WO2018205775A1

WO2018205775A1 - Data buffering method and session management functional entity

Info

Publication number: WO2018205775A1
Application number: PCT/CN2018/081803
Authority: WO
Inventors: 唐廷芳; 李岩; 倪慧
Original assignee: 华为技术有限公司
Priority date: 2017-05-11
Filing date: 2018-04-04
Publication date: 2018-11-15

Abstract

The present application relates to the technical filed of wireless communications, and provides a data buffering method, comprising: a session management functional entity interacting with a second user plane functional entity and a first user plane functional entity, such that the first user plane functional entity sends first downlink data of a first session to an access network device by means of the second user plane functional entity. The first user plane functional entity is an anchor point of the first session. The session management functional entity instructs, according to a preset condition, the first user plane functional entity to buffer second downlink data of the first session. The second downlink data is received after the first session is converted to a deactivated state. The solution provided in the present embodiment can avoid the out-of-order problem of downlink data received by the terminal, and furthermore can obtain buffered downlink data without the need to establish an additional forwarding tunnel and release the forwarding tunnel, reducing signaling interactions between UPF entities, thereby reducing time delay, improving user experience.

Description

Method of caching data and session management function entity

This application claims the priority of the Chinese Patent Application filed on June 20, 2017, the Chinese Patent Office, the application number is 201710470680.7, and the invention is entitled "Method of Cache Data and Session Management Function Entity", which is required on May 11, 2017. The priority of the Chinese Patent Application, which is hereby incorporated by reference in its entirety in its entirety in the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all all

Technical field

The present application relates to the field of wireless communication technologies, and in particular, to a method for buffering data and a session management function entity.

Background technique

In the fourth generation (the 4 ^th generation, 4G) communication system, a packet data network gateway (packet data network gateway, PGW) can be guaranteed as a network protocol (Internet Protocol, IP) continuity anchor. As shown in FIG. 1, at time T1, the terminal device obtains downlink data from the data network through a serving gateway (SGW) SGW1 and a PGW to implement transmission of service data. If the terminal device enters the idle state from SGW1, the downlink data is buffered in SGW1. At the time of T2, after the terminal device switches to the connected state, if the terminal device moves out of the service range of the SGW1 and selects the SGW2, the SGW2 needs to establish a forwarding tunnel with the SGW1 to obtain the downlink data buffered in the SGW1. That is to say, the transmission path of the buffered downlink data is SGW1→SGW2→terminal device. In addition, for the downlink data of the service after the terminal device switches to the connected state, the transmission path is PGW→SGW2→terminal device.

Thus, the two different data transmission paths cause the downlink data received by the terminal device to be out of order. If the downlink data received by the terminal device is out of order, the terminal device needs to suspend processing, and first adjusts the received downlink data, thereby seriously affecting the user experience (for example, the video service may cause a jam).

In order to meet the needs of different applications continuity of the fifth generation ^(the 5 ^th generation, 5G) systems support different sessions and business continuity (Session and Service continuity, SSC) mode: SSC1 mode, SSC2 mode and SSC3 mode. For the SSC1 mode, the user plane function (UPF) entity of the session remains unchanged until the end of the service, that is, the anchor IP is unchanged. For the SSC2 mode, when the terminal device moves out of the service area of the original anchor UPF, the connection with the original anchor UPF entity is released. For the SSC3 mode, before releasing the connection between the terminal device and the original anchor UPF entity, the terminal device may select a new anchor point UPF entity to establish a new connection, and release the connection between the terminal device and the original anchor point UPF entity after a specified time. In other words, multiple IPs can be served simultaneously for the terminal device.

The anchored UPF entity of the session with the SSC1 mode does not change during the movement of the terminal device. After the session enters the deactivated state under the other UPF entities of the non-anchor UPF entity, it is an urgent problem to be solved by which UPF entity caches the downlink data and ensures that the downlink data received by the terminal device is not out of order.

Summary of the invention

This application describes a method of caching data and a session management functional entity.

In one aspect, an embodiment of the present application provides a method for caching data, the method comprising: a session management function entity interacting with a second user plane function entity and a first user plane function entity, respectively, to enable a first user plane function entity The first downlink data of the first session is sent to the access network device by the second user plane function entity. The first user plane function entity is an anchor point of the first session. The session management function entity notifies the first user plane function entity to cache the second downlink data of the first session according to the preset condition. The second downlink data is downlink data received by the first user plane function entity after the first session is switched to the deactivated state.

According to the foregoing scheme of buffering data, the session management function entity notifies the anchor user plane function entity to cache the second downlink data according to the preset condition. In this way, after the first session is switched to the active state, the second downlink data buffered by the anchor user plane function entity is the same as the transmission path of the third downlink data newly received by the first session to the active state. Thereby, the disorder of the downlink data received by the terminal is avoided. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and improving the user experience.

In one possible design, the preset condition includes at least one of the following: the SSC information indicates that the first session has a first session and a traffic continuity SSC1 mode; the mobility information indicates that the terminal device is a high mobility device; session management The functional entity and the first user plane functional entity belong to the same carrier network. The first session has an SSC1 mode, indicating that the UPF that is the anchor of the PDU session remains unchanged when the PDU session is initially established. In other words, during the movement of the terminal device, the anchor UPF entity of the first session with the SSC1 mode does not change. The session management function entity and the first user plane function entity belong to the same carrier network, and may include non-roaming scenarios or local grooming LBO roaming scenarios. In addition, the choice of cache device may also need to consider the mobility of the terminal device.

In a possible design, the method further includes: the session management function entity interacting with the third user plane function entity and the first user plane function entity, respectively, such that the first user plane function entity passes through the third user plane function entity The access network device sends the second downlink data and the third downlink data. The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state.

In a possible design, the session management function entity notifies the first user plane function entity to cache the second downlink data of the first session according to the preset condition, including: the session management function entity selects the first user plane according to the preset condition. The function entity is used as a user plane function entity for buffering the second downlink data; the session management function entity notifies the first user plane function entity to cache the second downlink data after receiving the second downlink data.

In a possible design, the method further includes: the session management function entity obtains mobility information of the terminal device. For example, the session management function entity may obtain mobility information of the terminal device by: the session management function entity receiving the mobility attribute from the mobility management function entity, the mobility information being a mobility attribute; or the session management function entity acquiring the mobility statistics information The mobility information is mobility statistics information; or the session management function entity receives the mobility attribute from the mobility management function entity, acquires mobility statistics information, and determines mobility information according to the mobility attribute and the mobility statistics. The mobile attribute includes at least a high mobility attribute or a low mobility attribute, and the mobility statistics information is used to indicate a moving speed or a staying time of the terminal device.

For example, the session management function entity obtains mobility statistics, including: the session management function entity receives mobility statistics information from the mobility management function entity; or the session management function entity obtains mobility statistics information from the network data analysis NWDA device.

In a possible design, the method further includes: after the session management function entity selects the first user plane function entity as the user plane function entity that caches the second downlink data, the session management function entity releases the second user plane function entity. Therefore, when the anchor user plane function entity is selected as the cache device, the second user plane function entity can be directly released, thereby saving network resources.

In one possible design, the above method is suitable for routing HR roaming scenarios at home. The session management function entity and the third user plane function entity are located in the VPLMN in the HR roaming scenario, the method further includes: the session management function entity adjusts the cache device, and the cache device is configured to cache after the first session is switched to the deactivated state. The fourth downlink data of the first session.

For example, the session management function entity adjusts the cache device, including: the session management function entity determines that the third user plane function entity is the cache device; or the session management function entity determines that the session management function entity is a cache device. Thus, by updating the cache device, frequent interaction with the anchor user plane entity within the HPLMN can be avoided, thereby further enhancing the user experience.

In a further aspect, the present application further discloses a method for buffering data, comprising: a session management function entity interacting with a second user plane function entity and a first user plane function entity, respectively, such that the first user plane function entity passes the second The user plane function entity sends the first downlink data of the first session to the access network device, where the first user plane function entity is an anchor point of the first session. The session management function entity notifies the second user plane function entity to cache the second downlink data of the first session according to the preset condition. The preset condition includes the SSC information indicating that the first session has a third session and a service continuity SSC3 mode. The second downlink data is downlink data received by the second user plane function entity after the first session is switched to the deactivated state. The session management function entity interacts with the third user plane function entity and the second user plane function entity, respectively, to enable the second user plane function entity to send the second downlink data to the access network device through the third user plane function entity, and the The first user plane function entity sends the third downlink data to the access network device through the second user plane function entity and the third user plane function entity. The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state.

The first session has an SSC3 mode, indicating that in the SSC3 mode, multiple anchor points UPF may exist at the same time. In other words, there may be multiple "sessions" or multiple "session branches" of the session.

According to the foregoing scheme of buffering data, starting from the second user plane function entity, the data paths for transmitting the second downlink data and the third downlink data are the same, thereby avoiding the out-of-order problem of the downlink data received by the terminal, and improving the user experience. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and further improving the user experience.

In a possible design, the session management function entity notifies the second user plane function entity to cache the second downlink data of the first session according to the preset condition, including: the session management function entity selects the second user plane according to the preset condition. The function entity is used as a cache device for buffering the second downlink data; the session management function entity notifies the second user plane function entity to cache the second downlink data after receiving the second downlink data.

In one possible design, since the first session has the SSC3 mode, for the second session, the same or different cache device for buffering the downstream data may be selected. For example, for the second session, the initial anchor UPF or the current N3 UPF may be selected as the cache device, and the respective cache device is notified by the N4 message to buffer the received downlink data. Thereby, the independent processing of each session branch can be realized, so that the processing between the respective session branches does not affect each other and meet different requirements.

On the other hand, an embodiment of the present application provides a method for buffering data, where the method includes: the session management function network element interacts with the second user plane function network element and the first user plane function network element, respectively, so that the first The user plane function network element sends the first downlink data of the first session through the second user plane function network element. The second user plane function network element is a user plane function network element connected to the access network device in the first session, and the first user plane function network element is a user plane function network element connected to the second user plane function network element; for example In some scenarios, the first user plane function network element is an anchor point of the first session. The session management function network element releases the second user plane function network element when the first session enters the deactivated state (for example, determining release according to at least one of session and service continuity information, mobility information, and policy information) The second user plane function network element).

In a possible design, the session management function network element notifies the first user plane function network element to cache the second downlink data of the first session. In another possible design, after the second user plane function network element is released, the session management function network element notifies the first user plane function network element to release the connection with the second user plane function network element, so that the foregoing The first user plane function network element "automatically" becomes a cache device that caches the second downlink data after the first session transitions to the deactivated state.

According to the above solution, after the session management function network element deletes the second user plane function network element, the first user plane function network element becomes a new user plane function network element connected to the access network device, and caches the second downlink data. In this way, after the subsequent first session is switched to the active state, the second downlink data buffered by the first user plane function network element is the same as the transmission path of the third downlink data newly received by the first session to the active state. Thereby, the disorder of the downlink data received by the terminal is avoided. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF network elements, thereby reducing the delay and improving the user experience.

When the first session enters the deactivated state, the terminal device enters the idle state (IDLE), releases the related transmission resource of the access network of the first session, or the terminal device is still in the connected state (CM-Connected). ), in the process of releasing the relevant transmission resources of the access network of the first session.

On the other hand, the embodiment of the present application provides a session management function entity, which has the function of implementing the behavior of the session management function entity in the foregoing method. The functions may be implemented by hardware or by corresponding software implemented by hardware. The hardware or software includes one or more modules corresponding to the functions described above. In one possible design, the structure of the session management function entity includes a processor and a transceiver configured to process the session management function entity to perform the corresponding function in the above method. The transceiver is configured to implement communication between the session management function entity and the mobility management function entity/user plane function entity/other session management function entity. The session management function entity can also include a memory for coupling with the processor that holds program instructions and data necessary for the session management function entity.

In still another aspect, embodiments of the present application provide a computer readable storage medium having instructions stored therein that, when run on a computer, cause the computer to perform the methods described in the above aspects.

In still another aspect, embodiments of the present application provide a computer program product comprising instructions that, when run on a computer, cause the computer to perform the methods described in the above aspects.

DRAWINGS

In order to more clearly illustrate the embodiments of the present application, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present application, which are common in the art. For the skilled person, other drawings can be obtained from these drawings without paying for creative labor.

1 is a schematic diagram of cache data in the prior art;

2 is a schematic diagram of a communication system to which an embodiment of the present invention is applied;

3A and 3B are signaling interaction diagrams of a method of buffering data according to an embodiment of the present invention;

4 is a schematic diagram showing changes in data paths of the first session in FIGS. 3A and 3B;

FIG. 5 is another signaling interaction diagram of a method for buffering data according to an embodiment of the present invention; FIG.

6 is still another signaling interaction diagram of a method of buffering data according to an embodiment of the present invention;

7 is a flow chart of a method of buffering data according to an embodiment of the present invention;

FIG. 8A is a signaling interaction diagram of a method for buffering data according to another embodiment of the present invention; FIG.

8B is a schematic diagram of a data path change in FIG. 8A;

FIG. 9 is a flowchart of a method of buffering data according to another embodiment of the present invention; FIG.

10 and 11 are schematic views of a scenario in which the method of FIG. 9 can be applied;

12A and 12B are schematic diagrams showing the structure of a session management function entity according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present application will be clearly and completely described in the following with reference to the accompanying drawings in the embodiments.

The embodiment of the present application proposes a solution based on the communication system shown in FIG. 2, which is applicable to implementing data caching in a next-generation mobile network (such as a 5G network) architecture. For example, in the 5G mobile network architecture, the control plane function and the forwarding plane function of the mobile gateway are decoupled, and the separated control plane functions and the third generation partnership project (3GPP) traditional control network element MME And merge into a unified control plane entity. The user plane UPF entity can implement user plane functions (SGW-U and PGW-U) of a serving gateway (SGW) and a packet data network gateway (PGW). Further, the unified control plane entity can be decomposed into an access and mobility management function (AMF) entity and a session management function (SMF) entity. The AMF entity may be responsible for the attachment, mobility management, and tracking area update process of the terminal device. The SMF entity may be responsible for session management of the terminal device, selection of user plane devices, reselection of user plane devices, internet protocol (IP) address allocation, quality of service (QoS) control, and session establishment, Modify and release, etc.

In addition, the embodiments of the present application can also be applied to other communication technologies for the future. The system architecture and the service scenario described in the embodiments of the present application are for the purpose of more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation of the technical solutions provided by the embodiments of the present application. The technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

As shown in FIG. 2, the embodiment of the present application provides a communication system. For example, the communication system includes a terminal device 202, an access network device 204, an AMF entity 206, an SMF entity 208, and user plane entities 210a, 210b. In addition, the AMF entity, the SMF entity, and the user plane entity may also be referred to as an AMF network element, an SMF network element, and a user plane network element, respectively.

The terminal device 202 involved in the embodiments of the present application may include various handheld devices having wireless communication functions, in-vehicle devices, wearable devices, computing devices, or other processing devices connected to the wireless modem. The terminal device may also be referred to as a user equipment (UE), a mobile station (MS), a terminal, and may also include a subscriber unit, a cellular phone, a smart phone. (smart phone), wireless data card, personal digital assistant (PDA) computer, tablet computer, wireless modem (modem), handheld device, laptop computer, cordless phone (cordless) Phone) or wireless local loop (WLL) station, machine type communication (MTC) terminal, and the like.

The access network device 204 involved in the embodiment of the present application is a device deployed in a wired or wireless access network to provide wireless communication functions for the terminal device 102. The access network device may include various forms of base stations, such as a macro base station, a micro base station (also referred to as a small station), a relay station, an access point, and the like. In a system using different radio access technologies, the name of a device having a base station function may be different, for example, in an LTE system, an evolved Node B (evolved NodeB, eNB or eNodeB), in the third In a 3rd generation (3G) system, it is called a Node B or the like.

The AMF entity 206 involved in the embodiment of the present application may be responsible for attachment, mobility management, tracking area update procedure, and the like of the terminal device.

The SMF entity 208 involved in the embodiment of the present application may be responsible for session management of the terminal device, selection of a user plane entity (such as the user plane entity 210a or 210b), reselection of the user plane entity, IP address allocation, QoS control, and The establishment, modification, and release of a session.

In the example of Figure 2, two UPF entities are shown: UPF entity 210a and UPF entity 210b. Both the UPF entity 210a and the UPF entity 210b are connected to a data network (DN) 212 for effecting data transmission of services in different service areas. The UPF entity 210b may also be connected to other access network devices, and the invention is not limited. In addition, the embodiments of the present invention may also include other numbers of UPF entities, which are not limited by the present invention.

In a 5G communication system, the connection between the access network device 204 and the AMF entity 206 is an N2 connection, and the connection between the access network device 204 and the UPF entity 210a (or 210b) is an N3 connection, the SMF entity 208 and the UPF. The connection between entities 210a (or 210b) is an N4 connection, the connection between AMF entity 206 and SMF entity 208 is an N11 connection, and the connection between each SMF entity is an N16 connection. The connection between the various UPF entities is an N9 connection. A "connection" can also be referred to as a point-to-point reference point or a reference point. Further, the above connection is not limited to the above names, and may have other names. In the following description, if a message is named by a connection, it indicates that the message is a message transmitted through the connection. For example, "N2 message" represents a message transmitted over a connection between the access network device 204 and the AMF entity 206. The "N2 message" may have other specific names in different scenarios and processes, and the present invention is not limited thereto. The "N3 message", "N4 message", "N11 message", and "N16 message" are similar, and will not be described here.

Optionally, the communication system further includes a Network Data Analytics (DWDA) device 214. The NWDA device is used to count mobility statistics of the terminal device. For example, the mobility statistics are used to indicate the speed of movement of the terminal device or the dwell time under a certain UPF entity.

In the following description, "session" may refer to a packet data unit (PDU) session. The "data path" refers to a path for transmitting uplink or downlink data between the terminal device 202 and the UPF through a session, and may also be referred to as "user plane path".

A method for buffering data in the embodiment of the present application will be described below with reference to the embodiments of FIG. 3A to FIG. 7. 3A and 3B will be described in conjunction with FIG. Figure 4 illustrates the change in the data path of the first session of the terminal device 202 during the move.

Before performing the steps shown in FIG. 3A (for example, time T1 in FIG. 4), the terminal device establishes a first session with UPF1 and transmits data of the service through UPF1. For example, UPF1 is the UPF entity 210a in FIG. The first session has a first session and business continuity (SSC1) mode, and UPF1 is the anchor of the first session.

As shown in FIG. 3A, in step 301, the terminal device 202 transmits a session establishment request message to the AMF entity 206 via the access network device 204. For example, when the terminal device moves out of the service range of the UPF1, if the trigger condition for establishing the session is met, the terminal device 202 sends a session establishment request message.

Optionally, the session establishment request message may carry the SSC mode information of the first session.

Optionally, the session establishment request message may further carry PLMN information for indicating a public land mobile network (PLMN) that the terminal device 202 subscribes to. For example, the session establishment request message carries a subscriber permanent identifier (SUPI) of the terminal device, and the PLMN information can be represented by a field in the SUPI.

In step 302, the AMF entity 206 sends an N11 message to the SMF entity 208. The N11 message can be used to establish a PDU session (first session).

Optionally, the N11 message in step 302 may further carry the SSC mode information of the session. For example, the mode SSC information is used to indicate that the session has an SSC1 mode. After receiving the N11 message, the SMF entity 208 can learn that the session has the SSC1 mode.

Optionally, the N11 message in step 302 may further carry the PLMN information subscribed by the terminal device 202. After receiving the N11 message, the SMF entity 208 can also know whether the current terminal device 202 is located in the home public land mobile network (HPLMN), that is, whether the terminal device 202 is in a non-roaming state. For example, the SMF entity 208 determines whether the PLMN information of the current network is the same as the PLMN information obtained in step 302 to determine if the current terminal device 202 is located within the HPLMN.

Optionally, after receiving the N11 message from the AMF entity 206, the SMF entity 208 obtains the mobility information of the terminal device 202. The mobility information is used to indicate whether the terminal device 202 belongs to a high mobility device.

For example, the SMF entity can obtain the mobility information of the terminal device 202 in the following ways:

The first way to achieve:

Prior to step 302, the AMF entity obtains mobility statistics from the NWDA device 214 via step 302a. The N11 message in step 302 carries the acquired mobility statistics. After receiving the N11 message from the AMF entity 206, the SMF entity 208 obtains the mobility information of the terminal device 202 based on the mobility statistics. Alternatively, the N11 message in step 302 carries the mobility statistics obtained from the NWDA, and the mobility attribute of the terminal device 202 of the AMF. After receiving the N11 message from the AMF entity 206, the SMF entity 208 determines the mobility information of the terminal device 202 based on the mobility statistics and the mobility attributes.

The second way to achieve:

The N11 message in step 302 carries the mobility attribute of the terminal device 202 of the AMF. After receiving the N11 message from the AMF entity 206, the SMF entity 208 obtains mobility statistics from the NWDA device 214 via step 302b. Finally, the SMF entity obtains the mobility information of the terminal device 202 based on the mobility statistics information, or determines the mobility information of the terminal device 202 based on the mobility statistics information and the mobility attribute.

The third way to achieve:

After receiving the N11 message from the AMF entity 206, the SMF entity 208 obtains mobility statistics from the NWDA device 214 via step 302b. The SMF entity obtains mobility information of the terminal device 202 based on the mobility statistics.

The fourth way to achieve:

The N11 message in step 302 carries the mobility attribute of the terminal device 202 managed by the AMF. After receiving the N11 message from the AMF entity 206, the SMF entity 208 obtains the mobility information of the terminal device 202 based on the mobility attribute.

In several of the above implementations, the mobility attribute includes at least a first type of mobility (e.g., high mobility) or a second type of mobility (e.g., low mobility). Optionally, the mobility attribute may also include a third type of mobility (eg, medium mobility). For example, the mobility attribute may be a parameter in a mobility pattern or may be a parameter independent of the mobility mode. The mobility attributes may be configured by the AMF entity 206, or may be obtained by the AMF entity 206 from other network devices, and the invention is not limited thereto.

The mobility statistics may include at least one of a moving speed of the terminal device 202 and a dwell time of the terminal device 202 under a certain UPF entity. It should be noted that the moving speed here may be generated according to the instantaneous speed value of each terminal in the preset time period. Similarly, the dwell time can also be generated based on statistics.

For example, in the foregoing first, second, and third implementation manners, obtaining the mobility information of the terminal device 202 according to the mobility statistics information may include: if the mobility statistics information indicates that the moving speed of the terminal device 202 is higher than a first threshold or The staying time of the terminal device 202 under a certain UPF entity is not higher than the second threshold, and the determined mobility information indicates that the terminal device 202 belongs to the high mobility device. If the mobility statistics indicate that the moving speed of the terminal device 202 is not higher than the first threshold or the dwell time of the terminal device 202 under a certain UPF entity is higher than the second threshold, the determined mobility information indicates that the terminal device 202 does not belong to the high. Mobile device.

In the foregoing fourth implementation manner, obtaining the mobility information of the terminal device 202 according to the mobility attribute may include: if the mobility attribute is the first type of mobility (for example, high mobility), the determined mobility information indicates the terminal device. 202 belongs to a highly mobile device. If the mobility attribute is a second type of mobility (eg, low mobility) or a third type of mobility (eg, medium mobility), the determined mobility information indicates that the terminal device 202 does not belong to the high mobility device.

In the foregoing first and second implementation manners, determining the mobility information of the terminal device 202 according to the mobility statistics information and the mobility attribute may include: if the mobility statistics information indicates that the moving speed of the terminal device 202 is higher than a first threshold or the terminal If the dwell time of the device 202 under a certain UPF entity is not higher than the second threshold, and the mobility attribute is the first type of mobility (eg, high mobility), the determined mobility information indicates that the terminal device 202 belongs to the high mobility device. . If the mobility statistics indicate that the moving speed of the terminal device 202 is not higher than the first threshold or the dwell time of the terminal device 202 under a certain UPF entity is higher than the second threshold, and the mobility attribute is the second type of mobility (eg, low) Mobility) or a third type of mobility (e.g., medium mobility), the determined mobility information indicates that the terminal device 202 does not belong to the high mobility device. If the mobility statistics and the mobility attributes are inconsistent, the SMF entity 208 can further determine whether the terminal device 202 belongs to the high mobility device based on the local policy.

In step 303, the SMF entity 208 selects UPF2 (e.g., the UPF entity 210b in FIG. 2) to interact with the UPF2 through the N4 message to establish a PDU session (first session). For example, the SMF entity 208 sends an N4 session establishment request message to the UPF 2, and the UPF 2 returns an N4 session establishment response message to the SMF entity 208.

Among them, UPF2 is connected to UPF1. For example, UPF2 and UPF1 are connected through an N9 connection.

In step 304, the SMF entity 208 returns an N11 message to the AMF entity 206. The N11 message is a setup PDU session accept message. For example, the setup PDU session accept message of step 304 carries tunnel information (eg, address information of UPF2) on the core network side.

In step 305, the AMF entity 206 sends an N2 message to the access network device 204 to forward the establish PDU session accept message of step 304 to the access network device 204. The N2 message is used to activate an N3 connection between the AMF device 206 and the UPF 2 for the first session described above.

Step 306: After receiving the N2 message, the access network device 204 establishes a data radio bearer (DRB).

In step 307, the access network device 204 returns an N2 message to the AMF entity. The N2 message is a setup PDU session accept message. For example, the setup PDU session accept message of step 307 carries the tunnel information of the access network side.

In step 308, the AMF entity 206 sends an N11 message to the SMF entity 208 to forward the setup PDU session accept message of step 307 to the SMF entity 208.

In step 309, the SMF entity 208 exchanges the N4 message with the UPF2 to forward the tunnel information of the access network side to the UPF2 by modifying the PDU session. For example, SMF entity 208 sends an N4 session modification request message to UPF2. The UPF 2 returns an N4 session modification response to the SMF entity 208.

In step 309b, the SMF entity 208 interacts with the UPF1 N4 message to add the UPF2 to the data path of the first session of the UPF1 by modifying the PDU session. For example, SMF entity 208 sends an N4 Session Modification Request message to UPF1, which returns an N4 Session Modification Response message to SMF entity 208.

In step 310, the SMF entity 208 returns an N11 message to the AMF entity 206 as a response to the N11 message in step 308.

At this point, the UPF1 sends the first downlink data of the first session to the access network device (for example, the access network device 204) via the UPF2. As shown in FIG. 4, at time T2, the downlink data path of the first session is: UPF1→UPF2→access network device (not shown)→terminal device 202. Similarly, the uplink data path of the first session is: terminal device 202→access network device (not shown)→UPF2→UPF1.

At this time, the UPF2 is a UPF entity connected to the access network device 204, and may also be referred to as an N3 UPF. N3 UPF is used to terminate the N3 connection, which can also be called the endpoint of the N3 connection. In the following description, the UPF entity connected to the access network device 204 is simply referred to as N3 UPF. Of course, the UPF entity connected to the access network device 204 may also have other names, which are not limited by the present invention.

Step 311: When the trigger condition is met, triggering to convert the first session to an inactive state. At this time, the terminal device 202 transmits a trigger message to the access network device 204. Upon receiving the trigger message, the access network device 204 sends an N2 message to the AMF entity 206 to release the N2 connection between the access network device 204 and the AMF entity 206.

It should be noted that, in the above description, the first session is triggered to switch to the deactivated state. If all sessions on the terminal device 202 are switched to the deactivated state, the terminal device 202 switches to the CM-CONNECTED state accordingly.

In step 312, the AMF entity 206 sends an N11 message to the SMF entity 208 requesting to release the N3 connection between the access network device 204 and the UPF 2.

Optionally, if the AMF entity 206 detects that the mobility statistics or the mobility attributes of the terminal device 202 change, the N11 message may carry at least one of mobility statistics information and mobility attributes. After receiving the N11 message from the AMF entity 206, the SMF entity 208 may update the mobility information of the terminal device 202. For the manner in which the SMF entity 208 updates the mobility information of the terminal device 202, refer to the description of the mobility information of the terminal device 202 obtained by the SMF entity 208 in step 302, and details are not described herein again.

Step 313, the SMF entity 208 selects the UPF1 as a cache device for buffering the second downlink data after the first session is switched to the deactivated state according to the preset condition.

For example, the preset condition includes at least one of the following:

The SSC information indicates that the first session has an SSC1 mode;

The mobility information of the terminal device 202 indicates that the terminal device 202 belongs to a high mobility device;

The session management function entity and the first user plane function entity belong to the same carrier network (for example, a non-roaming scene or a local sparring local breakout, LBO, roaming scenario).

That is, when any of the preset conditions is satisfied, UPF1 may be selected as a cache device that caches the second downlink data after the first session transitions to the deactivated state.

For example, if the SSC information indicates that the first session has the SSC1 mode, the SMF entity 208 selects the UPF1 to buffer the second downlink data. Alternatively, if the mobility information of the terminal device indicates that the terminal device 202 belongs to the high mobility device, the SMF entity 208 selects the UPF1 to buffer the second downlink data. Alternatively, if the SSC information indicates that the first session has the SSC1 mode, and the mobility information of the terminal device indicates that the terminal device 202 belongs to the high mobility device, the SMF entity 208 selects the UPF1 to buffer the second downlink data. In addition, the above method can be applied to both non-roaming scenarios and LBO roaming scenarios. When the above method is applicable to the scenario of LBO roaming, the SMF entity 208 is located in the visited PLMN (VPLMN).

In step 314, the SMF entity 208 interacts with the UPF 2 for the N4 message to request to release the N3 connection between the access network device 204 and the UPF 2. For example, the SMF entity 208 sends an N3 connection release request message or a session modification request message to the UPF2, and the UPF2 returns an N3 connection release response message or a session modification response message to the SMF entity 208, thereby releasing An N3 connection between the access network device 204 and the UPF 2.

Alternatively, SMF entity 208 interacts with UPF2 with an N4 message to request release of UPF2. For example, the SMF entity 208 sends a session termination request to the UPF 2, and the UPF 2 returns a session termination response to the SMF entity 208, thereby directly releasing UPF2. It should be noted that the “release UPF” refers to the release of the specified/all sessions on the UPF, that is, the deletion of the information related to the specified/all sessions on the UPF, and may also be expressed as “delete UPF”. A similar description will follow.

In step 315, the SMF entity 208 sends an N4 message to the UPF1 to notify the UPF1 to buffer the second downlink data. For example, the SMF entity 208 sends an N4 session modification request message to the UPF1 by modifying the PDU session, and the UPF1 returns an N4 session modification response message to the SMF entity 208, thereby notifying the UPF1 to buffer the second downlink data.

Optionally, the foregoing steps 313-315 may be replaced by: the SMF entity 208 releases the UPF2, and sends an N4 message to the UPF1 to notify the UPF1 to release the connection between the UPF1 and the UPF2.

For example, the SMF entity 208 first determines whether the UPF 2 needs to be released based on the policy information. When the policy information indicates that UPF2 is released, SMF entity 208 determines to release UPF2. For example, the operator sets whether the user plane management policy deletes the N3 UPF for all sessions or deletes the N3 UPF for the specified session, thereby generating corresponding policy information. In addition, the SMF entity 208 may further determine whether the UPF2 needs to be released according to other parameters in the foregoing preset conditions (for example, session and service continuity information, mobility information), and may refer to the SMF entity 208 to select UPF1 as a cache device according to a preset condition. The description will not be repeated. That is, when any of the above is satisfied, the SMF entity 208 determines that UPF2 needs to be released.

The SMF entity 208 determines that the UPF2 needs to be released and then requests the release of UPF2 by interacting with the UPF2 N4 message. For example, the SMF entity 208 sends a session termination request message to the UPF 2, and the UPF 2 returns a session termination response message to the SMF entity 208, thereby directly releasing UPF2.

In addition, the SMF entity 208 requests the UPF 1 to release the connection between UPF1 and UPF2 by interacting with the UPF1 N4 message. For example, SMF entity 208 sends a session modification request message to UPF1, which returns a session modification response message to SMF entity 208. In an implementation manner, the UPF1 may be configured to buffer the second downlink data after receiving the second downlink data by carrying the displayed indication information (for example, buffer on/off) in the session modification request. In another implementation manner, the session modification request may not carry any indication. By not carrying the displayed indication information in the session request message, the UPF1 implicitly informs the UPF1 to cache the second downlink data after receiving the second downlink data. That is, the SMF entity 208 releases the connection between the UPF1 and the UPF2 by notifying the UPF1 that the UPF1 "automatically" becomes the cache device that caches the second downlink data after the first session transitions to the deactivated state.

It can be understood that after UPF2 is released, UPF1 becomes a new N3 UPF, and then UPF1 becomes a cache device that caches the second downlink data after the first session is switched to the deactivated state. It should be noted that the UPF1 may be an anchor UPF or may be an UPF between the anchor UPF and the UPF2.

In step 316, the SMF entity 208 returns an N11 message to the AMF entity 206 to confirm release of the N3 connection between the access network device 204 and the UPF 2. After receiving the N11 message, the AMF entity 206 records the first session transition to the deactivated state.

Through the above steps in FIG. 3A, after the SMF entity selects UPF1 according to the preset condition or deletes the UPF2 according to the preset condition, the anchor point UPF1 is notified to buffer the second downlink data. After the first session is switched to the active state, the second downlink data buffered by the anchor user plane function entity and the first session are switched again to the active state. The newly received third downlink data transmission path is UPF1→UPF3→access Network device → terminal device 202. Thereby, the disorder of the downlink data received by the terminal is avoided. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and improving the user experience. This will be described in detail in conjunction with FIG. 3B and FIG.

In addition, the selection of the cache device also needs to consider the mobility of the terminal device, and the anchor user plane function entity is selected when the terminal device is a high mobility device (which may lead to a high probability of occurrence of out-of-order and re-establishment of the forwarding path). Cache device. Similarly, whether to delete the N3 UPF connected to the access network device may also need to consider the mobility of the terminal device, and when the terminal device is a high mobility device (which may cause the problem of out-of-order and re-establishing the forwarding path to be high) The N3 UPF is selected to be deleted, and other UPFs (for example, anchor user plane function entities) connected to the N3 UPF through the N9 interface are set as the cache device. In addition, the UPF connected to the N3 UPF through the N9 interface may also be the UPF between the anchor user plane function entity and the N3 UPF.

Optionally, if the mobility information of the terminal device indicates that the terminal device 202 does not belong to the high mobility device (the probability of occurrence of the problem of out-of-order and re-establishing the forwarding path is relatively low), other cache devices may be selected (for example, the cache device is UPF2) That is, the UPF of the N3 connection is provided or the N3 UPF (for example, UPF2) is not deleted, and the N3UPF is directly set as the cache device. In this way, the data path of the core network still maintains UPF1→UPF2→access network device→terminal device 202. After the paging response, the buffered downlink data can be directly obtained from the UPF2 connected to the access network device, and the probability of removing the UPF2 is relatively low. (In the case where the problem of out-of-order and re-establishing the forwarding path has a low probability of occurrence), the buffered downlink data can be obtained nearby, thereby saving signaling resources.

Optionally, the SMF can also select the SMF as a cache device. For example, if the UPF does not have the ability to buffer downstream data, the SMF can select the SMF as the cache device. Alternatively, the SMF may select the SMF as a cache device according to the policy.

As shown in FIG. 3B, when the first session is in the deactivated state, the second downlink data from the data network 212 reaches UPF1.

In step 401, the UPF1 buffers the second downlink data.

Step 402a: After receiving the second downlink data, the UPF1 sends a data notification message to the SMF entity 208.

The present invention does not limit the execution sequence between step 401 and step 402a. Step 401 may be performed after step 401 is performed first, or step 402a may be performed first, or step 401 may be performed first, or step 401 and step 402a may be performed at the same time.

Optionally, in step 402b, the SMF entity 208 returns a data notification confirmation message to the UPF1.

Step 403, after receiving the data notification message, the SMF entity 208 determines the AMF entity 206 and sends an N11 message to the AMF entity 206.

In step 404, the AMF entity 206 sends a paging message to the terminal device 202 through the access network device 204 to trigger the terminal device 202 to switch to the connected state.

After receiving the paging message, the terminal device 202 performs a service request procedure through steps 405 to 411.

In step 405, the terminal device 202 sends a service request message to the access network device 204. After receiving the service request message, the access network device 204 forwards the service request message through the N2 message.

Optionally, in step 405a, the AMF entity 206 sends an N2 message to the access network device 204. The N2 message carries the address information of the UPF2. Since the N3 connection between the access network device 204 and the UPF 2 has been released through the above step 304, or the UPF 2 is released, the message is invalid and therefore may be omitted.

In step 405b, the AMF entity 206 sends an N11 message to the SMF entity 208.

Step 406: After receiving the N11 message, the SMF entity 208 selects UPF3 (not shown in FIG. 2) and interacts with the UPF3 to complete the N4 message to establish a PDU session (first session). For example, SMF entity 208 sends an N4 Session Establishment Request message to UPF3, which returns an N4 Session Establishment Response message to SMF entity 208.

In step 407, the SMF entity 208 interacts with the UPF1 to exchange the N4 message to add the UPF3 to the data path of the first session of the UPF1 by modifying the PDU session. For example, SMF entity 208 sends an N4 Session Modification Request message to UPF1, which returns an N4 Session Modification Response message to SMF entity 208.

Optionally, if only the N3 connection between the access network device 204 and the UPF2 is released in the foregoing step 314 in FIG. 3A without releasing the UPF2, step 408 may be performed. If UPF2 has been released in the above step 314 in FIG. 3A, step 408 may be omitted.

In step 408, the SMF entity 208 interacts with the UPF2 through the N4 message to release the UPF2. For example, the SMF entity 208 sends a session termination request message to the UPF 2, and the UPF 2 returns a session termination response message to the SMF entity 208, thereby releasing UPF2.

Step 409, after receiving the session establishment response message and the session modification response message, the SMF entity 208 sends an N11 message to the AMF entity 206.

In step 410, the AMF entity 206 sends an N2 message to the access network device 204. The N2 message indicates that the service is accepted. The N2 message carries the address information of the UPF3.

Step 411: After receiving the N2 message, the access network device 204 performs an RRC connection reconfiguration with the terminal device 202.

At this point, UPF3 is N3 UPF. The UPF1 sends the buffered second downlink data and the newly received third downlink data to the access network device 204 via the UPF3. As shown in FIG. 4, at time T3, the data paths for transmitting the second downlink data and the third downlink data of the first session are: UPF1→UPF3→access network device (not shown)→terminal device 202. Therefore, the data paths for transmitting the second downlink data and the third downlink data are the same, which avoids the disorder of the downlink data received by the terminal, and improves the user experience. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and further improving the user experience.

When the trigger condition is met, the first session transition to the deactivated state may be triggered again. For the process, reference may be made to the description of steps 311 to 316 in FIG. 3A, and details are not described herein again. Similarly, in this process, the N2 connection between the access network device 204 and the AMF entity 206, and the N3 connection between the access network device 204 and the UPF 3 (or direct release of the UPF 3) are released.

If the terminal moves out of the service scope of the original SMF entity 208 during the move, it needs to perform relocation of the SMF entity. For example, UPF1 and UPF2 described above are coupled to SMF entity 208, and UPF3 is coupled to SMF entity 208'.

As shown in FIG. 5, steps 501 to 505b may refer to the description of steps 401 to 405b in FIG. 3B, and details are not described herein again.

In step 506, the SMF entity 208 sends an N16 message to the SMF entity 208'.

Step 507, after receiving the N16 message, the SMF entity 208' selects the UPF3 and interacts with the UPF3 to establish a PDU session.

In step 508, the SMF entity 208' returns an N16 message to the SMF entity 208.

Steps 509 to 513 may refer to the description of steps 407 to 411 in FIG. 4, and details are not described herein again.

Similarly, when the trigger condition is met, the first session transition to the deactivated state can be triggered again. For the process, reference may be made to the description of steps 311 to 316 in FIG. 3A, and details are not described herein again. In this process, the N2 connection between the access network device 204 and the AMF entity 206 is released. In addition, after the SMF is migrated to the SMF entity 208', the receiving end of the N11 message in step 312 is the SMF entity 208' (or forwarded to the SMF entity 208' by the SMF entity 208), and the SMF entity 208' is released by interacting with the UPF3. The N3 connection between the network access device 204 and the UPF 3 or the UPF 3 is released.

In addition, for a session involving multiple SMF entities, the N3 UPF governed by the SMF that is recently served by the terminal device 202 can also be set (or updated) as a cache device, or the SMF that is recently served for the terminal device 202 is not deleted. N3 UPF.

Furthermore, the above method of the present invention can also be applied to a scene of roaming. For example, the roaming scenario includes a local break out (LBO) scenario or a home routed (HR) scenario.

For the roaming situation in the LBO scenario, it will be described in conjunction with FIG. 3A, FIG. 3B and FIG.

For example, at an initial time, the terminal device 202 acquires service data through UPF0 (not shown) within the HPLMN. At time T1, the terminal device 202 roams from the HPLMN to the visited PLMN (VPLMN), and the terminal device establishes a first session with the UPF1 in the VPLMN and transmits the data of the service through the UPF1. UPF1 is the anchor point of the first session within the VPLMN.

Thereafter, after the terminal device 202 moves from the service range of the UPF1 to the service range of the UPF2 under the VPLMN, the first session (e.g., at time T2) can be established with the UPF 2 through steps 301 to 310 in FIG. 3A. It should be noted that the SMF entity 208 at this time is an SMF entity located in the VPLMN. In the process of switching from the first session to the deactivated state, for example, by selecting steps 311 to 316 in FIG. 3A, selecting UPF1 according to a preset condition or deleting UPF2 according to a preset condition, the anchor point UPF1 is notified to buffer the downlink data of the first session. . Thereafter, downlink data may be buffered by the anchor point UPF1 through steps 401 to 411 in FIG. 3B, and the terminal device 202 is triggered to establish a first session with the UPF 3 (eg, at time T3).

In the flow of the first session switching to the deactivated state again (refer to the description of steps 311 to 316 in FIG. 3A), similarly, the N2 connection between the access network device 204 and the AMF entity 206 is released, and N3 connection between the network access device 204 and the UPF 3.

In addition, similar to step 313 in FIG. 3A, the cache device that caches the downlink data after the first session transitions to the deactivated state may be selected again based on the preset condition. If the foregoing preset condition is met, the anchor point UPF1 may be selected as the cache device, and the anchor point UPF1 is notified through step 315, and details are not described herein again. If the preset condition is not satisfied, UPF3 may also be selected as the cache device, and UPF3 is notified through step 314. Here, it is possible to select whether to delete the UPF2 based on the preset condition again, thereby determining the cache device. In addition, the SMF entity within the VPLMN can also be selected as a cache device (eg, when UPF3 does not have the ability to buffer downstream data).

As can be seen from the above description, the method of FIGS. 3A and 3B is also applicable to the scene of LBO roaming.

The roaming situation in the HR scenario will be described in conjunction with FIG. 6. Figure 6 shows the signaling interaction of the method in an HR roaming scenario. In the example of FIG. 6, at this time, UPF1 and the SMF entities located within the HPLMN may be referred to as H-UPF1 and hSMF, respectively, to indicate that they are located within the HPLMN. At this time, UPF2, UPF3, and SMF entities located in the VPLMN may be referred to as V-UPF2, V-UPF3, vSMF, respectively, to indicate that they are located within the VPLMN.

The terminal device 202 is still in a non-roaming state before performing the steps shown in FIG. 6. The terminal device 202 establishes a first session with the H-UPF1 and transmits data of the service through the H-UPF1. The first session has an SSC1 mode, and H-UPF1 is an anchor point of the first session.

As shown in FIG. 6, after the terminal device 202 roams to the VPLMN, in step 601, the terminal device 202 transmits a session establishment request message to the AMF entity 206 via the access network device 204.

In step 602, the AMF entity 206 sends an N11 message to the vSMF. The N11 message can be used to establish a PDU session (first session).

In step 603, the vSMF selects V-UPF2 to interact with the V-UPF2 through the N4 message to establish a PDU session (first session). For example, the vSMF sends an N4 Session Establishment Request message to V-UPF2, and V-UPF2 returns an N4 Session Setup Response message to the vSMF.

In step 604, the vSMF sends an N16 message to the hSMF to establish a first session.

In step 605, the hSMF interacts with the H-UPF1 to exchange the N4 message.

In a possible implementation, roaming between HPLMN and VPLMN can be supported to achieve normal session switching. In such a case, the original H-UPF1 can be kept as an anchor point to add V-UPF2 to the data path of the first session of H-UPF1 by modifying the PDU session.

In another possible implementation, the session cannot be switched normally, and a new anchor point UPF1' needs to be selected within the HPLMN. In this case, the data path of the first session with V-UPF2 as N3 UPF and UPF1' as anchor point can be formed by establishing a PDU session.

In step 606, the hSMF sends an N16 message to the vSMF.

In step 607, the vSMF returns an N11 message to the AMF entity 206. The N11 message is a setup PDU session accept message.

In step 608, the AMF entity 206 sends an N2 message to the access network device 204 to forward the establish PDU session accept message of step 605 to the access network device 204.

Step 609: After receiving the N2 message, the access network device 204 establishes a DRB.

In step 610, the access network device 204 returns an N2 message to the AMF entity. The N2 message is a setup PDU session accept message.

In step 611, the AMF entity 206 sends an N11 message to the vSMF to forward the setup PDU session accept message of step 609 to the hSMF.

Step 612: The vSMF exchanges the N4 message with the V-UPF2 to forward the tunnel information of the access network side to the UPF2 by modifying the PDU session.

In step 613, the vSMF returns an N11 message to the AMF entity 206 as a response to the N11 message in step 611.

The above steps may refer to the steps of steps 301 to 310 in FIG. 3A. It can be understood that since V-UPF2 and V-UPF3 are controlled by vSMF, they can be directly implemented by vSMF; while H-UPF1 is controlled by hSMF, and forwarding between hSMF and vSMF is required for messages involving H-UPF1.

Step 614: When the trigger condition is met, triggering to convert the first session to the deactivated state. At this time, the terminal device 202 transmits a trigger message to the access network device 204. Upon receiving the trigger message, the access network device 204 sends an N2 message to the AMF entity 206 to release the N2 connection between the access network device 204 and the AMF entity 206.

In step 615, the AMF entity 206 sends an N11 message to the vSMF to request to release the N3 connection between the access network device 204 and the V-UPF2.

Step 616: The vSMF notifies the V-UPF2 to cache the second downlink data of the first session according to the preset condition. The preset condition includes the SSC information indicating that the first session has the SSC1 mode.

For example, the vSMF interacts with V-UPF2 with an N4 message to request the release of the N3 connection between the access network device 204 and the V-UPF2. The optional vSMF may notify the V-UPF2 to cache the second downlink data of the first session by requesting to release the N4 message of the N3 connection. In other words, the N4 message of step 616 has two purposes: (1) requesting to release the N3 connection between the access network device 204 and the V-UPF2; (2) notifying the V-UPF2 to cache the second downlink data of the first session. .

In step 617, the vSMF returns an N11 message to the AMF entity 206 to confirm release of the N3 connection between the access network device 204 and the V-UPF 2. After receiving the N11 message, the AMF entity 206 records the first session transition to the deactivated state.

Thus, when H-UPF1 (or UPF1') receives the second downlink data, the second downlink data is forwarded to V-UPF2.

Step 618, V-UPF2 buffers the second downlink data.

Thereafter, the first session of the terminal device 202 and the V-UPF 3 can be triggered by steps 619a to 631. Steps 619a to 631 may refer to the description of steps 402a to 411 in FIG. 3B, with the difference that, since the second downlink data is buffered in V-UPF2, the data notification message is sent by V-UPF2 to the vSMF controlling V-UPF2, in FIG. 3B. The operation of the SMF entity 208 can be performed by the vSMF; and for the operation of the UPF1 controlled by the hSMF, it needs to be implemented by the forwarding of the vSMF and the hSMF.

In the process of switching the first session to the deactivated state again (refer to the description of steps 614 to 617), in step 632, the vSMF may also update the cache device that buffers the downlink data after the first session transitions to the deactivated state. For example, if the mobility statistics indicate that the terminal device 202 will stay in the VPLMN for a long time (eg, the time at which the terminal device 202 stays at the VPLMN is greater than a third threshold), the UPF3 may be updated as a cache device and notified to the UPF 3. Alternatively, the vSMF can be updated to be a cache device (eg, when UPF3 does not have the ability to buffer downstream data).

That is to say, in the roaming scenario of the HR, the vSMF selects the N3 UPF as the cache device.

In addition, through the above steps, when the session of the terminal device 202 in the roaming (LBO or HR) scenario is triggered to switch to the deactivated state again, the cache device can be updated, thereby avoiding frequent interaction with the anchor point in the HPLMN, thereby further improving user experience.

FIG. 7 illustrates a method of caching data in accordance with an embodiment of the present invention. The method may be performed by a session management function entity (e.g., the SMF entity 208 described above, or a vSMF under an LBO roaming scenario). FIG. 7 will be described in conjunction with FIGS. 2 through 6. For example, the method includes:

Step 702: The session management function entity interacts with the second user plane function entity (for example, the UPF2) and the first user plane function entity (for example, the UPF1), so that the first user plane function entity passes the second user plane function. The entity sends the first downlink data of the first session to the access network device (eg, the access network device 204). The first user plane function entity is an anchor point of the first session.

For example, step 702 can be implemented by steps 303 and 309b in Figure 3A.

Step 704: The session management function entity notifies the first user plane function entity to cache the second downlink data of the first session according to the preset condition. The preset condition includes the SSC information indicating that the first session has the first session and the service continuity SSC1 mode. The second downlink data is downlink data received by the first user plane function entity after the first session is switched to the deactivated state.

For example, step 704 can be implemented by step 315 in Figure 3A.

According to the foregoing scheme of buffering data, the session management function entity notifies the anchor user plane function entity to cache the second downlink data according to the preset condition. In this way, after the first session is switched to the active state, the second downlink data buffered by the anchor user plane function entity is the same as the transmission path of the third downlink data newly received by the first session to the active state. Thereby, the out-of-order problem of the downlink data received by the terminal is avoided, and the user experience is improved. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and further improving the user experience.

Optionally, the preset condition includes at least one of the following: the SSC information indicates that the first session has a first session and a service continuity SSC1 mode; the mobility information indicates that the terminal device is a high mobility device; the session management function entity and the A user plane functional entity belongs to the same carrier network. The first session has an SSC1 mode, indicating that the UPF that is the anchor of the PDU session remains unchanged when the PDU session is initially established. In other words, during the movement of the terminal device, the anchor UPF entity of the first session with the SSC1 mode does not change. The session management function entity and the first user plane function entity belong to the same carrier network, and may include non-roaming scenarios or local grooming LBO roaming scenarios. In addition, the choice of the cache device also needs to consider the mobility of the terminal device.

Optionally, the method further includes: the session management function entity interacts with the third user plane function entity (for example, the UPF3) and the first user plane function entity, respectively, so that the first user plane function entity passes the third user plane function. The entity sends the second downlink data and the third downlink data to the access network device (which may be the access network device 204 or other access network device). The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state (for example, refer to steps 406 and 407 in FIG. 3B).

Optionally, the step 704 includes: the session management function entity selects the first user plane function entity as the user plane function entity that caches the second downlink data according to the preset condition; and the session management function entity notifies the first user plane function entity to receive the After the second downlink data, the second downlink data is buffered (for example, refer to steps 313 to 315 in FIG. 3A).

Optionally, the method further includes: the session management function entity obtains mobility information of the terminal device. For example, the session management function entity may obtain mobility information of the terminal device by the session management function entity receiving the mobility attribute from the mobility management function entity (eg, the AMF entity 206), the mobility information being a mobile attribute; or, session management The functional entity obtains mobility statistics, and the mobility information is mobility statistics; or the session management function entity receives the mobility attribute from the mobility management function entity, obtains mobility statistics, and determines mobility according to the mobility attribute and the mobility statistics. information. The mobility attribute includes at least a high mobility attribute or a low mobility attribute, and the mobility statistics information is used to indicate a moving speed or a staying time of the terminal device (for example, refer to steps 302, 302a, and 302b in FIG. 3A).

For example, the session management function entity obtains mobility statistics, including: the session management function entity receives mobility statistics from the mobility management function entity; or the session management function entity obtains from the network data analysis NWDA device (eg, the NWDA device 214 described above) Mobility statistics.

Optionally, the method further includes: after the session management function entity selects the first user plane function entity as the user plane function entity that caches the second downlink data, the session management function entity releases the second user plane function entity (for example, reference may be made. Step 314) in Figure 3A. Therefore, when the anchor user plane function entity is selected as the cache device, the second user plane function entity can be directly released, thereby saving network resources.

Optionally, the foregoing steps 702 and 704 may be replaced by: the session management function entity interacting with the second user plane function entity and the first user plane function entity, respectively, such that the first user plane function entity passes the second user plane function entity Sending the first downlink data of the first session. The session management function entity releases the second user plane function entity when the first session enters the deactivated state (eg, the session management entity first determines to release the second user plane function entity). The second user plane function entity is a user plane function entity connected to the access network device in the first session. The first user plane function entity may be an anchor UPF or a UPF between the second user plane function entity and the anchor point UPF.

Optionally, the session management function entity notifies the first user plane function entity to cache the second downlink data of the first session. Or the session management function network element notifies the first user plane function network element to release the connection with the second household function network element, so that the first user plane entity "automatically" becomes the first session transition to the deactivated state. A cache device that caches the second downlink data.

According to the above solution, after the session management function entity deletes the second user plane function entity, the first user plane function entity becomes a new user plane function entity connected to the access network device, and caches the second downlink data. In this way, after the first session is switched to the active state, the second downlink data buffered by the first user plane function entity is the same as the transmission path of the third downlink data newly received by the first session to the active state. Thereby, the disorder of the downlink data received by the terminal is avoided. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and improving the user experience.

For example, the session management entity first determines to release the second user plane functional entity according to at least one of session and business continuity information, mobility information, and policy information. For example, when any of the following is satisfied, the session management entity determines to release the second user plane energy entity:

The session and service continuity information indicates that the first session has a first session and a business continuity mode;

The mobility information indicates that the terminal device is a high mobility device;

The local policy indicates that the second user plane entity is released;

The session management function entity and the first user plane function entity belong to the same carrier network (representing a scenario suitable for non-roaming scenarios or local grooming LBO roaming).

Optionally, the foregoing methods are all applicable to the home routing HR roaming scenario. The session management function entity (for example, the vSMF above) and the third user plane function entity are located in the VPLMN under the HR roaming scenario, the method further includes: the session management function entity adjusts the cache device, where the cache device is used to switch to the first session to After the deactivated state, the fourth downlink data of the first session is cached (for example, refer to step 632 in FIG. 6).

A method of buffering data according to another embodiment of the present application will be described below with reference to FIG. 8A and FIG. 8B. Figure 8A shows the signaling interaction of the method, and Figure 8B shows the change of the data path of the terminal device 202 during the move. This method is applicable to PDU sessions with SSC3 mode. In SSC3 mode, there may be multiple anchor points UPF at the same time. In this scenario, there may be multiple "sessions" (e.g., multiple PDU sessions), or multiple "session branches" of the session. Hereinafter, a description will be made by taking a plurality of "sessions" as an example.

Before performing the step shown in FIG. 8A (for example, time T1 in FIG. 8B), the terminal device establishes a first session with UPF1 and transmits data of the service through UPF1. The first session has an SSC3 mode, and UPF1 is the initial anchor point of the first session.

In FIG. 8A, steps 801 to 810 can refer to the description of steps 301 to 310 in FIG. 3A, and details are not described herein again.

It should be noted that, since the first session has the SSC3 mode, the N4 message of step 803 has two functions: (1) establishing the first session, that is, adding UPF2 as the N3 for the data path of the first session where the anchor point is UPF1. UPF; (2) establish a new second session with UPF2 as an anchor point.

Through the above steps, the UPF1 sends the first downlink data of the first session to the access network device 204 via the UPF2. As shown in FIG. 8B, at time T2, the data path of the first session is: UPF1 → UPF2 → access network device (not shown) → terminal device 202.

In addition, the data path (not shown) of the second session established with UPF2 as an anchor is: UPF2→access network device→terminal device 202.

Step 811: When the trigger condition is met, the trigger converts the first session to the deactivated state. At this time, the terminal device 202 transmits a trigger message to the access network device 204. Upon receiving the trigger message, the access network device 204 sends an N2 message to the AMF entity 206 to release the N2 connection of the first session between the access network device 204 and the AMF entity 206.

In step 812, the AMF entity 206 sends an N11 message to the SMF entity 208 requesting to release the N3 connection of the first session between the access network device 204 and the UPF 2.

In step 813, the SMF entity 208 selects the UPF2 according to the preset condition or determines that the UPF2 is not deleted according to the preset condition, and notifies the UPF2 to cache the second downlink data of the first session. The preset condition includes the SSC information indicating that the first session has the SSC3 mode.

For example, the SMF entity 208 interacts with the UPF 2 with an N4 message to request the release of the N3 connection of the first session between the access network device 204 and the UPF 2. Optionally, the SMF entity 208 can notify the UPF2 to cache the second downlink data of the first session by requesting to release the N4 message of the N3 connection. In other words, the N4 message of step 813 has two purposes: (1) requesting release of the N3 connection of the first session between the access network device 204 and the UPF 2; (2) notifying the UPF 2 to cache the second downlink data of the first session.

In step 814, the SMF entity 208 returns an N11 message to the AMF entity 206 to confirm the release of the N3 connection of the first session between the access network device 204 and the UPF 2. After receiving the N11 message, the AMF entity 206 records the first session transition to the deactivated state.

Similarly, when the trigger condition is met, the second session can be triggered to transition to the deactivated state. If all sessions on the terminal device 202 are switched to the deactivated state, the terminal device 202 switches to the CM-CONNECTED state accordingly.

In a possible implementation, the first session and the second session may be converted to a deactivated state by the same process.

In another possible implementation, the second session is switched to the deactivated state using a process independent of the first session. For the second session, a cache device for buffering downstream data that is the same as or different from the first session may be selected. For example, for the second session, the initial anchor point UPF1 (refer to the description of FIGS. 3A through 7) or the current N3 UPF (ie, UPF2) may be selected as the cache device, and the present invention is not limited thereto. For the SSC3 mode, there may be multiple "sessions" or multiple "session branches" of the session. The SMF entity 208 can select different cache devices for multiple sessions, or multiple session branches of the session, and notify the respective cache devices to buffer the received downlink data through the N4 message.

The following is still described with the first session (session branch) as the main line.

When the first session is in the deactivated state, the second downlink data from the first session of the data network 212 arrives at UPF2.

In step 815, the UPF2 caches the second downlink data.

Step 816a: After receiving the second downlink data, the UPF2 sends a data notification message to the SMF entity 208.

The present invention does not limit the execution sequence between step 815 and step 816a. Step 815 may be performed after step 815, or step 816 may be performed first, or step 815 may be performed first, or step 815 and step 816a may be performed at the same time.

Optionally, in step 816b, the SMF entity 208 returns a data notification confirmation message to the UPF 2.

Steps 817 to 819b may refer to the description of steps 403 to 405b in FIG. 3B, and details are not described herein again.

In step 820, the SMF entity 208 interacts with the UPF 3 for the N4 message to establish a PDU session. Here, through the N4 message interaction, on the one hand, the above-mentioned first session and the second session are established; on the other hand, the UPF3 is used as the anchor UPF to establish a new third session.

In step 821, the SMF entity 208 interacts with the UPF 2 with an N4 message to modify the PDU session. For example, the SMF entity 208 interacts with the UPF2 through the N4 message to add UPF3 to the data path of the existing session (for example, the first session and the second session) as the N3 UPF, so that the UPF2 is connected to the UPF3.

That is, through steps 820 and 821, the data path of the newly received third downlink data of the first session is changed to: UPF1→UPF2→UPF3→access network device→terminal device 202. The data path of the newly received downlink data in the second session is changed to: UPF2→UPF3→access network device→terminal device 202. The data path of the downlink data of the newly established third session is: UPF3→access network device→terminal device 202.

In addition, the data path of the second downlink data buffered by the first session is UPF2→UPF3→access network device→terminal device 202.

Steps 822 to 824 may refer to the description of steps 409 to 411 in FIG. 3B, and details are not described herein again.

So far, for the first session, UPF3 is N3 UPF. The UPF2 sends the buffered second downlink data to the terminal device 202 through the UPF3. The UPF1 sends the newly received third downlink data of the first session to the terminal device 202 through the UPF2 and the UPF3. For example, at time T3, the data path (not shown) of the buffered second downlink data is: UPF2→UPF3→access network device→terminal device 202; as shown in FIG. 8B, at time T3, the third downlink The transmission path of the data is: UPF1 → UPF2 → UPF3 → access network device (not shown) → terminal device 202. Therefore, starting from the UPF2, the data paths for transmitting the second downlink data and the third downlink data are the same, which avoids the disorder of the downlink data received by the terminal, and improves the user experience. In addition, the method of FIG. 8A can be used to obtain the buffered downlink data without the need to establish an additional forwarding tunnel and release the forwarding tunnel, thereby reducing signaling interaction between the UPF entities, thereby reducing the delay and further improving the user experience. .

Optionally, when the trigger condition is met, the first session transition to the deactivated state may be triggered again. For the process, reference may be made to the description of steps 811 to 814, and details are not described herein again. Similarly, in this process, the N2 connection between the access network device 204 and the AMF entity 206, and the N3 connection between the access network device 204 and the UPF 3 are released. Optionally, the SMF entity 208 may also update the cache device (eg, anchor point UPF3) and notify the updated cache device to buffer the downlink data.

FIG. 9 illustrates a method of caching data in accordance with an embodiment of the present invention. The method can be performed by a session management function entity, such as the SMF entity 208 described above. Figure 9 will be described in conjunction with Figures 2 through 4, and Figures 8A and 8B. For example, the method includes:

Step 902: The session management function entity interacts with the second user plane function entity (for example, the UPF2) and the first user plane function entity (for example, the UPF1), so that the first user plane function entity passes the second user plane function. The entity sends the first downlink data of the first session to the access network device (for example, the foregoing access network device 204), where the first user plane function entity is an anchor point of the first session.

For example, step 902 can be implemented by steps 803 and 809b in Figure 8A.

Step 904: The session management function entity notifies the second user plane function entity to cache the second downlink data of the first session according to the preset condition. The preset condition includes the SSC information indicating that the first session has a third session and a service continuity SSC3 mode. The second downlink data is downlink data received by the second user plane function entity after the first session is switched to the deactivated state.

For example, step 904 can be implemented by step 813 in Figure 8A.

Step 906: The session management function entity interacts with the third user plane function entity and the second user plane function entity, respectively, so that the second user plane function entity passes through the third user plane function entity to the access network device (which may be an access network) The device 204 or other access network device sends the second downlink data, and the first user plane function entity passes the second user plane function entity, the third user plane function entity, and the access network device (which may be an access network) The device 204 or other access network device transmits the third downlink data. The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state.

For example, step 906 can be implemented by steps 820 and 821 in Figure 8A.

Optionally, the step 904 includes: the session management function entity selects the second user plane function entity as a cache device for buffering the second downlink data according to the preset condition; and the session management function entity notifies the second user plane function entity to receive the second After the downlink data, the second downlink data is buffered.

Optionally, since the first session has the SSC3 mode, for the second session, the same or different cache device for buffering the downlink data may be selected. For example, for the second session, the initial anchor point UPF1 (refer to the description of FIG. 3A to FIG. 7) or the current N3 UPF (ie, UPF2) may be selected as the cache device, and the respective cache device is notified by the N4 message to buffer the received Downstream data.

In addition, the method shown in FIG. 8A can also be applied to a scenario of a multi-homing PDU session or an uplink classifier (ULCL) scenario.

Figure 10 shows a schematic diagram of a multi-homed PDU session scenario. The access network device 204 is connected to a UPF entity (abbreviated as BP UPF) with a branching point (BP) function. The BP UPF is connected to each PDU session anchor (eg, PDU Session Anchor 1 and PDU Session Anchor 2). The multi-homed PDU session provides multiple paths to the access network 212 through multiple PDU session anchors. The BP UPF is capable of forwarding upstream data to different PDU session anchors and merging downlink data from different PDU session anchors.

For example, PDU session anchor 1 may perform the operations of UPF1 in Figure 8A. UPF2 can be used to implement the functionality of the BP UPF, which is connected to the data network 212 through the session branch 1 of the PDU session anchor 1 and the session branch 2 of the PDU session anchor 2, respectively. The PDU session anchor 2 can be set separately from the BP UPF UPF2, or can be combined with the BP UPF UPF2. Similarly, UPF3 can also be used to implement the functionality of BP UPF, which is connected to data network 212 via session branch 1 of PDU session anchor 1 and session branch 2 of PDU session anchor 2, respectively. The PDU session anchor 2 can be set separately from BP UPF UPF3, or can be combined with BP UPF UPF3.

For example, at time T1, session branch 1 with SSC3 mode is created, and anchor point UPF1 is used as a cache device for buffering downlink data. At time T2, UPF2 is added as a BP UPF by the technique of multi-homing PDU session, and session branch 2 is created, and UPF2 is an aggregation point of session branch 1 and session branch 2. After the session branch enters the deactivated state, UPF2 is updated as a cache device for buffering downlink data. During the period from T2 to T3, the terminal device 202 moves, and the downlink data is buffered in the UPF2 after the downlink service is initiated. A BP UPF migration (relocation) is triggered after the paging response. That is, at time T3, BP UPF is changed to UPF3. UPF3 can obtain cached downlink data from UPF2 and establish a new session branch 3. UPF3 is the aggregation point of session branch 1, session branch 2, and session branch 3. After the session branch enters the deactivated state again, UPF3 is updated as a cache device for buffering downlink data.

In the scenario of the multi-homed PDU session, the N3 UPF establishes a forwarding tunnel with the BP UPF that buffers the downlink data, and obtains the buffered downlink data through the forwarding tunnel. After the cached downlink data is obtained, the forwarding tunnel can be deleted.

It should be noted that, in the above scenario, when the session branch is triggered to switch to the deactivated state, only the N3 connection of the BP UPF needs to be released, and the BP UPF does not need to be deleted.

Therefore, in the scenario of a multi-homed PDU session, the BP UPF that has recently served the terminal device 202 can be set as a cache device. Thus, the downlink data of each session branch under the BP UPF can be cached at the aggregation point BP UPF. The BP UPF is updated when the downlink data of any one of the session branches is activated. In addition, even if no downlink service activates any session branches, the process of obtaining cached data is optimized with the migration of BP UPF.

Similarly, Figure 11 shows a schematic diagram in a ULCL scenario. The access network device 204 is connected to a UPF entity (referred to as UPCL UPF) with ULCL functionality. The ULCL UPF is connected to each PDU session anchor (eg, PDU Session Anchor 1 and PDU Session Anchor 2). The ULCL technology provides multiple session branches to the access network 212 through multiple PDU session anchors. The ULCL UPF is capable of forwarding upstream data to different PDU session anchors and combining downstream data from different PDU session anchors.

For example, PDU session anchor 1 may perform the operations of UPF1 in Figure 8A. UPF2 may be used to implement the functionality of the ULCL UPF, which is connected to the data network 212 through the session branch 1 of the PDU session anchor 1 and the session branch 2 of the PDU session anchor 2, respectively. The PDU session anchor 2 can be set separately from the ULCL UPF UPF2 or can be combined with the ULCL UPF UPF2. Similarly, UPF3 can also be used to implement the function of ULCL UPF, which is connected to data network 212 through session branch 1 of PDU session anchor 1 and session branch 2 of PDU session anchor 2, respectively. The PDU session anchor 2 can be set separately from ULCL UPF UPF3, or can be combined with ULCL UPF UPF3.

For example, at time T1, session branch 1 with SSC3 mode is created, and anchor point UPF1 is used as a cache device for buffering downlink data. At time T2, UPF2 is added as a ULCL UPF by the ULCL technique, and session branch 2 is created, and UPF2 is the uplink classifier of session branch 1 and session branch 2. After the session branch enters the deactivated state, UPF2 is updated as a cache device for buffering downlink data. During the period from T2 to T3, the terminal device 202 moves, and the downlink data is buffered in the UPF2 after the downlink service is initiated. The ULCL UPF migration (relocation) is triggered after the paging response. That is, at time T3, the ULCL UPF is changed to UPF3. UPF3 can obtain cached downlink data from UPF2 and establish a new session branch 3. UPF3 is an uplink classifier for session branch 1, session branch 2, and session branch 3. After the session branch enters the deactivated state again, UPF3 is updated as a cache device for buffering downlink data.

Therefore, in the ULCL scenario, the ULCL UPF that has recently served the terminal device 202 can be set as a cache device.

In addition, for a multi-homed PDU session scenario and a ULCL scenario, different cache devices can be set for each session branch. For example, PDU Session Anchor 1 (UPF1) is set as a cache device for session branch 1 connected to UPF1, and PDU session anchor 2 is set as a cache device for session branch 2. Thereby, the independent processing of each session branch can be realized, so that the processing between the respective session branches does not affect each other and meet different requirements.

In the embodiment provided by the present application, the short message transmission methods and the like provided by the embodiments of the present application are introduced from the perspective of the interaction between the network elements and the network elements. It can be understood that each network element, such as the above-mentioned session management function entity, etc., in order to implement the above functions, includes hardware structures and/or software modules corresponding to the execution of the respective functions. Those skilled in the art will readily appreciate that the present application can be implemented in a combination of hardware or hardware and computer software in combination with the elements and algorithm steps of the various examples described in the embodiments disclosed herein. Whether a function is implemented in hardware or computer software to drive hardware depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present application.

For example, when the network element described above implements a corresponding function through a software module. The session management function entity may include a receiving module 1201 and a transmitting module 1203, as shown in FIG. 12A.

In an embodiment, the receiving module 1201 and the sending module 1203 are configured to interact with the second user plane function entity and the first user plane function entity, respectively, to enable the first user plane function entity to access through the second user plane function entity. The network device sends the first downlink data of the first session, where the first user plane function entity is an anchor point of the first session.

The sending module 1203 is further configured to notify the first user plane function entity to cache the second downlink data of the first session according to the preset condition.

Optionally, the preset condition includes at least one of the following:

The SSC information indicates that the first session has a first session and a traffic continuity SSC1 mode;

The session management function entity and the first user plane function entity belong to the same carrier network.

Optionally, the receiving module 1201 and the sending module 1203 are further configured to interact with the third user plane function entity and the first user plane function entity, respectively, so that the first user plane function entity passes through the third user plane function entity to the access network. The device sends the second downlink data and the third downlink data. The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state.

Optionally, the session management function entity further includes a selection module 1205 for implementing the function of the foregoing notification. The selecting module 1205 is configured to select the first user plane function entity as a cache device for buffering the second downlink data according to the preset condition. Therefore, the sending module 1203 is configured to notify the first user plane function entity to cache the second downlink data after receiving the second downlink data.

Optionally, the receiving module 1201 is further configured to obtain mobility information of the terminal device. For example, the receiving module 1201 is configured to receive a mobility attribute from the mobility management function entity, where the mobility information is a mobility attribute; or, the receiving module 1201 is configured to obtain mobility statistics information, and the mobility information is mobility statistics information; or, session management The functional entity further includes a determining module 1207, configured to receive the mobility attribute from the mobility management function entity, obtain mobility statistics, and the determining module 1207 determines the mobility information according to the mobility attribute and the mobility statistics. The mobile attribute includes at least a high mobility attribute or a low mobility attribute, and the mobility statistics information is used to indicate a moving speed or a staying time of the terminal device. For example, the receiving module 1201 is configured to receive mobility statistics information from the mobility management function entity; or obtain mobility statistics information from the network data analysis NWDA device.

Optionally, the session management function entity further includes a release module 1209. The release module 1209 is configured to release the second user plane function entity after the selection module 1205 selects the first user plane function entity as the cache device that caches the second downlink data.

Optionally, the session management function entity and the third user plane function entity are located in the VPLMN under the HR roaming scenario, and the session management function entity further includes an adjustment module 1211. The adjusting module 1211 is configured to adjust a cache device, where the cache device is configured to cache the fourth downlink data of the first session after the first session is switched to the active state. For example, the adjustment module 1211 is configured to determine that the third user plane function entity is a cache device; or determine that the session management function entity is a cache device.

Thereby, the session management function entity notifies the anchor user plane function entity to cache the second downlink data according to the preset condition. In this way, after the first session is switched to the active state, the second downlink data buffered by the anchor user plane function entity is the same as the transmission path of the third downlink data newly received by the first session to the active state. Thereby, the disorder of the downlink data received by the terminal is avoided. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and improving the user experience.

In another embodiment, the receiving module 1201 and the sending module 1203 are configured to interact with the second user plane function entity and the first user plane function entity, respectively, so that the first user plane function entity is connected through the second user plane function entity. The network access device sends the first downlink data of the first session. The first user plane function entity is an anchor point of the first session. The sending module 1203 is further configured to notify the second user plane function entity to cache the second downlink data of the first session. The preset condition includes SSC information (eg, obtained by the receiving module 1201) indicating that the first session has a third session and a business continuity SSC3 mode. The second downlink data is downlink data received by the second user plane function entity after the first session is switched to the deactivated state. The receiving module 1201 and the sending module 1203 are further configured to respectively interact with the third user plane function entity and the second user plane function entity, so that the second user plane function entity sends the second user plane function entity to the access network device by using the third user plane function entity. Downstream data, and the first user plane function entity sends the third downlink data to the access network device through the second user plane function entity and the third user plane function entity. The third downlink data is downlink data received by the first user plane function entity after the first session is switched to the active state.

Optionally, the session management function entity further includes a selection module 1205 for implementing the function of the foregoing notification. The selecting module 1205 is configured to select a second user plane function entity as a cache device for buffering the second downlink data according to the preset condition. The sending module 1203 is configured to notify the second user plane function entity to cache the second downlink data after receiving the second downlink data.

Therefore, starting from the second user plane function entity, the data paths for transmitting the second downlink data and the third downlink data are the same, thereby avoiding the out-of-order problem of the downlink data received by the terminal, and improving the user experience. In addition, there is no need to establish an additional forwarding tunnel and no need to release the forwarding tunnel to obtain the buffered downlink data, which reduces the signaling interaction between the UPF entities, thereby reducing the delay and further improving the user experience.

Optionally, in another embodiment, the session management function entity may include a receiving module 1201, a sending module 1203, and a releasing module 1209. The receiving module 1201 and the transmitting module 1203 can also be implemented by a transceiver module.

The transceiver module is configured to interact with the second user plane function entity and the first user plane function entity, respectively, to enable the first user plane function entity to send the first downlink data of the first session by using the second user plane function entity. The second user plane function entity is a user plane function entity connected to the access network device in the first session.

The release module 1209 is configured to release the second user plane function entity when the first session enters the deactivated state. For example, the release module 1209 determines to release the second user plane functional entity based on at least one of session and business continuity information, mobility information, and policy information. For details, refer to the previous description, and no further details are provided.

Optionally, the transceiver module is further configured to notify the first user plane function entity to cache the second downlink data of the first session. Alternatively, the transceiver module is further configured to notify the first user plane function network element to release the connection with the second household function network element, so that the first user plane entity "automatically" becomes the first session transition to deactivate The cache device that caches the second downlink data after the state.

The above selection module 1205, determination module 1207, release module 1209, and adjustment module 1211 may all be implemented by a processing module in the session management function entity.

In addition, the receiving module 1201 and the sending module 1203 in the session management function entity may also implement other operations or functions of the SMF device 206 (or vSMF) in the foregoing method, and may also include other modules that perform other functions, and details are not described herein. .

FIG. 12B is a schematic diagram showing another possible structure of the session management function entity involved in the above embodiment. The session management function entity includes a transceiver 1202 and a processor 1204, as shown in Figure 12B. For example, the processor 1204 is configured to process the session management function entity to perform the corresponding functions of the SMF device 206 (or vSMF) in the above method. The transceiver 1202 is configured to implement communication between the session management function entity and the mobility management function entity/user plane function entity/other session management function entity. The session management function entity can also include a memory 1206 for coupling with a processor that holds program instructions and data necessary for the session management function entity.

It will be appreciated that Figure 12B only shows a simplified design of the above described apparatus. In practical applications, each of the above devices may include any number of transmitters, receivers, processors, controllers, memories, communication units, etc., and all devices that can implement the present application are within the scope of the present application.

The controller/processor for performing the above-described session management function entity of the present application may be a central processing unit (CPU), a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), and a field programmable gate array. (FPGA) or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It is possible to implement or carry out the various illustrative logical blocks, modules and circuits described in connection with the present disclosure. The processor may also be a combination of computing functions, for example, including one or more microprocessor combinations, a combination of a DSP and a microprocessor, and the like.

The steps of a method or algorithm described in connection with the present disclosure may be implemented in a hardware or may be implemented by a processor executing software instructions. The software instructions may be comprised of corresponding software modules that may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable hard disk, CD-ROM, or any other form of storage well known in the art. In the medium. An exemplary storage medium is coupled to the processor to enable the processor to read information from, and write information to, the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. Additionally, the ASIC can be located in a session management functional entity. Of course, the processor and the storage medium can also exist as discrete components in the session management function entity.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, it 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 the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present invention are generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be from a website site, computer, server or data center Transfer to another website site, computer, server, or data center by wire (eg, coaxial cable, fiber optic, digital subscriber line (DSL), or wireless (eg, infrared, wireless, microwave, etc.). The computer readable storage medium can be any available media that can be accessed by a computer or a data storage device such as a server, data center, or the like that includes one or more available media. The usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (such as a solid state disk (SSD)).

The specific embodiments of the present invention have been described in detail with reference to the specific embodiments of the present application. It is to be understood that the foregoing description is only The scope of protection, any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application are included in the scope of protection of the present application.

Claims

A method for caching data, comprising:

The session management function entity interacts with the second user plane function entity and the first user plane function entity, respectively, to enable the first user plane function entity to send the first session to the access network device via the second user plane function entity The first downlink data, where the first user plane function entity is an anchor point of the first session;

The session management function entity notifies the first user plane function entity to cache the second downlink data of the first session according to a preset condition, where the second downlink data is the first session transition to deactivation The downlink data received by the first user plane function entity after the state.
The method of claim 1, wherein the predetermined condition comprises at least one of the following:

The session and service continuity information indicates that the first session has a first session and a business continuity mode;

The mobility information indicates that the terminal device is a high mobility device;

The session management function entity and the first user plane function entity belong to the same carrier network.
The method according to claim 1 or 2, further comprising:

The session management function entity interacts with the third user plane function entity and the first user plane function entity, respectively, such that the first user plane function entity sends the third user plane function entity to the access network device The second downlink data and the third downlink data;

The third downlink data is downlink data received by the first user plane function entity after the first session is switched to an active state.
The method according to any one of claims 1 to 3, wherein the session management function entity notifies the first user plane function entity to cache the second downlink data of the first session according to a preset condition, including :

The session management function entity selects the first user plane function entity as a cache device for buffering the second downlink data according to the preset condition;

The session management function entity notifies the first user plane function entity to cache the second downlink data after receiving the second downlink data.
The method according to any one of claims 2 to 4, wherein the method further comprises:

The session management function entity receives a mobility attribute from a mobility management function entity, and the mobility information is the mobility attribute;

Or the session management function entity acquires mobility statistics information, where the mobility information is the mobility statistics information;

Or the session management function entity receives the mobility attribute from the mobility management function entity, acquires mobility statistics, and determines the mobility information according to the mobility attribute and the mobility statistics information;

The mobility attribute includes at least a high mobility attribute or a low mobility attribute, and the mobility statistics information is used to indicate a moving speed or a staying time of the terminal device.
The method according to claim 5, wherein the session management function entity obtains mobility statistics, including:

The session management function entity receives the mobility statistics information from the mobility management function entity; or

The session management function entity acquires the mobility statistics information from a network data analysis device.
The method according to any one of claims 4 to 6, further comprising:

After the session management function entity selects the first user plane function entity as a cache device that caches the second downlink data, the session management function entity releases the second user plane function entity.
The method according to any one of claims 3 to 7, wherein the session management function entity and the third user plane function entity are located in a visited public land mobile network VPLMN under a home route roaming scenario, The method also includes:

The session management function entity adjusts a cache device, and the cache device is configured to cache fourth downlink data of the first session after the first session is switched to a deactivated state.
The method according to claim 8, wherein the session management function entity adjusts the cache device, including:

The session management function entity determines that the third user plane function entity is the cache device;

Alternatively, the session management function entity determines that the second session management function entity is the cache device.
A method for caching data, comprising:

The session management function entity interacts with the second user plane function entity and the first user plane function entity, respectively, to enable the first user plane function entity to send the first session to the access network device via the second user plane function entity a first downlink data, where the first user plane function entity is an anchor point of the first session;

The session management function entity notifies the second user plane function entity to cache the second downlink data of the first session according to the preset condition, where the preset condition includes the session and the service continuity information indicating the first session The third session data and the service continuity mode, where the second downlink data is downlink data received by the second user plane function entity after the first session is switched to the deactivated state;

The session management function entity interacts with the third user plane function entity and the second user plane function entity, respectively, such that the second user plane function entity sends the third user plane function entity to the access network device The second downlink data, and the first user plane function entity sends the third downlink data to the access network device through the second user plane function entity, the third user plane function entity, where The third downlink data is downlink data received by the first user plane function entity after the first session is switched to an active state.
The method according to claim 10, wherein the session management function entity notifies the second user plane function entity to cache the second downlink data of the first session according to a preset condition, including:

The session management function entity selects the second user plane function entity as a cache device for buffering the second downlink data according to the preset condition;

The session management function entity notifies the second user plane function entity to cache the second downlink data after receiving the second downlink data.
A method for caching data, comprising:

The session management function network element interacts with the second user plane function network element and the first user plane function network element, respectively, so that the first user plane function network element sends the first session through the second user plane function network element. The first downlink data, the second user plane function network element is a user plane function network element connected to the access network device in the first session;

The session management function network element releases the second user plane function network element when the first session enters a deactivated state.
The method of claim 12, further comprising:

The session management function network element notifies the first user plane function network element to cache the second downlink data after receiving the second downlink data.

or,

The session management function network element notifies the first user plane function network element to release a connection with the second user plane function network element, so that the first user plane function network element receives the second downlink After the data, the second downlink data is buffered.
The method according to claim 12 or 13, wherein the session management function network element releases the second user plane function network element, including:

The session management function network element determines to release the second user plane function network element according to at least one of session and service continuity information, mobility information, and policy information.
The method according to claim 14, wherein the session management function network element releases the second user plane function network element, including:

The session management function network element determines to release the second user plane function network element according to at least one of the following:

The session and service continuity information indicates that the first session has a first session and a business continuity mode;

The mobility information indicates that the terminal device is a high mobility device;

The policy information indicates that the second user plane function network element is released;

The session management function entity and the first user plane function entity belong to the same carrier network.
A session management function entity, comprising:

a receiving module and a sending module, configured to respectively interact with the second user plane function entity and the first user plane function entity, so that the first user plane function entity sends the second user plane function entity to the access network device The first downlink data of the first session, where the first user plane function entity is an anchor point of the first session;

The sending module is further configured to notify the first user plane function entity to cache second downlink data of the first session according to a preset condition, where the second downlink data is converted to the first session The downlink data received by the first user plane function entity after the activation state.
The session management function entity according to claim 16, wherein the preset condition comprises at least one of the following:

The session and service continuity information indicates that the first session has a first session and a business continuity mode;

The mobility information indicates that the terminal device is a high mobility device;

The session management function entity and the first user plane function entity belong to the same carrier network.
A session management function entity according to claim 16 or 17, wherein

The receiving module and the sending module are further configured to interact with the third user plane function entity and the first user plane function entity respectively, so that the first user plane function entity passes the third user plane function entity Transmitting the second downlink data and the third downlink data to the access network device;

The third downlink data is downlink data received by the first user plane function entity after the first session is switched to an active state.
The session management function entity according to any one of claims 16 to 18, further comprising:

a selection module, configured to select, according to the preset condition, the first user plane function entity as a cache device for buffering the second downlink data;

The sending module is configured to notify the first user plane function entity to cache the second downlink data after receiving the second downlink data.
A session management function entity according to any one of claims 17 to 19, characterized in that

The receiving module is configured to receive a mobile attribute from the mobility management function entity, where the mobility information is the mobile attribute; or the receiving module is configured to acquire mobility statistics, where the mobility information is the mobile Sexual statistical information;

or,

The session management function entity further includes a determining module, configured to receive a mobility attribute from the mobility management function entity, and obtain mobility statistics, where the determining module is configured to perform statistics according to the mobility attribute and the mobility Information determining the mobility information;

The mobility attribute includes at least a high mobility attribute or a low mobility attribute, and the mobility statistics information is used to indicate a moving speed or a staying time of the terminal device.
The session management function entity according to claim 20, wherein the receiving module is configured to receive the mobility statistics information from the mobility management function entity; or

The receiving module is configured to acquire the mobility statistics information from a network data analysis device.
The session management function entity according to any one of claims 19 to 21, further comprising:

And a releasing module, configured to release the second user plane function entity after the selecting module selects the first user plane function entity as a cache device that caches the second downlink data.
The session management function entity according to any one of claims 18 to 22, wherein the session management function entity and the third user plane function entity are located in a visited public land mobile network VPLMN under a home route roaming scenario. The session management function entity further includes:

And an adjustment module, configured to adjust a cache device, where the cache device is configured to cache fourth downlink data of the first session after the first session is switched to a deactivated state.
The session management function entity according to claim 23, wherein the adjustment module is configured to determine that the third user plane function entity is the cache device;

Alternatively, the adjusting module is configured to determine that the session management function entity is the cache device.
A session management function network element, comprising:

a transceiver module, configured to interact with the second user plane function network element and the first user plane function network element, respectively, to enable the first user plane function network element to send the first session by using the second user plane function network element The first downlink data, the second user plane function network element is a user plane function network element connected to the access network device in the first session;

And a releasing module, configured to release the second user plane function network element when the first session enters a deactivated state.
The session management function network element according to claim 25, wherein the transceiver module is further configured to notify the first user plane function network element to cache second downlink data of the first session;

or,

The transceiver module is further configured to notify the first user plane function network element to release a connection with the second household function network element, so that the first user plane function network element receives the second downlink. After the data, the second downlink data is buffered.
The session management function network element according to claim 25 or 26, wherein the release module is configured to determine release of the first part according to at least one of session and service continuity information, mobility information, and policy information. Two user plane function network elements.
The session management function network element according to claim 27, wherein the release module is configured to determine to release the second user plane function network element according to at least one of the following:

The session and service continuity information indicates that the first session has a first session and a business continuity mode;

The mobility information indicates that the terminal device is a high mobility device;

The policy information indicates that the second user plane function network element is released:

The session management function network element and the first user plane function network element belong to the same carrier network.
A session management function entity for buffering data, comprising:

a receiving module and a sending module, configured to respectively interact with the second user plane function entity and the first user plane function entity, so that the first user plane function entity sends the second user plane function entity to the access network device a first downlink data of the first session, where the first user plane function entity is an anchor point of the first session;

The sending module is further configured to notify the second user plane function entity to cache the second downlink data of the first session, where the preset condition includes the session and the service continuity information indicating that the first session has a third session. And the service continuity mode, the second downlink data is downlink data received by the second user plane function entity after the first session is switched to the deactivated state;

The receiving module and the sending module are further configured to interact with the third user plane function entity and the second user plane function entity respectively, so that the second user plane function entity passes the third user plane function entity Sending the second downlink data to the access network device, and the first user plane function entity sends the third downlink to the access network device through the second user plane function entity, the third user plane function entity, and the access network device Data; wherein the third downlink data is downlink data received by the first user plane function entity after the first session is switched to an active state.
The session management function entity according to claim 29, further comprising:

a selection module, configured to select, according to the preset condition, the second user plane function entity as a cache device for buffering the second downlink data;

The sending module is configured to notify the second user plane function entity to cache the second downlink data after receiving the second downlink data.
A session management function entity, comprising:

a communication interface for receiving and transmitting data;

a memory for storing instructions;

At least one processor for executing the instructions in the memory, such that the session management function entity performs the method of any one of claims 1 to 15.
A computer readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of any of claims 1-15.
A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any of claims 1-15.