRF) in the visited network, V-PCF +V-PCRF registers the binding information with the BSF located in the visited network (ie V-BSF), the user identity of the V-BSF UE, the user IP address, the selected V-PCF+V-PCRF identity). And the H-PCF+H-PCRF located in the home network is further selected by the V-PCF+V-PCRF.

3 and 4, in the home route roaming mode, SMF+PGW-C, PCF+PCRF (ie H-PCF+H-PCRF), BSF (ie H-BSF) are all located in the home network. The H-BSF located in the home network receives the registration binding information request sent by the H-PCF+H-PCRF, and stores the UE's user identity, user IP address, and the identity of the H-PCF+H-PCRF selected for the UE.

S602: Receive a request from the AMF to query the PCF+PCRF selected by the UE, and feed back the PCF+PCRF selected by the UE to the AMF.

Specifically, in the non-roaming mode, the H-BSF located in the home network receives the request of the AMF to query the H-PCF+H-PCRF selected by the UE, and feeds back the H-PCF+H-PCRF selected by the UE to the AMF. identification;

In the local grooming roaming mode, the V-BSF located in the visited network receives the request of the AMF to query the V-PCF+V-PCRF selected by the UE, and feeds back the identifier of the V-PCF+V-PCRF selected by the UE to the AMF.

In the home roaming mode, the H-BSF in the home network receives the request of the AMF to query the H-PCF+H-PCRF selected for the UE, and feeds back the identifier of the H-PCF+H-PCRF selected for the UE to the AMF.

Embodiment 3

As shown in FIG. 7 , an embodiment of the present invention provides a PCF+PCRF selection method applied in a non-roaming scenario, and the method includes:

S701, the UE requests to establish a session through the SMF+PGW-C of the 4G access home network;

S702, SMF+PGW-C selects the H-PCF+H-PCRF of the home network, and requests session policy control from the selected H-PCF+H-PCRF;

S703, the H-PCF+H-PCRF registers the binding information with the H-BSF of the home network;

S704, the UE switches from 4G access to 5G access;

S705, the AMF queries the H-BSF of the home network for the H-PCF+H-PCRF selected by the SMF+PGW-C;

S706. The AMF selects the H-PCF+H-PCRF according to the query result returned by the H-BSF, and requests the selected H-PCF+H-PCRF for access and mobility policy control.

Embodiment 4

As shown in FIG. 8, an embodiment of the present invention provides a PCF+PCRF selection method applied to a local grooming roaming scenario, the method includes:

S801, the UE requests the SMF+PGW-C of the visited network to establish a session through 4G access;

S802, SMF+PGW-C selects V-PCF+V-PCRF, and requests session policy control from the selected V-PCF+V-PCRF;

S803, V-PCF+V-PCRF selects H-PCF+H-PCRF and negotiates session policy control;

S804, V-PCF+V-PCRF registers binding information with the BSF of the visited network;

S805, the UE switches from 4G access to 5G access;

S806, the AMF queries the BSF of the visited network for the V-PCF+V-PCRF selected by the SMF+PGW-C;

S807, AMF selects V-PCF+V-PCRF according to the query result returned by BSF, and requests access and mobility policy control to the selected V-PCF+V-PCRF;

S808, V-PCF+V-PCRF selects H-PCF+H-PCRF, and requests access and mobility policy control to the selected H-PCF+H-PCRF.

Embodiment 5

As shown in FIG. 9, FIG. 9 is a PCF+PCRF selection method applied to a home route roaming scenario provided by an embodiment of the present invention, and the method includes:

S901, the UE requests the SMF+PGW-C of the home network to establish a session through 4G access;

S902, SMF+PGW-C selects the PCF+PCRF of the home network, and requests session policy control from the selected H-PCF+H-PCRF;

S903, the H-PCF+H-PCRF registers the binding information with the BSF of the home network;

S904, the UE switches from 4G access to 5G access;

S905, the AMF queries the BSF of the visited network for the H-PCF+H-PCRF selected by the SMF+PGW-C;

S906, AMF selects V-PCF+V-PCRF by itself, requests access and mobility policy control from the selected V-PCF+V-PCRF, and provides the selected V-PCF+V-PCRF with the selected H -PCF+H-PCRF logo;

S907, the V-PCF+V-PCRF requests the H-PCF+H-PCRF selected by the AMF for access and mobility policy control.

Embodiment 6

An embodiment of the present invention provides an AMF. The AMF includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the computer program is executed by the processor, the PCF+PCRF of the above method embodiment is implemented. Steps for selecting a method.

It should be noted that the AMF in this embodiment belongs to the same concept as the PCF+PCRF selection method embodiment, and the specific implementation process is detailed in the method embodiment, and the technical features in the method embodiment are all correspondingly applicable in this embodiment. I won't go into details here.

Embodiment 7

An embodiment of the present invention provides a BSF. The BDF includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the computer program is executed by the processor, the PCF+PCRF of the above method embodiment is implemented. Steps for selecting a method.

It should be noted that the BSF in this embodiment belongs to the same concept as the above-mentioned PCF+PCRF selection method embodiment, and the specific implementation process is detailed in the method embodiment, and the technical features in the method embodiment are correspondingly applicable in this embodiment. , which will not be repeated here.

Embodiment 9

Embodiments of the present invention further provide a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the PCF+ of any of the foregoing Embodiments 1 to 5 is implemented. Steps of PCRF selection method.

It should be noted that the computer-readable storage medium of the embodiment of the present invention belongs to the same concept as the PCF+PCRF selection method embodiment, and the specific implementation process is detailed in the method embodiment, and the technical features in the method embodiment are in the computer-readable It is applicable to all storage media, and will not be repeated here.

The PCF+PCRF selection method, AMF, BSF, and storage medium provided by the embodiments of the present invention select PCF+PCRF for the UE by querying the BSF newly introduced in 5G by SMF+PGW-C in 4G access, and select PCF+PCRF for the selected PCF. +PCRF requests access and mobility policy control, so that when the UE switches from 4G to 5G, AMF can select the PCF+PCRF that has been selected by SMF+PGW-C during 4G access, so as to satisfy PCF+PCRF for AMF policy control and pairing The policy control of SMF+PGW-C needs to be associated with the associated application scenarios.

Those of ordinary skill in the art can understand that all or some of the steps in the methods disclosed above, functional modules/units in the systems, and devices can be implemented as software, firmware, hardware, and appropriate combinations thereof.

In hardware implementations, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical pool elements; for example, one physical pool element may have multiple functions, or one function or step may be composed of Several physical pool pieces execute cooperatively. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as a special-purpose integrated circuit. Such software may be distributed on computer-readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). As known to those of ordinary skill in the art, the term computer storage media includes both volatile and nonvolatile implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules or other data flexible, removable and non-removable media. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cartridges, magnetic tape, magnetic disk storage or other magnetic storage devices, or may Any other medium used to store desired information and which can be accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and can include any information delivery media, as is well known to those of ordinary skill in the art .

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but are not intended to limit the scope of the rights of the present invention. Any modifications, equivalent substitutions and improvements made by those skilled in the art without departing from the scope and spirit of the present invention shall fall within the right scope of the present invention.

Claims (10)

1. a PCF+PCRF selection method, applied to access and mobility management function AMF, is characterized in that, the method comprises: When the AMF detects that the user equipment UE is switched from the 4G network to the 5G network, the AMF queries the binding support function BSF to integrate the session management function and the packet data network gateway control plane SMF+PGW when the UE accesses the 4G network -C is the fusion policy control function and the policy and charging rule function PCF+PCRF selected by the UE; The AMF requests access and mobility policy control from the PCF+PCRF selected by the SMF+PGW-C for the UE. 2. The PCF+PCRF selection method according to claim 1, wherein the AMF queries the BSF for the PCF+PCRF selected by the UE when the UE accesses the 4G network, and the SMF+PGW-C is the selected PCF+PCRF for the UE. The AMF requests access and mobility policy control to the PCF+PCRF selected by the SMF+PGW-C for the UE, specifically including: In a non-roaming scenario, the AMF queries the H-BSF located in the home network for the H-PCF+H-PCRF selected by the SMF+PGW-C for the UE when the UE accesses the 4G network, and asks the H-PCF+H-PCRF for the UE to access the 4G network. The selected H-PCF+H-PCRF requests access and mobility policy control; In the local grooming and roaming scenario, the AMF queries the V-BSF located in the visited network for the V-PCF+V-PCRF selected by the UE when the SMF+PGW-C is the UE's access to the 4G network, The requested access and mobility policy control of the selected V-PCF+V-PCRF, the H-PCRF+H-PCF is selected by the selected V-PCF+V-PCRF, and is controlled by the V-PCF+V-PCRF. - PCF+V-PCRF requests access and mobility policy control from selected H-PCRF+H-PCF; In the home route roaming scenario, the AMF queries the H-BSF located in the home network for the H-PCRF+H-PCF selected by the SMF+PGW-C for the UE when the UE accesses the 4G network, and Select V-PCF+V-PCRF, tell the selected H-PCRF+H-PCF to the selected V-PCF+V-PCRF, and send the selected V-PCF+V-PCRF to the selected V-PCF+V-PCRF The H-PCRF+H-PCF request access and mobility policy control. 3. The PCF+PCRF selection method according to claim 1, wherein before the AMF detects that the user equipment UE is switched from a 4G network to a 5G network, the method further comprises: When the UE accesses the 4G network, the SMF+PGW-C selects the PCF+PCRF for the UE; The selected PCF+PCRF registers the binding information of the UE to the BSF; Wherein, the binding information of the UE includes a user identity, a user IP address, and the identity of the PCF+PCRF selected for the UE. 4. The PCF+PCRF selection method according to claim 3, wherein the SMF+PGW-C selects a PCF+PCRF for the UE, and the selected PCF+PCRF selects the binding information of the UE. Register with the BSF, which includes: In the non-roaming mode or the home route roaming mode, the SMF+PGW-C selects the H-PCF+H-PCRF of the home network, and the H-PCF+H-PCRF of the home network combines the binding information of the UE with the H-PCF+H-PCRF of the home network. Register to H-BSF; In the local grooming roaming mode, the SMF+PGW-C selects the V-PCF+V-PCRF located in the visited network, and the V-PCF+V-PCRF registers the binding information of the UE to the V-PCF+V-PCRF located in the visited network. BSF. 5. a selection method of PCF+PCRF, is characterized in that, is applied to binding support function BSF, and this method comprises: The BSF receives the request for registration and binding information of the PCF+PCRF, and stores the binding information of the user equipment UE, wherein the PCF+PCRF is the integration of the session management function and the packet data network gateway when the UE accesses the 4G network The control plane SMF+PGW-C is selected by the UE; The BSF receives the access and mobility management function AMF when detecting that the UE is switched from the 4G network to the 5G network to query the SMF+PGW-C for the UE to select when the UE accesses the 4G network. When the UE accesses the 4G network, the PCF+PCRF selected by the SMF+PGW-C for the UE is fed back to the AMF, so that the AMF can report to the AMF SMF+PGW-C requests access and mobility policy control for the PCF+PCRF selected by the UE; Wherein, the binding information of the UE includes the user identity of the UE, the user IP address, and the identity of the PCF+PCRF selected for the UE. 6. The method for selecting PCF+PCRF according to claim 5, wherein the BSF receives the registration binding information request of the PCF+PCRF, and stores the binding information of the UE of the user equipment, specifically comprising: In the non-roaming mode or the home routing roaming mode, the H-BSF located in the home network receives the registration binding information request sent by the H-PCF+H-PCRF, stores the UE's user identity, user IP address, and the identifier of the H-PCF+H-PCRF selected by the UE; Under the local grooming roaming mode, the V-BSF located in the visited network receives the registration binding information request sent by the V-PCF+V-PCRF located in the visited network, stores the user identity of the UE, the user IP address, and selects a user ID for the UE. The identification of the specified V-PCF+V-PCRF. 7. The method for selecting PCF+PCRF according to claim 5, wherein the BSF receives the access and mobility management function AMF, when detecting that the UE is switched from the 4G network to the 5G network, is used to query the When the UE accesses the 4G network, the SMF+PGW-C is the request of the PCF+PCRF selected by the UE, and feeds back the queried SMF+PGW when the UE accesses the 4G network to the AMF -C is the PCF+PCRF selected by the UE, specifically including: In the non-roaming mode or the home roaming mode, the H-BSF located in the home network receives the AMF used to query when the UE accesses the 4G network when it detects that the UE is switched from the 4G network to the 5G network. SMF+PGW-C is the request of the H-PCF+H-PCRF selected by the UE, and feeds back the identifier of the H-PCF+H-PCRF selected by the UE to the AMF; In the local grooming roaming mode, the V-BSF in the visited network receives the AMF and uses it to query the SMF+PGW-C when the UE accesses the 4G network when it detects that the UE is switched from the 4G network to the 5G network. For the request of the V-PCF+V-PCRF selected for the UE, the identifier of the V-PCF+V-PCRF selected for the UE is fed back to the AMF. 8. An AMF comprising a memory, a processor and a computer program stored on the memory and running on the processor, wherein the computer program is executed by the processor, Steps for implementing the PCF+PCRF selection method as claimed in any one of claims 1 to 4. 9. A BSF comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the computer program is implemented when executed by the processor The steps of the PCF+PCRF selection method according to any one of claims 5 to 7. 10. A storage medium, characterized in that, a computer program is stored on the storage medium, and when the computer program is executed by a processor, the PCF+PCRF according to any one of claims 1 to 4 is realized The steps of the selection method, or the steps of implementing the PCF+PCRF selection method as claimed in any one of claims 5 to 7.

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