CN110140333B

CN110140333B - Session management method and terminal

Info

Publication number: CN110140333B
Application number: CN201780081870.8A
Authority: CN
Inventors: 窦凤辉; 金辉; 欧阳国威; 杨皓睿; 李小娟
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-09-11
Filing date: 2017-09-11
Publication date: 2021-06-08
Anticipated expiration: 2037-09-11
Also published as: WO2019047209A1; CN110140333A

Abstract

The embodiment of the application relates to a session management method and a terminal. The method comprises the following steps: a terminal receives a first message sent by an access and mobility management function (AMF), wherein the first message comprises or does not comprise information of an LADN; the terminal determines that the available state of the LADN changes according to the first message; and the terminal modifies or releases the PDU session. By the embodiment of the application, data loss caused by PDU session modification or release of a network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU session accessed to the LADN by the network equipment is also reduced.

Description

Session management method and terminal

Technical Field

The embodiment of the application relates to the technical field of communication, in particular to a session management method and a terminal.

Background

In the 5G Network, a concept of Local Area Data Network (LADN) is introduced, and when a terminal is in a Registration process (Registration Procedure), an access and mobility management entity (AMF) provides, to the terminal, LADN information (e.g., LADN availability information) including a LADN Data Network name (LADN DNN) and a Service Area (LADN Service Area) of the LADN, which is a specific set of Tracking Areas (TAs) in a terminal Registration Area, and when the terminal is located in the LADN Area, a session with a protocol Data Unit (Packet, PDU) of the LADN may be established, and when the terminal is removed from the terminal, the session cannot be performed based on the LADN Data Area.

Generally, an Access and Mobility Management Function (AMF) provides a Session Management Function (SMF) with information about whether a terminal is in a LADN Service Area, so that the SMF determines whether the terminal can establish a Session for accessing a LADN or manages the currently established Session for the purpose of ensuring that the terminal can transmit data based on the LADN only when the terminal is in the LADN Service Area.

After the SMF determines that the terminal moves out of the service area of the LADN, a User Plane Function (UPF) may be notified to drop the Downlink Data of the session accessing the LADN or stop sending a Notification (DDN) of the Downlink Data associated with the session to the SMF, but when the terminal is in an idle state, Data loss may be caused. After the SMF determines that the terminal moves out of the service area of the LADN, the SMF does not notify the UPF to discard the downlink data of the session or stop sending the DDN associated with the session to the SMF, which may waste signaling resources.

Disclosure of Invention

The embodiment of the application provides a session management method and session management equipment. The management of the session accessing the LADN is realized, and the problems of data loss or signaling waste are reduced.

In a first aspect, a method of session management is provided. The terminal has a PDU session accessing the LADN, and the method comprises the following steps: a terminal receives a first message sent by an access and mobility management function (AMF) in a first Registration Area (RA), wherein the first message comprises or does not comprise the information of the LADN; wherein the first RA is a current registration area of the terminal; the terminal determines that the available state of the LADN changes according to the first message; and the terminal modifies or releases the PDU session. The first message may be a Registration Accept message (Registration Accept) or a UE configuration Update Command message (UE configuration Update Command), and the information of the LADN may be available information of the LADN. According to the embodiment of the application, for the session of the LADN, when the terminal enters the information registration area which does not support the LADN from the registration area which supports the information of the LADN, the PDU session is modified or released by the terminal, or when the terminal enters the registration area which supports the information of the LADN from the registration area which does not support the information of the LADN, the PDU session is modified by the terminal, so that the signaling waste caused by paging the terminal due to the fact that downlink data arrive in the PDU session which is accessed to the LADN when the terminal is in an idle state because the registration area does not include the information of the LADN is reduced.

It can be understood that the first message does not include the information of the LADN, and specifically, the first message may not include the information of the LADN, or the information of the LADN in the first message is null, or the first message includes information indicating that other indication information indicates that no LADN is included, which is not limited in the present invention.

It should be noted that the existence of the PDU session accessing the LADN by the terminal may refer to that the terminal stores a context of the PDU session accessing the LADN, where the context of the PDU session may include one or more of the following: an identification of a PDU session; a Session Service Continuity (SSC) mode of a PDU session; a type of PDU session (e.g., IP type), ethernet (ethernet) type, unstructured (unstructured) type, etc.; a Data Network Name (DNN) corresponding to the PDU session; network slice information (e.g., single network slice selection information (S-NSSAI)), a Network Slice Identifier (NSI), etc., corresponding to the PDU session; a QoS Flow Identifier (QFI) of the PDU Session, QoS parameters corresponding to the QoS flow, such as a 5G QoS indicator (5G QoS indicator, 5QI), a Guaranteed Flow Bit Rate (GFBR), a Maximum Flow Bit Rate (MFBR), a Session aggregation maximum bit rate (Session-AMBR), radio bearer information corresponding to the PDU Session, such as a Data Radio Bearer (DRB), or may refer to a PDU Session established by the UE with an access LADN, through which the terminal may transmit uplink and downlink data. Specifically, the PDU session accessed to the LAND means that the DNN attribute corresponding to the PDU session is the landn DNN.

In a first optional implementation of the first aspect, the determining, by the terminal according to the first message, that the availability status of the LADN changes includes: when the first message does not comprise the information of the LADN, and further the terminal judges that the second registration area comprises the information of the LADN, the terminal determines that the information of the LADN in the registration area changes; or, when the first message does not include the information of the LADN and the first registration area includes the information of the LADN before receiving the first message, the terminal determines that the information of the LADN in the registration area changes; the first registration area is a current registration area of the terminal, and the second registration area is a registration area before the terminal enters the current registration area.

In a second optional implementation of the first aspect, the modifying, by the terminal, the PDU session includes: the terminal sends a first session modification request message to the SMF, wherein the first session modification request message comprises a first indication, and the first indication is used for indicating information when the first RA does not comprise the LADN. It can be understood that the terminal further needs to access the PDU session identifier of the LADN to the SMF, and the PDU session identifier may be included in the first session modification request message or may be included in the NAS message sent by the terminal to the AMF, and then forwarded by the AMF to the SMF. The embodiment of the application can realize that the PDU conversation is managed based on the current registration area and the service area of the LADN, and the granularity is fine.

In a third optional implementation of the first aspect, the terminal releasing the PDU session includes: the terminal sends a session release request message to the session management entity SMF. The embodiment of the application can realize that when the terminal is positioned outside the service area of the LADN, the terminal initiates the release of the PDU session, thereby reducing the signaling waste caused by paging the terminal when the PDU session exists but the terminal is not positioned in the service area of the LADN.

In a fourth optional implementation of the first aspect, the method further comprises: the terminal receives a first session modification command message sent by the SMF, wherein the first session modification command message comprises an identification of the PDU session and a first parameter, the first parameter is used for indicating that the PDU session is unavailable, and the identification of the PDU session is used for identifying the PDU session. Wherein the PDU session unavailable comprises one or a combination of: the user plane connection of the LADN session is released; the UPF has been notified to drop the downlink data for the LADN session; the notified UPF stops sending Downlink Data Notification (DDN) related to the session to the SMF, and the gating setting corresponding to the LADN session is closed. The embodiment of the application can realize that the terminal is informed after the network side modifies or releases the PDU session so that the terminal can modify or release the PDU session synchronously, thereby reducing the signaling waste caused by paging the terminal when the PDU session exists but the terminal is not in the service area of the LADN.

In a fifth optional implementation of the first aspect, the method further comprises: the terminal marks the PDU session as unavailable. The method and the device can realize that the terminal can count the times of the terminal continuously entering the registration area of the service area without the LADN by marking the PDU session, thereby setting a rule, modifying the PDU session by the terminal under the condition that the registration area continuously entering the service area without the LADN is less than or equal to the set times, releasing the PDU session by the terminal under the condition that the set times is reached or exceeded, and making the management granularity of the PDU session accessing the LADN finer.

In a sixth optional implementation of the first aspect, the determining, by the terminal according to the first message, that the availability of the LADN changes includes: when the first message includes information of the LADN and the information of the LADN is not included in the first RA before the terminal receives the first message, the terminal determines that the availability status of the LADN changes; or when the first message includes the information of the LADN and the information of the LADN is not included in the second RA, the terminal determines that the available state of the LADN changes; the second RA is an RA before the terminal enters the first RA.

In a seventh optional implementation of the first aspect, the method further comprises: and the terminal sends a second session modification request message to the SMF, wherein the second session modification request message comprises a second indication, and the second indication is used for indicating that the information of the LADN is not included in the first RA. The embodiment of the application can realize that when the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

In an eighth optional implementation of the first aspect, the method further comprises: and the terminal receives a second session modification command message sent by the SMF, wherein the second session modification command message comprises a second parameter, and the second parameter is used for indicating that the PDU session is available. The embodiment of the application can realize the synchronization of the PDU session state between the network side and the terminal side, thereby reducing the possibility of data loss.

In a ninth optional implementation of the first aspect, the method further comprises: the terminal marks the PDU session as available. The method and the device can realize that the terminal can count the times of the terminal continuously entering the registration area of the service area without the LADN by marking the PDU session, thereby setting a rule, modifying the PDU session by the terminal under the condition that the registration area continuously entering the service area without the LADN is less than or equal to the set times, releasing the PDU session by the terminal under the condition that the set times is reached or exceeded, and making the management granularity of the PDU session accessing the LADN finer.

According to the embodiment of the application, for the session of the LADN, when the terminal enters the registration area which does not support the LADN, the terminal modifies or releases the PDU session, so that the signaling waste caused by paging the terminal due to the fact that downlink data arrive in the PDU session which is accessed to the LADN by the network equipment is reduced. PDU conversation can be managed based on the current registration area and the service area of the LADN, and granularity is fine.

In a second aspect, a method of session management is provided. The SMF has a PDU session for accessing the terminal to the LADN, and the method comprises the following steps: the SMF receives a session modification request message sent by the terminal, wherein the session modification request message comprises an indication which is used for indicating that the registration area comprises or does not comprise the information of the LADN; the SMF modifies the PDU session according to the indication, and the information of the LADN can be available information of the LADN. The embodiment of the application can realize that the PDU conversation is managed based on the current registration area and the service area of the LADN, and the granularity is fine.

In a first optional implementation of the second aspect, when the indication indicates that the RA does not include the information of the LADN, the SMF modifying the PDU session according to the indication, comprising: the SMF sends a first session modification command message to the terminal, the first session modification command message comprising an identification of the PDU session and a first parameter indicating that the PDU session is not available. The embodiment of the application can realize that the PDU conversation is managed based on the current registration area and the service area of the LADN, and the granularity is fine.

In a second optional implementation of the second aspect, the SMF modifies the PDU session according to the indication, including one or more of: SMF marks the PDU session as unavailable; the SMF informs a user plane functional entity UPF to discard the downlink data corresponding to the PDU session; and the SMF informs the UPF to stop sending the downlink data notification DDN to the SMF.

In a third optional implementation of the second aspect, when the indication indicates that the RA does not include a LADN, the SMF modifying the PDU session according to the indication, comprising: the SMF sends a second session modification command message to the terminal, the second session modification command message including an identification of the PDU session and a second parameter indicating that the PDU session is available. The embodiment of the application can realize that when the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

It will be appreciated that the SMF modifies the PDU session in accordance with the indication, and the SMF modifies the PDU session in accordance with the received identification of the PDU session and the indication.

In a third aspect, a method of service subscription is provided. The SMF has a PDU session for accessing the terminal to the LADN, and the method comprises the following steps: the SMF subscribes to a notification service from the AMF, wherein the AMF notifies the SMF when a preset event occurs, wherein the availability status of the LADN changes. The method and the device can realize that the RA moved to the AMF subscription terminal by the SMF comprises the change notice of the service area of the LADN, and when the condition is met, the AMF notifies the SMF. The granularity for PDU session management is finer.

In a first optional implementation of the third aspect, the subscribing, by the SMF, to the AMF, of the notification service includes: the SMF sends the AMF the data network name of the LADN and preset events to subscribe to the notification service. According to the embodiment of the application, the change notification of the service area of RA including LADN, which is moved to the AMF subscription terminal by the SMF, can be realized. The granularity for PDU session management is finer.

In a second optional implementation of the third aspect, the available state of the LADN changes, including at least one of: the first registration area does not comprise the information of the LADN, and the second registration area comprises the information of the LADN; changing from information including the LADN to information not including the LADN within a first registration area; the first registration area comprises the information of the LADN, and the second registration area does not comprise the information of the LADN; or, changing from not including the LADN information to including the LADN information in the first registration area; the first registration area is a current registration area of the terminal, the second registration area is a registration area before the terminal enters the first registration area, and the information of the LADN may be available information of the LADN.

In a third optional implementation of the third aspect, the SMF receives notification information sent by the AMF, where the notification information is used to notify that the registration area of the terminal includes or does not include the LADN. The SMF modifies the PDU session according to the notification information. The AMF informs the terminal of the change of the service area of the RA including the LADN to which the terminal moves, and the SMF initiates the release or modification of the LADN session, thereby reducing the signaling waste caused by paging the terminal because the PDU session accessing the LADN has the downlink data arrival.

In a fourth optional implementation of the third aspect, the modifying, by the SMF, the PDU session according to the notification information includes: when the notification information is used to notify that the registration area of the terminal does not include the information of the LADN, the SMF performs one or more of the following: informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session; informing the UPF to stop sending downlink data notification DDN corresponding to the PDU session to the SMF; or, when the notification information is used to notify that the registration area of the terminal includes the information of the LADN, the SMF performs one or more of the following: informing the UPF to send downlink data corresponding to the PDU session; and informing the UPF to send a downlink data notification DDN corresponding to the PDU session. The embodiment of the application can realize that the SMF determines whether to initiate the release or modification of the LADN session according to the support condition of the registration area to the LADN, the management granularity is fine, and the signaling waste caused by paging the terminal because the PDU session accessing the LADN has the arrival of downlink data is reduced, so that the terminal does not need to be paged, and the signaling is saved.

The method and the device can realize that the AMF informs the SMF of the change notice of the service area of the RA including the LADN to which the terminal moves, and the SMF initiates the release or modification of the LADN session, thereby reducing the signaling waste caused by paging the terminal because the PDU session accessing the LADN has downlink data arrival. Or, when the SMF does not modify the PDU session, the SMF can discard the downlink data, so that the terminal does not need to be paged, and the signaling is saved.

In a fourth aspect, a method of service subscription is provided. The AMF has a PDU session for accessing the terminal to the LADN, and the method comprises the following steps: the method comprises the steps that an AMF receives a subscription notification service request sent by an SMF, and the notification service is used for notifying the SMF when a preset event occurs, wherein the preset event is that the available state of a LADN changes, and the information of the LADN can be the available information of the LADN. According to the embodiment of the application, the change notification of the service area of RA including LADN, which is moved to the AMF subscription terminal by the SMF, can be realized, and when the condition is met, the AMF notifies the SMF.

In a first optional implementation of the fourth aspect, the receiving, by the AMF, the subscription notification service request sent by the SMF includes:

and the AMF receives the data network name DNN of the LADN sent by the SMF and a preset event so as to receive the SMF subscription notification service.

In a second optional implementation of the fourth aspect, the available state of the LADN changes, including at least one of: the first registration area does not include information of a LADN, the second registration area includes information of a LADN, and the first registration area is changed from information including a LADN to information not including a LADN; the first registration area comprises information of the LADN, and the second registration area does not comprise information of the LADN; changing a first registration area from not including the LADN to including the LADN; wherein the first registration area is a current registration area of the terminal, and the second registration area is a registration area before the terminal enters the first registration area.

In a third optional implementation of the fourth aspect, after the AMF receives the subscription notification service request sent by the SMF, the method further includes: and the AMF sends notification information to the SMF, wherein the notification information is used for notifying that the registration area of the terminal comprises or does not comprise the information of the LADN. The notification information may specifically include a LADN DNN and an indication indicating that the registration area does not include the LADN

By the embodiment of the application, the SMF can discard the downlink data when the PDU session is not modified, so that the terminal does not need to be paged, and signaling is saved.

In a fifth aspect, a session management method is provided. The SMF has a PDU session accessing the LADN, and the method comprises the following steps: the SMF receives a downlink data notification corresponding to the PDU session sent by the UPF; the SMF invokes a first service provided by AN AMF, where the first service is used for the SMF to request the AMF to send a message or information, such as N2 SM information, to AN access node AN. The SMF receives an indication parameter sent by the AMF, wherein the indication parameter is used for indicating that the information of the LADN is not included in the current registration area; and the SMF modifies the PDU session according to the indication parameter. By the embodiment of the application, the SMF can discard the downlink data when the PDU session is not modified, so that the terminal does not need to be paged, and signaling is saved.

In a sixth aspect, a session management method is provided. The SMF has a PDU session accessing the LADN, and the method comprises the following steps: the AMF receives a first service request called by the SMF, wherein the first service request is used for the SMF to request the AMF to send a message or information to AN access node AN; and when the registration area of the terminal does not comprise the service area of the LADN, the AMF sends an indication parameter to the SMF, wherein the indication parameter is used for indicating that the registration area does not comprise the information of the LADN. The indication parameter may specifically include a LADN DNN and an indication, where the indication is used to indicate that the registration area does not include information of a LADN. By the embodiment of the application, the SMF can discard the downlink data when the PDU session is not modified, so that the terminal does not need to be paged, and signaling is saved.

In a seventh aspect, there is provided a terminal having functionality to implement the terminal behaviour of the first aspect and optionally implementations thereof. 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. According to the embodiment of the application, for the PDU session accessed to the LADN, when the terminal enters the registration area which does not support the LADN, the terminal modifies or releases the PDU session, so that the signaling waste caused by paging the terminal due to the fact that downlink data arrive in the PDU session accessed to the LADN by the network equipment is reduced. PDU conversation can be managed based on the current registration area and the service area of the LADN, and granularity is fine. The method and the device solve the problem that when the terminal is located outside the service area of the LADN, the terminal initiates the release of the PDU session, thereby reducing the signaling waste caused by paging the terminal when the PDU session exists but the terminal is not located in the service area of the LADN. The terminal can also be notified after the network side modifies or releases the PDU session, so that the terminal synchronously modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal when the terminal does not exist in the service area of the LADN. The terminal can count the times of the terminal continuously entering the registration area of the service area without the LADN by marking the PDU session, thereby setting a rule, under the condition that the registration area continuously entering the service area without the LADN is less than or equal to the set times, the terminal modifies the PDU session, and under the condition that the set times is reached or exceeded, the terminal releases the PDU session, and the management granularity of the PDU session accessing the LADN is finer. When the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

In an eighth aspect, there is provided an SMF entity having functionality to implement the SMF entity behaviour in the second and optional implementations 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. According to the embodiment of the application, the PDU session is managed based on the current registration area and the service area of the LADN, and the granularity is fine. When the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

In a ninth aspect, there is provided an SMF entity having the functionality to implement the third aspect described above and optionally the SMF entity behaviour of the or fifth 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. Through the embodiment of the application, the AMF informs the SMF of the change notice of the service area of the RA including the LADN to which the terminal moves, and the SMF initiates the release or modification of the LADN session, thereby reducing the signaling waste caused by paging the terminal because the PDU session accessing the LADN has downlink data arrival. The SMF may notify the SMF by a change notification of a service area to which the RA moved to the AMF subscriber terminal includes the LADN, and when the condition is satisfied, the AMF notifies the SMF. Or, when the SMF does not modify the PDU session, the SMF can discard the downlink data, so that the terminal does not need to be paged, and the signaling is saved.

In a tenth aspect, there is provided an AMF entity having the functionality to implement the actions of the AMF entity in the fourth aspect and optionally in the sixth 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. Through the embodiment of the application, the AMF informs the SMF of the change notice of the service area of the RA including the LADN to which the terminal moves, and the SMF initiates the release or modification of the LADN session, thereby reducing the signaling waste caused by paging the terminal because the PDU session accessing the LADN has downlink data arrival. The SMF may notify the SMF by a change notification of a service area to which the RA moved to the AMF subscriber terminal includes the LADN, and when the condition is satisfied, the AMF notifies the SMF. Or, when the SMF does not modify the PDU session, the SMF can discard the downlink data, so that the terminal does not need to be paged, and the signaling is saved.

In an eleventh aspect, there is provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of any one or more of the first, second, third, fourth, fifth and sixth aspects described above.

In a twelfth aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one or more of the first, second, third, fourth, fifth and sixth aspects described above.

The embodiment of the application can realize that for the session of the LADN, when the terminal enters the registration area which does not support the LADN, the terminal modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal because the PDU session accessing the LADN has the downlink data arrival. PDU conversation can be managed based on the current registration area and the service area of the LADN, and granularity is fine. The method and the device solve the problem that when the terminal is located outside the service area of the LADN, the terminal initiates the release of the PDU session, thereby reducing the signaling waste caused by paging the terminal when the PDU session exists but the terminal is not located in the service area of the LADN.

Drawings

Fig. 1 is a schematic structural diagram of a 5G communication network;

fig. 2 is a schematic diagram of a service area of a LADN.

Fig. 3 is a schematic signaling interaction diagram of a session management method according to an embodiment of the present application;

fig. 4 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application;

fig. 5 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application;

FIG. 6 is an example provided by an embodiment of the present application;

fig. 7 is a schematic signaling interaction diagram of a service subscription method according to an embodiment of the present application;

fig. 8 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application;

fig. 9 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application;

FIG. 10 provides another example of an embodiment of the present application;

fig. 11 is a schematic structural diagram of a terminal according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of an SMF according to an embodiment of the present disclosure;

fig. 13 is a schematic structural diagram of another SMF provided in an embodiment of the present application;

FIG. 14 is a schematic structural diagram of an AMF according to an embodiment of the present application;

fig. 15 is a schematic structural diagram of another SMF provided in an embodiment of the present application;

FIG. 16 is a schematic structural diagram of another AMF provided in an embodiment of the present application;

fig. 17 is a schematic structural diagram of another terminal according to an embodiment of the present application;

fig. 18 is a schematic structural diagram of another SMF provided in an embodiment of the present application;

fig. 19 is a schematic structural diagram of another SMF provided in an embodiment of the present application;

FIG. 20 is a schematic structural diagram of another AMF provided in an embodiment of the present application;

fig. 21 is a schematic structural diagram of another SMF provided in an embodiment of the present application;

fig. 22 is a schematic structural diagram of another AMF according to an embodiment of the present application.

Detailed Description

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

The embodiment of the application provides a session management method and session management equipment, which are applied to a 5G communication network.

In embodiments of the present application, a terminal (terminal) may also be referred to as a user equipment (user equipment), may be a device that provides voice and/or data connectivity to a user, a handheld device with wireless connectivity, or other processing device connected to a wireless modem. Wireless terminals, which may be mobile terminals such as mobile telephones (or "cellular" telephones) and computers having mobile terminal equipment, for example, mobile devices that may be portable, pocket, hand-held, computer-included, or vehicle-mounted, communicate language and/or data with a Radio Access Network (RAN). Examples of such devices include Personal Communication Service (PCS) phones, cordless phones, Session Initiated Protocol (SIP) phones, Wireless Local Loop (WLL) stations, Personal Digital Assistants (PDAs), and the like. A wireless terminal may also be referred to as a system, a subscriber unit (subscriber unit), a subscriber station (subscriber station), a mobile station (mobile), a remote station (remote station), an access point (access point), a remote terminal (remote terminal), an access terminal (access terminal), a user terminal (user terminal), a user agent (user agent), a user equipment (user device), or a terminal equipment (terminal equipment), which is not limited in the embodiments of the present application. According to the service type division, the terminal related to the embodiment of the present invention may be a terminal device having higher requirements for speed and mobility in the foregoing, such as a mobile phone, a multimedia device, and the like, or may be a terminal of the internet of things, or may be a terminal of the internet of vehicles.

Fig. 1 is a schematic structural diagram of a 5G communication network according to an embodiment of the present application.

As shown in fig. 1, the authentication service function (AUSF), the AMF, the SMF, the UDM (unified data management), the AF (application function), the PCF (policy control function), and the UPF may be one or more servers in a core network of the 5G communication network. The terminals can realize network interconnection by accessing a communication network. For example, a PDU session, which may be managed by the SMF, may be established for data transfer with the UPF over the access communication network.

The functions of the respective modules in the 5G communication network are briefly described below.

The AUSF is mainly used for authentication.

The AMF has the functions of mobile management, registration management, connection management, lawful monitoring, support of Session Management (SM) information between the transmission terminal and the SMF, access authentication, access authorization and the like of the terminal. The AMF can determine information such as TA, RA, and LADN of the terminal.

The SMF has functions of session management, roaming and the like. Among them, session management functions, such as session establishment, modification, and release, include UPF and Access Network (AN) node (node) tunnel maintenance. Roaming functions may include charging data collection, signaling to support authentication/authorization with an external Data Network (DN). For example, the SMF may be used to manage PDU sessions for access to the LADN, including PDU sessions for modification or release of access to the LADN, a DDN corresponding to a PDU session for reception of access to the LADN, and so on.

The UPF has functions of data packet routing, lawful interception and the like. The UPF can route and lawfully listen to packets corresponding to PDU sessions accessing the LADN.

The UDM has the functions of certificate authentication, user identification, access authorization, registration and mobility management, subscription management, short message management and the like.

The AF may interact with the 3GPP core network.

The PCF is capable of supporting a policy framework as well as policy rules.

The interface between each entity can be referred to the 3GPP standard. It should be appreciated that the 5G communication network structure shown in fig. 1 is merely an example, and the 5G communication network structure used in the embodiment of the present invention may include more or less network devices.

The applicant of the present application finds, through analysis, that there is a certain relationship between the LADN in the 5G network and the RA, and a Tracking Area (TA) in the RA may support the LADN in whole or in part, or the TA in the RA may not support the LADN in whole. When all or part of the TAs in the RA support the LADN, that is, the LADN Service Area intersects with the Registration Area, the RA is considered to include the Service Area of the LADN. And when all the TAs in the RA do not support the LADN, namely the LADN service Area does not intersect with the RA, the RA is considered to comprise the service Area of the LADN.

It is understood that TA support of the LADN means that when the terminal is in the coverage of the TA, a PDU session for access to the LADN can be established by the base station under the TA and data transmission is performed on the PDU session of the LADN. The TA does not support the LADN means that when the terminal is in the coverage of the TA, a PDU session accessed to the LADN cannot be established, and for the established PDU session of the LADN, the corresponding user plane connection cannot be activated for data transmission.

For example, as shown in fig. 2, fig. 2 is a schematic diagram of a service area of a LADN. TA1-TA16 collectively form four RA's (RA1-RA4), of which TA1-TA5 support LADN. At this time, all TAs in RA1 support the LADN, and thus the RA1 is considered to include the service area of the LADN; if only TA5 in RA2 supports the LADN, the RA1 is considered to include the service area of the LADN; all TAs in RA3 and RA4 do not support the LADN, and the service areas in RA3 and RA4 that do not include the LADN are considered.

The embodiments of the present application will be further described with reference to the accompanying drawings.

Fig. 3 is a schematic signaling interaction diagram of a session management method according to an embodiment of the present application. Wherein, the terminal has a PDU session accessing the LADN.

The terminal has a PDU session accessing the LADN, which may refer to a context of the PDU session stored by the terminal and including one or more of the following: an identification of a PDU session; SSC pattern of PDU sessions; a type of PDU session (e.g., IP type), ethernet (ethernet) type, unstructured (unstructured) type, etc.; DNN corresponding to PDU session; network slice information corresponding to the PDU session, such as S-NSSAI, Network Slice Identity (NSI), etc.; QFI of PDU Session, QoS parameters (e.g. 5QI) corresponding to QoS flow, GFBR, MFBR, Session-AMBR, and radio bearer information corresponding to PDU Session, e.g. DRB, may also refer to a PDU Session where UE establishes access to LADN, and the terminal may transmit uplink and downlink data through the PDU Session. Specifically, the PDU session accessed to the LAND means that the DNN attribute corresponding to the PDU session is the landn DNN.

As shown in fig. 3, the method specifically includes:

s310, the terminal receives the first message sent by the AMF. The AMF registered by the terminal sends the information of the LADN in the registration area of the terminal to the terminal through the first message. The LADN information includes LADN DNN and LADN Service Area. Of course, the LADN information sent to the terminal is a set of LADN information corresponding to the LADN subscribed by the terminal. And if the terminal signs a plurality of LADNs, the LADN information corresponding to the LADNs is sent to the terminal. When the registration area RA in which the terminal is located supports the LADN information, the first message may carry the information of the LADN, for example, the information of the LADN may be available information (LADN availability info) of the LADN. For example, the first message may be a Registration accept message (Registration accept) including information of the LADN; alternatively, the first message may be a UE configuration update command message (UE configuration update command) including information of the LADN, or the like. Wherein, the terminal executes the registration process, and the AMF sends a registration acceptance message to the terminal.

When the registration area where the terminal is located does not support the LADN information, the first message may not carry the information of the LADN.

In one example of the information of the LADN, the information of the LADN includes a LADN data network name (LADN DNN) and a LADN service area (LADN service area). The LADN service area may refer to a TA set of the LADN.

Among them, a plurality of LADNs may be included in the 5G network, and the plurality of LADNs are not necessarily all available to the terminal. The information of the LADN received by the terminal comprises the LADN DNN of the LADN which can be accessed by the terminal and the corresponding LADN service area.

Specifically, the AMF stores a service area of an available LADN for the terminal, and the AMF may determine whether the current RA of the terminal includes information of the LADN according to the current RA of the terminal and the service area of the available LADN for the terminal, that is, whether the current RA of the terminal overlaps with the service area of the available LADN for the terminal. When the current RA of the terminal includes information of a LADN, that is, the current RA of the terminal overlaps with a service area of the LADN available to the terminal, the first message may carry information of the LADN, where the information of the LADN indicates a LADN (LADN dnn) included in the current RA and the service area of the LADN; when the current RA of the terminal does not include the information of the LADN, that is, the current RA of the terminal does not overlap with the service area of the LADN available to the terminal, the first message may not carry the information of the LADN.

As an example, in connection with fig. 2, TA1-TA5 belongs to the service area of the LADN available to the terminal, and if the current RA of the terminal is RA1, since RA1 includes TA1-TA4, the information of the LADN may be carried in the first message. If the current RA of the terminal is RA3, since RA3 does not overlap with the service area of the LADN available to the terminal, the information of the LADN may not be carried in the first message. If the current RA of the terminal is RA2, since RA2 includes TA5, the first message may carry information of the LADN.

S320, the terminal determines that the first message does not include the information of the LADN.

After the terminal receives the first message, the terminal can determine that the state of the LADN in the registration area changes according to the first message, thereby triggering the PDU session of the access LADN to be modified or released.

Specifically, when a first message received by a terminal does not include information of a LADN, the terminal determines that the information of the LADN is not included in a first RA, further, when the terminal judges that the information of the LADN is included in the first RA before the first message is received, that is, the terminal currently stores the information of the LADN, the terminal determines that an available state of the LADN in the RA changes, so that a PDU session accessing the LADN is triggered to be modified or released, and the first RA is the current RA of the terminal.

In another scenario, when a first message received by a terminal does not include information of an LADN, the terminal determines that the first RA does not include the information of the LADN, and further, when the terminal determines that the second RA includes the information of the LADN, that is, the terminal currently stores the information of the LADN, the terminal determines that the available state of the LADN in the RA changes. The first RA is a current RA of the terminal, and the second RA is an RA before the terminal enters the first RA.

In another embodiment, the terminal may determine whether a preset condition is reached according to the first message, and if so, release the PDU session accessing the LADN. If not, the PDU session accessing the LADN is modified.

For example, the preset condition may be the number of times the terminal is continuously in RA that does not support LADN. I.e. the number of times the current RA of the terminal does not continuously include the information of the LADN. For example, a PDU session accessing a LADN may be marked as unavailable the first time the terminal is in an RA that does not support the LADN. And then, when the terminal is continuously in the RA which does not support the LADN for the second time, the terminal determines that the PDU session accessing the LADN is marked as unavailable, and releases the PDU session accessing the LADN. Wherein unavailability may include a suspend state.

For the PDU session with modified access to the LADN, as shown in fig. 3, the method specifically includes S330-S360:

s330, the terminal sends a first session Modification request message (PDU session Modification request) to the SMF. The first session modification request message includes a first indication, which may be used to indicate that the current RA does not include information of the LADN (no LADN available information in current RA). Wherein the LADN information includes at least one of a LADN DNN and a LADN Service Area.

The terminal further needs to send a PDU session identifier to the SMF, where the PDU session identifier may be included in the first session modification request message or may be included in an NAS message sent by the terminal to the AMF, and the AMF sends a PDU session ID to the SMF, where the PDU session ID identifies a PDU session of the terminal accessing the LADN.

S340, the SMF modifies the PDU session accessing the LADN according to the first session modification request message.

The SMF modifying the PDU session for accessing the LADN according to the first session modification request message includes one or more of:

the SMF instructs the UPF to set the gating corresponding to the PDU session accessing the LADN to OFF, e.g., the SMF may send a GATE OFF command (GATE OFF) to the PDU;

the SMF informs the UPF to stop sending the DDN related to the PDU session accessing the LADN;

the SMF informs the UPF to discard downlink data corresponding to the PDU session accessed to the LADN;

the SMF marks the PDU session for access to the LADN as unavailable or pending. Wherein the unavailable or suspended state includes one or more of:

the user plane connection of the PDU session does not exist;

the SMF cannot trigger the user plane connection that activates the PDU session;

the SMF cannot accept the terminal-requested user plane connection request to activate the PDU session.

In addition, after receiving the first session modification request message, the SMF may determine whether the status of the PDU session corresponding to the first session modification request message is available, for example, if the PDU session corresponding to the first session modification request message is unavailable or suspended, it means that the PDU session is unavailable before receiving the first session modification request message, and at this time, the PDU session may be directly released, that is, the context of the PDU session is deleted. And if the PDU session corresponding to the first session modification request message is in an available state, the PDU session is available before the first session modification request message is received, and at the moment, the PDU session is marked as unavailable or suspended after the first session modification request message is received. Wherein the available status of the PDU session includes one or more of:

a user plane connection of a PDU session exists;

the SMF can trigger the user plane connection for activating the PDU session;

the SMF can receive a user plane connection request for activating the PDU session requested by the terminal;

the SMF may send a message to other network elements regarding the PDU session.

S350, the SMF sends a first session modification command message (PDU session modification command) to the terminal. The first session modification command message includes an identification of the PDU session and a first parameter that may be used to indicate that the PDU session is unavailable or pending.

After marking the PDU session as unavailable or suspended, the SMF can also instruct the terminal to mark the PDU session as unavailable or suspended.

S360, the terminal marks the PDU conversation as unavailable or in a suspended state.

The terminal marks the PDU session for access to the LADN as unavailable or pending.

In another implementation, the terminal may also maintain a record that the first indication has been sent to the SMF. Wherein, for the PDU session, if the terminal has a record that the first indication has been sent to the SMF, it may indicate that the PDU session is marked as unavailable.

Wherein S350 and S360 are optional steps. For example, the process of the terminal marking the PDU session as unavailable may also be performed locally by the terminal, in which case the terminal may perform before receiving the first session modification command message, or the SMF need not send the first session modification command message.

Through S360, the terminal can also realize the statistics of the number of times of RA which continuously does not support LADN. Further, a rule may be set that the terminal modifies the PDU session in a case where the number of registrations continuously into the service area not including the LADN is less than or equal to a set number of times, and releases the PDU session in a case where the set number of times is reached or exceeded, with finer management granularity for the PDU session accessing the LADN.

Therefore, the method can realize that the terminal is informed after the network side modifies or releases the PDU session so that the terminal synchronously modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal when the terminal does not exist in the service area of the LADN. .

In the case where a PDU session accessing a LADN is marked as unavailable, the terminal may also mark a PDU session accessing a LADN as available when the terminal determines to re-enter an RA supporting the LADN. Fig. 4 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application. As shown in fig. 4, the method may specifically include S410-S460:

and S410, the terminal receives the second message sent by the AMF.

The AMF also determines whether the current RA of the terminal includes information of the LADN based on the current RA of the terminal and a service area of the LADN available to the terminal. When the current RA of the terminal includes the information of the LADN, the second message may carry the information of the LADN, and the information of the LADN indicates the service area of the LADN and the service area of the LADN included by the current RA; when the current RA of the terminal does not include the information of the LADN, the second message may not carry the information of the LADN. The second message may be a registration accept message or a terminal configuration update command message. For example, the information of the LADN may be available information of the LADN.

As an example, in connection with fig. 2, TA1-TA5 belongs to the service area of the LADN available to the terminal, and if the current RA of the terminal is RA1, since RA1 includes TA1-TA4, the information of the LADN may be carried in the second message. If the current RA of the terminal is RA3, since RA3 does not overlap with the service area of the LADN available to the terminal, the information of the LADN may not be carried in the second message. If the current RA of the terminal is RA2, since RA2 includes TA5, the information of the LADN may be carried in the second message.

And S420, the terminal determines that the second message comprises the information of the LADN.

After receiving the second message, the terminal may determine that the available state of the LADN changes according to the change of the available state of the information LADN carried by the second message. Thereby triggering a PDU session that modifies access to the LADN.

Specifically, when a first message received by a terminal includes information of an LADN, the terminal determines that a first RA includes the information of the LADN, and further, when the terminal does not include the information of the LADN in the first RA before receiving the second message, that is, the terminal does not currently have the information of the LADN, the terminal determines that an available state of the LADN changes; or

When the second message includes the information of the LADN and the information of the LADN is not included in the second RA, namely the terminal does not have the information of the LADN at present, and the terminal determines that the available state of the LADN changes;

the first RA is a current registration area of a terminal, and the second RA is an RA before the terminal enters the first RA.

S430, the terminal sends a second session Modification request message (PDU session Modification request) to the SMF. The second session modification request message includes a second indication, which may be used to indicate that the current RA includes information of the LADN (no LADN available info indication in current RA).

The terminal further needs to send an identifier of the PDU session to the SMF, where the identifier of the PDU session may be included in the second session modification request message or may be included in an NAS message sent by the terminal to the AMF, and the AMF sends the identifier of the PDU session to the SMF, and the PDU session ID identifies the PDU session of the access LADN of the terminal.

S440, the SMF modifies the PDU session accessing the LADN according to the second session modification request message.

The SMF modifying the PDU session for accessing the LADN according to the second session modification request message may include one or more of:

the SMF instructs the UPF to set the gating corresponding to the PDU session accessing the LADN to ON, e.g., the SMF may send a GATE open command (GATE ON) to the PDU;

SMF informs UPF to send DDN related to PDU session of LADN;

the SMF informs the UPF to send downlink data corresponding to the PDU session accessed to the LADN;

the SMF marks the PDU session for access to the LADN as available.

In addition, after receiving the second session modification request message, the SMF may determine whether the status of the PDU session corresponding to the second session modification request message is available, for example, if the PDU session corresponding to the second session modification request message is unavailable, it represents that the PDU session is unavailable before receiving the second session modification request message, and at this time, the PDU session may be marked as available. If the PDU session corresponding to the second session modification request message is in a usable state, it means that the PDU session is usable before receiving the second session modification request message, and at this time, no modification may be made.

S450, the SMF sends a second session modification command message (PDU session modification command) to the terminal. The second session modification command message includes an identification of the PDU session and a second parameter indicating that the PDU session is available.

After marking the PDU session as available, the SMF can also instruct the terminal to mark the PDU session as available.

S460, the terminal marks the PDU session as available.

The terminal marks a PDU session for access to the LADN as available.

Wherein S450 and S460 are optional steps. For example, the process of marking the PDU session as available by the terminal may be performed locally by the terminal, and in this case, may be performed before receiving the second session modification command message, after determining that the second message includes the LADN information, or the SMF need not send the second session modification command message.

Therefore, when the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

Fig. 5 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application. As shown in fig. 5, for releasing the established PDU session related to the LADN, the method may specifically include S510-S520:

and S510, the terminal sends a session release message to the SMF. The session release message may include a PDU session ID indicating a PDU session for the terminal to access the LADN.

S520, the SMF releases the PDU session of the access LADN according to the session release message.

Fig. 6 is an example provided by an embodiment of the present application. The terminal has a PDU session accessing the LADN, as shown in fig. 6, the method includes:

s601, the terminal executes a Registration procedure (Mobility Registration procedure), and receives a Registration acceptance message sent by the AMF.

S602, when the registration acceptance message received by the terminal does not include the information of the LADN, the terminal determines that the available state of the LADN changes, thereby triggering the PDU session modification process of the LADN. For example, the information of the LADN may be available information of the LADN.

Specifically, the terminal determines that the available state of the LADN has changed in the same manner as in the step S320. The registration accept message in this flow is equivalent to the first message in S320.

S603, the terminal sends a PDU session Modification request message (PDU session Modification request) to the AMF. The PDU session modification request message includes indication information (no LADN available information indication) without availability information of the LADN, where the indication information without availability information of the LADN is used to indicate that the current RA does not include a LADN service area.

S604, the AMF sends a PDU session modification request message to the SMF with a request to invoke the SMF service.

S605, the SMF judges whether the PDU session accessing the LADN is in a suspended state.

If yes, directly executing S612, and releasing the PDU session; if not, S606-S611 are performed.

S606, the SMF marks the state of the PDU session accessing the LADN as a suspension state according to the PDU session modification request message.

S607, the SMF sends a response to the AMF invoking the SMF service, where the response to invoke the SMF service includes a PDU session modify command message. The PDU session modify command message includes a session suspend parameter for instructing the terminal to mark the PDU session as a suspended state.

S608, the AMF sends a PDU session modification command message to the terminal.

The terminal can be notified after the network side modifies or releases the PDU session, so that the terminal synchronously modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal when the terminal does not exist in the service area of the LADN.

S609, the terminal marks the PDU session accessing the LADN to be in a suspended state.

Alternatively, in another implementation, the terminal may maintain a record of indication that no information for the LADN has been sent to the SMF. And after the terminal enters the RA including the LADN service area again, initiating the PDU session modification flow again to inform the SMF, and the terminal enters the RA including the LADN service area again.

The terminal can count the times of the terminal continuously entering the registration area of the service area without the LADN by marking the PDU session, thereby setting a rule, under the condition that the registration area continuously entering the service area without the LADN is less than or equal to the set times, the terminal modifies the PDU session, and under the condition that the set times is reached or exceeded, the terminal releases the PDU session, and the management granularity of the PDU session accessing the LADN is finer.

S610, the SMF sends a session modification request message to the UPF. Wherein the session modification request message may be sent through an N4 interface.

The session modification request message carries an indication (GATE OFF) that the gating is set to be closed, or notifies the UPF to stop sending Downlink Data Notification (DNN) related to the PDU session accessing the LADN, and discards the corresponding Downlink Data.

S611, the UPF sends a session modification response to the SMF. Wherein, the UPF may set a gating of a data flow (flow) corresponding to the PDU session to a closed state, or stop transmitting the DDN related to the PDU session accessing the LADN, and discard the corresponding data.

When the terminal reenters the RA of the service area comprising the LADN, the PDU session of the access LADN is restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

Fig. 7 is a schematic signaling interaction diagram of a service subscription method according to an embodiment of the present application. As shown in fig. 7, the method specifically includes:

s710, the SMF subscribes to the notification service to the AMF. For example, the SMF sends a request for a subscription notification service to the AMF, that is, the SMF invokes the subscription notification service provided by the AMF, to implement the SMF subscribing to the notification service from the AMF. The notification service is used for notifying the SMF by the AMF when a preset event occurs, wherein the preset event is that the available state of the LADN changes, and the change in the available state of the LADN may be that the available state of the LADN in the registration area changes.

When subscribing to the notification service from the AMF, the SMF may send a data network name of the LADN (LADN DNN) and a preset event to the AMF to subscribe to the notification service from the AMF. Of course, the SMF may also send to the AMF a filter about the preset event, so that the AMF may determine the occurrence of the preset event through the filter, and in addition, the SMF may also send to the AMF other parameters capable of identifying the occurrence of the preset event, which is not limited in the present invention.

The preset event is that the available state of the LADN changes, and specifically may refer to that the registration area is switched between including the LADN information and not including the LADN information, including one or more of the following situations:

the terminal enters a second RA which does not comprise the information of the LADN from a first RA which comprises the information of the LADN;

the terminal enters a second RA comprising the information of the LADN from a first RA not comprising the information of the LADN;

the terminal does not replace the RA, but the LADN available for the terminal is changed, so that the first RA of the terminal is changed from the information comprising the LADN to the information not comprising the LADN;

the terminal does not replace the RA, but the LADN available to the terminal is changed so that the first RA of the terminal is changed from information not including the LADN to information including the LADN.

Wherein the first RA is a current RA of the terminal and the second RA is an RA before the terminal enters the first RA. The information of the LADN may be available information of the LADN.

For example, as shown in connection with fig. 2, TA1-TA5 belongs to a service area of an available LADN for a terminal, and when the current registration area of the terminal is moved from RA1 (or RA2) to RA3 or from RA2 to RA4, that is, the terminal is moved from an RA including information of the LADN to an RA not including information of the LADN, it is considered that the registration area entered by the terminal is changed between information including and not including the LADN, and vice versa.

As another example, shown in connection with fig. 2, TA1-TA5 belong to the service area of the LADN available to the terminal. When the network side cancels the LADN service with TA1-TA5, if the current registration area of the terminal is RA1, the RA of the terminal is changed from the information including the LADN to the information not including the LADN, and the registration area entered by the terminal is considered to be changed between the information including the LADN and the information not including the LADN. When the network side sets TA10 to support the LADN and TA10 belongs to the service area of the available LADN for the terminal, if the current registration area of the terminal is RA3, the RA of the terminal is changed from the information not including the LADN to the information including the LADN, and it is considered that the registration area entered by the terminal is changed between the information including and not including the LADN.

S720, the AMF determines that the available state of the LADN changes.

The AMF determines whether the current RA of the terminal comprises information of the LADN according to the change condition of the RA of the terminal and the change condition of the service area of the LADN available for the terminal, and judges whether the information of the LADN in the registration area entered by the terminal is changed or not, or whether the change between the information comprising the LADN and the information not comprising the LADN is generated in the same registration area, namely whether the available state of the LADN is changed or not.

And S730, the AMF sends notification information to the SMF, wherein the notification information is used for notifying the SMF of the occurrence of the preset event subscribed by the SMF. The notification information may include a LADN DNN and/or an indication parameter, where the LADN DNN is used to identify the LADN, and the indication parameter is used to indicate that a preset event subscribed by the SMF occurs, and specifically may be information (LADN available/unavailable indication in current RA) that the RA of the terminal includes or does not include the LADN, or information that the RA of the terminal converts between the information that includes the LADN and that does not include the LADN, or other parameters used to indicate that the preset event changes, which is not particularly limited in the present invention.

Specifically, the AMF sends the registration area of the terminal to the SMF including the LAND information in the sense that the registration area of the terminal transitions from information not including the landn to information available including the landn. If sent to the SMF, the registration area of the terminal does not include the available information of the LADN in the sense that the registration area of the terminal is switched from information including the LADN to information not including the LADN. Of course, the AMF may send other parameters to the SMF to instruct the registration area of the terminal to switch between including and not including the LADN information.

For example, when the AMF determines that the terminal enters a first registration area not including information of the LADN from a second registration area including information of the LADN, the AMF transmits a notification message to the SMF when the terminal registers in the first registration area, the notification message not including information of the LADN.

Or, when the AMF determines that the terminal enters a first registration area comprising the information of the LADN from a second registration area not comprising the information of the LADN, and the AMF sends a notification message to the SMF when the terminal registers in the first registration area, wherein the notification message comprises the information of the LADN.

Or, when the AMF determines that the registration area of the terminal is the first registration area, and the first registration area is reconfigured to not include the LADN from the information including the LADN, the AMF sends a notification message to the SMF, wherein the notification message does not include the information of the LADN.

Or, when the AMF determines that the registration area of the terminal is the first registration area, and the first registration area is reconfigured to include the LADN from the information not including the LADN, the AMF sends a notification message to the SMF, wherein the notification message includes the information of the LADN.

For another example, as shown in fig. 2, when the current registration area of the terminal is moved from RA1 (or RA2) to RA3 or from RA2 to RA4, that is, the terminal is moved from an RA including information of a LADN to an RA not including information of the LADN, the AMF sends notification information that the current RA of the terminal does not include information of the LADN to the SMF. When the current registration area of the terminal is moved from RA3 to RA1 (or RA2) or from RA4 to RA2, that is, the terminal is moved from an RA not including information of the LADN to an RA including information of the LADN, the AMF transmits notification information that the current RA of the terminal includes information of the LADN to the SMF.

And S740, the SMF modifies or releases the PDU session according to the notification information.

After receiving the notification message and determining that the availability status of the LADN changes, the SMF may modify or release the PDU session accessing the LADN.

If the PDU session accessing the LADN is unavailable, the SMF modifies the PDU session accessing the LADN to be in an available state after receiving the notification information that the current RA of the terminal comprises the information of the LADN. Further, the SMF may also perform one or more of the following steps: informing the UPF to set the gate control corresponding to the PDU session accessed to the LADN to be on; informing the UPF to send the DDN related to the PDU session accessing the LADN; informing the UPF to send downlink data associated with the PDU session accessing the LADN.

If the PDU session accessing the LADN is in an available state, after the SMF receives the notification information that the current RA of the terminal does not include the information of the LADN, the SMF modifies the PDU session accessing the LADN to be unavailable, and further, the SMF may further perform one or more of the following steps: informing the UPF to set the gate control corresponding to the PDU session accessed to the LADN to be off; informing the UPF to stop sending the DDN related to the PDU session accessing the LADN; the UPF is notified to discard the downlink data associated with the PDU session accessing the LADN.

In another possible implementation, after the SMF receives notification information that the current RA of the terminal does not include the information of the LADN, the PDU session for accessing the LADN may be released. For example, if the PDU session accessing the LADN is in the available state, after the SMF receives the notification information that the current RA of the terminal does not include the information of the LADN, the PDU session accessing the LADN is released to be in the available state.

In another possible implementation, when the SMF obtains the registration information of the terminal when the downlink data arrives, and after the AMF sends the SMF notification information that the current RA of the terminal does not include the information of the LADN, the SMF may further perform one or more of the following steps: informing the UPF to discard the downlink data; informing the UPF to set the gate control corresponding to the PDU session accessed to the LADN to be off; informing the UPF to stop sending the DDN related to the PDU session accessing the LADN; the PDU session for access to the LADN is modified to be unavailable. When the SMF does not modify the PDU session, the downlink data can be discarded, so that the terminal does not need to be paged, and the signaling is saved.

The embodiment of the application can realize that the AMF informs the SMF, and when the RA moved by the terminal is converted between the service area including the LADN and the service area not including the LADN, the SMF initiates the release or modification of the LADN session, thereby reducing the signaling waste caused by paging the terminal because downlink data arrives in the PDU session accessing the LADN when the terminal is in the RA not supporting the LADN.

Fig. 8 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application. As shown in fig. 8, the method specifically includes:

s810, the terminal receives the first message sent by the AMF in the first RA. Wherein the first message includes or does not include information of the LADN (for example, the first message shown in fig. 8 may be the first message shown in fig. 3 or the second message shown in fig. 4), and the first RA is a current registration area of the terminal.

The first message may be a registration accept message or a terminal configuration update command message.

For example, when the AMF determines that the terminal enters the first registration area from the second registration area, if the first registration area includes the information of the LADN, the AMF sends a registration acceptance message to the terminal, where the registration acceptance message includes the information of the LADN, and if the first registration area does not include the information of the LADN, the AMF sends a registration acceptance message to the terminal, where the registration acceptance message does not include the information of the LADN.

It is to be understood that the registration acceptance message does not include the information of the LADN, and specifically may be no LADN information, or the information of the LADN is null, or other information indicating that the information indicates no LADN

Or, when the AMF determines that the terminal enters a first registration area without the information of the LADN from a second registration area with the information of the LADN, and when the terminal registers in the first registration area, the AMF sends a registration acceptance message to the terminal, wherein the registration acceptance message does not include the information of the LADN.

Or, when the AMF determines that the terminal enters a first registration area including the information of the LADN from a second registration area not including the information of the LADN, and when the terminal registers in the first registration area, the AMF sends a registration acceptance message to the terminal, wherein the registration acceptance message includes the information of the LADN.

Or, when the AMF determines that the registration area of the terminal is the first registration area, and the first registration area is reconfigured to not include the LADN from the information including the LADN, the AMF sends a terminal configuration update command message to the terminal, and the terminal configuration update command message does not include the information of the LADN.

Or, when the AMF determines that the registration area of the terminal is the first registration area, and the first registration area is reconfigured to include the LADN from the information not including the LADN, the AMF sends a terminal configuration update command message to the terminal, and the terminal configuration update command message includes the information of the LADN.

In this embodiment, the first registration area is a current registration area of the terminal, and the second registration area is a registration area before the terminal enters the current registration area.

The information of the LADN may refer to the related description in S310 in the embodiment shown in fig. 3, and is not described herein again.

And S820, the terminal determines that the available state of the LADN changes according to the first message.

Changes in the availability status of the LADN include: the registration area is changed from information including an LADN to information not including an LADN, or the registration area is changed from information not including an LADN to information including an LADN.

For example, when the first message does not include information of the LADN, it is described that the current registration area does not include information of the LADN and the second registration area includes information of the LADN, the terminal determines that the availability status of the LADN changes; or, the terminal determines that the availability status of the LADN changes when the first message includes information of the LADN, indicating that the current registration area includes information of the LADN, and the second registration area does not include information of the LADN.

Wherein the information that the second registration area includes or does not include the LADN may be determined according to a second message received by the terminal while in the second registration area. The second message may or may not include information of the LADN. The second message includes information of the LADN indicating that the second registration area includes the LADN; the second message does not include information of the LADN, indicating that the second registration area does not include information of the LADN. Wherein the second message may be a registration accept message or a terminal configuration update command message. The second message received by the terminal when the terminal is in the second registration area may be recorded, or information that the second registration area includes or does not include the LADN may be recorded, and when the terminal receives the first message, it may be determined that the second registration area includes or does not include the LADN directly from the recording.

In addition, the second registration area may or may not include the information of the LADN, and may also be determined according to a status of a PDU session in which the terminal accesses the LADN when receiving the first message. For example, when receiving the first message, the status of the PDU session in which the terminal accesses the LADN is unavailable, which indicates that the second registration area does not include the information of the LADN; when the first message is received, the state of the PDU session of the terminal accessing the LADN is an available state, and the PDU session indicates that the second registration area comprises the information of the LADN.

For another example, when the first message does not include information of the LADN, and the terminal includes the information of the LADN in the first registration area before receiving the first message, the terminal determines that the availability status of the LADN is changed; or, when the first message includes the information of the LADN and the terminal does not include the information of the LADN before receiving the first message, the terminal determines that the state of the LAND available in the registration area is changed.

The first registration area may or may not include the information of the LADN before receiving the first message, and may be determined according to the third message received in the first registration area, or according to a status of a PDU session accessing the LADN. The third message may or may not include information of the LADN. The third message includes information indicating that the first registration area includes the LADN, and the third message does not include information indicating that the first registration area does not include the LADN. Wherein the third message may be a registration accept message or a terminal configuration update command message. The second message received by the terminal at the second registration area may be recorded, or the information that the first registration area includes or does not include the LADN may be recorded, and when the terminal receives the first message, the information that the first registration area includes or does not include the LADN before receiving the first message may be directly determined according to the recording.

In addition, the first registration area may or may not include information of the LADN before the first message is received, and may also be determined according to a status of a PDU session in which the terminal accesses the LADN when the first message is received. For example, when receiving the first message, the status of the PDU session in which the terminal accesses the LADN is unavailable, indicating that the first registration area does not include the information of the LADN before receiving the first message; when the first message is received, the state of the PDU session for accessing the LADN by the terminal is available, which indicates that the first registration area comprises the information of the LADN before the first message is received.

The status of the PDU session in which the terminal accesses the LADN is unavailable can be seen in conjunction with the related description of the embodiments shown in fig. 3, fig. 4 and fig. 6.

The SMF may manage PDU sessions with finer granularity based on the current registration area and the service area of the LADN. The method and the device solve the problem that when the terminal is located outside the service area of the LADN, the terminal initiates the release of the PDU session, thereby reducing the signaling waste caused by paging the terminal when the PDU session exists but the terminal is not located in the service area of the LADN.

S830, modifying or releasing the PDU session.

When the first message does not include information of a LADN and the second registration area includes information of a LADN, or when the first message does not include information of a LADN and the first registration area includes information of a LADN before receiving the first message, modifying or releasing the PDU session includes one or more of the following (see e.g., S330-S360 in connection with the embodiment shown in fig. 3, and S510-S520 in connection with the embodiment shown in fig. 5, and the associated description of S603-S611 in connection with the embodiment shown in fig. 6):

the terminal informs the SMF to modify or release the PDU session;

the terminal marks the PDU session as unavailable;

SMF marks PDU conversation as unavailable;

the SMF informs the UPF to discard the downlink data corresponding to the PDU session;

and the SMF informs the UPF to stop sending the downlink data notification DDN to the SMF.

When the first message includes information of a LADN and the second registration area does not include information of a LADN; or, when the first message includes information of a LADN and the first registration area does not include information of a LADN before the first message is received; modifying or releasing a PDU session may include one or more of the following (see the relevant description of S430-S460 in connection with the embodiment shown in fig. 4):

the terminal informs the SMF to modify the PDU session;

the terminal marks the PDU session as available;

SMF marks PDU conversation as available;

the SMF informs the UPF to send downlink data corresponding to the PDU session;

and the SMF informs the UPF to send a downlink data notification DDN corresponding to the PDU session.

The terminal can be notified after the network side modifies or releases the PDU session, so that the terminal synchronously modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal when the terminal does not exist in the service area of the LADN. The terminal can count the times of the terminal continuously entering the registration area of the service area without the LADN by marking the PDU session, thereby setting a rule, under the condition that the registration area continuously entering the service area without the LADN is less than or equal to the set times, the terminal modifies the PDU session, and under the condition that the set times is reached or exceeded, the terminal releases the PDU session, and the management granularity of the PDU session accessing the LADN is finer.

In addition, when the terminal reenters the RA of the service area including the LADN, the PDU session of the access LADN can be restarted for data transmission, so that the PDU session is managed from finer granularity, the paging of the network equipment to the terminal is more reasonable, the signaling is saved, and the efficiency is improved.

The embodiment of the application can realize that for the session of the LADN, when the terminal enters the registration area which does not support the LADN, the terminal modifies or releases the PDU session, thereby reducing the signaling waste caused by paging the terminal because the terminal is in the RA which does not support the LADN and the PDU session which is accessed to the LADN has downlink data arrival. And also

Fig. 9 is a schematic signaling interaction diagram of another session management method according to an embodiment of the present application. As shown in fig. 9, the method includes:

s910, the UPF sends the DDN to the SMF. The DNN is used to indicate that downlink data corresponding to the PDU session with access to the LADN needs to be transmitted.

S920, the SMF invokes a first service provided by the AMF, where the first service is used for the SMF to request the AMF to send a message or information, such as N2 SM information, to the access node AN. The message or information sent by the SMF to the access node AN via the AMF is used to instruct the SMF to request the AMF to send the message or information to the AN.

S930, the AMF determines that the PDU session is a session corresponding to the LADN, and the current registration area of the terminal has no service area of available LADN.

S940, the AMF sends an indication parameter to the SMF, where the indication parameter is used to indicate that the information in the current registration area does not include the LADN, and the indication parameter may be an acknowledgement of the information in S920.

If the downlink data belongs to a PDU session accessed to the LADN, the AMF judges that no service area of the LADN exists in the current RA, and then an indication (LADN unavailable indication in current TA) that the LADN in the current registration area is unavailable is sent to the SMF. The AMF stores an indication that the LADN unavailable indication in current TA is sent to the SMF, and notifies the SMF after the terminal enters the RA of the service area including the LADN again.

The AMF may maintain information that indicates parameters have been sent to the SMF. When the terminal re-enters the RA of the service area including the LADN, the SMF can be informed to re-enable the PDU session of the access LADN so as to carry out data transmission, thereby managing the PDU session from finer granularity, leading the paging of the network equipment to the terminal to be more reasonable, saving signaling and improving efficiency.

S950, the SMF modifies the PDU session according to the indication parameter.

The SMF modifies the PDU session according to the indication parameter, including the SMF performing one or more of:

informing the UPF to discard the downlink data corresponding to the PDU session;

and informing the UPF to stop sending the downlink data notification DDN corresponding to the PDU session to the SMF.

Fig. 10 is another example provided for an embodiment of the present application. As shown in fig. 10, the method specifically includes the following steps:

s1001, the terminal sends a registration request message to the AMF.

When a terminal moves from one RA to another RA, the AMF may change, and at this time, the terminal may register with the new AMF.

S1002, the AMF determines that the available state of the LADN of the terminal changes.

If the SMF subscribes to the notification service from the AMF before S1001. The notification service is used for notifying the SMF by the AMF when a preset event occurs, wherein the preset event is that the information of the existence of the LADN changes. S1002 may be executed at this time. Wherein, the SMF subscribing to the notification service from the AMF may be as described in connection with the embodiment shown in fig. 7.

S1003, the AMF sends notification information to the SMF.

If the SMF subscribes to the notification service to the AMF, the AMF needs to send notification information to the SMF when determining in S1002 that the availability status of the LADN of the terminal changes, and the notification information may be as described in the embodiment shown in fig. 7.

The SMF may return a response after receiving the notification information.

After receiving the notification information, the SMF may perform S1005b, where the SMF modifies or releases the PDU session accessing the LADN. The modification or release of the access to the LADN by the SMF for the PDU session can be seen in the description of the embodiment shown in fig. 7.

S1004, the AMF sends a registration accept message to the terminal.

The registration reception message from the AMF to the terminal may include the information of the LADN if the registration area of the terminal includes the information of the LADN, or not. Wherein, the AMF sends a registration accept message to the terminal, as described in the embodiments shown in fig. 3-6 and fig. 8.

When the terminal determines whether the information of the presence or absence of the LADN in the registration area is changed according to the registration accept message received in S1004, S1005a is executed, and the terminal modifies or releases the PDU session accessing the LADN. The terminal modifies or releases the PDU session for access to the LADN as described in connection with the embodiments shown in fig. 3-6 and fig. 8.

Fig. 11 is a schematic structural diagram of a terminal according to an embodiment of the present application. As shown in fig. 11, the terminal includes a receiving unit 1101, a determining unit 1102, a modifying unit 1103, and may further include a sending unit 1104. Wherein, the terminal has a protocol data unit PDU session accessing to the local area data network LADN, specifically,

a receiving unit 1101, configured to receive a first message sent by an access and mobility management function entity AMF in a first registration area RA, where the first message includes or does not include information of the LADN; wherein the first RA is a current registration area of the terminal;

a determining unit 1102, configured to determine that an available state of the LADN changes according to a first message;

a modifying unit 1103, configured to modify the PDU session; or, a release unit, configured to release the PDU session.

Optionally, the determining unit 1102 is further configured to,

determining that an available state of the LADN changes when the first message does not include information of the LADN and the information of the LADN is included in the first RA before the terminal receives the first message; or

Determining that an available state of the LADN changes when the first message does not include information of the LADN and information of the LADN is included in a second RA;

the second RA is an RA before the terminal enters the first RA.

Optionally, the sending unit 1104 is configured to send a first session modification request message to the session management function entity SMF, where the first session modification request message includes a first indication, and the first indication indicates that the information of the LADN is not included in the first RA; alternatively, a session release request message is sent to the SMF.

Optionally, the receiving unit 1101 is further configured to receive a first session modification command message sent by the SMF, where the first session modification command message includes an identifier of the PDU session and a first parameter, the identifier of the PDU session is used to identify the PDU session, and the first parameter is used to indicate that the PDU session is unavailable.

Optionally, the modifying unit 1103 is further configured to mark, by the terminal, the PDU session as unavailable.

Optionally, the determining unit 1102 is further configured to determine that the availability status of the LADN changes when the first message includes the information of the LADN and the information of the LADN is not included in the first RA before the terminal receives the first message; or when the first message includes the information of the LADN and the information of the LADN is not included in the second RA, determining that the available state of the LADN changes; the second RA is an RA before the terminal enters the first RA.

Optionally, the sending unit 1101 is further configured to send a second session modification request message to the SMF, where the second session modification request message includes a second indication, and the second indication is used to indicate that the information in the first RA includes the LADN.

Optionally, the receiving unit 1104 is further configured to,

and receiving a second session modification command message sent by the SMF, wherein the second session modification command message comprises a second parameter, and the second parameter is used for indicating that the PDU session is available.

Optionally, the modifying unit 1103 is further configured to mark the PDU session as available.

The terminal may be a terminal of the session management method as described in fig. 3 to 6, 8 and 10, and perform the steps performed by the terminal in fig. 3 to 6, 8 and 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 12 is a schematic structural diagram of an SMF according to an embodiment of the present application. As shown in fig. 12, the SMF includes a receiving unit 1201, a modifying unit 1202, and a transmitting unit 1203. The SMF has a Protocol Data Unit (PDU) session accessing a Local Area Data Network (LADN), and the SMF comprises:

a receiving unit 1201, configured to receive a session modification request message sent by a terminal, where the session modification request message includes an indication, and the indication is used to indicate that a registration area includes or does not include the information of the LADN;

a modifying unit 1202, configured to modify the PDU session according to the indication.

Optionally, a sending unit 1203 is further included for sending a first session modification command message to the terminal when the indication indicates that the RA of the terminal does not include the LADN, where the first session modification command message includes an identification of the PDU session and a first parameter, and the first parameter is used for indicating that the PDU session is unavailable.

Optionally, the modifying unit 1202 is further configured to mark the PDU session as unavailable; informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session; and informing the UPF to stop sending downlink data notification DDN to the SMF.

Optionally, the sending unit 1203 is further configured to send, when the indication indicates that the RA of the terminal does not include the LADN, a second session modification command message to the terminal, where the second session modification command message includes an identifier of the PDU session and a second parameter, and the second parameter is used to indicate that the PDU session is available.

Optionally, the modifying unit 1202 is further configured to mark the PDU session as available; informing the UPF to send downlink data corresponding to the PDU session; and informing the UPF to send a downlink data notification DDN corresponding to the PDU session.

The SMF may be used as the SMF of the session management method described in fig. 3 to 6, 8, and 10, and perform the steps performed by the SMF in fig. 3 to 6, 8, and 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 13 is a schematic structural diagram of another SMF provided in an embodiment of the present application. As shown in fig. 13, the SMF includes a subscription unit 1301, and may further include a receiving unit 1302 and a modifying unit 1303. The SMF has a protocol data unit PDU session for a terminal to access a local area data network, LADN, specifically,

a subscribing unit 1301, configured to subscribe to a notification service to an access and mobility management function entity AMF, where the notification service is configured to notify the SMF when a preset event occurs, where the preset event is a change in an available state of an LADN.

Optionally, the subscription unit 1301 is also used for,

sending a data network name DNN of the LADN and the preset event to the AMF to subscribe the notification service to the AMF.

Optionally, the available status of the LADN changes, including at least one of:

the first registration area does not comprise the information of the LADN, and the second registration area comprises the information of the LADN;

changing from information including the LADN to information not including the LADN within a first registration area;

the first registration area comprises the information of the LADN, and the second registration area does not comprise the information of the LADN; or,

changing from not including the LADN to including the LADN information within a first registration area;

wherein the first registration area is a current registration area of the terminal, and the second registration area is a registration area before the terminal enters the first registration area.

Optionally, the method further comprises:

a receiving unit 1302, configured to receive notification information sent by the AMF, where the notification information is used to notify that the information that includes or does not include the LADN in the registration area of the terminal.

Optionally, the method further comprises:

and a modifying unit 1303, configured to modify the PDU session according to the notification information.

Optionally, the modification unit 1303 is also adapted to,

when the notification information is used for notifying that the registration area of the terminal does not include the information of the LADN, notifying a user plane functional entity (UPF) to discard downlink data corresponding to the PDU session; informing the UPF to stop sending downlink data notification DDN corresponding to the PDU session to the SMF;

or,

when the notification information is used for notifying that the registration area of the terminal comprises the information of the LADN, notifying the UPF to send downlink data corresponding to the PDU session; and informing the UPF to send a downlink data notification DDN corresponding to the PDU session.

The SMF may be used as the SMF of the service subscription method described in fig. 7 and 10, and perform the steps performed by the SMF in fig. 7 and 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 14 is a schematic structural diagram of an AMF according to an embodiment of the present application. As shown in fig. 14, the AMF includes a subscription unit 1401 and may further include a reception unit 1402. The session management function entity SMF has a protocol data unit PDU session of a terminal access local area data network LADN, and comprises the following steps:

a subscription unit 1401, configured to receive the SMF subscription notification service, where the notification service is configured to notify the SMF of a preset event when the preset event occurs, where the preset event is that an available state of a LADN changes.

Optionally, the subscription unit 1402 is further configured to,

and receiving the data network name DNN of the LADN sent by the SMF and the preset event so as to receive the SMF to subscribe the notification service.

Optionally, the available state of the LADN is changed, including at least one of:

the first registration area comprises the information of the LADN, and the second registration area does not comprise the information of the LADN;

Optionally, the method further comprises:

a sending unit 1402, configured to send notification information to the SMF, where the notification information is used to notify that a registration area of the terminal includes or does not include the information of the LADN.

The AMF may be an AMF of a method of service subscription as described in fig. 7 and 10, and performs the steps performed by the SMF in fig. 7 and 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 15 is a schematic structural diagram of another SMF provided in the embodiment of the present application. As shown in fig. 15, the SMF has a PDU session accessing to a LADN, and includes:

a receiving unit 1501, configured to receive a downlink data notification corresponding to the PDU session sent by a user plane function entity UPF;

a sending unit 1502 is configured to invoke a first service provided by AN access and mobility management entity AMF, where the first service is used for the SMF to send a message to AN access node AN through the AMF. (ii) a

The receiving unit 1501 is further configured to receive an indication parameter sent by the AMF, where the indication parameter is used to indicate that the information of the LADN is not included in the current registration area;

a modifying unit 1503, configured to modify the PDU session according to the indication parameter.

Optionally, the modifying unit 1503 is also configured to,

informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session;

The SMF may be used as the SMF of the session management method described in fig. 9, and performs the steps performed by the SMF in fig. 9. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 16 is a schematic structural diagram of another AMF according to an embodiment of the present application. As shown in fig. 16, the SMF has a protocol data unit PDU session accessing the local area data network LADN, and the AMF includes:

a receiving unit 1601, configured to receive a first service invoked by the SMF, where the first service is used for the SMF to send a message to AN access node AN through the AMF;

a sending unit 1602, configured to send, to the SMF, an indication parameter when a service area of the terminal does not include a LADN in the registration area, where the indication parameter is used to indicate that the information of the LADN is not included in the registration area.

Optionally, the method further comprises:

and the storage unit is used for storing the information of the indication parameters sent to the SMF.

The AMF may be an AMF of the session management method as described in fig. 9, and performs the steps performed by the AMF in fig. 9. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 17 is a schematic structural diagram of another terminal according to an embodiment of the present application. As shown in fig. 17, the terminal includes a transceiver 1701, a processor 1702, and a memory 1703, the transceiver 1701 being used for communicating with an AMF, a UPF, or an SMF; the memory 1703 is used for storing programs; the processor 1702 is configured to execute the program stored in the memory to perform the steps performed by the terminal in fig. 3-6 and 8. Where the terminal has a PDU session to access the LADN, specifically,

a transceiver 1701 for receiving a first message sent by an access and mobility management function entity (AMF) in a first Registration Area (RA), wherein the first message includes or does not include the information of the LADN; wherein the first RA is a current registration area of the terminal;

a processor 1702 for determining that an available status of the LADN changes based on a first message;

a processor 1702 for modifying the PDU session; or, for releasing the PDU session.

Optionally, the processor 1702 is also configured to,

Determining that an available state of the LADN changes when the first message does not include information of the LADN and the second RA includes information of the LADN;

the second RA is an RA before the terminal enters the first RA.

Optionally, the transceiver 1701 is configured to send a first session modification request message to the session management function entity SMF, where the first session modification request message includes a first indication indicating that the information of the LADN is not included in the first RA; alternatively, a session release request message is sent to the SMF.

Optionally, the transceiver 1701 is further configured to receive a first session modification command message sent by the SMF, where the first session modification command message includes an identifier of the PDU session and a first parameter, the identifier of the PDU session is used for identifying the PDU session, and the first parameter is used for indicating that the PDU session is unavailable.

Optionally, processor 1702 is further configured for marking the PDU session as unavailable by the terminal.

Optionally, the processor 1702 is further configured to determine that an available status of the LADN changes when the first message includes the information of the LADN and the information of the LADN is not included in the first RA before the terminal receives the first message; or when the first message includes the information of the LADN and the information of the LADN is not included in the second RA, determining that the available state of the LADN changes;

the second RA is an RA before the terminal enters the first RA.

Optionally, the transceiver 1701 is further configured to send a second session modification request message to the SMF, the second session modification request message including a second indication indicating that the registration area of the terminal includes the information of the LADN.

Optionally, the transceiver 1701 is also used to,

Optionally, the processor 1702 is further configured to mark the PDU session as available.

Fig. 18 is a schematic structural diagram of another SMF according to an embodiment of the present application. As shown in fig. 18, the SMF includes a transceiver 1801, a processor 1802, and a memory 1803, the transceiver 1801 being used for communicating with the AMF, the UPF, or the terminal; the memory 1803 is used for storing programs; the processor 1802 is configured to execute the program stored in the memory to perform the steps performed by the SMF in fig. 3-6, 8, and 10. The SMF has a PDU session accessing the LADN, specifically:

a transceiver 1801, configured to receive a session modification request message sent by a terminal, where the session modification request message includes an indication, and the indication is used to indicate that a registration area includes or does not include the information of the LADN;

a processor 1802 configured to modify the PDU session in accordance with the indication.

Optionally, the method further includes sending a first session modification command message to the terminal, when the indication indicates that the RA of the terminal does not include the LADN, the first session modification command message including an identification of the PDU session and a first parameter, the first parameter indicating that the PDU session is unavailable.

Optionally, processor 1802 is further configured to mark the PDU session as unavailable; informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session; and informing the UPF to stop sending downlink data notification DDN to the SMF.

Optionally, the transceiver 1801 is further configured to send, to the terminal, a second session modification command message when the indication indicates that the RA of the terminal does not include the LADN, the second session modification command message including an identification of the PDU session and a second parameter, the second parameter indicating that the PDU session is available.

Optionally, processor 1802 is further configured to mark the PDU session as available; informing the UPF to send downlink data corresponding to the PDU session; and informing the UPF to send a downlink data notification DDN corresponding to the PDU session.

Fig. 19 is a schematic structural diagram of another SMF according to an embodiment of the present application. The SMF includes a transceiver 1901, a processor 1902, and a memory 1903, the transceiver 1901 being used for communicating with the AMF, UPF, or terminal; the memory 1903 is used for storing programs; the processor 1902 is configured to execute the program stored in the memory to perform the steps performed by the SMF in fig. 7 and 10. The SMF has a PDU session accessing the LADN, specifically:

a processor 1902, configured to subscribe to a notification service to an access and mobility management function, AMF, where the notification service is configured to notify, when a preset event occurs, the SMF, where the preset event is that an available state of a LADN changes.

Optionally, the processor 1902 is also configured to,

Optionally, the method further comprises:

a transceiver 1901, configured to receive notification information sent by the AMF, where the notification information is used to notify that a registration area of the terminal includes or does not include the information of the LADN.

Optionally, the method further comprises:

a processor 1902 is configured to modify the PDU session according to the notification information.

Optionally, the processor 1902 is also configured to,

or,

The SMF may be an SMF of the service subscription method as described in fig. 7 or fig. 10, and perform the steps performed by the SMF in fig. 7 or fig. 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 20 is a schematic structural diagram of another AMF according to an embodiment of the present application. The AMF includes a transceiver 2001, a processor 2002 and a memory 2003, the transceiver 2001 for communicating with the SMF or the terminal; the memory 2003 is used for storing programs; the processor 2002 is configured to execute the program stored in the memory to perform the steps performed by the AMF in fig. 7 or fig. 10. The SMF has a PDU session accessing the LADN, specifically:

a processor 2002, configured to receive the SMF subscription notification service, where the notification service is configured to notify the SMF by the AMF when a preset event occurs, where the preset event is a change in an available state of a LADN.

Optionally, the processor 2002 is also configured to,

Optionally, the method further comprises:

a transceiver 2001 for transmitting notification information for notifying that the registration area of the terminal includes or does not include the information of the LADN to the SMF.

The AMF may be an AMF of a method of service subscription as described in fig. 7 or fig. 10, and performs the steps performed by the SMF in fig. 7 or fig. 10. Therefore, data loss caused by PDU conversation modification or release by the network when the terminal is in an idle state is reduced, and signaling waste caused by paging the terminal due to downlink data arrival of the PDU conversation of the network equipment accessing the LADN is also reduced.

Fig. 21 is a schematic structural diagram of another SMF provided in the embodiment of the present application. As shown in fig. 21, the SMF includes a transceiver 2101, a processor 2102 and a memory 2103, the transceiver 2101 being used to communicate with an AMF, a UPF or a terminal; the memory 2103 is used for storing programs; the processor 2102 is configured to execute the program stored in the memory to perform the steps performed by the SMF in fig. 9. The SMF has a PDU session accessing the LADN, and the SMF comprises:

a transceiver 2101 configured to receive a downlink data notification corresponding to the PDU session sent by a user plane functional entity UPF;

a transceiver 2101 configured to invoke a first service provided by AN access and mobility management entity, AMF, where the first service is used for the SMF to send a message to AN access node, AN, through the AMF. (ii) a

The transceiver 2101 is configured to receive an indication parameter sent by the AMF, where the indication parameter is used to indicate that the information of the LADN is not included in the current registration area;

a processor 2102 configured to modify the PDU session in accordance with the indicated parameter.

Optionally, the processor 2102 is further configured to notify the user plane function entity UPF to discard the downlink data corresponding to the PDU session; and informing the UPF to stop sending the downlink data notification DDN corresponding to the PDU session to the SMF.

Fig. 22 is a schematic structural diagram of another AMF according to an embodiment of the present application. As shown in fig. 22, the AMF includes a transceiver 2201, a processor 2202, and a memory 2203, the transceiver 2201 being used to communicate with the SMF or the terminal; the memory 2203 is used for storing programs; the processor 2202 is configured to execute the program stored in the memory to perform the steps performed by the SMF in fig. 9. The SMF has a PDU session accessing to a LADN, and the AMF comprises:

a transceiver 2201, configured to receive a first service invoked by the SMF, where the first service is used for the SMF to send a message to AN access node AN through the AMF;

a transceiver 2201, configured to send an indication parameter to the SMF when a service area of the LADN is not included in the registration area of the terminal, where the indication parameter is used to indicate that the information of the LADN is not included in the registration area.

Optionally, a processor 2202 is further included, configured to store the information that the indication parameter is sent to the SMF.

The present embodiments provide a computer program product comprising instructions for performing the methods/steps of fig. 3 to 10 described above when the instructions are run on a computer.

The present application provides a computer-readable storage medium for storing instructions, which when executed on a computer, perform the methods/steps of fig. 3 to 10 described above.

The embodiment of the application provides a communication system. The system includes any one or more of the devices of the embodiments described above in connection with fig. 3-10.

In the various embodiments of the invention described above, implementation may be in whole or in part via software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk), among others.

The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for managing session, wherein a Protocol Data Unit (PDU) session accessing a Local Area Data Network (LADN) exists in a terminal, comprising:

the terminal receives a first message sent by an access and mobility management function (AMF) entity in a first Registration Area (RA), wherein the first message comprises or does not comprise the information of the LADN; wherein the first RA is a current registration area of the terminal;

the terminal determines that the available state of the LADN changes according to the first message;

and the terminal modifies or releases the PDU session.

2. The method of claim 1, wherein the terminal determines from the first message that the availability of the LADN has changed, comprising:

when the first message does not include information of the LADN and includes information of the LADN in the first RA before the terminal receives the first message, the terminal determines that an available state of the LADN changes; or,

when the first message does not comprise the information of the LADN and the second RA comprises the information of the LADN, the terminal determines that the available state of the LADN changes;

the second RA is an RA before the terminal enters the first RA.

3. The method of claim 2, wherein the terminal modifies the PDU session, comprising:

the terminal sends a first session modification request message to a Session Management Function (SMF), wherein the first session modification request message comprises a first indication, and the first indication is used for indicating that information of a LADN is not included in the first RA; or,

the terminal releases the PDU session, including: and the terminal sends a session release request message to the SMF.

4. The method of claim 3, further comprising:

and the terminal receives a first session modification command message sent by the SMF, wherein the first session modification command message comprises an identifier of the PDU session and a first parameter, the identifier of the PDU session is used for identifying the PDU session, and the first parameter is used for indicating that the PDU session is unavailable.

5. The method according to any of claims 2-4, wherein the terminal modifying the PDU session comprises:

the terminal marks the PDU session as unavailable.

6. The method of claim 1,

the terminal determines that the available state of the LADN changes according to the first message, and the method comprises the following steps:

when the first message includes information of the LADN and the information of the LADN is not included in the first RA before the terminal receives the first message, the terminal determines that the availability status of the LADN changes; or,

when the first message comprises the information of the LADN and the information of the LADN is not included in the second RA, the terminal determines that the available state of the LADN changes;

the second RA is an RA before the terminal enters the first RA.

7. The method of claim 6, wherein the terminal modifies the PDU session, comprising:

and the terminal sends a second session modification request message to the SMF, wherein the second session modification request message comprises a second indication, and the second indication is used for indicating that the information of the LADN is not included in the first RA.

8. The method of claim 7, further comprising:

and the terminal receives a second session modification command message sent by the SMF, wherein the second session modification command message comprises a second parameter, and the second parameter is used for indicating that the PDU session is available.

9. The method according to any of claims 6-8, wherein the terminal modifying the PDU session comprises:

the terminal marks the PDU session as available.

10. A method for managing session, wherein a Protocol Data Unit (PDU) session accessing a Local Area Data Network (LADN) exists in a terminal, comprising:

the terminal receives a first session modification command message sent by the SMF, wherein the first session modification command message comprises an identifier of the PDU session and a first parameter, the identifier of the PDU session is used for identifying the PDU session, and the first parameter is used for indicating that the PDU session is unavailable;

and the terminal modifies the PDU session according to the first session modification command message.

11. The method of claim 10, wherein the terminal modifying the PDU session according to the first session modification command message comprises:

the terminal marks the PDU session as unavailable.

12. The method of claim 10, further comprising:

the terminal receives a second session modification command message sent by the SMF, wherein the second session modification command message comprises a second parameter, and the second parameter is used for indicating that the PDU session is available;

and the terminal modifies the PDU session according to the second session modification command message.

13. The method of claim 12, wherein the terminal modifying the PDU session according to the second session modification command message comprises:

the terminal marks the PDU session as available.

14. A session management method is characterized in that a Session Management Function (SMF) has a Protocol Data Unit (PDU) session accessing a Local Area Data Network (LADN), and the method comprises the following steps:

a session management function entity (SMF) receives a session modification request message sent by a terminal, wherein the session modification request message comprises an indication, and the indication is used for indicating that a Registration Area (RA) comprises or does not comprise information of a Location Area (LADN);

when the indication is used for indicating that the RA comprises LADN information, the SMF sends a first session modification command message to the terminal, wherein the first session modification command message comprises an identification of the PDU session and a first parameter, the identification of the PDU session is used for identifying the PDU session, and the first parameter is used for indicating that the PDU session is unavailable.

15. The method of claim 14, wherein the SMF modifies the PDU session based on the indication, including one or more of:

the SMF marks the PDU session as unavailable;

the SMF informs a user plane functional entity UPF to discard the downlink data corresponding to the PDU session; or,

16. The method of claim 14, wherein before the SMF sends the first session modification command message to the terminal, the method further comprises:

the SMF receives a session modification request message sent by the terminal, wherein the session modification request message comprises an indication, and the indication is used for indicating that a registration area RA does not comprise LADN information.

17. The method of claim 16, wherein when the indication indicates that the RA does not include a LADN, the method further comprises:

and the SMF sends a second session modification command message to the terminal, wherein the second session modification command message comprises an identifier of the PDU session and a second parameter, the identifier of the PDU session is used for identifying the PDU session, and the second parameter is used for indicating that the PDU session is available.

18. The method of claim 17, wherein the SMF modifies the PDU session based on the indication, including one or more of:

the SMF marks the PDU session as available;

the SMF informs a UPF to send downlink data corresponding to the PDU session; or,

19. The method of claim 18, wherein before the SMF sends the first session modification command message to the terminal, the method comprises:

the SMF subscribes a notification service to an access and mobile management function (AMF), wherein the notification service is used for notifying the SMF by the AMF when a preset event occurs, and the preset event is that the available state of the LADN changes.

20. The method of claim 19, the SMF subscribing to the notification service from the AMF, comprising:

and the SMF sends the data network name DNN of the LADN and the preset event to the AMF.

21. The method of claim 19 or 20, wherein the availability of the LADN changes, including at least one of:

22. The method of claim 19 or 20, after the SMF subscribes to the notification service from the AMF, further comprising:

and the SMF receives notification information sent by the AMF, wherein the notification information is used for notifying that the information of the LADN is included or not included in the current registration area of the terminal.

23. The method of claim 22, wherein after the SMF receives the notification message, further comprising:

and the SMF modifies the PDU session according to the notification information.

24. The method of claim 23, wherein the SMF modifies the PDU session based on the notification information, comprising:

when the notification information is used for notifying that the current registration area of the terminal does not include the information of the LADN, the SMF performs one or more of the following:

25. The method of claim 23, wherein the SMF modifies the PDU session based on the notification information, comprising:

when the notification information is used for notifying that the current registration area of the terminal includes the information of the LADN, the SMF performs one or more of the following:

informing the UPF to send downlink data corresponding to the PDU session;

and informing the UPF to send a downlink data notification DDN corresponding to the PDU session.

26. The method of claim 14, further comprising:

the SMF receives a downlink data notification corresponding to the PDU session sent by a user plane functional entity UPF;

the SMF calls a first service provided by AN access and mobile management entity (AMF), wherein the first service is used for the SMF to send a message to AN Access Node (AN) through the AMF;

the SMF receives an indication parameter sent by the AMF, wherein the indication parameter is used for indicating that the information of the LADN is not included in the current registration area;

and the SMF modifies the PDU session according to the indication parameter.

27. The method of claim 26, wherein the SMF modifying the PDU session based on the indication parameter comprises the SMF performing one or more of:

28. A session management method is characterized in that a Protocol Data Unit (PDU) session of an access and mobile management function (AMF) presence terminal accessing a Local Area Data Network (LADN) comprises the following steps:

and the AMF sends a first message to a terminal, wherein the first message comprises or does not comprise the information of the LADN, so that the terminal determines that the available state of the LADN changes according to the first message and modifies or releases the PDU session, the terminal is located in a first registration area RA, and the first RA is the current registration area of the terminal.

29. The method of claim 28, further comprising:

the method comprises the steps that an AMF receives a subscription notification service request sent by an SMF, wherein the notification service request is used for notifying the SMF when a preset event occurs, and the preset event is that the available state of a LADN changes.

30. The method of claim 29, wherein the AMF receiving the subscription notification service request sent by the SMF comprises:

and the AMF receives the data network name DNN of the LADN and the preset event sent by the SMF.

31. The method of claim 29 or 30, wherein the availability of the LADN changes, including at least one of:

32. The method according to claim 29 or 30, wherein after the AMF receives the subscription notification service request sent by the SMF, the method further comprises:

and the AMF sends notification information to the SMF, wherein the notification information is used for notifying that the current registration area of the terminal comprises or does not comprise the information of the LADN.

33. The method of claim 29, wherein the method comprises:

the AMF receives a first service request called by a Session Management Function (SMF), wherein the first service request is used for the SMF to request the AMF to send a message to AN Access Node (AN); wherein, the first service request includes an identifier of the PDU session;

and when the registration area of the terminal does not comprise the service area of the LADN, the AMF sends an indication parameter to the SMF, wherein the indication parameter is used for indicating that the registration area of the terminal does not comprise the information of the LADN.

34. The method of claim 33, wherein after sending the indication parameter to the SMF, the AMF further comprises:

the AMF stores the information that the indication parameter has been sent to the SMF.

35. A terminal, wherein the terminal has a protocol data unit, PDU, session to access a local area data network, LADN, the terminal comprising:

a receiving unit, configured to receive, in a first registration area RA, a first message sent by an access and mobility management function entity AMF, where the first message may or may not include the information of the LADN; wherein the first RA is a current registration area of the terminal;

a determining unit, configured to determine that an available state of the LADN changes according to a first message;

a modification unit for modifying the PDU session; or, a release unit, configured to release the PDU session.

36. The terminal according to claim 35, wherein the determining unit is further configured to,

determining that an available state of the LADN changes when the first message does not include information of the LADN and the information of the LADN is included in the first RA before the terminal receives the first message; or,

determining that an available state of the LADN changes when the first message does not include information of the LADN and information of the LADN is included in a second RA; the second RA is an RA before the terminal enters the first RA.

37. The terminal of claim 36, further comprising: a sending unit, configured to send a first session modification request message to a session management function entity, SMF, where the first session modification request message includes a first indication, and the first indication is used to indicate that the information of the LADN is not included in the first RA; alternatively, a session release request message is sent to the SMF.

38. The terminal of claim 37, wherein the receiving unit is further configured to receive a first session modification command message sent by the SMF, and wherein the first session modification command message comprises an identifier of the PDU session and a first parameter, and wherein the identifier of the PDU session is used for identifying the PDU session, and wherein the first parameter is used for indicating that the PDU session is unavailable.

39. The terminal according to any of claims 36-38, wherein said modifying unit is further configured to mark said PDU session as unavailable by said terminal.

40. The terminal of claim 35, wherein the determining unit is further configured to determine that the availability of the LADN changes when the first message includes information of the LADN and the information of the LADN is not included in the first RA before the terminal receives the first message; or,

determining that an available state of the LADN changes when the first message includes information of the LADN and information of the LADN is not included in a second RA; the second RA is an RA before the terminal enters the first RA.

41. The terminal of claim 40, further comprising: a sending unit, configured to send a second session modification request message to the SMF, where the second session modification request message includes a second indication, and the second indication is used to indicate that the first RA includes the information of the LADN.

42. The terminal of claim 41, wherein the receiving unit is further configured to,

43. The terminal according to any of claims 40-42, wherein said modifying unit is further adapted to mark said PDU session as available.

44. A terminal, wherein the terminal has a protocol data unit, PDU, session to access a local area data network, LADN, the terminal comprising:

a receiving unit, configured to receive a first session modification command message sent by an SMF, where the first session modification command message includes an identifier of the PDU session and a first parameter, the identifier of the PDU session is used to identify the PDU session, and the first parameter is used to indicate that the PDU session is unavailable;

and the modifying unit is used for modifying the PDU conversation according to the first conversation modifying command message.

45. The terminal of claim 44, wherein the modifying unit is further configured to mark the PDU session as unavailable.

46. The terminal of claim 44, wherein the receiving unit is further configured to receive a second session modification command message sent by the SMF, and wherein the second session modification command message includes a second parameter, and wherein the second parameter is used to indicate that a PDU session is available;

the modifying unit is further configured to modify the PDU session according to the second session modification command message.

47. The terminal of claim 46, wherein the modifying unit is further configured to mark the PDU session as available.

48. A session management function, SMF, wherein the SMF has a PDU session for accessing a local area data network, LADN, the SMF comprising:

a receiving unit, configured to receive a session modification request message sent by a terminal, where the session modification request message includes an indication that indicates that a registration area RA includes or does not include the information of the LADN;

and a sending unit, configured to send a first session modification command message to the terminal when the indication is used to indicate that the RA includes the information of the LADN, where the first session modification command message includes an identifier of the PDU session and a first parameter, the identifier of the PDU session is used to identify the PDU session, and the first parameter is used to indicate that the PDU session is unavailable.

49. The SMF of claim 48, further comprising:

a modification unit for marking the PDU session as unavailable;

informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session; or,

and informing the UPF to stop sending downlink data notification DDN to the SMF.

50. The SMF of claim 48, further comprising:

a receiving unit, configured to receive a session modification request message sent by the terminal, where the session modification request message includes an indication, and the indication is used to indicate that a registration area RA does not include the information of the LADN.

51. The SMF of claim 50, wherein the sending unit is further configured to, when the indication is information indicating that the RA of the terminal does not include a LADN,

and sending a second session modification command message to the terminal, wherein the second session modification command message comprises the identification of the PDU session and a second parameter, and the second parameter is used for indicating that the PDU session is available.

52. The SMF of claim 51, further comprising:

a modification unit for marking the PDU session as available;

informing the UPF to send downlink data corresponding to the PDU session; or,

53. The SMF of claim 48, further comprising:

the system comprises a subscription unit and a mobile management function (AMF) unit, wherein the subscription unit is used for subscribing a notification service to an AMF (access and mobile management function) entity, and the notification service is used for notifying the SMF when a preset event occurs, wherein the preset event is that the available state of the LADN changes.

54. The SMF of claim 53, the subscription unit further to,

and sending the data network name DNN of the LADN and the preset event to the AMF.

55. The SMF of claim 53 or 54, wherein the availability of the LADN changes, including at least one of:

56. The SMF according to claim 53 or 54, wherein the receiving unit is further configured to receive notification information sent by the AMF, and the notification information is used to notify that the information of the LADN is included or excluded in the current registration area of the terminal.

57. The SMF of claim 56, further comprising: and the modifying unit is used for modifying the PDU session according to the notification information.

58. The SMF according to claim 57, wherein the modifying unit is further configured to perform one or more of the following when the notification information is used to notify that the current registration area of the terminal does not include the information of the LADN: informing a user plane functional entity UPF to discard downlink data corresponding to the PDU session; and informing the UPF to stop sending the downlink data notification DDN corresponding to the PDU session to the SMF.

59. The SMF according to claim 57, wherein the modifying unit is further configured to perform, when the notification information is used to notify that the current registration area of the terminal includes the information of the LADN, one or more of: informing the UPF to send downlink data corresponding to the PDU session; and informing the UPF to send a downlink data notification DDN corresponding to the PDU session.

60. The SMF according to claim 48, wherein the receiving unit is further configured to receive a downlink data notification corresponding to the PDU session sent by a user plane function entity (UPF);

the sending unit is further configured to invoke a first service provided by AN access and mobility management entity (AMF), where the first service is used for the SMF to send a message to AN Access Node (AN) through the AMF;

the receiving unit is further configured to receive an indication parameter sent by the AMF, where the indication parameter is used to indicate that the information of the LADN is not included in the current registration area;

and the modifying unit is used for modifying the PDU session according to the indication parameter.

61. The SMF of claim 60, wherein the modification unit is further configured to,

62. An access and mobility management function (AMF), wherein a Session Management Function (SMF) exists a Protocol Data Unit (PDU) session of a terminal accessing a Local Area Data Network (LADN), and the AMF comprises:

a sending unit, configured to send a first message to a terminal, where the first message includes or does not include information of the LADN, so that the terminal determines, according to the first message, that an available state of the LADN changes, and modifies or releases the PDU session, where the terminal is located in a first registration area RA, and the first RA is a current registration area of the terminal.

63. The AMF of claim 62, further comprising:

and the subscription unit is used for receiving a subscription notification service request message sent by the SMF, and the notification service is used for notifying the SMF by the AMF when a preset event occurs, wherein the preset event is that the available state of the LADN changes.

64. The AMF of claim 63, wherein the subscription unit is further configured to receive a Data Network Name (DNN) of the LADN and the predetermined event sent by the SMF.

65. The AMF of claim 63 or 64, wherein the availability of the LADN changes, including at least one of:

66. The AMF of claim 63 or 64, wherein the sending unit is further configured to send notification information to the SMF, the notification information being used for notifying that the registration area of the terminal includes or does not include the LADN.

67. The AMF of claim 62, further comprising:

a receiving unit, configured to receive a first service invoked by a session management function entity, SMF, where the first service is used for the SMF to send a message to AN access node, AN, through the AMF;

the sending unit is further configured to send an indication parameter to the SMF when the registration area of the terminal does not include a service area of the LADN, where the indication parameter is used to indicate that the registration area does not include the information of the LADN.

68. The AMF of claim 67, further comprising:

69. A Session Management Function (SMF) is characterized by comprising a transceiver, a processor and a memory, wherein the transceiver is used for communicating with an access and mobile management function (AMF), a User Plane Function (UPF) or a terminal; the memory is used for storing programs; the processor is configured to execute the program stored in the memory to perform the method of any of claims 14-27.

70. An access and mobility management function (AMF), comprising a transceiver, a processor and a memory, wherein the transceiver is configured to communicate with a Session Management Function (SMF) or a terminal; the memory is used for storing programs; the processor is configured to execute the program stored in the memory to perform the method of any of claims 28-34.

71. A terminal, comprising a transceiver, a processor and a memory, the transceiver being configured to communicate with an access and mobility management function, AMF, or a session management function, SMF; the memory is used for storing programs; the processor is configured to execute the program stored in the memory to perform the method of any of claims 1-9 or 10-13.

72. A computer readable storage medium comprising computer readable instructions which, when read and executed by a computer, cause the computer to perform the method of any of claims 1-34.

73. A communication system, comprising: a terminal according to any of claims 35-43 and a session management function, SMF, according to any of claims 48-61; or a terminal according to any of claims 44-47 and a session management function, SMF, according to any of claims 48-61.

74. A communication system, comprising: a session management function entity, SMF, according to any of claims 48-61 and an access and mobility management function entity, AMF, according to any of claims 62-68.