CN109819485B

CN109819485B - Communication method, device and system

Info

Publication number: CN109819485B
Application number: CN201711168911.5A
Authority: CN
Inventors: 刘睿智; 吴义壮; 熊春山; 周铮
Original assignee: Huawei Technologies Co Ltd
Current assignee: XFusion Digital Technologies Co Ltd
Priority date: 2017-11-21
Filing date: 2017-11-21
Publication date: 2020-11-27
Anticipated expiration: 2037-11-21
Also published as: CN109819485A; WO2019101074A1

Abstract

A communication method, a communication device and a communication system are used for notifying the terminal of the information of the subscription change of DNN. The method comprises the following steps: a first core network element receives notification information of a second core network element, wherein the notification information is used for indicating subscription change of a data network name DNN; and the first core network element sends first information to a terminal, wherein the first information is used for informing the terminal of the subscription change of the DNN.

Description

Communication method, device and system

Technical Field

The embodiment of the application relates to the technical field of communication, in particular to a communication method, device and system.

Background

The system architecture of the fifth generation (5th generation, 5G) communication system is divided into two parts, namely an access network and a core network. The access network is used to implement radio access related functions. The core network includes a plurality of network elements, wherein a Unified Data Management (UDM) entity is used to manage subscription data of the terminal and registration information related to the terminal. The UDM stores therein the identification (DN number, DNN) of the Data Network (DN), which is used to identify the different DNs. Subscription data corresponding to a subscription between a user and an operator using different terminals may be identified with DNN and user ID. An access and mobility management function (AMF) entity in the core network is responsible for registration of the terminal, mobility management, tracking area update procedures, and the like. In the process of establishing a session by a terminal, the SMF entity acquires the subscription data of the terminal from the UDM entity. Specifically, the SMF entity sends a subscription data request message to the UDM entity, and the UDM entity returns a subscription data response message carrying subscription data to the SMF entity. The communication system then performs session authentication, the SMF selects a policy and charging control function (PCF) entity for the terminal, and obtains Policy and Charging Control (PCC) rules from the PCF entity. And the SMF entity selects a proper UPF entity for the terminal according to the position information, the subscription data, the SSC mode(s) and other information of the terminal, and allocates an IP address for the terminal aiming at the session.

The subscription change of the DNN means that the subscription identified by the DNN changes, when the subscription of the DNN changes, if the terminal already establishes a session with the DN identified by the DNN, the session needs to be released, and if the terminal does not establish a session with the DN identified by the DNN, the terminal cannot establish a session with the DN identified by the DNN.

How to notify the terminal of the information of the subscription change between the terminal and the DNN is a technical problem to be solved.

Disclosure of Invention

The embodiment of the application provides a communication method, device and system, which are used for notifying the terminal of the information of the subscription change between the terminal and a DNN.

The embodiment of the application provides the following specific technical scheme:

in a first aspect, a communication method is provided, which may include the steps of: a first core network element receives notification information of a second core network element, wherein the notification information is used for indicating subscription change of DNN; and after receiving the notification information, the first core network element sends first information to a terminal, wherein the first information is used for notifying the terminal of the subscription change of the DNN. Thus, the information carrying the subscription change of the DNN is sent to the terminal by the network element of the core network, and the purpose of informing the terminal of the subscription change of the DNN can be achieved.

In one possible design, the subscription change of the DNN is a subscription data deletion of the DNN or a subscription data addition of the DNN.

In one possible design, the subscription change of the DNN may be understood as a subscription data change of the DNN.

Optionally, the subscription change for DNN may also be DNN unavailable.

In one possible design, the DNN is a local area data network LADN DNN, and the first core network element may notify a terminal of subscription change of the LADN DNN in a manner of implicitly carrying information, specifically, any one of the following manners: the first information carries the LADN DNN and does not carry a service area of the LADN; or the first information carries service area lists of the LADN DNN and the LADN, and the service area list of the LADN is empty; or the first information carries service areas of the LADN DNN and the LADN, and the size of the service area of the LADN is 0; in this application scenario, the first information is further used to instruct the terminal to set the LADN DNN as unavailable or delete the LADN DNN or delete the LADN information. Therefore, the terminal is informed in a mode of implicitly carrying the information, so that the first information can be saved from carrying the indication information, and the signaling overhead can be saved.

In a possible design, if the first core network element is an access and mobility management function AMF, sending, by the first core network element, the first information to the terminal may be implemented by: the first core network element sends first information to the terminal when meeting the condition; wherein the conditions are: the terminal does not establish a packet data unit, PDU, session with the data network DN identified by the DNN. That is to say, if the terminal and the DN identified by the DNN have already established a PDU session, the AMF does not send the first information to the terminal according to the notification information of the UDM, and the SMF sends the first information to the terminal according to the notification information of the UDM, where the SMF sends the first information to the terminal through the AMF and the access network device, and the AMF forwards the first information sent by the SMF after receiving the first information sent by the SMF, where the first information carries information about subscription change of the DNN. Therefore, when the UDM sends the notification information to the AMF and the SMF respectively, the AMF only sends the information to the terminal once, so that the subscription change can be notified to the terminal, and the signaling overhead of a network side and the signaling overhead of an air interface are saved. And for the scene that the terminal is in an idle state, the network side is prevented from initiating paging at least twice, thereby further saving signaling overhead.

In a possible design, if the first core network element is an AMF, the first core network element sends the first information to the terminal, which may be implemented in the following manner: and the AMF sends the first information to the terminal after receiving the second information sent by the session management function SMF. Therefore, when the UDM sends the notification information to the AMF and the SMF respectively, the AMF only sends the information to the terminal once, so that the subscription change can be notified to the terminal, and the signaling overhead of a network side and the signaling overhead of an air interface are saved. And for the scene that the terminal is in an idle state, the network side is prevented from initiating paging at least twice, thereby further saving signaling overhead.

In a possible design, if the first core network element is an AMF and the second core network element is a unified data management UDM, the first core network element sends the first information to the terminal, which may be implemented in the following manner: the AMF determines that the terminal establishes a PDU session with the DN identified by the DNN, and starts a timer; the AMF sends the first information to the terminal when the timer expires; or, before the timer expires, the AMF determines that the number of received second messages sent by the SMF reaches a predetermined value, and sends the first message to the terminal. Optionally, before the timer expires, the AMF waits to receive the second message sent by the SMF. Therefore, when the UDM sends the notification information to the AMF and the SMF respectively, the AMF only sends the information to the terminal once, so that the subscription change can be notified to the terminal, and the signaling overhead of a network side and the signaling overhead of an air interface are saved. And for the scene that the terminal is in an idle state, the network side is prevented from initiating paging at least twice, thereby further saving signaling overhead. And signaling waste caused by transmitting PDU session related information once per PDU release flow is avoided, subscription change information transmitted by the AMF to the terminal, subscription change information transmitted by the SMF to the terminal and multiple times of PDU session related information transmitted by the SMF to the terminal are transmitted to the terminal at one time, so that empty signaling overhead is saved, and system resources are further saved if the indication of subscription change is carried in the PDU session related information.

In a possible design, when the timer expires, if the second information sent by the SMF entity is received, the AMF entity sends first information to the terminal according to the second information, where the first information is further used to instruct the terminal to delete PDU session information. Therefore, the AMF can realize the notification of the subscription change to the terminal only by sending the information to the terminal once, thereby saving the signaling overhead of the network side and the signaling overhead of an air interface.

In one possible design, the second information is PDU session related information, and the first information is used to instruct the terminal to delete PDU session information. Therefore, the information of the subscription change of the terminal DNN can be notified in the PDU session release flow, and system resources are saved.

In a possible design, if the first core network element is an AMF, the second core network element is a UDM, and the first information is further used to instruct the terminal to delete PDU session information; the method may further comprise the steps of: the first core network element receives third information sent by the SMF, wherein the third information is used for indicating the access network equipment to delete the context of the PDU session established between the terminal and the data network DN identified by the DNN; and the first core network element sends fourth information to the access network equipment according to the third information, wherein the fourth information is used for indicating the access network equipment to delete the PDU session context. Thus, when the UDM sends notification information of DNN subscription change to both the AMF and the SMF, the SMF side only notifies the DNN subscription change information to the access network equipment, but does not notify the terminal, and the air interface signaling overhead from the access network equipment to the terminal is saved.

In a possible design, the third information is further used to indicate to the first core network element that the terminal is not paged if the terminal is in an idle state.

In one possible design, if the first core network element is an AMF and the second core network element is a UDM, the method further includes the following steps: the first core network element informs a policy control function PCF of: the subscription change is used for indicating the PCF to update a UE routing strategy URSP; the first information carries the updated URSP and is used for indicating the terminal to update the URSP. In this way, when the subscription of the DNN changes, the updated URSP can be notified to the terminal.

In a possible design, if the first core network element is an SMF, the second core network element may be a UDM or an AMF.

In a second aspect, a communication method is provided, which may include the steps of: a Session Management Function (SMF) receives notification information, wherein the notification information is used for indicating subscription change of a Data Network Name (DNN); and the SMF sends information to access network equipment, wherein the information is used for indicating the access network equipment to delete the context of a Packet Data Unit (PDU) session established between the terminal and the data network DN identified by the DNN. Thus, when the UDM respectively sends the notification information of the DNN subscription change to the AMF and the SMF, the AMF notifies the terminal of the DNN subscription change, and the SMF side only notifies the access network equipment of the DNN subscription change information and does not notify the terminal, so that the air interface signaling overhead from the access network equipment to the terminal is saved.

In one possible design, the SMF may also instruct the access and mobility management functions AMF to: and if the terminal is in an idle state, not paging the terminal.

In a third aspect, a communication method is provided, which includes the following steps: the unified data management UDM determines the subscription change of the data network name DNN; the UDM sends notification information to a Session Management Function (SMF), and/or the UDM sends notification information to an access and mobile management function (AMF); wherein the notification information is used for indicating subscription change of the data network name DNN. Thus, the information carrying the subscription change of the DNN is sent to the terminal by the network element of the core network, and the purpose of informing the terminal of the subscription change of the DNN can be achieved. When the UDM selects one of the core network elements to notify the subscription change, the information of the subscription change is notified to the terminal through the selected core network element (such as SMF or AMF), which can help to reduce signaling overhead and avoid resource waste.

In one possible design, when a terminal has established a packet data unit, PDU, session with a data network DN identified by the DNN, the UDM sends notification information to the SMF, or the UDM sends notification information to both the SMF and the AMF, respectively; and when the terminal does not establish a PDU session with the DN identified by the DNN, the UDM only sends notification information to the AMF.

In a fourth aspect, a communication method is provided, the method comprising: a terminal receives first information sent by a core network element, wherein the core network element is an access and mobility management function (AMF) or a Session Management Function (SMF), and the first information is used for indicating the subscription change of a Data Network Name (DNN); and the terminal deletes the DNN data and context or adds DNN data according to the first information. In this way, the terminal can achieve the purpose of notifying the terminal of the subscription change of the DNN by receiving the information carrying the subscription change of the DNN sent by the network element of the core network.

Optionally, the core network element is a PCF, and the terminal updates a UE routing policy URSP according to the first information.

In a fifth aspect, a communications apparatus is provided, which has the functionality to implement the first core network element behavior in any of the possible designs of the first aspect and the first aspect. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

In one possible design, the apparatus may be structured to include a transceiver and a processor, wherein the processor is configured to invoke a set of programs to perform the method as set forth in any one of the possible designs of the first aspect and the first aspect.

Optionally, the apparatus further comprises a memory for storing a program executed by the processor.

In a sixth aspect, there is provided an AMF having the functionality to achieve AMF behaviour in any one of the above aspects and any one of the possible designs of any one of the above aspects. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

In a seventh aspect, there is provided an SMF having functionality to enable SMF behaviour in any one of the above aspects and any one of the possible designs of any one of the above aspects. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

In an eighth aspect, a UDM is provided having functionality to implement UDM behavior in any of the above aspects and any of the possible designs of any of the above aspects. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

In a ninth aspect, there is provided a PCF having functionality to implement PCF behavior in any one of the above aspects and in any one of the possible designs of any one of the above aspects. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

A tenth aspect provides a communication apparatus having a function of implementing a terminal behavior in any one of the possible designs of the first aspect and the first aspect described above. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.

In an eleventh aspect, a communication system is provided, the communication system comprising a unified data management UDM for sending notification information to an access and mobility management function AMF and/or a session management function SMF, the notification information indicating a subscription change for a data network name DNN; the AMF or the SMF is used for receiving notification information of the UDM and sending first information to the terminal, wherein the first information is used for notifying the terminal of subscription change of the DNN; and the terminal is used for receiving the first information sent by the AMF and/or the SMF, and deleting the data and context of the DNN or adding the DNN data according to the first information.

In one possible design, the communication system further includes a PCF configured to perform the functions performed by the UDM in any of the above aspects and in any of the possible designs of any of the above aspects.

In one possible design, the UDM in the communication system is configured to perform functions performed by the UDM in any one of the above aspects and any one of the above possible designs, the SMF in the communication system is configured to perform functions performed by the SMF in any one of the above aspects and any one of the above possible designs, and the terminal in the communication system is configured to perform functions performed by the terminal in any one of the above aspects and any one of the above possible designs.

In a twelfth aspect, there is provided a computer storage medium storing a computer program comprising instructions for performing the method of the above aspects.

In a thirteenth aspect, there is provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of the above aspects.

Drawings

FIG. 1 is a schematic diagram of a communication system architecture according to an embodiment of the present application;

fig. 2 is a schematic diagram illustrating a PDU session release process in an embodiment of the present application;

fig. 3 is a schematic diagram of an application scenario of an LADN in the embodiment of the present application;

FIG. 4 is a flow chart illustrating a communication method according to an embodiment of the present application;

fig. 5a is a schematic diagram of a main flow of a first implementation manner in the embodiment of the present application;

fig. 5b is a schematic diagram of a signaling interaction flow in an implementation manner in the embodiment of the present application;

fig. 6a is a schematic diagram of a main flow of a second implementation manner in the embodiment of the present application;

fig. 6b is a schematic diagram of a signaling interaction flow in an implementation manner two in the embodiment of the present application;

fig. 7a is a schematic diagram of a main flow of a third implementation manner in the embodiment of the present application;

fig. 7b is a schematic diagram of a signaling interaction flow in an implementation manner of this application embodiment;

fig. 8a is a schematic diagram of a main flow of a fourth implementation manner in the embodiment of the present application;

fig. 8b is a schematic diagram of a signaling interaction flow of an implementation manner four in the embodiment of the present application;

fig. 9a is a schematic diagram of a main flow of a fifth implementation manner in the embodiment of the present application;

fig. 9b is a schematic diagram of a signaling interaction flow in an implementation manner of the embodiment of the present application;

fig. 10a is a schematic diagram of a main flow of a sixth implementation manner in the embodiment of the present application;

fig. 10b is a schematic diagram of a six-signaling interaction flow in an implementation manner in an embodiment of the present application;

fig. 11a is a schematic diagram of a main flow of a seventh implementation manner in the embodiment of the present application;

fig. 11b is a schematic diagram of a seven-signaling interaction flow in an implementation manner in an embodiment of the present application;

fig. 12 is a schematic structural diagram of a communication device according to an embodiment of the present application;

FIG. 13 is a schematic diagram of an AMF structure according to an embodiment of the present application;

FIG. 14 is a diagram of an SMF structure in an embodiment of the present application;

FIG. 15 is a schematic view of a PCF structure in an embodiment of the present application;

fig. 16 is a second schematic structural diagram of a communication device in the embodiment of the present application;

fig. 17 is a schematic diagram of a network element structure of a core network in an embodiment of the present application;

FIG. 18 is a schematic diagram of the AMF structure in an embodiment of the present application;

FIG. 19 is a diagram of an SMF structure in an embodiment of the present application;

FIG. 20 is a schematic view of a PCF structure in an embodiment of the present application;

fig. 21 is a third schematic structural diagram of a communication device in the embodiment of the present application.

Detailed Description

The application provides a communication method, device and system, which are used for notifying the terminal of the information of the subscription change of DNN. The method and the equipment are based on the same inventive concept, and because the principles of solving the problems of the method and the equipment are similar, the implementation of the device and the method can be mutually referred, and repeated parts are not repeated.

It should be noted that, in the description of the embodiment of the present application, "and/or" describes an association relationship of an associated object, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. At least one referred to in this application means one or more; plural means two or more. In addition, it is to be understood that the terms first, second, etc. in the description of the present application are used for distinguishing between the descriptions and not necessarily for describing a sequential or chronological order.

The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Fig. 1 shows an architecture of an alternative communication system to which the communication method provided in the embodiment of the present application is applied, and referring to fig. 1, the communication system includes: a terminal 101, AN Access Network (AN) device 102, AN access and mobility management function (AMF) 103, a Session Management Function (SMF) 104, a PCF105, AN Application Function (AF) 106, a User Plane Function (UPF) 107, a Data Network (DN) 108, a Unified Data Management (UDM) 110, and AN authentication server function (AUSF) 110.

Among them, the terminal 101, also called User Equipment (UE), a Mobile Station (MS), a Mobile Terminal (MT), etc., is a device for providing voice and/or data connectivity to a user. For example, the terminal device includes a handheld device, an in-vehicle device, and the like having a wireless connection function. Currently, the terminal device may be: a mobile phone (mobile phone), a tablet computer, a notebook computer, a palm top computer, a Mobile Internet Device (MID), a wearable device, a Virtual Reality (VR) device, an Augmented Reality (AR) device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote surgery (remote medical supply), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety (smart security), a wireless terminal in city (smart city), a wireless terminal in smart home (smart home), and the like. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

The AN apparatus 102 is AN apparatus for accessing the terminal 101 to a wireless network in the communication system. The AN device is a node in a radio access network, which may also be referred to as a base station, and may also be referred to as a Radio Access Network (RAN) node (or device). Currently, some examples of AN devices are: a gbb, a Transmission Reception Point (TRP), an evolved Node B (eNB), a Radio Network Controller (RNC), a Node B (NB), a Base Station Controller (BSC), a Base Transceiver Station (BTS), a home base station (e.g., home evolved Node B, or home Node B, HNB), a Base Band Unit (BBU), or a wireless fidelity (Wifi) Access Point (AP), etc.

DN108 may be the Internet (Internet), an IP Multimedia Service (IMS) network, a regional network (i.e., a local network such as a Mobile Edge Computing (MEC) network), etc. The DN includes an application server, and the application server provides a service to the terminal 101 by performing data transmission with the terminal 101.

The core network is used to access the terminal 101 to the DN108 that can implement the service of the terminal 101. The functions of each network element in the core network are described below.

The AMF103 may be configured to be responsible for registration of the terminal 101, mobility management, tracking area update procedures, reachability detection, selection of the SMF104, mobility state transition management, and the like.

The SMF104 may be configured to be responsible for session management (including session establishment, modification, and release) of the terminal 101, selection and reselection of the UPF107, IP address allocation, QoS control, and the like of the terminal 101.

PCF105 may be used to take care of policy control decisions, provide functions such as traffic data flow and application detection, gating, QoS, and flow-based charging control.

The AF106 mainly functions to interact with a 3GPP core network to provide services, which affect traffic routing, access network capability opening, policy control, and the like.

The UDM109 may be configured to manage subscription data of the terminal apparatus 101 and registration information related to the terminal apparatus 101.

AUSF110, the main function is to provide authentication services.

UPF107, which may be used to forward user plane data for terminal 101. The main functions are Packet routing and forwarding, mobility anchor, upstream classifier to support routing traffic to the Data network, branch point to support multi-homed Packet Data Unit (PDU) sessions, etc.

DN108, such as an operator service, internet access, or third party service.

The above respective network element functions may also be referred to as functional entities, or network elements, for example, the AMF103 is referred to as the AMF entity 103. The network element functions may be network elements implemented on dedicated hardware, or may be software instances running on dedicated hardware, or instances of virtualized functions on a suitable platform, which may be a cloud platform, for example.

It should be noted that, in the embodiment of the present application, a distribution form of each network element function in the core network is not limited, and optionally, the network element function in the core network may also include other functional entities formed by fusing any of the multiple network element functions, for example, a functional entity having two functions of session management and policy control, or a functional entity having three functions of session management, access and mobility management and policy control, and the like.

The communication system shown in fig. 1 is not intended to limit the communication system to which the embodiments of the present application can be applied. The communication system architecture shown in fig. 1 is a non-roaming 5G system architecture, and optionally, the method of the embodiment of the present application is also applicable to a roaming 5G system architecture and to various future communication networks.

Based on the architecture of the communication system shown in fig. 1, some terms of the embodiments of the present application are explained below to facilitate understanding by those skilled in the art.

1) PDU session, is the connection between the terminal and the DN, providing PDU connectivity services. The type of connection may be Internet Protocol (IP), ethernet or unstructured data. The PDU connection service supported by the core network refers to a service providing PDU exchange between a terminal and a DN determined by a DN number (DNN). The terminal may establish multiple PDU sessions to connect to the same DN or different DNs. The terminal may establish PDU sessions serviced by different UPFs to connect to the same DN. The activated state of the PDU session refers to the state that the user plane resource of the PDU session is established, and an end-to-end connection is established between the terminal and the DN and can transmit data; the deactivated state of the PDU session means that the PDU session only reserves part of user plane resources, the user plane air interface resources between the UE and (R) AN, and the connection between (R) AN and UPF are not established, and data cannot be transferred between the UE and DN. Part of the PDU session information is still retained in SMF and UPF.

2) And PDU conversation release flow. An alternative PDU session release procedure is illustrated in figure 2.

201. The SMF, upon receiving a request from another network device, decides to release a PDU session. For example, a request for a DN is received, or a request for a UDM is received, or a request for an Online Charging System (OCS) is received. The request includes a condition or cause for triggering a PDU session release, e.g., a change in subscription of the terminal with the DNN.

202. The SMF releases the IP address/prefix and corresponding user plane resources allocated to the PDU session.

Specifically, the method is completed by two steps 2a and 2b.

Smf sends N4 session release request (including N4 session Identification (ID)) message to UPF, which discards any remaining packets of PDU session and releases all tunnel resources and context associated with N4 session.

Upf replies to the N4 session release request by sending an N4 session release response (including N4 session ID) message to SMF.

203. Comprising two steps 3a and 3b.

Smf responds to AMF by Namf _ Communication _ N1N2message transformation (Namf _ Communication _ N1N2MessageTransfer) service operation. Wherein, the Namf _ Communication _ N1N2MessageTransfer includes N1 SM Information (Information) and N2 SM resource release request. The N1 SM Information contains a PDU Session Release Command (PDU Session Release Command). The PDU Session Release Command includes PDU Session ID (PDU Session ID), and the reason for Release.

If the PDU session release is initiated by the SMF, the SMF responds to the AMF with a Namf _ Communication _ N1N2MessageTransfer) service operation. The Namf _ Communication _ N1N2MessageTransfer includes N1 SM Information, a skip indicator (skip indicator). The N1 SM Information contains a PDU Session Release Command. Wherein, the Skip indicator is used for indicating whether the AMF can Skip the AMF to send the N1 SM container to the terminal.

If the data plane connection of the PDU Session is activated, the SMF also needs to carry AN N2 Resource Release request (N2 Resource Release request) in the Namf _ Communication _ N1N2MessageTransfer, and the N2 Resource Release request carries a PDU Session ID for releasing (R) AN resources related to the PDU Session.

204. If the terminal is in a CM-IDLE (CM-IDLE) state and the skip indicator is included in a Namf _ Communication _ N1N2MessageTransfer service operation, AMF sends an N11 message to the terminal, and the N11 message carries the skip indicator. Step 205-207 is skipped.

If the terminal is in a CM-IDLE state, and the Namf _ Communication _ N1N2MessageTransfer service operation does not contain a skip indicator, namely, does not indicate that the transmission of the N1 SM can be skipped, the AMF initiates a network triggered service request flow to transmit a Non-Access Stratum (NAS) message to the terminal, wherein the NAS message carries a PDU session ID and an N1 SM information.

If the terminal is in a CM-CONNECTED (CM-CONNECTED) state, the AMF forwards AN SM message (containing N2 SM Resource Release request, N1 SM information) received from the SMF to the (R) AN.

205. And (R) the AN receives the SM message (containing N2 SM Resource Release request, N1 SM information) sent by the AMF, releases air interface resources of the (R) AN side related to the PDU session, and deletes the PDU session context.

Specifically, the (R) AN and the terminal exchange AN-specific signaling (e.g., AN-specific resource modification) to release AN air interface resource of the (R) AN side related to the PDU session, for example, in the case of a 3GPP RAN, the air interface resource of the (R) AN side related to the PDU session is released through radio resource control Connection Reconfiguration (RRC). (R) the AN may carry any NAS message received from the AMF in RRC signaling, e.g., N1 SM PDU Session Release Command.

The terminal feeds back a NAS message (containing PDU Session ID, N1 SM information (PDU Session Release Ack)) in response to the PDU Session Release command, e.g., through N1 SM signaling of (R) AN.

206. If (R) AN receives AN N2 SM request to Release AN resources, then (R) AN responds to the N2 SM Resource Release request to the AMF by sending AN N2 SM Resource Release Ack message. The N2 SM Resource Release Ack message contains N1 SM Information (PDU Session Release Ack) and User Location Information (User Location Information).

Otherwise, (R) the AN forwards only NAS messages from the terminal to the AMF (PDU Session ID, N1 SM information (PDU Session Release Ack)).

In practical applications, the PDU session release procedure further includes more signaling interactions, and fig. 2 only shows the interaction process related to the embodiment of the present application.

3) Local Area Data Network (LADN), is a specific form of DN. Networks deployed primarily for businesses, stadium events, concert halls, and the like. A Service Area (SA) of a LADN includes a Tracking Area (TA) list, which can be accessed only when a terminal is located at the SA of the LADN. When the terminal leaves the LADN SA, the network should release the PDU session (LADN PDU session) for which the terminal accesses the LADN or deactivate the user plane of the PDU session. For example, as shown in FIG. 3: assume that the LADN SA includes three TAs, denoted TA1, TA2, and TA3, respectively. Since the RAN1 is within the LADN SA coverage, a session to access the LADN may be established through the RAN1 when the terminal moves under the RAN 1. When the terminal moves to the RAN2, the terminal cannot access the LADN through the RAN2 because the RAN2 is not within the coverage of the LADN SA.

4) And signing: refers to a subscription between a user using a terminal and an operator.

5) DNN, for identifying different DNs. The storage and notification of subscription data in the network side and the terminal side may be identified by the ID and DNN of the terminal.

6) The subscription data refers to data related to the subscription that is stored in the network side and the terminal side, respectively. The UDM stores and manages subscription data related to each terminal, and for each terminal, the subscription data related to the terminal (which may be simply referred to as subscription data of the terminal) includes subscription data according to which all DNs for subscription authorization are accessed by using the terminal, and the DNs are identified by DNNs. The subscription data of the UDM for the terminal may be stored and managed with DNN as granularity, for example, the subscription data of one terminal includes subscription data of one or more DNNs, and the subscription data of one DNN is subscription data according to which the terminal communicates with a DN identified by the DNN. The subscription data may also be stored in other functional entities/network elements. Wherein, the subscription data in the UDM exists for a long time; other network elements or terminals may obtain subscription data directly or indirectly from the UDM when the terminal registers with the network or establishes a PDU session or other related procedures.

7) The subscription for DNN may be subscription data for DNN, or may be a subscription to which the DN identified by the access to DNN of the user terminal needs to comply.

8) The subscription change means that the subscription between the user using the terminal and the carrier changes.

A subscription change for a DNN refers to a change in subscription data for the DNN or a subscription change that needs to be observed using the DN identified by the terminal accessing the DNN. Subscription changes to DNN may include the following: the subscription data of the DNN is deleted, the subscription data of the DNN is newly added, the subscription of the DNN is deleted, and the subscription of the DNN is newly added. The subscription newly-added DNN refers to the subscription which needs to be observed by adding the DNN identified by the terminal access new DNN. The subscription data addition of the DNN refers to subscription data added on the basis of adding a new DNN. The subscription data deletion of the DNN means that all subscription data of the DNN is deleted. Optionally, it may also include that the DNN is not available, for example, the user using the terminal cannot use the DNN, or the user using the terminal cannot access the DN identified by the DNN, etc. When a subscription change of the DNN occurs, the terminal may not be able to establish a PDU session with the DN identified by the DNN with the subscription change, or the terminal needs to delete the PDU session information already established by the terminal and the DN identified by the DNN with the subscription change, or the terminal needs to delete the data and context of the DNN, or the terminal needs to add new DNN data.

9) The subscription data change means that data related to subscription stored in the network side and the terminal side is changed. The subscription data changes may include: and deleting the subscription data and newly adding the subscription data. Subscription data deletion, which may be due to subscription deletion, may also cause some old subscription data to be unavailable.

The subscription change described in the following description of the embodiment of the present application is a subscription change in a broad sense, and includes the subscription change described in the above 8) and the subscription data change described in the above 9). When referring to a subscription change, the subscription change is a broad meaning, and the subscription change is a change in subscription between a user using a terminal and an operator, or a change in subscription data between the user using the terminal and the operator, which is stored on a network side or a terminal side.

The embodiment of the application provides a communication method, which is used for notifying the information of the subscription change of the DNN to a terminal through a core network element when the subscription change of the DNN occurs. In the following description, for convenience of description, the subscription change of DNN may be briefly described as a subscription change. The communication method provided in the embodiment of the present application is applied to the communication system shown in fig. 1, and referring to fig. 4, the flow of the method includes:

s401, the second core network element sends notification information to the first core network element, the first core network element receives the notification information of the second core network element, and the notification information is used for indicating subscription change.

S402, the first core network element sends first information to the terminal, the terminal receives the first information sent by the first core network element, and the first information is used for informing the terminal of the subscription change of the DNN.

S403, the terminal deletes the data and context of the DNN with subscription change or adds the data of the DNN.

And if the DNN is the LADN DNN, the terminal needs to delete the LADN DNN information.

In this step, if the terminal has established a PDU session with the DN identified by the DNN, the terminal may also delete the PDU session information.

By the method, the purpose of informing the terminal of the subscription change can be achieved by sending the information for indicating the subscription change to the terminal through the core network element.

Several possible implementations of the method shown in fig. 4 are described below according to different specific functional entities of the first core network element and the second core network element.

First, it is noted that the UDM stores subscription data, and the UDM can determine whether a subscription change occurs, and when the UDM determines the subscription change, the UDM may send notification information to the AMF, or send notification information to the SMF, or send notification information to both the AMF and the SMF, where the notification information is used to indicate the subscription change. Specifically, when the UDM determines that the terminal has established a PDU session with the DN identified by the DNN according to the stored context of the terminal about session management or the PDU session, the UDM notifies the SMF of a subscription change, or the UDM notifies both the SMF and the AMF of the subscription change, and the notification may be sent through a notification message or carried in another message. After receiving the notification, the SMF triggers a PDU session release procedure, and the SMF sends the information of the subscription change to the terminal in the PDU session release procedure, for example, the subscription change may specifically be subscription data deletion or subscription data addition, and a specific sending form is described in detail below. When the UDM determines that the terminal does not establish a PDU session with the DN identified by the DNN according to the stored context about session management or the stored context about PDU session of the terminal, the UDM may notify only the AMF of the subscription change, may not notify the SMF of the subscription change, and the AMF sends the subscription change information to the terminal after receiving the notification. If the UDM notifies the AMF and the SMF of the subscription change respectively, signaling waste at the network side may be caused, and after receiving the notification, the AMF and the SMF both notify the terminal of the subscription change, which may cause empty signaling waste, and if the notification of the AMF and the SMF is asynchronous, paging may be triggered repeatedly when the terminal is in an empty state, thereby increasing signaling overhead. In the embodiment of the application, when the UDM selects one of the core network elements to notify the subscription change, the information of the subscription change is notified to the terminal through the selected core network element (such as SMF or AMF), which can help to reduce signaling overhead and avoid resource waste.

In the following fig. 5a, 6a, 7a, 8a, 9a, 10a and 11a, the solid lines without arrows identify interfaces between network elements, the solid lines with arrows represent the information sent through the interfaces, and for convenience of illustration, only some network elements or devices in the communication system architecture are shown in fig. 5a, 6a, 7a, 8a, 9a, 10a and 11 a.

The first implementation mode,

The first implementation may be applicable to an application scenario in which the DNN is a LADN DNN.

Fig. 5a is a schematic diagram of a main flow of the first implementation mode. As shown in fig. 5a, the first core network element is an AMF entity, and the second core network element is a UDM entity. The UDM sends notification information used for indicating subscription change to the AMF, the AMF sends first information to the terminal after receiving the notification information, and the terminal receives the first information sent by the AMF, wherein the first information is used for notifying the terminal of subscription change. Fig. 5b shows a schematic diagram of a signaling interaction flow in the first implementation manner. As shown in fig. 5 b:

s501, determining a subscription change by the UDM;

s502, the UDM sends notification information to the AMF, where the notification information is used to indicate a subscription change to the AMF.

Optionally, the notification message may include DNN, an indication of subscription change of DNN, and a user permanent identifier (SUPI). The indication of subscription change of the DNN may include at least one of: DNN unavailable indication (DNN unavailable indication), DNN deleted indication (DNN deleted indication), DNN subscription data deletion indication, DNN subscription data addition indication, DNN subscription data newly added, subscription data type (e.g. mobility subscription, or session management subscription). If the DNN is a LADN DNN, the notification includes: LADN DNN, an indication that LADN DNN has changed, and an indication that SUPILADN DNN has changed may include at least one of: an LADN DNN unavailable indication (LADN unavailable indication), a LADN DNN deleted indication (LADN deleted indication), a LADN DNN subscription data deleted indication, a LADN DNN subscription data newly added indication, newly added LADN DNN subscription data, and a subscription data type (e.g., mobility subscription, or session management subscription). The content of the notification information may also be applicable to issuing notification information for indicating subscription changes for DNNs in other implementations.

S503, the AMF performs a certain operation according to the received notification information, for example, setting the DNN as unavailable, deleting data of the DNN, or storing information of the newly added DNN.

S504, the AMF sends first information to the terminal, and the first information is used for informing the terminal of subscription change.

Optionally, the AMF sends the first information to the terminal, where the first information may carry indication (indication) information, and the indication information is used to indicate a subscription change of the terminal.

If the DNN is a LADN DNN, the first information may carry an indication information, where the indication information is used to notify the terminal of subscription change; or, the AMF may also notify the terminal of the subscription change in an implicit indication manner, for example, the first information only carries the LADN DNN and does not carry the service area of the LADN; or the first information carries service area lists of the LADN DNN and the LADN, and the service area list of the LADN is empty; or the first information carries service areas of the LADN DNN and the LADN, and the size of the service area of the LADN is 0. Generally, the AMF sends a service area of a LADN DNN and a LADN with a size of not 0 to the terminal, and notifies the terminal of the LADN and the service area that can be used.

And S505, after receiving the first information, the terminal determines the subscription change of the DNN according to the first information. And determining the specific type of the subscription change of the DNN according to the first information, deleting the data and the context of the DNN by the terminal if the specific type is the subscription data deletion of the DNN, and storing the newly added DNN data by the terminal if the subscription data with the specific type of the DNN is newly added. And if the specific type is DNN unavailable, the terminal sets the DNN as unavailable.

And if the DNN is the LADN DNN, the terminal deletes the LADN DNN information after receiving the first information.

After receiving the first information, if the first information only carries a LADN DNN, the size of a service area not carrying the LADN or a service area carrying the LADN is 0, or the first information carries a service area list of the LADN DNN and the LADN and the service area list of the LADN is empty. Determining the subscription change of the LADN and deleting the LADN information by the terminal.

It should be noted that S503 and S504 do not have a sequential execution order, and both steps may also be performed simultaneously.

The AMF determines that the terminal configuration needs to be updated or the terminal needs to initiate a registration procedure for one or more reasons (e.g., terminal mobility change, network policy, subscription data change). Specifically, the AMF sends a terminal configuration update command to the terminal, including the parameters of the terminal: 5G global unique temporary identity (5G-GUTI), tracking area identity List (TAI List), LADN information (LADN information), Network Identity and Time Zone (NITZ), and terminal configuration update cause (UE configuration update cause). If the reason for updating the terminal configuration requires a response to the terminal configuration update command, the terminal sends a terminal configuration update completion message to the AMF. In an application scenario where the terminal configuration needs to be updated or the terminal needs to initiate a registration procedure, the first information may be a terminal configuration update command (UE configuration update command), that is, the AMF carries an instruction of subscription change in the UE configuration update command sent to the terminal.

The second implementation mode,

As shown in fig. 6a, the first core network element is an SMF, and the second core network element is a UDM. And the UDM notifies the SMF of the subscription change of the DNN, the SMF sends first information to the terminal after receiving the notification information, and the terminal receives the first information sent by the SMF, wherein the first information is used for notifying the terminal of the subscription change of the DNN.

Based on the second implementation manner, if the terminal has established a PDU session with the DN identified by the DNN, the first information may be notified to the terminal through a PDU session release procedure. Fig. 6b is a signaling diagram illustrating the first information notified to the terminal through the PDU session release procedure. As shown in fig. 6b, the specific signaling flow includes:

s601, the UDM determines the subscription change of the DNN.

Optionally, the UDM determines that the terminal has established a PDU session with the DN identified by the DNN according to the stored context information about the session management context or about the PDU session of the terminal, and then the UDM determines that the terminal can be notified of the subscription change information through the SMF. For example, the notification may be through a PDU session release procedure. Alternatively, the UDM may only notify the SMF and not the AMF.

S602, the UDM sends a notification to the SMF, where the notification information is used to indicate a subscription change of the DNN.

S603, the SMF decides to release the PDU session established by the terminal and the DN identified by the DNN.

The reason for triggering the release of the PDU session is a subscription change.

S604, the SMF sends first information to the terminal, and the first information is used for informing the terminal DNN of subscription change.

The first information sent by the SMF to the terminal is sent to the terminal through the AMF and the access network equipment. Specifically, after the SMF determines to release the PDU session, information is sent to the terminal through the AMF and the access network device in the PDU session release process, the information sent in each step carries an indication of subscription change, and finally the information of subscription change of the DNN is notified to the terminal.

In combination with the PDU session release procedure shown in fig. 2, specifically, the SMF sends the subscription change information to the AMF through 3a or 3b, and specifically, the information indicating the subscription change may be carried in the Namf _ Communication _ N1N2MessageTransfer operation service. The AMF sends the subscription change information to the access network device in step 204, and specifically, the information for indicating the subscription change may be carried in the N2 SM Resource Release request. The access network device sends the subscription change information to the terminal in step 205, and specifically, the information for indicating the subscription change may be carried by AN-specific resource modification.

The AMF needs to perform some operations after receiving the information indicating the subscription change sent by the SMF. For example, if the subscription data of which the specific type of subscription change is DNN is deleted, the AMF deletes the data of DNN, and if the subscription data of which the specific type is DNN is newly added, the AMF saves the newly added DNN data. If the specific type is DNN unavailable, the AMF sets DNN as unavailable.

And S605, after receiving the first information, the terminal determines the subscription change and determines the subscription change of the DNN according to the first information. And determining the specific type of the subscription change of the DNN according to the first information, deleting the data and the context of the DNN by the terminal if the specific type is the subscription data deletion of the DNN, and storing the newly added DNN data by the terminal if the subscription data with the specific type of the DNN is newly added. And if the specific type is DNN unavailable, the terminal sets the DNN as unavailable.

The third implementation mode,

Fig. 7a is a schematic main flow chart of the third implementation mode. As shown in fig. 7a, the first core network element is an SMF, the second core network element is an AMF, the UDM sends notification information for indicating a subscription change to the AMF, the AMF receives the notification information sent by the UDM, and the AMF sends notification information for indicating a subscription change to the SMF. The specific process comprises the following steps: after determining the subscription change, the UDM only notifies the AMF of the subscription change, and does not notify the SMF of the subscription change; after receiving the notification information of the UDM, the AMF notifies the SMF of the subscription change, after receiving the notification, the SMF sends first information to the terminal, and the terminal receives the first information sent by the SMF, wherein the first information is used for notifying the terminal of the subscription change.

Based on the third implementation manner, if the terminal has established a PDU session with the DN identified by the DNN, the first information may be notified to the terminal through a PDU session release procedure. Fig. 7b is a signaling diagram illustrating the first information notification to the terminal through the PDU session release procedure. As shown in fig. 7b, the specific signaling flow includes:

s701, the UDM determines the subscription change of the DNN.

S702a, the UDM sends a notification message to the AMF, and the AMF receives the notification message sent by the UDM, where the notification message is used to indicate a subscription change of the DNN.

S702b, after receiving the notification information sent by the UDM, the AMF performs a certain operation, for example, delete subscription data and context of the DNN, or set the DNN as unavailable, or save information of the newly added DNN.

And S703, the AMF sends notification information to the SMF, and the AMF receives the notification information sent by the UDM, wherein the notification information is used for indicating subscription change.

The steps of S704 to S706 are the same as those of S603 to S605, and are not described again.

The implementation mode four,

Fig. 8a is a schematic main flow chart of the fourth implementation mode. As shown in fig. 8a, the first core network element is an AMF, the second core network element is a UDM, the system further includes a third core network element, the second core network element further sends a notification to the third core network element, the third core network element receives notification information of the second core network element, the notification information is used for indicating a subscription change, and the third core network element is an SMF. The specific process comprises the following steps: and after determining the subscription change, the UDM selects to respectively notify the AMF and the SMF of the subscription change. And after receiving the notification information of the UDM, the AMF sends first information to the terminal, wherein the first information is used for indicating the subscription change. And the terminal receives the first information sent by the AMF, determines subscription change, deletes subscription data and context of the DNN, or sets the DNN as unavailable. In addition, if the terminal establishes the PDU session with the DN identified by the DNN, the first information is also used for indicating the terminal to delete the PDU session information. After receiving the notification information of the UDM, the SMF sends indication information (which may be referred to as information for short) to the access network device, where the indication information is used to indicate the access network device to delete the PDU session context established by the terminal and the DN identified by the DNN.

Based on the fourth implementation manner, in practical application, if the terminal establishes the PDU session with the DN identified by the DNN, the SMF may notify the access network device through the PDU session release procedure. Fig. 8b is a specific signaling diagram in this application scenario. As shown in fig. 8b, the specific signaling flow includes:

s801, the UDM determines the subscription change of the DNN.

S802a, the UDM sends a notification message to the AMF, and the AMF receives the notification message sent by the AMF, where the notification message is used to indicate subscription change of the DNN.

S802b, the UDM sends a notification message to the SMF, and the SMF receives the notification message sent by the AMF, where the notification message is used to indicate subscription change of the DNN.

S803a, the AMF sends first information to the terminal, where the first information is used to notify the terminal of a subscription change of the DNN.

S803b, after receiving the first information, the terminal determines the subscription change of the DNN according to the first information. And determining the specific type of the subscription change of the DNN according to the first information, deleting the data and the context of the DNN by the terminal if the specific type is the subscription data deletion of the DNN, and storing the newly added DNN data by the terminal if the subscription data with the specific type of the DNN is newly added. And if the specific type is DNN unavailable, the terminal sets the DNN as unavailable.

S803c, the SMF decides to release the PDU session established by the terminal with the DN identified by the DNN.

S803c and S803a have no sequential execution order, and S803c and S803b have no sequential execution order.

S804, SMF sends indication information to access network equipment, which is used for indicating to the access network equipment to delete PDU session context and release the empty port resource of PDU session at the side of the access network equipment.

In this step, the SMF does not send the N1 SM message to the terminal. Optionally, the indication information is further used to instruct the access network device to: and if the terminal is in an idle state, not paging the terminal.

Wherein, the indication information sent by the SMF to the access network device is sent to the access network device through the AMF. Specifically, after the SMF determines to release the PDU session, the SMF sends the indication information to the access network device through the AMF in the PDU session release procedure.

In conjunction with the PDU session release procedure shown in fig. 2, specifically, the SMF sends the indication information (may be referred to as third information) to the AMF through 3a or 3b, and specifically, the indication information may be carried in the Namf _ Communication _ N1N2MessageTransfer operation service. The AMF sends the indication information (which may be referred to as fourth information) to the access network equipment through step 204, and specifically, the indication information may be carried in an N2 SM Resource Release request.

And S805, after the access network equipment receives the indication information, deleting the PDU session context and releasing the empty port resource of the PDU session at the access network equipment side.

The implementation mode five,

Fig. 9a is a schematic main flow chart of the fifth implementation mode. As shown in fig. 9a, the first core network element is an AMF, the second core network element is a UDM, the system further includes a third core network element, the second core network element further sends a notification to the third core network element, the third core network element receives notification information of the second core network element, the notification information is used to indicate subscription change of the DNN, and the third core network element is an SMF. The specific process comprises the following steps: after the UDM determines the subscription change for the DNN, the UDM chooses to notify both AMF and SMF of the subscription change, respectively. And after receiving the notification information of the UDM, the AMF sends first information to the terminal when a certain condition is met, wherein the first information is used for indicating the subscription change. Specifically, after receiving the notification information of the UDM, the AMF determines whether the terminal establishes a PDU session with the DN identified by the DNN, and sends the first information to the terminal only when the PDU session is not established between the terminal and the DN identified by the DNN, and does not send the first information to the terminal when the PDU session is established between the terminal and the DN identified by the DNN. The AMF forwards the first information sent by the SMF, because if a PDU session is established between the terminal and the DN identified by the DNN, the UDM sends a notification to the SMF, so that the SMF notifies the terminal of the information of subscription change; if no PDU session is established between the terminal and the DN identified by the DNN, the UDM does not send a notification to the SMF, and at this time, the AMF needs to send a first message to the terminal to notify subscription change. And after receiving the first information, the terminal determines the subscription change, deletes the DNN or sets the DNN as unavailable, or stores the information of the newly added DNN. After receiving the notification information of the UDM, the SMF sends instruction information (which may be referred to as information for short) to the terminal, where the instruction information is used to notify the terminal of subscription change.

Based on the fifth implementation manner, in practical application, the indication information may be notified to the terminal through a PDU session release procedure. Fig. 9b is a schematic diagram of a specific signaling flow in such an application scenario. As shown in fig. 9b, the specific signaling flow includes:

s901, the UDM determines the subscription change of the DNN.

S902a, the UDM sends a notification message to the AMF, and the AMF receives the notification message sent by the UDM, where the notification message is used to indicate a subscription change of the DNN.

After receiving the notification information sent by the UDM, the AMF performs a certain operation, for example, deletes subscription data and context of the DNN, or sets the DNN as unavailable, or stores information of a newly added DNN.

S902b, the UDM sends a notification message to the SMF, and the SMF receives the notification message sent by the AMF, where the notification message is used to indicate a subscription change.

S903a, when a PDU session is established between a terminal and a DN identified by a DNN, the AMF does not send first information to the terminal according to the notification information of the UDM, and the SMF sends the first information to the terminal according to the notification information of the UDM, where the SMF sends the first information to the terminal through the AMF and an access network device, and the AMF forwards the first information sent by the SMF after receiving the first information sent by the SMF, where the first information carries information about subscription change of the DNN. And when the PDU session is not established between the terminal and the DN identified by the DNN, the AMF sends first information to the terminal, wherein the first information is used for informing the terminal of the subscription change of the DNN.

S903b, the SMF decides to release the PDU session established by the terminal with the DN identified by the DNN.

The steps of S904 to S905 are the same as those of S604 to S605, and are not described again.

The realization mode is six,

Fig. 10a is a schematic main flow chart of a sixth implementation mode. As shown in fig. 10a, the first core network element is an AMF, the second core network element is a UDM, the system further includes a third core network element, the second core network element further sends a notification to the third core network element, the third core network element receives notification information of the second core network element, the notification information is used to indicate subscription change of the DNN, and the third core network element is an SMF. The specific process comprises the following steps: and after determining the subscription change of the DNN, the UDM selects to respectively send notification information to the AMF and the SMF, and indicates the subscription change of the DNN through the notification information. And after receiving the notification information of the UDM, the AMF judges whether a PDU session established by the terminal and the DN identified by the DNN exists, and if so, the AMF waits for receiving the second information sent by the SMF. In practical application, if the terminal establishes a PDU session with the DN identified by the DNN, the UDM notifies the terminal of the subscription change information through the SMF. Here, if the AMF determines that the PDU session exists, indicating that the UDM will send notification information to the SMF, the AMF will not immediately indicate the subscription change information to the terminal. The second information is PDU session related information, which refers to information exchanged between each device in the PDU session release process. The second information is information sent by the SMF to the terminal and is transmitted through the AMF. And after receiving the second information sent by the SMF, the AMF sends the first information to the terminal. Optionally, the AMF sends the second information and the first information to the terminal, or carries the subscription change indication in one of the first information and the second information, and sends the information carrying the subscription change indication to the terminal. After receiving the first information and/or the second information sent by the AMF, the terminal deletes the PDU session information and performs other operations of the subscription change, for example, deletes DNN information and sets DNN as unavailable. Therefore, when the UDM sends the notification information to the AMF and the SMF respectively, the AMF only sends the information to the terminal once, so that the subscription change can be notified to the terminal, and the signaling overhead of a network side and the signaling overhead of an air interface are saved. And for the scene that the terminal is in an idle state, the network side is prevented from initiating paging at least twice, thereby further saving signaling overhead.

Fig. 10b shows a signaling flow in a specific application scenario, which includes:

s1001 and UDM determine subscription change of DNN.

S1002a, the UDM sends a notification to the AMF, and the SMF receives notification information sent by the UDM, where the notification information is used to indicate subscription change of the DNN.

S1002b, the UDM sends a notification to the SMF, and the AMF receives notification information sent by the UDM, where the notification information is used to indicate subscription change of the DNN.

S1003a, after receiving the notification information sent by the UDM, the AMF waits to receive the second information sent by the SMF when a PDU session is established between the terminal and the DN identified by the DNN, where the second information may be PDU session related information.

And after receiving the notification information sent by the UDM, the AMF performs a certain operation, such as deleting subscription data and context of the DNN, setting the DNN as unavailable, or saving information of the newly added DNN.

S1003b, after receiving the notification message sent by the UDM, the SMF determines to release the PDU session established between the terminal and the DN identified by the DNN.

S1004, the SMF sends the second message to the AMF, and the AMF receives the second message sent by the SMF, where the second message includes the subscription change information.

In conjunction with the PDU session release procedure shown in fig. 2, the SMF sends the second information to the AMF through 3a or 3b, and specifically, the second information may be carried in the Namf _ Communication _ N1N2message transfer operation service.

S1005, after receiving the second information sent by the SMF, the AMF sends the first information to the terminal. Optionally, at least one of the first information or the second information is transmitted. The first information and the second information are both used for indicating subscription change. It can also be considered that the second information is identical to the first information, i.e. the AMF sends the first information to the terminal is identical to the AMF sends the second information to the terminal.

In combination with the PDU session Release procedure shown in fig. 2, the AMF sends the first information and the second information to the access network device through step 204, and specifically may carry the first information and/or the second information in the N2 SM Resource Release request. The access network device sends the first information and/or the second information to the terminal through step 205, and specifically, the first information and/or the second information may be carried through AN-specific resource modification.

In the embodiment of the application, after the PDU session between the terminal and the DN identified by the DNN is established, the AMF stores the DNN and the PDU session ID, and is used for judging whether the second information is PDU session related information when the AMF receives the second information.

In practical applications, there may be more than one PDU session established between the terminal and the DN identified by the DNN, and when multiple PDU sessions are established between the terminal and the DN, after receiving the notification information sent by the UDM, the SMF may trigger multiple PDU session release procedures, that is, the SMF may send multiple second information to the AMF. Optionally, in S1004a, after receiving the notification message sent by the UDM, the AMF starts a timer, and keeps silent before the timer expires, where the silent is defined as that the AMF does not send the subscription change message to the terminal, and waits to receive the second message sent by the SMF; when the timer expires, the first information may be transmitted to the terminal regardless of whether the second information transmitted by the SMF is received. Or keeping silent before the timer expires, waiting for receiving the second information sent by the SMF during the silent period, and sending the first information and/or at least one second information to the terminal at one time if the second information sent by the SMF reaches a predetermined value, wherein the predetermined value is specified by a protocol or is notified to the AMF by the UDM. Alternatively, before the timer expires, if the AMF determines that all the second information for releasing the PDU session has been received, the first information and/or at least one second information may be transmitted to the terminal at once. Therefore, signaling waste caused by sending PDU session related information once per PDU release flow is avoided, subscription change information sent by the AMF to the terminal, subscription change information sent by the SMF to the terminal and multiple times of PDU session related information sent by the SMF to the terminal are sent to the terminal at one time, empty signaling overhead is saved, and system resources are further saved if the indication of subscription change is carried in the PDU session related information.

And S1006, after the terminal receives the first information and determines the subscription change, deleting the data and the context of the DNN, or setting the DNN as unavailable, or storing the information of the newly added DNN.

The implementation modes are seven,

Fig. 11a shows a main flow diagram of the seventh implementation. As shown in fig. 11a, the first core network element is an AMF entity, and the second core network element is a UDM entity. The UDM notifies the AMF of the subscription change, the AMF sends notification information for indicating the subscription change to the PCF after receiving the notification, the PCF updates a UE routing Policy (URSP) and sends the updated URSP to the AMF, the AMF sends first information to the terminal after receiving the updated URSP, and the terminal receives the first information sent by the AMF, wherein the first information is used for notifying the terminal of the subscription change and the updated URSP.

Fig. 11 is a schematic diagram of a signaling interaction flow in the seventh implementation manner. The first core network element is an AMF entity, and the second core network element is a UDM entity. As shown in fig. 11 a:

s1101, the UDM determines the subscription change.

S1102, the UDM sends a notification to the AMF, where the notification is used to indicate a subscription change to the AMF.

S1103 and the AMF perform a certain operation according to the received notification information, for example, delete subscription data and context of the DNN, or set the DNN as unavailable, or save information of a newly added DNN.

S1104, after receiving the notification, the AMF sends notification information indicating subscription change to the PCF, and the PCF receives the notification information sent by the AMF.

S1105, after receiving the notification information sent by AMF, PCF updates URSP.

For example, the content in the URSP that is related to the DNN is deleted, or the content in the URSP that is related to the newly added DNN is added.

S1106, PCF sends the updated URSP to AMF, AMF receives URSP sent by PCF.

S1107, after receiving the URSP sent by the PCF, the AMF sends first information to the terminal, where the first information is used to notify the terminal of the subscription change, and indicate the updated URSP to the terminal.

S1108, after receiving the first information, the terminal determines a subscription change and determines a URSP update. The terminal determines the specific type of the subscription change of the DNN according to the first information, if the specific type is subscription data deletion of the DNN, the terminal deletes the data and the context of the DNN, and if the specific type is subscription data addition of the DNN, the terminal stores the addition DNN data. And if the specific type is DNN unavailable, the terminal sets the DNN as unavailable. The terminal updates the URSP according to the first information.

Based on the same inventive concept as the communication method shown in fig. 4, the present application further provides a communication apparatus 1200, where the communication apparatus 1200 may be applied to the communication system shown in fig. 1 for implementing the communication method shown in fig. 4. The communication apparatus 1200 is a first core network element. Referring to fig. 12, the communication apparatus 1200 includes: a receiving unit 1201 and a sending unit 1202, wherein:

a receiving unit 1201, configured to receive notification information of a second core network element, where the notification information is used to indicate a subscription change.

A sending unit 1202, configured to send first information to the terminal, where the first information is used to notify the terminal of a subscription change.

The core network element 1200 provided in the embodiment of the present application sends the information for indicating the subscription change to the terminal through the core network element 1200, so as to achieve the purpose of notifying the terminal of the subscription change.

Based on the above embodiments, the present application further provides an AMF1300, where the AMF1300 may be applied to the communication system shown in fig. 1, and is used to implement the function performed by the AMF in any implementation manner in the foregoing embodiments. The AMF1300 is capable of performing all functions performed by the core network element 1200, and when the AMF1300 performs the method shown in fig. 4, the second core network element may be a UDM. The AMF1300 includes a receiving unit 1301 and a transmitting unit 1302. The reception unit 1301 performs the steps performed by the reception unit 1201 in fig. 12, and the transmission unit 1302 performs the steps performed by the transmission unit 1202 in fig. 12.

In addition, the receiving unit 1301 and the sending unit 1302 in the AMF1300 may also implement other operations or functions of the AMF in any implementation manner of the foregoing embodiments, and details are not described here.

Based on the above embodiments, the present application further provides an SMF1400, where the SMF1400 may be applied to the communication system shown in fig. 1, and is used to implement the function executed by the SMF in any implementation manner in the foregoing embodiments. The SMF1400 is capable of performing all functions performed by the core network element 1200, and when the SMF1400 performs the method shown in fig. 4, the second core network element may be a UDM or an AMF. The SMF1400 includes a receiving unit 1401 and a transmitting unit 1402. The reception unit 1401 executes the steps executed by the reception unit 1201 in fig. 12, and the transmission unit 1402 executes the steps executed by the transmission unit 1202 in fig. 12.

In addition, the receiving unit 1401 and the sending unit 1402 in the SMF1400 may also implement other operations or functions of the SMF in any implementation manner of the foregoing embodiments, and are not described herein again.

Based on the above embodiments, the present application further provides a PCF1500, where the PCF1500 may be applied to the communication system shown in fig. 1, and is configured to implement the functions performed by the PCF in the seventh implementation manner in the foregoing embodiments. The PCF1500 is capable of performing all the functions performed by the core network element 1200, and the second core network element may be an AMF when the PCF1500 performs the method shown in fig. 4. PCF1500 includes a receiving unit 1501, a processing unit 1502, and a transmitting unit 1503. The reception unit 1501 executes the reception unit 1201 to perform the steps in fig. 12, and the transmission unit 1502 executes the transmission unit 1202 to perform the steps in fig. 12.

Specifically, the receiving unit 1501 is configured to receive notification information of subscription change sent by the AMF;

a processing unit 1502 is configured to update the URSP according to the notification information.

A sending unit 1502, configured to send the updated URSP to the terminal through the AMF and the access network device.

In addition, receiving unit 1501, processing unit 1502, and sending unit 1503 in PCF1500 may also implement other operations or functions of the PCF in implementation seventh of the foregoing embodiment, which are not described herein again.

Based on the above embodiments, the present application further provides a communication apparatus 1600, where the communication apparatus 1600 can be applied to the communication system shown in fig. 1, and is used to implement the functions executed by the terminal in any implementation manner in the foregoing embodiments. The communication device 1600 includes a receiving unit 1601 and a processing unit 1602. A receiving unit 1601, configured to receive first information sent by a core network element, where the core network element is an access and mobility management function AMF or a session management function SMF, and the first information is used to indicate a subscription change of a data network name DNN; the processing unit 1602 deletes the DNN data and context or adds the DNN data according to the first information.

In addition, the receiving unit 1601 and the processing unit 1602 in the communication device 1600 may also implement other operations or functions of the terminal in any implementation manner of the foregoing embodiments, and are not described herein again.

It should be noted that, the division of the modules in the embodiments of the present application is schematic, and is only a logical function division, and in actual implementation, there may be another division manner, and in addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or may exist alone physically, or two or more units are integrated in one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Based on the same inventive concept of the communication method shown in fig. 4, the present application further provides a core network element 1700, where the core network element 1700 may be applied to the communication system shown in fig. 1, and is used to implement the communication method shown in fig. 4. The core network element 1700 is denoted as a first core network element. Referring to fig. 17, the core network element 1700 includes: a transceiver 1701, and a processor 1702, optionally including a memory 1703. Wherein:

the transceiver 1701 is used for receiving and transmitting data to enable communication with other devices in the communication system.

The processor 1702 is configured to execute a set of programs, and when the programs are executed, the execution enables the processor 1702 to implement the communication method provided in the embodiment shown in fig. 4, which may specifically refer to the description in the foregoing embodiment, and is not described herein again.

The memory 1703 is used for storing programs executed by the processor 1702. In particular, the program may include program code comprising computer operating instructions. The memory 1703 may include Random Access Memory (RAM), and may also include non-volatile memory (e.g., at least one disk memory). The processor 1702 executes the program stored in the memory 1703 to implement the above functions, thereby implementing the communication method provided in the above embodiments.

Based on the foregoing embodiments, the present application further provides an AMF1800, where the AMF1800 may be applied to the communication system shown in fig. 1, and is used to implement the function performed by the AMF in any implementation manner in the foregoing embodiments. Referring to fig. 18, the AMF1800 includes: a transceiver 1801 and a processor 1802, and optionally a memory 1803. Wherein:

the transceiver 1801 is configured to receive and transmit data, so as to implement communication with other devices in the communication system.

The processor 1802 is configured to execute a set of programs, and when the programs are executed, the execution causes the processor 1802 to implement the functions performed by the AMF in any implementation manner in the foregoing embodiments, which may specifically refer to the description in the foregoing embodiments, and details are not described herein again.

The memory 1803 is used for storing programs executed by the processor 1802. In particular, the program may include program code comprising computer operating instructions. The memory 1803 may include a Random Access Memory (RAM) and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory. The processor 1802 executes the program stored in the memory 1803 to implement the above functions, thereby implementing the method of AMF execution in any one of the implementations described above.

Based on the foregoing embodiments, the present application further provides an SMF1900, where the SMF1900 may be applied to the communication system shown in fig. 1, and is configured to implement the function executed by the SMF in any implementation manner in the foregoing embodiments. Referring to fig. 19, the SMF1900 includes: a transceiver 1901, and a processor 1902, optionally including a memory 1903. Wherein:

a transceiver 1901, configured to receive and transmit data, and implement communication with other devices in the communication system.

The processor 1902 is configured to execute a set of programs, and when the programs are executed, the execution causes the processor 1902 to implement the functions performed by the SMF in any implementation manner in the foregoing embodiments.

The memory 1903 is used for storing programs executed by the processor 1902. In particular, the program may include program code comprising computer operating instructions. The memory 1903 may include a Random Access Memory (RAM) and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory. The processor 1902 executes the program stored in the memory 1903 to implement the above-described functions, thereby implementing the method performed by the SMF in any of the implementations of the above embodiments.

Based on the foregoing embodiments, the present application further provides a PCF2000, where the PCF2000 may be applied to the communication system shown in fig. 1, and is configured to implement the functions performed by the PCF in the seventh implementation manner in the foregoing embodiments. Referring to fig. 20, the PCF2000 comprises: a transceiver 2001 and a processor 2002, optionally including a memory 2003. Wherein:

a transceiver 2001 for receiving and transmitting data to enable communication with other devices in the communication system.

The processor 2002 is configured to execute a set of programs, and when the programs are executed, the execution causes the processor 2002 to implement the functions performed by the PCF in the seventh implementation manner in the foregoing embodiment, which may be specifically referred to the description in the foregoing embodiment, and details are not described here again.

The memory 2003 is used for storing programs executed by the processor 2002. In particular, the program may include program code comprising computer operating instructions. The memory 2003 may include Random Access Memory (RAM) and may also include non-volatile memory (non-volatile memory), such as at least one disk memory. The processor 2002 executes the program stored in the memory 2003 to implement the above functions, thereby implementing the method performed by the PCF in the seventh implementation manner in the above embodiment.

Based on the foregoing embodiments, the present application further provides a communication apparatus 2100, where the communication apparatus 2100 may be applied to a communication system as shown in fig. 1, and is used to implement the functions performed by the terminal in the foregoing embodiments. Referring to fig. 21, the communication device 2100 includes: a transceiver 2101 and a processor 2102, optionally including a memory 2103. Wherein:

the transceiver 2101 is configured to receive and transmit data, and implement communication with other devices in the communication system.

The processor 2102 is configured to execute a set of programs, and when the programs are executed, the execution causes the processor 2102 to implement the functions performed by the terminal in the foregoing embodiments, which may specifically refer to the description in the foregoing embodiments, and is not described herein again.

The memory 2103 is used for storing programs executed by the processor 2102. In particular, the program may include program code comprising computer operating instructions. The memory 2103 may include Random Access Memory (RAM), and may also include non-volatile memory (non-volatile memory), such as at least one disk memory. The processor 2102 executes the program stored in the memory 2103 to implement the above-described functions, thereby implementing the method performed by the terminal in the above-described embodiment.

The embodiment of the present application provides a computer storage medium, which stores a computer program, where the computer program includes a program for executing the communication method described in fig. 4 and a method provided in any one implementation manner of the foregoing embodiment.

The embodiment of the present application provides a computer program product containing instructions, which when run on a computer, causes the computer to execute the communication method described in fig. 4 and the method provided by any one of the implementation manners of the above embodiments.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to encompass such modifications and variations.

Claims

1. A method of communication, comprising:

a first core network element receives notification information of a second core network element, wherein the notification information is used for indicating subscription change of a data network name DNN; the first core network element is an access and mobility management function (AMF), and the second core network element is a Unified Data Management (UDM);

the first core network element judges whether a PDU session established between a terminal and a DN identified by a DNN exists, and if the PDU session of a packet data unit is not established between the terminal and a data network DN identified by the DNN, the first core network element sends first information to the terminal; if a PDU session has been established between the terminal and the DN identified by the DNN, the AMF does not send first information to the terminal, or if a PDU session has been established between the terminal and the DN identified by the DNN, the first core network element waits to receive second information sent by a session management function SMF, and after receiving the second information sent by the SMF, the first core network element sends first information to the terminal, where the first information is used to notify the terminal of a subscription change of the DNN.

2. The method of claim 1, wherein the subscription change of the DNN is a subscription data deletion of the DNN or a subscription data addition of the DNN.

3. The method of claim 1 or 2, wherein the DNN is a local area data network, LADN, DNN;

the first information carries the LADN DNN and does not carry a service area of the LADN; or the first information carries service area lists of the LADN DNN and the LADN, and the service area list of the LADN is empty; or the first information carries service areas of the LADN DNN and the LADN, and the size of the service area of the LADN is 0;

the first information is also used for indicating the terminal to set the LADN DNN as unavailable or delete the LADN information.

4. The method according to claim 1 or 2, wherein the first core network element is an AMF and the second core network element is a unified data management UDM;

the first core network element sends first information to the terminal, including:

the AMF determines that the terminal establishes a PDU session with the DN identified by the DNN, and starts a timer;

the AMF sends the first information to the terminal when the timer expires; or, before the timer expires, the AMF determines that the number of received second messages sent by the SMF reaches a predetermined value, and sends the first message to the terminal.

5. The method of claim 1 or 2, wherein the second information is PDU session related information, and the first information is used to instruct the terminal to delete PDU session information.

6. The method of claim 1 or 2, wherein the first core network element is an AMF and the second core network element is a UDM;

the first information is also used for indicating the terminal to delete PDU session information;

the method further comprises the following steps:

the first core network element receives third information sent by the SMF, wherein the third information is used for indicating the access network equipment to delete the context of the PDU session established between the terminal and the data network DN identified by the DNN;

and the first core network element sends fourth information to the access network equipment according to the third information, wherein the fourth information is used for indicating the access network equipment to delete the PDU session context.

7. The method of claim 6, wherein the third information is further used to indicate to the first core network element that the terminal is not to be paged if the terminal is in an idle state.

8. The method of claim 1 or 2, wherein the first core network element is an AMF and the second core network element is a UDM;

the method further comprises the following steps:

the first core network element informs a policy control function PCF of: the subscription change is used for indicating the PCF to update a UE routing strategy URSP;

the first information carries the updated URSP and is used for indicating the terminal to update the URSP.

9. A method of communication, comprising:

the unified data management UDM determines the subscription change of the data network name DNN;

the UDM sends notification information to a Session Management Function (SMF), and/or the UDM sends notification information to an access and mobile management function (AMF);

the notification information is used for indicating subscription change of a data network name DNN;

when a terminal and a data network DN identified by the DNN have established a Packet Data Unit (PDU) session, the UDM sends notification information to the SMF, or the UDM respectively sends notification information to both the SMF and the AMF;

and when the terminal does not establish a PDU session with the DN identified by the DNN, the UDM only sends notification information to the AMF.

10. A communication device, for application in a first core network element, the device being an access and mobility management function, AMF, the device comprising a transceiver and a processor, the processor being configured to invoke a set of programs, and when a program is executed, the processor being configured to:

receiving notification information of a second core network element through the transceiver, wherein the notification information is used for indicating subscription change of a data network name DNN;

the second core network element is a Unified Data Management (UDM);

the processor is specifically configured to:

judging whether a PDU session established between a terminal and a DN identified by a DNN exists, and if the PDU session of a packet data unit is not established between the terminal and a data network DN identified by the DNN, sending first information to the terminal through the transceiver; if a PDU session is established between the terminal and the DN identified by the DNN, first information is not sent to the terminal, or if the PDU session is established between the terminal and the DN identified by the DNN, second information sent by a Session Management Function (SMF) is waited to be received through the transceiver, the first information is sent to the terminal through the transceiver after the second information sent by the SMF is received through the transceiver, and the first information is used for informing the terminal of the subscription change of the DNN.

11. The apparatus of claim 10, wherein the subscription change to DNN is a subscription data deletion of DNN or a subscription data addition of DNN.

12. The apparatus of claim 10 or 11, wherein the DNN is a local area data network, LADN, DNN;

13. The apparatus according to claim 10 or 11, wherein the apparatus is an AMF, and the second core network element is a unified data management, UDM;

the processor is specifically configured to:

determining that the terminal establishes a PDU session with the DN identified by the DNN, and starting a timer;

transmitting, by the transceiver, the first information to the terminal when the timer expires; or, before the timer expires, determining that the number of received SMF-transmitted second messages reaches a predetermined value, and transmitting the first message to the terminal through the transceiver.

14. The apparatus of claim 10 or 11, wherein the second information is PDU session related information, and the first information is used to instruct the terminal to delete PDU session information.

15. The apparatus according to claim 10 or 11, wherein the apparatus is an AMF, and the second core network element is a UDM;

the processor is further configured to:

receiving third information sent by the SMF through the transceiver, wherein the third information is used for instructing the access network equipment to delete the context of the PDU session established between the terminal and the data network DN identified by the DNN;

and according to the third information, sending fourth information to the access network equipment through the transceiver, wherein the fourth information is used for indicating the access network equipment to delete the PDU session context.

16. The apparatus of claim 15, wherein the third information is further for indicating to the first core network element that the terminal is not to be paged if the terminal is in an idle state.

17. The apparatus according to claim 10 or 11, wherein the apparatus is an AMF, and the second core network element is a UDM;

the processor is further configured to:

-notifying, by said transceiver, to a policy control function PCF: the subscription change is used for indicating the PCF to update a UE routing strategy URSP;

18. A unified data management, UDM, comprising a transceiver and a processor, wherein the processor is configured to invoke a set of programs, and wherein when a program is executed, the processor is configured to: the method comprises the following steps:

determining subscription change of a data network name DNN;

sending notification information to a session management function, SMF, and/or sending notification information to an access and mobility management function, AMF, through the transceiver;

the processor is specifically configured to:

when a terminal and a data network DN identified by the DNN have established a Packet Data Unit (PDU) session, sending notification information to the SMF through the transceiver, or sending notification information to both the SMF and the AMF respectively;

and when the terminal does not establish a PDU session with the DN identified by the DNN, only sending notification information to the AMF.

19. A communication system, comprising:

the unified data management UDM is used for sending notification information to an access and mobile management function AMF and/or a session management function SMF, and the notification information is used for indicating subscription change of a data network name DNN; and the terminal is used for sending notification information to the SMF when a Packet Data Unit (PDU) session is established between the terminal and the data network DN identified by the DNN, or sending notification information to the SMF and the AMF respectively; when the terminal does not establish a PDU session with the DN identified by the DNN, only sending notification information to the AMF;

the AMF or the SMF is used for receiving notification information of the UDM and sending first information to a terminal, wherein the first information is used for notifying the terminal of subscription change of the DNN;

and the terminal is used for receiving the first information sent by the AMF and/or the SMF, and deleting the data and context of the DNN or adding the DNN data according to the first information.