CN109819488B

CN109819488B - Session switching method, device and system

Info

Publication number: CN109819488B
Application number: CN201810490565.0A
Authority: CN
Inventors: 景昊; 宗在峰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-11-20
Filing date: 2018-05-21
Publication date: 2021-01-15
Anticipated expiration: 2038-05-21
Also published as: CN109819488A

Abstract

The embodiment of the application provides a session switching method, equipment and a system, which are used for solving the problem that the existing PDN connection cannot be switched to PDU session. The method comprises the following steps: the method comprises the steps that first equipment determines corresponding network slice information when PDN connection is switched to a 5G network; and sending the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity. The embodiment of the application is used for the session switching process.

Description

Session switching method, device and system

The present application claims priority of chinese patent application having application number 201711157254.4 and application name "a session switching method, device and system" filed in 2017 on 20/11.8, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to the field of communications technologies, and in particular, to a session switching method, device, and system.

Background

With the rapid development of wireless communication technology, a Fifth Generation (5G) mobile communication network (5G network for short) has come up, and the 5G network can coexist with an existing fourth Generation (4G) network, and the two networks can be interworked.

A network slice is defined in a 5G network, and is a logically isolated network for supporting specific network capabilities and network characteristics, and the network slice may be end-to-end (E2E) including the entire network, or part of network functions may be shared in multiple network slices, and is a key technology for meeting the requirements of the 5G mobile communication technology proposed by 3GPP on network differentiation. In a 5G network, a terminal device may establish a Protocol Data Unit (PDU) session through a network slice to access a Data Network (DN).

In a scenario of interworking between a 5G network and a 4G network, when Packet Data Network (PDN) connection of the 4G network is switched to a PDU session, a network slice corresponding to the PDN connection switching to the 5G network needs to be selected, so as to establish the PDU session corresponding to the PDN connection switching through the network slice. However, the prior art does not consider the problem of network slicing in the process of switching the PDN connection to the PDU session, and cannot switch the PDN connection to the PDU session.

Disclosure of Invention

The embodiment of the application provides a session switching method, equipment and a system, which are used for solving the problem that PDN connection cannot be switched to PDU session in the prior art.

In order to achieve the above purpose, the embodiments of the present application provide the following technical solutions: the method comprises the steps that the first equipment determines corresponding network slice information when PDN connection is switched to a fifth generation 5G network; the method comprises the steps that first equipment sends corresponding network slice information when PDN connection is switched to a 5G network to a mobility management entity; and the mobility management entity receives corresponding network slice information when the PDN connection is switched to the 5G network, and sends a session switching request for requesting to switch the PDN connection to the PDU session to the control plane functional entity, so that the control plane functional entity switches the PDN connection to the PDU session. In one possible design, the first device is a terminal device, and the Mobility Management Entity is a Mobility Management Entity (MME) or an access and Mobility Management function (AMF) Entity. When the mobility management entity is an MME, the MME may send, to the control plane function entity through the AMF, a session handover request for requesting handover of the PDN connection to the PDU session. In particular, this possible design can be described with reference to the first to nineteenth aspects below. In another possible design, the first device is a control plane functional entity, the mobility management entity is an MME, and the MME sends a session handover request for requesting handover of the PDN connection to the PDU session to the control plane functional entity through the AMF. In particular, this further possible design may be described with reference to the twentieth to thirty-eighth aspects below.

In a first aspect, a session handover method is provided, where the method includes: the method comprises the steps that terminal equipment determines corresponding network slice information when PDN connection is switched to a fifth generation 5G network; and sending the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity. Based on the session switching method provided by the embodiment of the application, the terminal device sends the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity on the network side, so that the mobility management entity cooperates with other devices in the network, determines the corresponding network slice information when the PDN connection that can be switched in the PDN connection is switched to the 5G network according to the corresponding network slice information and the other information when the PDN connection is switched to the 5G network, creates the PDU session according to the determined network slice information, and realizes the switching of the PDN connection to the PDU session. The problem that PDN connection can not be switched to PDU conversation caused by the fact that network slicing in the process of switching PDN connection to PDU conversation can not be determined at present is solved.

In one possible design, the terminal equipment determines corresponding network slice information when the PDN connection is switched to the 5G network according to the corresponding relation between the information of the PDN connection and the network slice information; the corresponding relation between the information of the PDN connection and the network slice information may be configured in a network slice selection policy of the terminal device in advance, where the information of the PDN connection includes any one of an access point name APN corresponding to the PDN connection, an application corresponding to the PDN connection, and a data network name DNN corresponding to the PDN connection when the PDN connection is switched to the 5G network. Therefore, the network slice information can be determined according to the corresponding relation between the preset PDN connection information and the network slice information, and the PDN connection information is used for indicating the PDN connection, so that the network slice information determined according to the corresponding relation is close to the corresponding network slice information after the PDN connection is switched to the 5G network to a great extent, and the accuracy of the subsequent network side equipment for determining the corresponding network slice information when the PDN connection capable of being switched in the PDN connection is switched to the 5G network according to the corresponding network slice information when the PDN connection is switched to the 5G network is improved.

In one possible design, before the terminal device determines corresponding network slice information when the PDN connection is handed over to a fifth-generation 5G network, the method further includes: the terminal equipment determines PDN connection switched to a 5G network in the established PDN connection according to applied strategy information corresponding to the PDN connection; or, when the terminal device determines that the terminal device supports the 5G network communication capability, the terminal device determines that all established PDN connections are switched to the 5G network. Therefore, the terminal equipment can be triggered to determine the corresponding network slice information when the PDN connection is switched to the fifth generation 5G network according to the service requirement applied to the terminal equipment or according to the communication capacity of the terminal equipment, the PDU conversation in the 5G network is realized by switching the PDN connection of the terminal equipment with higher service requirement or stronger communication capacity, and the service quality is improved.

In one possible implementation, the method further comprises: and the terminal equipment sends the priority information of the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity. Therefore, the information of the priority of the network slice information can be sent to the mobility management entity, so that under the condition that the mobility management entity and the network side equipment work cooperatively, the PDN connection corresponding to the network slice information with higher priority is preferentially switched to the PDU session according to the priority of each network slice information.

In one possible design, the method further includes: when the terminal equipment is in roaming, network slice information when the PDN connection is switched to the 5G network is network slice information of a visited place when the PDN connection is switched to the 5G network, and the terminal equipment determines network slice information of a home place when the PDN connection is switched to the 5G network according to applied strategy information corresponding to the PDN connection; and determining the network slice information of the visited place when the PDN connection is switched to the 5G network according to the network slice information of the home place when the PDN connection is switched to the 5G network and the mapping relation between the network slice information of the home place and the network slice information of the visited place. Therefore, the network slice information of the visited place of the terminal equipment can be obtained when the terminal equipment is in roaming, so that the subsequent network side equipment can switch the PDN connection to the network slice of the visited place according to the network slice information of the visited place, and the service continuity when the home route of the terminal equipment is in roaming is ensured.

In a possible design, the Mobility Management Entity is a Mobility Management Entity (MME) in a 4G network or an access and Mobility Management function (AMF) Entity in a 5G network, that is, in this embodiment, the terminal device may send, to the MME or the AMF Entity, network slice information corresponding to when the PDN connection is switched to the 5G network.

In one possible design, when the mobility management entity is an MME, the terminal device carries corresponding network slice information in a first message when switching the PDN connection to the 5G network and sends the first message to the MME; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network. In this way, when the MME receives the first message carrying the network slice information corresponding to the time when the PDN connection is switched to the 5G network, only the content carried in the first message (the network slice information corresponding to the time when the PDN connection is switched to the 5G network) is stored in the context of the terminal device, without parsing the content carried in the first message, so as to reduce the burden of the MME.

In one possible design, when the mobility management entity is an AMF entity, the terminal device carries corresponding network slice information in a registration request when the PDN connection is switched to the 5G network, and sends the registration request to the AMF entity, where the registration request is used to request registration to the 5G network. Therefore, the terminal device can register in the 5G network through the AMF entity, the corresponding network slice information when the PDN connection is switched to the 5G network is carried in the registration request and is sent to the AMF entity, the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network does not need to be sent to the AMF entity through the MME, and the burden of the MME is reduced.

In one possible design, when the mobility management entity is an MME, the method further includes: the terminal equipment sends DNN corresponding to the PDN connection to the MME, so that when the terminal equipment is in a home routing scene, the MME sends the DNN to network equipment (such as an AMF entity) so that the AMF entity determines a visited control plane functional entity according to the DNN and other information, and establishes PDU session corresponding to the PDN connection through intercommunication of the visited control plane functional entity and the home control plane functional entity corresponding to the PDN connection, thereby ensuring service continuity in a terminal equipment roaming scene.

In a second aspect, a session handover method is provided, where the method includes: and the MME acquires network slice information corresponding to the PDN connection determined by the terminal equipment when the PDN connection is switched to the 5G network from the terminal equipment, and sends the context of the terminal equipment to the AMF entity, wherein the context of the terminal equipment comprises the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network and the PDN connection information, and the PDN connection information comprises address information of a control plane function entity corresponding to the PDN connection. Based on the session switching method provided by the embodiment of the application, an MME acquires network slice information corresponding to the PDN connection switched to the 5G network from terminal equipment, and sends the network slice information corresponding to the PDN connection switched to the 5G network to an AMF entity, so that the AMF entity determines the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network according to the network slice information corresponding to the PDN connection switched to the 5G network and other information, and further creates a PDU session according to the determined network slice information, and the switching of the PDN connection to the PDU session is realized. The problem that the PDN connection can not be switched to the PDU conversation due to the fact that the network slicing in the process of switching the PDN connection to the PDU conversation can not be determined at present is solved.

In a possible design, an MME receives a first message sent by a terminal device and carrying network slice information corresponding to when a PDN connection is switched to a 5G network; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network. In this way, when the MME receives the first message carrying the network slice information corresponding to the time when the PDN connection is switched to the 5G network, only the content carried by the first message (the network slice information corresponding to the time when the PDN connection is switched to the 5G network) is stored in the context of the terminal device, without parsing the content carried in the first message, so as to reduce the burden of the MME itself.

In a possible design, the information of the PDN connection further includes an Access Point Name (APN) corresponding to the PDN connection, so that after the AMF entity receives the APN corresponding to the PDN connection, a DNN can be determined according to the APN corresponding to the PDN connection, and a visited control plane function entity is determined according to the DNN and other information, and a PDU session corresponding to the PDN connection is established through interworking of the visited control plane function entity and an affiliation control plane function entity corresponding to the PDN connection, thereby ensuring service continuity of the terminal device in a roaming scenario.

A third aspect provides a session switching method, where the method includes that an AMF entity obtains network slice information corresponding to when a PDN connection determined by a terminal device is switched to a 5G network, address information of a control plane function entity corresponding to the PDN connection, and network slice information signed by the terminal device, obtains network slice information corresponding to when a PDN connection that can be switched in the PDN connection is switched to the 5G network, and network slice information signed by the terminal device, and determines a target AMF entity that supports a network slice corresponding to when the PDN connection that can be switched is switched to the 5G network; and when the target AMF entity is the AMF entity, the AMF entity sends a session switching request to the home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection, wherein the session switching request is used for requesting that the PDN connection is switched to a Protocol Data Unit (PDU) session. Based on the session switching method provided by the embodiment of the application, the terminal device sends network slice information corresponding to the PDN connection switched to the 5G network to a mobility management entity on a network side, the AMF entity obtains the network slice information corresponding to the PDN connection switched to the 5G network, determines the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network according to the network slice information corresponding to the PDN connection switched to the 5G network and other information, and sends the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network to a home control plane function entity, so that the home control plane function entity creates a PDU session according to the determined network slice information, and realizes the switching of the PDN connection to the PDU session. The problem that the PDN connection can not be switched to the PDU conversation due to the fact that the network slicing in the process of switching the PDN connection to the PDU conversation can not be determined at present is solved.

In one possible design, the AMF entity obtains corresponding network slice information when the PDN connection is switched to the 5G network from the MME; or acquiring corresponding network slice information when the PDN connection is switched to the 5G network from the terminal equipment. Therefore, the corresponding network slice information when the PDN connection is switched to the 5G network can be obtained in different modes, and the flexibility of the AMF entity for obtaining the information is improved.

In one possible design, when the AMF entity obtains, from the terminal device, network slice information corresponding to when the PDN connection is switched to the fifth-generation 5G network, the AMF entity receives a registration request, which is sent by the terminal device and carries the network slice information corresponding to when the PDN connection is switched to the 5G network, and obtains, from the registration request, the network slice information corresponding to when the PDN connection is switched to the 5G network, where the registration request is used to request registration to the 5G network. Therefore, the terminal device can register in the 5G network through the AMF entity, the corresponding network slice information when the PDN connection is switched to the 5G network is carried in the registration request and is sent to the AMF entity, the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network does not need to be sent to the AMF entity through the MME, and the burden of the MME is reduced.

In one possible design, when the AMF entity determines that the terminal is in home routing roaming, the AMF entity determines a visited control plane function entity according to a network slice indicated by network slice information when a switched PDN connection in the PDN connection is switched to the 5G network and a data network name DNN corresponding to the switched PDN connection to the 5G network; and the AMF entity sends a session establishment request carrying network slice information corresponding to the switched PDN connection in the PDN connection and address information of a control plane functional entity corresponding to the PDN connection to the 5G network to the visited control plane functional entity, wherein the session establishment request is used for indicating the visited control plane functional entity to send a session switching request to the home control plane functional entity. Therefore, when the terminal equipment is in the home routing scene, the AMF entity determines the visited control plane functional entity according to the DNN and other information, and establishes the PDU session corresponding to the PDN connection through the intercommunication of the visited control plane functional entity and the home control plane entity, thereby ensuring the service continuity of the terminal equipment in the roaming scene.

In a possible design, when the AMF entity determines that the terminal is in home routing roaming and the AMF entity cannot select the visited control plane function entity, the AMF entity sends a selection request to the NRF, the NRF selects an SMF entity supporting the DN identified by the DNN as the visited control plane function entity according to a network slice indicated by network slice information when a PDN connection capable of being switched in the PDN connection is switched to the 5G network and a DNN corresponding to the network slice, and feeds back address information of the visited control plane function entity to the initial AMF entity, and the initial AMF entity sends a session switching request to the home control plane function entity through the visited control plane function entity according to a feedback result of the NRF. Therefore, when the terminal equipment is in the home routing scene and the AMF entity does not select the visited control plane functional entity, the AMF entity can select the visited control plane functional entity by the aid of the NRF, the visited control plane functional entity and the home control plane functional entity which are selected by the NRF are communicated, the home control plane functional entity establishes a PDU session corresponding to PDN connection, and service continuity of the terminal equipment in the roaming scene is guaranteed.

A fourth aspect provides a terminal device, where the terminal device may implement the function executed by the terminal device element in the foregoing method embodiment, and the function may be implemented by hardware or by hardware executing corresponding software. The hardware or software comprises one or more modules corresponding to the functions. Such as: the terminal device may include:

the determining unit is used for determining corresponding network slice information when the PDN connection of the packet data network is switched to a fifth generation 5G network; and the sending unit is used for sending the corresponding network slice information when the PDN connection is switched to the 5G network to a mobility management entity.

The specific implementation manner of the terminal device may refer to the behavior function of the terminal device in the session switching method provided in the first aspect or the possible implementation manner of the first aspect, and details are not repeated here. Therefore, the terminal device provided can achieve the same advantageous effects as the first aspect.

In a fifth aspect, a terminal device is provided, which includes: a processor and a memory; the memory is configured to store computer executable instructions, and when the terminal device runs, the processor executes the computer executable instructions stored in the memory, so as to enable the terminal device to perform the session switching method according to any one of the above first aspects.

A sixth aspect provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the session switching method of any one of the above first aspects.

In a seventh aspect, there is provided a computer program product comprising instructions which, when run on a computer, enable the computer to perform the session switching method of any one of the above first aspects.

In an eighth aspect, a chip system is provided, where the chip system includes a processor, configured to support a terminal device to implement the functions recited in the foregoing aspects, for example, the terminal device is supported to determine network slice information corresponding to when a PDN connection is switched to a 5G network, and send the network slice information corresponding to when the PDN connection is switched to the 5G network to a mobility management entity through a communication interface. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the terminal device. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any one of the design manners in the fourth aspect to the eighth aspect, reference may be made to technical effects brought by different design manners in the first aspect, and details are not described herein.

In a ninth aspect, an MME is provided, which has the function of implementing the method of the first aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above. Such as: the MME may include:

a receiving unit, configured to receive, from an MME, network slice information corresponding to switching of a packet data network PDN connection determined by the MME to a fifth generation 5G network;

the sending unit is further configured to send a context of the MME to an access and mobility management function AMF entity, where the context of the MME includes network slice information corresponding to when the PDN connection is switched to a fifth generation 5G network and information of the PDN connection, and the information of the PDN connection includes address information of a control plane function entity corresponding to the PDN connection.

The specific implementation manner of the MME may refer to the second aspect or a behavior function of the MME in the session handover method provided by the possible implementation manner of the second aspect, and details are not repeated here. Therefore, the provided MME can achieve the same advantageous effects as the first aspect.

In a tenth aspect, there is provided an MME comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the MME runs, the processor executes the computer executable instructions stored in the memory, so as to cause the MME to perform the session handover method according to any one of the above second aspects.

In an eleventh aspect, there is provided a computer-readable storage medium having stored therein instructions, which when run on a computer, enable the computer to execute the session switching method of any one of the second aspects above.

In a twelfth aspect, there is provided a computer program product containing instructions which, when run on a computer, enable the computer to perform the session switching method of any one of the second aspects above.

In a thirteenth aspect, a chip system is provided, where the chip system includes a processor, configured to support an MME to implement the functions recited in the foregoing aspects, for example, the MME is supported to obtain, from a terminal device through a communication interface, network slice information corresponding to when the terminal device determines that a PDN connection is switched to a 5G network, and send a context of the terminal device to an AMF entity. In one possible design, the chip system further includes a memory for storing program instructions and data necessary for the MME. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

The technical effects brought by any one of the design manners of the ninth aspect to the thirteenth aspect can be referred to the technical effects brought by different design manners of the second aspect, and are not described herein again.

In a fourteenth aspect, there is provided an AMF entity having the functionality of implementing the method of the third aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above. Such as: the AMF entity comprises:

a receiving unit, configured to receive network slice information corresponding to a packet data network PDN connection determined by a terminal device when the PDN connection is switched to a fifth-generation 5G network, address information of a control plane functional entity corresponding to the PDN connection, and network slice information signed by the terminal device;

an obtaining unit, configured to obtain, according to network slice information corresponding to when the PDN connection is switched to a 5G network and network slice information signed by the terminal device, network slice information corresponding to when a PDN connection allowed to be switched in the PDN connection is switched to the 5G network;

and a sending unit, configured to send a session switching request to a home control plane function entity according to address information of a control plane function entity corresponding to the PDN connection, where the session switching request is used to request to switch the PDN connection to a protocol data unit PDU session.

The specific implementation manner of the AMF entity may refer to the second aspect or a behavior function of the AMF entity in the session handover method provided by the possible implementation manner of the second aspect, and details are not repeated here. Thus, the provided AMF entity may achieve the same advantageous effects as the first aspect.

In a fifteenth aspect, there is provided an AMF entity, comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the AMF entity runs, the processor executes the computer executable instructions stored in the memory, so as to cause the AMF entity to perform the session handover method according to any one of the third aspects.

In a sixteenth aspect, there is provided a computer-readable storage medium having stored therein instructions, which when run on a computer, cause the computer to perform the session switching method of any one of the above third aspects.

A seventeenth aspect provides a computer program product containing instructions that, when run on a computer, causes the computer to perform the session switching method of any one of the third aspects above.

Eighteenth aspect, a chip system is provided, where the chip system includes a processor, configured to support an AMF entity to implement the functions related in the foregoing aspects, for example, the AMF entity is supported to obtain network slice information corresponding to when a PDN connection determined by a terminal device is switched to a 5G network, address information of a control plane function entity corresponding to the PDN connection, and network slice information signed by the terminal device, and according to the network slice information corresponding to when the PDN connection is switched to the 5G network and the network slice information signed by the terminal device, network slice information corresponding to when a PDN connection that can be switched in the PDN connection is switched to the 5G network is obtained, and a target AMF entity that supports a network slice corresponding to when the PDN connection that can be switched is switched to the 5G network is determined; and when the target AMF entity is the AMF entity, the AMF entity sends a session switching request to the home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection. In one possible design, the system-on-chip further includes a memory for storing necessary program instructions and data for the AMF entity. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

The technical effects brought by any one of the design manners in the fourteenth aspect to the eighteenth aspect can be seen in the technical effects brought by different design manners in the second aspect, and are not described herein again.

A nineteenth aspect provides a session handover system, the system comprising the terminal device of any one of the fourth to eighth aspects, the MME of any one of the ninth to thirteenth aspects, and the AMF entity of any one of the fourteenth to eighteenth aspects.

In a twentieth aspect, a session handover method is provided, and the method includes: and the control plane functional entity determines corresponding network slice information when the PDN connection is switched to the 5G network, and sends the corresponding network slice information when the PDN connection is switched to the 5G network to the MME. Based on the session switching method provided by the embodiment of the application, the control plane functional entity sends the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity on the network side, so that the mobility management entity cooperates with other equipment in the network, determines the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network according to the corresponding network slice information and other information when the PDN connection is switched to the 5G network, creates the PDU session according to the determined network slice information, and realizes the switching of the PDN connection to the PDU session. The problem that the PDN connection can not be switched to the PDU conversation due to the fact that the network slicing in the process of switching the PDN connection to the PDU conversation can not be determined at present is solved.

In a possible design, with reference to the twentieth aspect, the determining, by the control plane function entity, network slice information corresponding to when the PDN connection is handed over to the 5G network includes: and the control surface functional entity determines corresponding network slice information when the PDN connection is switched to the 5G network according to the corresponding relation between the information of the PDN connection and the network slice information, wherein the information of the PDN connection comprises an APN (access point name) corresponding to the PDN connection, or address information of the control surface functional entity corresponding to the PDN connection, or address information of the APN corresponding to the PDN connection and the control surface functional entity. Therefore, the network slice information can be determined according to the corresponding relation between the preset PDN connection information and the network slice information.

In another possible design, with reference to the twentieth aspect or any possible design of the twentieth aspect, the sending, by the control plane function entity, network slice information corresponding to the PDN connection handover to the 5G network to the MME, includes: and the control plane functional entity carries the corresponding network slice information when the PDN connection is switched to the 5G network in a first message which is used for indicating that the corresponding network slice information is stored in the context of the terminal equipment when the MME switches the PDN connection to the 5G network, and sends the first message to the MME. Further, when the control plane functional entity sends, to the MME, the corresponding network slice information when the PDN connection is switched to the 5G network, the control plane functional entity may also send, to the MME, information of the control plane functional entity, where the information of the control plane functional entity may be carried in the first message or may not be carried in the first message. In this way, when the MME receives the first message carrying the network slice information corresponding to the time when the PDN connection is switched to the 5G network, only the content carried in the first message is stored in the context of the terminal device, without analyzing the content carried in the first message, so as to reduce the burden of the MME; and meanwhile, after receiving the network slice information determined by the control plane function entity, the MME sends the network slice information to the AMF, so that the switching of the connection of the PDN to the PDU session is realized.

In yet another possible implementation, in combination with any one of the possible designs of the twentieth aspect or the twentieth aspect, the method further includes: and the control plane functional entity sends information of the priority of the corresponding network slice information when the PDN connection is switched to the 5G network to the MME. Therefore, the information of the priority of the network slice information can be sent to the mobility management entity, so that under the condition that the mobility management entity and the network side equipment work cooperatively, the PDN connection corresponding to the network slice information with higher priority is preferentially switched to the PDU session according to the priority of each network slice information.

In yet another possible implementation, in combination with any one of the possible designs of the twentieth aspect or the twentieth aspect, the method further includes: when terminal equipment for establishing PDN connection is in home routing roaming, network slice information when the PDN connection is switched to the 5G network is network slice information of a visited place when the PDN connection is switched to the 5G network, and a control plane functional entity determines the network slice information of the home place when the PDN connection is switched to the 5G network according to applied strategy information corresponding to the PDN connection; and determining the network slice information of the visited place when the PDN connection is switched to the 5G network according to the network slice information of the home place when the PDN connection is switched to the 5G network and the mapping relation between the network slice information of the home place and the network slice information of the visited place. Therefore, the network slice information of the visited place of the terminal equipment can be obtained when the terminal equipment is in home routing roaming, so that the subsequent network side equipment can switch the PDN connection to the network slice of the visited place according to the network slice information of the visited place, and the service continuity when the terminal equipment is in home routing roaming is ensured.

In a twenty-first aspect, a control plane functional entity is provided, where the control plane functional entity may implement a function executed by the control plane functional entity in the foregoing method embodiment, and the function may be implemented by hardware or may be implemented by hardware executing corresponding software. The hardware or software comprises one or more modules corresponding to the functions. Such as: the control plane functional entity may include: the determining unit is used for determining corresponding network slice information when the PDN connection of the packet data network is switched to a fifth generation 5G network; and the sending unit is used for sending the corresponding network slice information when the PDN connection is switched to the 5G network to MME.

For a specific implementation manner of the control plane functional entity, reference may be made to the behavior function of the control plane functional entity in the session switching method provided in the twentieth aspect or a possible implementation manner of the twentieth aspect, which is not repeated herein. Thus, the control plane functional entity provided can achieve the same advantageous effects as those of the twentieth aspect.

In a twenty-second aspect, there is provided a control plane functional entity, comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the control plane functional entity runs, the processor executes the computer executable instructions stored in the memory, so as to enable the control plane functional entity to perform the session switching method according to any one of the twentieth aspects.

A twenty-third aspect provides a computer-readable storage medium having stored therein instructions, which when run on a computer, cause the computer to perform the session switching method of any one of the twentieth aspects.

A twenty-fourth aspect provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the session switching method of any one of the above twentieth aspects.

A twenty-fifth aspect provides a chip system, where the chip system includes a processor, configured to support a control plane function entity to implement the functions involved in the foregoing aspects, for example, the control plane function entity is supported to determine network slice information corresponding to when a PDN connection is switched to a 5G network, and send the network slice information corresponding to when the PDN connection is switched to the 5G network to an MME through a communication interface. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the control plane functional entity. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any one of the design manners in the twentieth aspect to the twenty-fifth aspect, reference may be made to technical effects brought by different design manners in the twentieth aspect, and details are not described herein again.

In a twenty-sixth aspect, a session handover method is provided, the method comprising: and the MME acquires network slice information corresponding to the PDN connection switched to the 5G network from the control plane function entity, and sends the context of the terminal equipment to the AMF entity, wherein the context of the terminal equipment comprises the network slice information corresponding to the PDN connection switched to the 5G network and the PDN connection information, and the PDN connection information comprises the address information of the control plane function entity corresponding to the PDN connection. Based on the session switching method provided by the embodiment of the application, an MME acquires network slice information corresponding to the PDN connection switched to the 5G network from a control plane function entity, and sends the network slice information corresponding to the PDN connection switched to the 5G network to an AMF entity, so that the AMF entity determines the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network according to the network slice information corresponding to the PDN connection switched to the 5G network and other information, and further creates a PDU session according to the determined network slice information, and the switching of the PDN connection to the PDU session is realized. The problem that the PDN connection can not be switched to the PDU conversation due to the fact that the network slicing in the process of switching the PDN connection to the PDU conversation can not be determined at present is solved.

In a possible design, an MME receives a first message sent by a control plane functional entity and carrying network slice information corresponding to when a PDN connection is switched to a 5G network; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network. In this way, when the MME receives the first message carrying the network slice information corresponding to the time when the PDN connection is switched to the 5G network, only the content carried by the first message (the network slice information corresponding to the time when the PDN connection is switched to the 5G network) is stored in the context of the terminal device, without parsing the content carried in the first message, so as to reduce the burden of the MME itself.

In one possible design, the information for the PDN connection further includes a PDN connection corresponding APN.

A twenty-seventh aspect provides an MME having a function of implementing the method of the twenty-sixth aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above. Such as: the MME may include:

a receiving unit, configured to receive, from a control plane function entity, network slice information corresponding to when a PDN connection is switched to a fifth-generation 5G network; and the sending unit is used for sending the context of the terminal equipment to the AMF entity, wherein the context of the terminal equipment comprises network slice information corresponding to the switching of the PDN connection to the fifth generation 5G network and PDN connection information, and the PDN connection information comprises address information of a control plane function entity corresponding to the PDN connection.

The specific implementation manner of the MME may refer to a behavior function of the MME in the session handover method provided in the twenty-sixth aspect or a possible implementation manner of the twenty-sixth aspect, and details are not repeated here. Therefore, the provided MME can achieve the same advantageous effects as those of the twenty-sixth aspect.

In a twenty-eighth aspect, there is provided an MME comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the MME runs, the processor executes the computer executable instructions stored in the memory, so as to cause the MME to perform the session handover method according to any one of the twenty-sixth aspects.

A twenty-ninth aspect provides a computer-readable storage medium having stored therein instructions which, when run on a computer, cause the computer to perform the session switching method of any one of the twenty-sixth aspects above.

A thirty-first aspect provides a computer program product comprising instructions which, when run on a computer, causes the computer to perform the session switching method of any one of the twenty-sixth aspects above.

In a thirty-first aspect, a chip system is provided, where the chip system includes a processor, configured to support an MME to implement the functions in the foregoing aspects, for example, support the MME to obtain, from a control plane function entity through a communication interface, network slice information corresponding to when a PDN connection is switched to a 5G network, and send a context of a terminal device to an AMF entity. In one possible design, the chip system further includes a memory for storing program instructions and data necessary for the MME. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any one of the design manners in the twenty-seventh aspect to the thirty-first aspect, reference may be made to technical effects brought by different design manners in the twenty-sixth aspect, and details are not described here.

A thirty-second aspect provides a session switching method, where the method includes that an AMF entity obtains network slice information corresponding to PDN connection switching to a 5G network and address information of a control plane function entity corresponding to PDN connection, and optionally, the AMF further obtains network slice information signed by a terminal device; the AMF entity acquires network slice information corresponding to the PDN connection which can be switched in the PDN connection when the PDN connection is switched to the 5G network and network slice information signed by the terminal equipment according to the network slice information corresponding to the PDN connection which can be switched when the PDN connection is switched to the 5G network, and determines a target AMF entity supporting the network slice corresponding to the PDN connection which can be switched when the PDN connection which can be switched is switched to the 5G network; and when the target AMF entity is the AMF entity, the AMF entity sends a session switching request to the control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection, wherein the session switching request is used for requesting to switch the PDN connection to the PDU session. Based on the session switching method provided by the embodiment of the application, the AMF entity obtains network slice information corresponding to the PDN connection switched to the 5G network, determines network slice information corresponding to the switched PDN connection switched to the 5G network in the PDN connection according to the network slice information corresponding to the switched PDN connection switched to the 5G network and other information, and sends the network slice information corresponding to the switched PDN connection switched to the 5G network in the PDN connection to the control plane function entity, so that the control plane function entity creates a PDU session according to the determined network slice information, and realizes the switching of the PDN connection to the PDU session. The problem that the PDN connection can not be switched to the PDU conversation due to the fact that the network slicing in the process of switching the PDN connection to the PDU conversation can not be determined at present is solved.

In one possible design, the AMF entity obtains, from the MME, network slice information corresponding to when the PDN connection is switched to the 5G network, where the network slice information corresponding to when the PDN connection is switched to the 5G network is determined by the control plane function entity.

In one possible design, when the AMF entity determines that the terminal device establishing the PDN connection is in home routing roaming, the AMF entity determines a visited control plane function entity according to a network slice indicated by network slice information when the PDN connection that can be switched in the PDN connection is switched to the 5G network; and the AMF entity sends a session establishment request carrying network slice information corresponding to the switched PDN connection in the PDN connection and address information of a control plane functional entity corresponding to the PDN connection to the 5G network to the visited control plane functional entity, wherein the session establishment request is used for indicating the visited control plane functional entity to send a session switching request to the home control plane functional entity. Therefore, when the terminal equipment is in the home routing scene, the AMF entity can determine the visited control plane functional entity, and establishes the PDU session corresponding to the PDN connection through the intercommunication of the visited control plane functional entity and the home control plane entity, thereby ensuring the service continuity of the terminal equipment in the roaming scene.

In a possible design, when the AMF entity determines that the terminal device establishing the PDN connection is in home routing roaming and the AMF entity does not select the visited control plane function entity, the AMF entity sends a selection request to the NRF, the NRF selects the visited control plane function entity according to a network slice indicated by network slice information when the PDN connection that can be switched in the PDN connection is switched to the 5G network, and feeds back address information of the visited control plane function entity to the initial AMF entity, and the initial AMF entity sends a session switching request to the home control plane function entity through the visited control plane function entity according to a feedback result of the NRF. Therefore, when the terminal equipment is in the home routing scene and the AMF entity does not select the visited control plane functional entity, the AMF entity can select the visited control plane functional entity by the aid of the NRF, the visited control plane functional entity and the home control plane functional entity which are selected by the NRF are communicated, the home control plane functional entity establishes a PDU session corresponding to PDN connection, and service continuity of the terminal equipment in the roaming scene is guaranteed.

In a thirty-third aspect, there is provided an AMF entity having the functionality to implement the method of the thirty-second aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above. Such as: the AMF entity comprises:

a receiving unit, configured to receive network slice information corresponding to when a PDN connection is switched to a fifth-generation 5G network, and address information of a control plane functional entity corresponding to the PDN connection; optionally, the method may also be used to receive network slice information signed by the terminal device;

an obtaining unit, configured to obtain, according to network slice information corresponding to when the PDN connection is switched to the 5G network and network slice information signed by the terminal device, network slice information corresponding to when the PDN connection that is allowed to be switched in the PDN connection is switched to the 5G network;

The specific implementation manner of the AMF entity may refer to a behavior function of the AMF entity in the session handover method provided by the thirty second aspect or a possible implementation manner of the thirty second aspect, and details are not repeated here. Thus, the provided AMF entity can achieve the same advantageous effects as those of the thirty-second aspect.

In a thirty-fourth aspect, there is provided an AMF entity comprising: a processor and a memory; the memory is configured to store computer-executable instructions, and when the AMF entity runs, the processor executes the computer-executable instructions stored in the memory, so as to cause the AMF entity to perform the session handover method according to any one of the thirty-second aspects.

A thirty-fifth aspect provides a computer-readable storage medium having stored therein instructions, which when run on a computer, cause the computer to perform the session switching method of any one of the thirty-second aspects described above.

A thirty-sixth aspect provides a computer program product containing instructions which, when run on a computer, causes the computer to perform the session switching method of any one of the thirty-second aspects above.

A thirty-seventh aspect provides a chip system, where the chip system includes a processor, configured to support an AMF entity to implement the functions in the foregoing aspects, for example, support the AMF entity to obtain network slice information corresponding to when a PDN connection is switched to a 5G network, and address information of a control plane function entity corresponding to the PDN connection; optionally, network slice information signed by the terminal device may also be obtained; acquiring network slice information corresponding to the PDN connection capable of being switched in the PDN connection when the PDN connection is switched to the 5G network and network slice information signed by the terminal equipment, and determining a target AMF entity supporting the network slice corresponding to the PDN connection capable of being switched when the PDN connection is switched to the 5G network; and when the target AMF entity is the AMF entity, the AMF entity sends a session switching request to the control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection. In one possible design, the system-on-chip further includes a memory for storing necessary program instructions and data for the AMF entity. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any one of the design manners in the thirty-third aspect to the thirty-seventh aspect, reference may be made to technical effects brought by different design manners in the thirty-second aspect, and details are not described here.

A thirty-eighth aspect provides a session handover system, which includes the control plane function entity of any of the twenty-fifth aspect, the MME of any of the twenty-seventh aspect to the thirty-eleventh aspect, and the AMF entity of any of the thirty-third aspect to the thirty-seventh aspect.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

Fig. 1 is a schematic diagram of a network architecture for interworking between a 4G network and a 5G network in the prior art;

fig. 2 is a schematic diagram of a network architecture for interworking between a 4G network and a 5G network in an LBO roaming scenario;

fig. 3 is a schematic diagram of a network architecture for interworking between a 4G network and a 5G network in a home router roaming scenario;

fig. 4 is a schematic composition diagram of a communication device according to an embodiment of the present application;

fig. 5 is a flowchart of a session switching method according to an embodiment of the present application;

fig. 6 is a flowchart of another session switching method provided in the embodiment of the present application;

fig. 7 is a flowchart of another session switching method provided in the embodiment of the present application;

fig. 8 is a flowchart of another session switching method provided in the embodiment of the present application;

fig. 9 is a schematic composition diagram of a terminal device according to an embodiment of the present application;

fig. 10 is a schematic composition diagram of an MME according to an embodiment of the present application;

fig. 11 is a schematic composition diagram of an AMF entity according to an embodiment of the present application;

fig. 12 is a flowchart of another session switching method provided in an embodiment of the present application;

fig. 13 is a schematic diagram illustrating a control plane functional entity according to an embodiment of the present application;

fig. 14 is a schematic composition diagram of an MME according to an embodiment of the present application;

fig. 15 is a schematic composition diagram of an AMF entity according to an embodiment of the present application.

Detailed Description

To facilitate understanding of the technical solutions of the embodiments of the present application, a brief description of the related art of the present application is first given as follows.

Network Slice Selection Assistance Information (NSSAI)

NSSAI is used to indicate one or more network slices, and includes a plurality of single NSSAIs (S-NSSAIs). The S-NSSAI is composed of a service type (SST) and a Slice Differentiator (SD). Wherein SST includes standardized and operator-customized types; SD is optional information that supplements SST to distinguish multiple network slices of the same SST. 23.501 the types and roles of NSSAI as defined in the Standard are shown in Table one. In the embodiment of the present application, S-NSSAI is simply referred to as network slice information.

Watch 1

Access Point Name (APN):

the terminal device may provide an APN to a Mobility Management Entity (MME) when initiating the packet service. The MME performs domain name resolution through a Domain Name Server (DNS) according to the APN provided by the terminal device, thereby obtaining an Internet Protocol (IP) address of a packet data gateway (PGW), and accessing the terminal device to a PDN corresponding to the APN.

The technical solution in the embodiments of the present application is described below with reference to the drawings in the embodiments of the present application.

The scheme provided by the embodiment of the application can be applied to a network in which a 4G network and a 5G network shown in fig. 1 are intercommunicated, so as to realize switching the PDN connection in the 4G network to a PDU session in the 5G network.

As shown in fig. 1, the network may include: terminal device, evolved universal terrestrial Radio Access Network (E-UTRAN) device, next generation Radio Access Network (NG-RAN) device, MME in 4G Network, Serving Gateway (SGW) in 4G Network, AMF entity in 5G Network, User Plane Function (UPF) entity in 4G Network and 5G Network, packet data Network (packet data Network, PDN) Gateway user plane function (PDN) entity, PGW-U) entity, Session Management Function (SMF) entity, PDN Gateway control plane function (PDN control plane function, PGW-C) entity, PGW-C entity, PCRF policy control function (policy control function, PCF) entity, and charging function (charging policy and charging function, PCRF policy control function, and charging function, A Home Subscriber Server (HSS) + a Unified Data Management (UDM) entity, etc. Here, "+" indicates a convergence, where UPF is a user plane function of a 5G network, PGW-U is a gateway user plane function of a 4G network corresponding to the UPF, an SMF entity is a session management function of the 5G network, PGW-C is a gateway control plane function in the 4G network corresponding to the SMF entity, PCF is a policy control function of the 5G network, and PCRF is a policy charging rule function of the 4G network corresponding to the PCF. In the embodiment of the present application, for convenience of description, an HSS + UDM entity is referred to as a user data management entity, a PGW-C entity + SMF entity is referred to as a control plane function entity, an MME and an AMF entity are referred to as different mobility management entities, and an E-UTRAN device and an NG-RAN device are referred to as different access network devices, which are described herein in a unified manner and will not be described in detail below. Of course, the combined network device may also use other names, and this embodiment of the present application is not limited to this specifically.

It should be noted that fig. 1 is only an exemplary architecture diagram, and may include other entities besides the entities shown in fig. 1, such as: a General Packet Radio System (GPRS) service support node (SGSN) in a 4G network, an authentication service function (AUSF) entity and a Network Slice Selection Function (NSSF) entity in a 5G network, and the like, which are not specifically limited in this embodiment of the present invention.

The terminal device in fig. 1 may be a User Equipment (UE), or may be various handheld devices, vehicle-mounted devices, wearable devices, computing devices or other processing devices connected to a wireless modem, which have a wireless communication function; but may also include, without limitation, a subscriber unit (subscriber unit), a cellular telephone (cellular telephone), a smart phone (smart phone), a wireless data card, a Personal Digital Assistant (PDA) computer, a tablet computer, a wireless modem (modem), a handheld device (dhhand), a laptop computer (laptop computer), a cordless telephone (cordless telephone) or Wireless Local Loop (WLL) station, a Machine Type Communication (MTC) terminal device, a Mobile Station (MS), and so on. The terminal device in fig. 1 can access the 4G network through the E-UTRAN device and the terminal device can access the 5G network through the NG-RAN device. E-UTRAN equipment communicates with MME through S1-MME interface, E-UTRAN equipment communicates with SGW through S1-U interface, MME communicates with SGW through S11 interface, MME communicates with user data management entity through S6a interface, MME communicates with AMF entity through N26 interface, SGW communicates with PGW-U entity + UPF entity through S5-U interface, SGW communicates with PGW-C entity + SMF entity through S5-C interface, PGW-U entity + UPF entity communicates with NG-RAN equipment through N3 interface, PGW-U entity + UPF entity communicates with PGW-C entity + SMF entity through N4 interface, PGW-C entity + SMF entity communicates with PCRF entity + PCF entity through N7 interface, HSS + UDM entity communicates with PGW-C entity + SMF entity through N10 interface, HSS + UDM entity communicates with AMF entity through N8 interface, the PCRF entity and the PCF entity communicate with the AMF entity through an N15 interface, the PGW-C entity and the SMF entity communicate with the AMF entity through an N11 interface, the AMF entity communicates with NG-RAN equipment through an N2 interface, and the AMF entity communicates with terminal equipment through an N1 interface. It should be noted that the interface name between each network element in fig. 1 is only an example, and the interface name may be other names in a specific implementation, which is not specifically limited in this embodiment of the present application.

Due to the mobility of the terminal device, when the terminal device moves in the framework of interworking between the 4G Network and the 5G Network, the terminal device may be in a Local Breakout (LBO) roaming scenario or a Home routed (Home routed) roaming scenario, where the LBO roaming may refer to a roaming user obtaining a corresponding service through a gateway access Network of a visited Network, and a service provider may be a Home Public Land Mobile Network (HPLMN) (abbreviated as HPLMN) or a visited Public Land Mobile Network (PLMN) (abbreviated as VPLMN). For example, as shown in fig. 2, a user accesses a network to obtain a corresponding service through an SMF entity + PGW-C entity in a VPLMN, and user plane traffic of all access services is forwarded to an h-PCF entity + h-PCRF entity in the HPLMN through the v-PCF entity + v-PCRF entity in the VPLMN, that is, the SMF entity + PGW-C entity is located at a visited place under local breakout roaming, and the function thereof is not changed, which is not described herein. home routed roaming refers to that a v-SMF entity of a visited place is connected with a home SMF entity + PGW-C entity through a home routing to perform control signaling transmission, and the home UPF entity + PGW-U entity is connected with a data network, such as: fig. 3 shows a network system architecture for interworking between 4G network and 5G network in a home routed roaming scenario, where the v-SMF entity is a visited SMF entity, and the v-PCF entity is a visited PCF entity, and functions thereof are not changed, which is not described herein.

Specifically, the terminal device, MME, AMF entity, and other devices in fig. 1 may be implemented by the communication device in fig. 4. The communication device 400 includes at least one processor 401, communication lines 402, memory 403 and at least one communication interface 404.

The processor 401 may be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present application, such as: one or more microprocessors (digital signal processors, DSPs), or one or more Field Programmable Gate Arrays (FPGAs).

The communication link 402 may include a path for communicating information between the aforementioned components.

The communication interface 404 may be any device, such as a transceiver, for communicating with other devices or communication networks, such as an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), etc.

The memory 403 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, optical disk storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to these. The memory may be separate and coupled to the processor via a communication line 402. The memory may also be integral to the processor.

The memory 403 is used for storing computer-executable instructions for executing the present invention, and is controlled by the processor 401. Processor 401 is configured to execute computer-executable instructions stored in memory 403 to implement the session handoff method provided by the embodiments described below in the present application.

Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.

In particular implementations, processor 401 may include one or more CPUs such as CPU0 and CPU1 in fig. 4 as an example.

In particular implementations, communication device 400 may include multiple processors, such as processor 401 and processor 408 in fig. 4, for example, as an embodiment. Each of these processors may be a single core processor or a multi-CPU processor. A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

In particular implementations, communication device 400 may also include an output device 405 and an input device 406, as one embodiment. An output device 405 is in communication with the processor 401 and may display information in a variety of ways. For example, the output device 405 may be a Liquid Crystal Display (LCD), a Light Emitting Diode (LED) display device, a Cathode Ray Tube (CRT) display device, a projector (projector), or the like. The input device 406 is in communication with the processor 401 and may receive user input in a variety of ways. For example, the input device 406 may be a mouse, a keyboard, a touch screen device, or a sensing device, among others.

The communication device 400 described above may be a general purpose device or a special purpose device. In particular implementations, communication device 400 may be a desktop, laptop, web server, PDA, mobile phone, tablet, wireless terminal device, embedded device, or a device with a similar structure as in fig. 4. The embodiment of the present application does not limit the type of the communication apparatus 400.

The following describes a session handover method provided in the embodiment of the present application in detail with reference to fig. 1 to 4.

Fig. 5 is a schematic flowchart illustrating a session handover method according to an embodiment of the present application, and as shown in fig. 5, the session handover method may include:

step 501: the terminal device registers to the 4G network and establishes a PDN connection.

The terminal device may be any one of the terminal devices in fig. 1, fig. 2, or fig. 3.

Optionally, the terminal device may be registered in the 4G network through the MME, and after the terminal device is registered in the 4G network, when the terminal device determines to apply the PDN to be accessed, the terminal device sends the APN corresponding to the PDN to the MME, and the MME establishes an Evolved Packet System (EPS) bearer in cooperation with a control plane function entity (SMF entity + PGW-C entity), until the PDN connection establishment is completed. One PDN connection may correspond to one or more applications, one PDN connection corresponds to one APN, and multiple PDN connections may be established under one APN, without limitation.

After the terminal device establishes the PDN connection, the terminal device may store a corresponding relationship between the PDN connection, the application, and the APN, and the MME may store address information of a control plane function entity (i.e., SMF entity + PGW-C entity) corresponding to the PDN connection, or an APN corresponding to the PDN connection in a context of the terminal device, where at least one of the address information of the control plane function entity corresponding to the application and the PDN connection corresponding to the PDN connection, and the APN corresponding to the PDN connection may be referred to as information of the PDN connection, and the information of the PDN connection is used to indicate a certain PDN connection corresponding to the SMF entity + PGW-C entity or the APN or the application.

In each embodiment of the present application, the address information of the control plane functional entity may be used to identify the control plane functional entity, and the address information of the control plane functional entity may be information of a Public Land Mobile Network (PLMN) where the control plane functional entity is located, or an Internet Protocol (IP) address of the control plane functional entity, or a full domain name (FQDN) of the control plane functional entity. It should be noted that, in the embodiments of the present application, the address information of the control plane functional entity is information for identifying the control plane functional entity, and the information may be named as address information of the control plane functional entity, and may also have other names, for example, different expressions such as information of the control plane functional entity, and may also be included in the scope of the idea of the present application.

Step 502: and the terminal equipment determines corresponding network slice information when the PDN connection is switched to the 5G network.

The network slice information corresponding to the PDN connection being switched to the 5G network may include an S-NSSAI of a network slice corresponding to the PDN connection being switched to the 5G network.

After the terminal device establishes the PDN connection in the 4G network, the terminal device first determines that subsequent PDN connections that may be switched to the 5G network in the PDN connection, and then determines corresponding network slice information when the subsequent PDN connections that may be switched to the 5G network are switched to the 5G network.

In a possible implementation manner, the terminal device determines that a PDN connection in the established PDN connection may be subsequently switched to a PDN connection in the 5G network according to policy information of an application corresponding to the PDN connection, where the policy information is used to indicate a requirement of the application on the network, and for example, the policy information may be a Service-level agreement (SLA) of a Service or a network switching policy (for example, the Service preferentially uses the 5G network, or uses the 4G network if the 5G network does not cover the Service). For example, when the terminal device determines that an application triggering establishment of a first PDN connection has a 5G communication requirement, the terminal device determines that the first PDN connection is a PDN connection that may be subsequently handed over to a 5G network. Such as: when the application corresponding to the triggering of establishing the first PDN connection for switching to the 5G network has requirements for low latency, high bandwidth, and the like, the terminal device determines that the first PDN connection is a PDN connection that may be subsequently switched to the 5G network.

In another possible implementation manner, when the terminal device determines that the terminal device itself supports the 5G network communication capability, the terminal device determines that all currently established PDN connections are likely to be subsequently switched to the 5G network, and further determines corresponding network slice information when the PDN connections are switched to the 5G network.

The terminal device may determine, according to a correspondence between PDN connection information and network slice information, corresponding network slice information when the PDN connection is switched to the 5G network. The correspondence between the information of the PDN connection and the network slice information may be stored in a Network Slice Selection Policy (NSSP), where the NSSP is mainly used to select a network slice in which the PDN connection is switched to the 5G network, and the NSSP configuration may be obtained in the terminal device or from other entity devices by the terminal device, without limitation.

Illustratively, the information of the PDN connection includes an application corresponding to the PDN connection, and the terminal device determines, according to the application corresponding to the PDN connection being switched to the 5G network and a correspondence between the application and the network slice information, network slice information corresponding to the PDN connection being switched to the 5G network. For example, the correspondence between the application and the network slice information is shown in table two, and when the application corresponding to the PDN connection switched to the 5G network is application 1, the terminal device may determine, through table two, that the S-NSSAI of the network slice corresponding to the PDN connection switched to the 5G network is S-NSSAI1 and S-NSSAI 2.

Watch two

Applications of	Network slicing information
		Applications 1	S-NSSAI1、S-NSSAI2
Application 2	S-NSSAI2
		Application 3	S-NSSAI3、S-NSSAI4
……	……

Exemplarily, the information of the PDN connection includes an APN corresponding to the PDN connection, and at this time, the terminal device determines, according to the APN corresponding to the PDN connection being switched to the 5G network and the correspondence between the APN and the network slice information, the network slice information corresponding to the PDN connection being switched to the 5G network. For example, as shown in table three, when the PDN connection is switched to the 5G network, and the APN corresponding to the APN is APN3, the terminal device may determine, according to table three, that the S-NSSAI of the network slice corresponding to the PDN connection switched to the 5G network is S-NSSAI3 and S-NSSAI 4.

Watch III

APN	Network slicing information
		APN1	S-NSSAI1、S-NSSAI2
APN2	S-NSSAI2
		APN3	S-NSSAI3、S-NSSAI4
……	……

Since the APN and the Data Network Name (DNN) are equivalent, the information of the PDN connection may further include a DNN corresponding to the PDN connection, and at this time, the terminal device determines, according to the DNN corresponding to the PDN connection switched to the 5G network and the corresponding relationship between the DNN and the network slice information, the network slice information corresponding to the PDN connection switched to the 5G network. The terminal device may determine the APN corresponding to the PDN connection as a DNN corresponding to the PDN connection, or obtain the DNN corresponding to the PDN connection in a mapping relationship between the APN and the DNN configured in advance.

It should be noted that, when the terminal device is in home router roaming, the network slice information determined by the terminal device in step 502 is the network slice information corresponding to the location visited when the PDN connection is switched to the 5G network, and at this time, the terminal device may determine the network slice information of the home location when the PDN connection is switched to the 5G network according to the corresponding relationship between the information of the PDN connection and the network slice information, and then determine the network slice information of the home location when the PDN connection is switched to the 5G network according to the determined network slice information of the home location when the PDN connection is switched to the 5G network and the mapping relationship between the network slice information of the home location and the network slice information of the home location, and determine the network slice information of the home location when the PDN connection is switched to the 5G network; or, when the terminal device is in home router roaming, the network slice information corresponding to the network slice information determined by the terminal device in step 502 when the PDN connection is switched to the 5G network may be the network slice information of the home location when the PDN connection is switched to the 5G network, and in the subsequent step, when the AMF entity receives the network slice information of the home location when the PDN connection is switched to the 5G network, the AMF entity determines the network slice information of the visited location when the PDN connection is switched to the 5G network according to the mapping relationship between the network slice information of the home location and the network slice information of the visited location, which is not limited.

For example, the mapping relationship between the home network slice information and the visited network slice information is shown in table four, and after the terminal device determines that the network slice information of the home is S-NSSAI3 and S-NSSAI4 when the PDN connection is switched to the 5G network according to table three, the terminal device may determine that the network slice information of the visited network when the PDN connection is switched to the 5G network is S-NSSAI1, S-NSSAI2, and S-NSSAI8 according to the mapping relationship between the home network slice information and the visited network slice information shown in table four.

Watch four

Home network slice information	Visited place network slicing information
		S-NSSAI3	S-NSSAI1、S-NSSAI2
S-NSSAI4	S-NSSAI8
		S-NSSAI5	S-NSSAI7
……	……

It should be noted that, this embodiment of the application only exemplarily provides a specific implementation of the above several terminal devices for determining the network slice information corresponding to the PDN connection being switched to the 5G network, and of course, the terminal device may also obtain the network slice information corresponding to the PDN connection being switched to the 5G network by other manners, which is not limited.

In step 502, the terminal device may compare a Public Land Mobile Network (PLMN) identifier of the terminal device with a PLMN identifier sent by an access Network device (E-UTRAN device or NG-RAN device in fig. 1) in an area where the terminal device is located, and when the two identifiers are the same, the terminal device determines that the terminal device is not roaming, and when the two identifiers are different, the terminal device determines that the terminal device is roaming.

Step 503: the terminal equipment sends network slice information corresponding to the PDN connection switched to the 5G network to the MME, and the MME receives the network slice information corresponding to the PDN connection switched to the 5G network sent by the terminal equipment.

Wherein, the MME may be the MME in fig. 1, fig. 2, or fig. 3.

Optionally, when the terminal device switches the PDN connection to the 5G network, the corresponding network slice information is carried in the first message and is directly sent to the MME; or the terminal device sends the corresponding network slice information when the PDN connection is switched to the 5G network to a control plane function entity (SMF entity + PGW-C entity), and the control plane function entity carries the corresponding network slice information when the PDN connection is switched to the 5G network in the first message and sends the first message to the MME after receiving the corresponding network slice information when the PDN connection is switched to the 5G network. The first message may further carry indication information, where the indication information may be used to indicate that the MME only stores network slice information corresponding to the PDN connection being switched to the 5G network, and does not resolve the network slice information corresponding to the PDN connection being switched to the 5G network, which is included in the first message, for example: the first message may be an information element, which may be a transparent container (transparent container), and may include a header and a payload, where the header carries indication information and the payload carries corresponding network slice information when the PDN connection is switched to the 5G network.

In addition, while the terminal device sends the MME network slice information corresponding to the PDN connection handover to the 5G network, the terminal device may send at least one of a DNN corresponding to the PDN connection handover to the 5G network and priority information of the network slice information corresponding to each PDN connection handover to the 5G network to the MME. The priority information of the corresponding network slice information when the PDN connection is switched to the 5G network is used to indicate the priority of the a-NSSAI of the network slice or the priority of the PDN connection, which is not limited.

In a possible implementation manner, the terminal device determines, according to at least one of importance of the PDN connection, a load condition of a network slice indicated by network slice information corresponding to the PDN connection being switched to the 5G network, and requirement information of the terminal device, priority information of the network slice information corresponding to each PDN connection being switched to the 5G network. Wherein, the requirement information of the terminal device may instruct the terminal device which PDN connections of the established PDN connections to switch to the 5G network, such as: when the terminal device wants to switch the PDN connection 1 to the 5G network preferentially, the terminal device sets the priority of the network slice information corresponding to the switching of the PDN connection 1 to the 5G network to be higher, and when the subsequent AMF entity receives the network slice information of the PDN connection 1 and the PDN connection 2 and selects a suitable network slice and the target AMF entity, the terminal device preferentially considers the network slice information corresponding to the switching of the PDN1 to the 5G network, that is, the S-NSSAI corresponding to the selected network slice includes the S-NSSAI of the PDN connection 1, and then considers the S-NSSAI of the PDN connection 2.

After the MME receives the network slice information corresponding to the PDN connection being switched to the 5G network, the MME may store the network slice information corresponding to the PDN connection being switched to the 5G network in the context of the terminal device.

Step 504: the MME receives a Handover (HO) request sent by the source access network equipment, and sends the context of the terminal equipment to the AMF entity.

Wherein, the source access network device may be an E-UTRAN device in fig. 1 or fig. 2 or fig. 3. The context of the terminal device includes information of PDN connection and network slice information corresponding to when the PDN connection is switched to the 5G network, and the information of PDN connection includes at least one of address information of a control plane functional entity corresponding to the PDN connection and an APN corresponding to the PDN connection, as shown in step 501.

Optionally, after determining that the terminal device moves from the 4G network to the 5G network according to the cell measurement information reported by the terminal device, the source access network device sends a handover request to the MME through an S1-MME interface, where the handover request may carry an identifier of the terminal device, and after receiving the HO request, the MME sends the context of the terminal device to the AMF entity according to the identifier of the terminal device.

The AMF entity may be a default AMF entity corresponding to the MME, or the handover request carries information of the current area of the terminal device, and the MME determines an AMF entity set according to the current area of the terminal device and a correspondence between the target area and the AMF entity set, and then selects one AMF entity from the selected AMF entity set as the AMF entity in step 504 according to a corresponding policy; or, the MME determines the AMF entity set according to the correspondence between the MME and the AMF entity set, and selects one AMF entity from the selected AMF entity set as the AMF entity in step 504 according to a corresponding policy, without limitation. The policy may specifically be a method for determining one AMF entity from the AMF entity set based on information such as priority, capacity, or load of each AMF entity in the AMF entity set.

Step 505: and the AMF entity receives the context of the terminal equipment from the MME, acquires the corresponding network slice information when the PDN connection is switched to the 5G network, and acquires the subscription data of the terminal equipment from the user data management entity.

The user data management entity may be the HSS + UDM entity in fig. 1, fig. 2 or fig. 3. The subscription data of the terminal device may include network slice information (Subscribed S-NSSAI) Subscribed by the terminal device, may further include DNN Subscribed by the terminal device, and the like, without limitation.

Optionally, the AMF entity obtains subscription data of the terminal device from the user data management entity through the numm message, where the numm message carries the subscription data of the terminal device, and the numm is a service interface of the UDM entity, where the numm message is Nudm subscription data management (subframe data management) in an existing protocol, and has a function of allowing a network function (network function, NF) consumer to retrieve the subscription data of the terminal device when necessary, and providing updated subscription data of the terminal device to the subscribed NF consumer.

It should be noted that, when the terminal device is in a roaming scenario and the network slice information determined by the terminal device when the PDN connection is switched to the 5G network in step 502 is network slice information of a home location when the PDN connection is switched to the 5G network, in step 505, after the AMF entity obtains the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network, the network slice information of the visited location when the PDN connection is switched to the 5G network is determined according to a mapping relationship between the home location network slice information and the visited location network slice information, and the network slice information of the visited location when the PDN connection is switched to the 5G network is used as the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network in step 506.

Step 506: and the AMF entity acquires the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network according to the corresponding network slice information when the PDN connection is switched to the 5G network and the signed network slice information, and determines a target AMF entity supporting the corresponding network slice when the switched PDN connection is switched to the 5G network.

In a possible implementation manner, an AMF entity determines candidate network slice information corresponding to a PDN connection according to at least one of the priority of S-NSSAI corresponding to each PDN connection in network slice information corresponding to a plurality of PDN connections switched to a 5G network, load information of S-NSSAI corresponding to each PDN connection and NSSAI supported by each AMF entity in an AMF entity set configured in the AMF entity, and NSSAI in an intersection of the candidate network slice information and signed network slice information is taken as network slice information corresponding to a PDN connection capable of being switched to the 5G network;

after determining corresponding network slice information when a switched PDN connection in the PDN connection is switched to a 5G network, an AMF entity determines whether the AMF entity supports a network slice corresponding to the switched PDN connection in the PDN connection when the switched PDN connection is switched to the 5G network according to the priority of the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network and the configuration capacity of the AMF entity, if the AMF entity supports the network slice information, the AMF entity is determined to be a target AMF entity, if the AMF entity does not support the target AMF entity, the AMF entity supporting the network slice information with a high priority level or the AMF entity supporting the most network slices is selected from the target AMF entity set; or the AMF entity directly determines a target AMF entity set according to the configuration capability of the AMF entity and the priority of the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network, and selects the AMF entity supporting the network slice information with high priority level or the AMF entity supporting the most network slices from the target AMF entity set as the target AMF entity.

The AMF entity may directly determine, according to the priority information of the network slice information corresponding to the PDN connection switch to the 5G network sent by the terminal device in step 503, the priority of the S-NSSAI corresponding to the PDN connection, or determine, according to the priority of the PDN connection indicated by the priority information of the network slice information corresponding to the PDN connection switch to the 5G network sent by the terminal device, the priority of the S-NSSAI corresponding to the PDN connection, or, when the terminal device does not send the priority information of the network slice information corresponding to the PDN connection switch to the 5G network, configure, by the AMF entity, the S-NSSAI corresponding to the PDN connection according to at least one of the importance of the PDN connection and the load condition of the network slice indicated by the network slice information corresponding to the PDN connection switch to the 5G network, without limitation.

In another possible implementation manner, the AMF entity sends a slice selection request carrying network slice information corresponding to when the PDN connection is switched to the 5G network and network slice information of the subscription to a Network Slice Selection Function (NSSF) entity, the NSSF determines, according to the network slice information corresponding to when the PDN connection is switched to the 5G network and the network slice information of the subscription to the terminal device, the network slice information corresponding to when the PDN connection capable of being switched in the PDN connection is switched to the 5G network, and determining a target AMF entity supporting a corresponding network slice when the switched PDN connection is switched to the 5G network, the NSSF returning a determination result to the AMF entity, the AMF entity obtaining corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network according to the determination result, and determining a target AMF entity supporting a corresponding network slice when the PDN connection capable of being switched is switched to the 5G network.

The NSSF entity determines, according to network slice information corresponding to when the PDN connection is switched to the 5G network and the subscribed network slice information, network slice information corresponding to when the PDN connection capable of being switched in the PDN connection is switched to the 5G network, and a specific manner of determining a target AMF entity that supports the network slice information corresponding to when the PDN connection capable of being switched is switched to the 5G network may refer to the manner of determining, by the AMF entity, the network slice information corresponding to when the PDN connection capable of being switched in the PDN connection is switched to the 5G network and the subscribed network slice information, the network slice information corresponding to when the PDN connection capable of being switched in the PDN connection is switched to the 5G network, and the manner of determining the target AMF entity that supports the network slice information corresponding to when the PDN connection capable of being switched is switched to the 5G network, which.

Step 507: and when the target AMF entity is the AMF entity, the AMF entity sends a session switching request to the home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection.

The home control plane function entity may be the SMF entity + PGW-C entity in fig. 1, fig. 2, or fig. 3, and the address information of the control plane function entity is used to identify the location of the home control plane function entity in the network; the session switching request is used for requesting to switch the PDN connection to the PDU session, and the session switching request may carry network slice information corresponding to when the switched PDN connection in the PDN connection is switched to the 5G network.

In a possible implementation manner, when the AMF entity determines that the terminal device is in non-roaming or LBO roaming, the AMF entity sends a session handover request to the home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection in the context of the terminal device in step 506.

In another possible implementation manner, when the AMF entity determines that the terminal device is in the home router roaming shown in fig. 3, that is, the terminal device is the terminal device in fig. 3, the AMF entity determines a visited control plane function entity (for example, a vSMF entity in fig. 3), the AMF entity sends, to the visited control plane function entity, a session establishment request carrying network slice information corresponding to when a PDN connection that can be switched in the PDN connection is switched to the 5G network and address information of the control plane function entity corresponding to the PDN connection, and the visited control plane function entity sends, to the home control plane function entity, the session switching request according to the address information of the control plane function entity corresponding to the PDN connection.

In this possible implementation manner, the AMF entity may select, according to a network slice indicated by network slice information corresponding to when a PDN connection capable of being switched in the PDN connection is switched to the 5G network and a DNN corresponding to when the PDN connection is switched to the 5G network, a control plane function entity that can access the DN identified by the DNN from control plane function entities included in the network slice as a visited control plane function entity. For example, when a PDN connection capable of being switched in the PDN connection is switched to the 5G network, the corresponding network slice information is S-NSSAI1, and the S-NSSAI1 corresponds to a network slice 1, and the network slice 1 includes a plurality of control plane functional entities, and the terminal device may select one control plane functional entity that can access the DN identified by the DNN in the network slice 1 as the visited control plane functional entity. It can be understood that, when there are multiple control plane functional entities capable of accessing the DN identified by the DNN, the AMF entity may use the control plane functional entity with a low load as the visited control plane functional entity according to the load condition of the control plane functional entity, or select the visited control plane functional entity according to other conditions of the control plane functional entity, without limitation.

In step 503, the DNN corresponding to the PDN connection handover to the 5G network may be sent to the MME by the terminal device, and the MME sends the MME again to the AMF entity, or when the terminal device does not send the DNN corresponding to the PDN connection handover to the 5G network to the MME, the context of the terminal device received by the AMF entity from the MME includes an APN corresponding to the PDN connection, and the AMF entity may determine, according to the APN included in the PDN connection information and the mapping relationship between the APN and the DNN, the DNN corresponding to the PDN connection handover to the 5G network, without limitation.

In another possible implementation manner, when the AMF entity determines that the terminal device is in home router roaming as shown in fig. 3 and the AMF entity cannot select the visited control plane function entity, the AMF entity sends a selection request to the NRF, where the selection request carries information of a network slice corresponding to when the PDN connection that can be switched in the PDN connection is switched to the 5G network, the NRF selects a control plane function entity that can access the DN identified by the DNN from the control plane function entities included in the network slice as the visited control plane function entity according to a network slice indicated by information of the network slice and DNN corresponding to the network slice when the PDN connection that can be switched in the PDN connection is switched to the 5G network in the PDN connection, and feeds back address information of the visited control plane function entity to the AMF entity, and the AMF entity sends, according to a feedback result of the NRF, the control plane function entity that carries the network slice corresponding to when the PDN connection that can be switched in the DNN connection is switched to the 5G network to the visited control plane function entity And the visited place home control plane functional entity sends a session switching request to the home control plane functional entity according to the address information of the control plane functional entity corresponding to the PDN connection. The DNN in this implementation may be sent to the MME by the terminal device in step 503, and sent to the AMF entity by the MME in the context of the terminal device. The address information of the control plane functional entity in the visited place may be an IP address or an FQDN of the control plane functional entity, which is not specifically limited in this embodiment of the present application.

In the above possible implementation manner, the AMF entity may determine, according to the PLMN identifier of the terminal device and the PLMN of the AMF entity, that the terminal device is in the non-roaming, LBO roaming, or home router roaming scenario.

Optionally, when the target AMF entity is another AMF entity, the AMF entity sends a redirection instruction to the target AMF entity; and the target AMF entity receives the redirection indication from the AMF entity, and sends a session switching request to the home control plane functional entity according to the redirection indication. The redirection instruction may carry network slice information corresponding to the PDN connection that can be switched in the PDN connection determined by the AMF entity when the PDN connection is switched to the 5G network, and address information of a control plane function entity corresponding to the PDN connection in the context of the terminal device received by the AMF entity from the MME.

It should be noted that, in the embodiments of the present application, the session handover request is information for requesting to switch the PDN connection to the PDU session, and the information may be named as a session handover request, and may also have other names, for example, different expressions such as a session update request, and may also be included in the scope of the idea of the present application. Similarly, the session establishment request is a message for instructing the visited control plane function entity to send a session handover request to the home control plane function entity, and the message may also have other names besides named session establishment request, for example, different expressions such as session update request, and may also be included in the scope of the idea of the present application.

Step 508: and the home control plane functional entity receives the session switching request and establishes the PDU session according to the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network.

The method for establishing the PDU session by the home control plane functional entity according to the corresponding network slice information when the PDN connection that can be switched in the PDN connection is switched to the 5G network may include: and the home control plane functional entity establishes the PDU session in the corresponding network slice when the PDN connection which can be switched in the PDN connection is switched to the 5G network in cooperation with the terminal equipment or other network elements according to the network slice indicated by the corresponding network slice information when the PDN connection which can be switched in the PDN connection is switched to the 5G network. Specifically, the process of establishing the PDU session may refer to the existing flow, which is not described herein.

So far, the switching of the PDN connection into a PDU session is achieved. It should be noted that, steps 501 to 508 only exemplarily illustrate the process of switching one PDN connection to a PDU session, and the process of switching other PDN connections to PDU sessions may refer to this process, which is not described herein again.

Based on the session switching method provided in fig. 5, when the terminal device needs to switch the PDN connection to the PDU session, the terminal device determines network slice information corresponding to the PDN connection, and the determined corresponding network slice information when the PDN connection is switched to the 5G network is sent to the AMF entity through the MME, so that the AMF entity determines the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network according to the corresponding network slice information when the PDN connection is switched to the 5G network and the network slice information signed by the terminal equipment, and the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network is sent to the home control plane functional entity which, according to the network slice information, and establishing a PDU session in a network slice corresponding to the PDN connection, and realizing switching of the PDN connection to the PDU session. That is to say, the scheme solves the problem that the network slice supporting the PDN connection slice cannot be determined in the prior art, and realizes the switching between the PDN connection and the PDU session.

It should be noted that, when the AMF entity in step 506 is not the target AMF entity, it means that the AMF entity cannot support the target AMF entity of the corresponding network slice when the PDN connection capable of being switched is switched to the 5G network, at this time, the AMF entity may send a redirection indication carrying address information of the control plane function entity to the target AMF entity, and instruct the target AMF entity to send the session handover request to the home control plane function entity according to the control plane function entity. Such as: after the AMF entity 1 entity performs step 506, it determines that the target AMF entity is the AMF entity 2, and then the AMF entity 1 sends a redirection indication carrying address information of the control plane function entity to the AMF entity 2, and the AMF entity 2 sends a session handover request to the home control plane function entity.

Further, after the PDN connection is switched to the PDU session, in order to facilitate the subsequent terminal device to select a suitable network slice supporting the PDU session when a new PDU session is created, the scheme shown in fig. 5 may further include: the terminal equipment initiates a registration request to the AMF entity, the AMF entity determines the allowed network slice information of the terminal equipment according to the signed network slice information and the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network, and the AMF entity returns a registration acceptance message to the terminal equipment. Specifically, the implementation process may refer to the scheme shown in fig. 5, and is not described herein again.

The following describes the scheme shown in fig. 5 by taking an example that the terminal device is in the home router scenario shown in fig. 3, the home control plane functional entity is an SMF entity + PGW-C entity (in this scheme, the SMF entity is used for replacement), and the visited control plane functional entity is a vSMF entity in fig. 3. Fig. 6 is a flowchart illustrating a further session switching method provided in an embodiment of the present application, and as shown in fig. 6, the method may include:

step 601 to step 606; the steps 601 to 606 are the same as the steps 501 to 506, and reference may be made to the embodiment shown in fig. 5, which is not described herein again.

Step 607: and when the AMF entity is the target AMF entity and the AMF entity determines that the terminal equipment is in home router roaming, the AMF entity determines the vSMF entity according to the corresponding network slice information when the PDN connection which can be switched in the PDN connection is switched to the 5G network and the corresponding DNN when the PDN connection is switched to the 5G network.

The manner of determining the visited control plane functional entity by the AMF entity may refer to the manner described in step 507, and is not described herein again.

Step 608: the AMF entity sends a session establishment request to the vSMF entity.

The session establishment request may carry network slice information corresponding to the PDN connection that can be switched in the PDN connection and address information of the control plane functional entity when the PDN connection is switched to the 5G network.

Step 609: the vSMF entity receives a session establishment request from the AMF entity and sends a session switching request to the SMF entity according to the session establishment request.

Wherein, the session switching request can carry the corresponding network slice information when the PDN connection is switched to the 5G network

Step 610: and the SMF entity receives the session switching request and establishes the PDU session according to the corresponding network slice information when the PDN connection which can be switched in the PDN connection is switched to the 5G network.

Step 610 is the same as step 508, and reference may be made to the embodiment shown in fig. 5, which is not described herein again.

So far, the switching of the PDN connection into a PDU session is achieved.

Further optionally, after the PDN connection is switched to the PDU session, in order to facilitate a subsequent terminal device to select a suitable network slice supporting the PDU session when a new PDU session is established, the method further includes:

step 611: the terminal equipment initiates a registration request to the AMF entity.

The registration request is used for requesting to register the terminal device to the 5G network, and the registration request may carry network slice information requested by the terminal device.

The AMF entity may be the AMF entity in step 505 above.

Step 612: and the AMF entity determines the allowed network slice information of the terminal equipment according to the signed network slice information, the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network and the network slice information requested by the terminal equipment.

Specifically, the implementation manner of step 612 may refer to the network slice information corresponding to the PDN connection that can be switched in the PDN connection and the network slice information corresponding to the 5G network when the PDN connection is switched to the 5G network in step 506, and is not described herein again.

Step 613: and the AMF entity returns a registration acceptance message to the terminal equipment.

Wherein, the registration acceptance message may carry the allowed network slice information.

Based on the session switching method provided in fig. 6, when the terminal device needs to switch the PDN connection to the PDU session, the terminal device determines network slice information corresponding to the PDN connection, and sends the determined network slice information when the PDN connection is switched to the 5G network to the AMF entity through the MME, so that the AMF entity determines, according to the network slice information corresponding to the PDN connection switched to the 5G network and the network slice information signed by the terminal device, network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network, and sends the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network to the SMF entity, and the SMF entity establishes, according to the network slice information, a PDU session in the network slice corresponding to the PDN connection, and realizes switching of the PDN connection to the PDU session. That is to say, the scheme solves the problem that the network slice supporting the PDN connection slice cannot be determined in the prior art, and realizes the switching between the PDN connection and the PDU session, and meanwhile, the terminal device initiates a registration request to the AMF entity, and the AMF entity determines the allowed network slice information after receiving the request, so that the subsequent PDN connection is switched to the PDU session according to the allowed network slice information.

In another implementation, after the terminal device registers in the 4G network and establishes the PDN connection, the terminal device is in an idle state for some reason and moves to a coverage of a 5G base station, at this time, the terminal device may initiate a registration request to the 5G base station, and register in a 5G core network through the 5G base station, so as to initiate a handover procedure of connecting the PDN to the PDU session, specifically, the procedure may refer to fig. 7. Fig. 7 is a schematic flowchart illustrating a session handover method according to an embodiment of the present application, and as shown in fig. 7, the session handover method may include:

step 701: the terminal device registers to the 4G network and establishes a PDN connection.

The specific implementation of step 701 may refer to the manner described in step 501, and is not described herein again.

Step 702: and the terminal equipment determines corresponding network slice information when the PDN connection is switched to the 5G network.

The specific implementation of step 702 refers to the manner described in step 502, and is not described herein again.

Step 703: and the terminal equipment sends a registration request to the target access network equipment.

The target access network device is an access network device in a 5G network, such as: may be the NG-RAN device of fig. 1 or fig. 2 or fig. 3.

The registration request may be used to request registration to the 5G network, where the registration request may carry information of a globally unique temporary identifier (5G global unique temporary Identity, 5G-GUTI) of the terminal device in the 5G network, network slice information corresponding to the PDN connection determined by the terminal device when the PDN connection is switched to the 5G network, and network slice information (NSSAI) requested by the terminal device. The 5G-GUTI information comprises 5G-GUTI, the 5G-GUTI information is used for indicating that the 5G-GUTI is mapped from a 4G-GUTI in an Evolved Packet Core (EPC) network, and the 4G-GUTI comprises information of an MME (such as MME group identity (MMEGI) and MME CODE number (MME CODE)) used for identifying the MME providing access service for the terminal equipment. Specifically, the method for mapping 4G-GUTI to 5G-GUTI may refer to the prior art, and is not described herein again.

It should be noted that, when the PDN connection determined by the terminal device is switched to 5G, both the S-NSSAI of the corresponding network slice and the S-NSSAI of the other network slices requested by the terminal device are placed in the requested NSSAI (requested NSSAI) and sent to the AMF entity, and optionally, the terminal device notifies the AMF entity of which S-NSSAIs in the "requested NSSAI" correspond to the established PDN connection; or the terminal equipment puts the S-NSSAI of the other requested network slice in the requested NSSAI, and puts the S-NSSAI of the corresponding network slice in another independent NSSAI when the determined PDN connection is switched to the 5G network and sends the S-NSSAI to the AMF entity. The embodiment of the present application does not limit a method for how the terminal device sends the S-NSSAI of the corresponding network slice to the AMF entity through the registration request when switching the determined PDN connection to the 5G network.

Such as: if the corresponding network slice information when the PDN connection determined by the terminal device is switched to the 5G network is S-NSSAI1, and the other network slice information requested by the terminal device is S-NSSAI2, the registration request sent by the terminal device may include the network slice information requested by the terminal device (S-NSSAI1 and S-NSSAI 2).

Step 704: the target access network device sends a registration request to the AMF entity.

Wherein, the AMF entity in step 704 may be a default AMF entity.

Step 705: and the AMF entity receives the registration request from the target access network equipment, acquires the corresponding network slice information when the PDN connection is switched to the 5G network and the network slice information requested by the terminal equipment, and acquires the subscription data of the terminal equipment from the user data management entity.

The subscription data of the terminal device includes network slice information signed by the terminal device, and the manner in which the AMF entity obtains the subscription data of the terminal device from the user data management entity in step 705 may refer to the manner shown in step 505, which is not described herein again.

Step 706: and the AMF entity determines the allowed network slice information of the terminal equipment according to the corresponding network slice information when the PDN connection is switched to the 5G network, the network slice information requested by the terminal equipment and the signed network slice information.

The specific implementation manner of step 706 may refer to the manner shown in step 506.

Such as: in a possible implementation manner, an AMF entity determines candidate network slice information corresponding to PDN connections according to at least one of a priority of an S-NSSAI corresponding to each PDN connection in network slice information corresponding to when a plurality of PDN connections are switched to a 5G network, network slice information requested by a terminal device and a priority of signed network slice information, load information of the S-NSSAI corresponding to each PDN connection, and NSSAI supported by each AMF entity in an AMF entity set configured in the AMF entity, and takes NSSAI in an intersection of the candidate network slice information and the signed network slice information as allowable network slice information of the terminal device; alternatively, the first and second electrodes may be,

in another possible implementation manner, the AMF entity sends a slice selection request carrying network slice information corresponding to when the PDN connection is switched to the 5G network, network slice information requested by the terminal device, the subscribed network slice information, and the subscribed network slice information to the NSSF entity, the NSSF determines the allowed network slice information of the terminal device according to the network slice information corresponding to when the PDN connection is switched to the 5G network, the network slice information requested by the terminal device, the subscribed network slice information, and the subscribed network slice information of the terminal device, the NSSF returns the determination result to the AMF entity, and the AMF entity obtains the allowed network slice information of the terminal device according to the determination result.

Step 707: and the AMF entity sends an acquisition request to the MME according to the 5G-GUTI information in the registration request.

The obtaining request is used for requesting to obtain the context of the terminal equipment, and the context of the terminal equipment comprises address information of a control plane function entity corresponding to the PDN connection.

Optionally, the AMF entity determines the 4G-GUTI corresponding to the 5G-GUTI according to the 5G-GUTI information in the registration request and the mapping relationship between the 4G-GUTI and the 5G-GUTI, and sends the acquisition request to the MME according to the information of the MME included in the 4G-GUTI.

Step 708: and the MME receives the acquisition request sent by the AMF entity and sends the context of the terminal equipment to the AMF entity.

The context of the terminal device includes address information of a control plane functional entity corresponding to the PDN connection.

Step 709: and the AMF entity sends a session switching request to the home control plane functional entity according to the address information of the control plane functional entity.

The home control plane functional entity may be the SMF entity + PGW-C entity in fig. 1, fig. 2, or fig. 3, the session handover request may be used to request the control plane functional entity to switch the PDN connection to the PDU session, and the session handover request may carry the allowed network slice information acquired by the AMF entity in step 709.

Specifically, the implementation of step 709 can refer to step 508, and is not described herein.

Step 710: and the home control plane functional entity receives the session switching request and establishes the PDU session according to the allowed network slice information.

Wherein, the home control plane function entity establishing the PDU session according to the allowed network slice information may refer to: and the home control plane functional entity establishes the PDU session in the network slice corresponding to the PDN connection in cooperation with the terminal equipment or other network elements according to the network slice indicated by the allowed network slice information. The process of establishing the PDU session may refer to the existing flow, which is not described herein.

Step 711: and the AMF entity returns a registration acceptance message to the terminal equipment.

In the embodiment shown in fig. 7, step 706 may be executed before step 707 to step 708, or may be executed after step 707 to step 708 and before step 709, which is not limited.

Based on the session switching method shown in fig. 7, when the terminal device registers in the 5G network, the terminal device sends the requested network slice information and the network slice information corresponding to the PDN connection that has been established by the terminal device to the AMF entity, the AMF entity determines the allowed network slice information of the terminal device according to the network slice information corresponding to the PDN connection, the requested network slice information and the network slice information signed by the terminal device, and sends the determined network slice information to the SMF entity, and the SMF entity establishes a PDU session in the network slice corresponding to the PDN connection according to the network slice information, thereby implementing switching of the PDN connection to the PDU session. That is to say, the scheme solves the problem that the network slice supporting the PDN connection slice cannot be determined when the terminal equipment is registered in the 5G network, and realizes the switching between the PDN connection and the PDU session.

In another implementation scheme, when the terminal device registers in the 4G network and establishes the PDN connection, the terminal device is in an idle state for some reason and moves to a coverage area of the 5G base station, and at this time, the terminal device may initiate a registration request to the 5G base station to implement switching of the PDN connection to the PDU session, and the terminal device may further send, through the MME, network slice information corresponding to the PDN connection determined by the terminal device when the PDN connection is switched to the 5G network to the AMF entity. In particular, this implementation is shown in fig. 8.

Fig. 8 is a flowchart illustrating a further session switching method provided in an embodiment of the present application, and as shown in fig. 8, the method may include:

step 801 to step 802, and step 801 to step 802 are the same as step 701 to step 702, and are not described herein again.

Step 803: the terminal equipment sends network slice information corresponding to the PDN connection switched to the 5G network to the MME, and the MME receives the network slice information corresponding to the PDN connection switched to the 5G network sent by the terminal equipment.

The specific implementation of step 803 may refer to the manner described in step 503, which is not described herein again.

Step 804: and the terminal equipment sends a registration request to the target access network equipment.

The registration request may be used to request registration to the 5G network, and the registration request may carry the 5G-GUTI information of the terminal device and the network slice information requested by the terminal device.

Step 805: the target access network device sends a registration request to the AMF entity.

Wherein, the AMF entity in step 805 may be a default AMF entity.

Step 806: and the AMF entity sends an acquisition request to the MME according to the 5G-GUTI information in the registration request.

Step 806 is the same as step 707, and is not described herein again.

Step 807: and the MME receives the acquisition request sent by the AMF entity and sends the context of the terminal equipment to the AMF entity.

The context of the terminal equipment comprises network slice information corresponding to the switching of the PDN connection to the 5G network and address information of a control plane functional entity corresponding to the PDN connection.

Step 808: and the AMF entity acquires corresponding network slice information when the PDN connection is switched to the 5G network from the context of the MME receiving terminal equipment, acquires the network slice information requested by the terminal equipment from the registration request, and acquires the subscription data of the terminal equipment from the user data management entity.

The specific implementation of step 808 can refer to the manner shown in step 505, and is not described herein again.

Step 809: and the AMF entity determines the allowed network slice information of the terminal equipment according to the corresponding network slice information when the PDN connection is switched to the 5G network, the network slice information requested by the terminal equipment and the signed network slice information.

The specific implementation manner of step 809 may refer to the manner shown in step 706, and is not described herein again.

Step 810: and the AMF entity sends a session switching request to the control plane function entity according to the address information of the control plane function entity.

The session handover request may be used to request that the PDN connection is switched to the PDU session, and the session handover request may carry the allowed network slice information acquired by the AMF entity in step 809.

Specifically, the implementation of step 810 can refer to that shown in step 508, and is not described herein again.

Step 811: and the control plane functional entity receives the session switching request and establishes the PDU session according to the allowed network slice information.

The control plane functional entity establishing the PDU session according to the allowed network slice information may refer to: and the control plane functional entity establishes the PDU session in the network slice corresponding to the PDN connection in cooperation with the terminal equipment or other network elements according to the network slice indicated by the allowed network slice information. The process of establishing the PDU session may refer to the existing flow, which is not described herein.

Step 812: and the AMF entity returns a registration acceptance message to the terminal equipment.

Based on the session switching method shown in fig. 8, when the terminal device registers in the 5G network, the terminal device sends the requested network slice information and the network slice information corresponding to the PDN connection that has been established by the terminal device to the AMF entity, the AMF entity determines the allowed network slice information according to the network slice information corresponding to the PDN connection, the requested network slice information and the network slice information signed by the terminal device, and sends the determined network slice information to the control plane function entity, and the control plane function entity establishes a PDU session in the network slice corresponding to the PDN connection according to the network slice information, thereby implementing switching of the PDN connection to the PDU session. That is to say, the scheme solves the problem that the network slice supporting the PDN connection slice cannot be determined when the terminal equipment is registered in the 5G network, and realizes the switching between the PDN connection and the PDU session.

The above-mentioned scheme provided by the embodiment of the present application is introduced mainly from the perspective of interaction between network elements. It is to be understood that the terminal device, the first mobility management entity and the second mobility management entity include hardware structures and/or software modules for performing the respective functions in order to implement the functions. Those of skill in the art would readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiment of the present application, the terminal device, the first mobility management entity, and the second mobility management entity may be divided into the functional modules according to the above method example, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation.

In the case of dividing each functional module by corresponding functions, fig. 9 shows a possible composition diagram of the terminal device involved in the foregoing embodiment, as shown in fig. 9, the terminal device may include: a determination unit 91, a transmission unit 92, and a reception unit 93.

A determining unit 91, configured to determine network slice information corresponding to when the PDN connection of the packet data network is switched to a fifth generation 5G network; a sending unit 92, configured to send, to the mobility management entity, network slice information corresponding to the PDN connection being switched to the 5G network.

In a possible design, the determining unit 91 is specifically configured to determine, according to a correspondence between information of the PDN connection and network slice information, corresponding network slice information when the PDN connection is switched to the 5G network; the information of the PDN connection comprises an Access Point Name (APN) corresponding to the PDN connection or an application corresponding to the PDN connection.

In yet another possible design, the determining unit 91 is further configured to determine, according to policy information of an application corresponding to the PDN connection, a PDN connection switched to the 5G network among PDN connections already established by the terminal device, before the determining unit 91 determines network slice information corresponding to when the PDN connection of the packet data network is switched to the fifth-generation 5G network; alternatively, when the terminal device itself supports the 5G network communication capability, the determination unit 91 determines that all the established PDN connections are switched to the 5G network.

In yet another possible design, the sending unit 92 is further configured to send, to the mobility management entity, information of priority of corresponding network slice information when the PDN connection is switched to the 5G network.

In yet another possible design, when the terminal device is roaming; the determining unit 91 is specifically configured to determine, according to the applied policy information corresponding to the PDN connection, network slice information of the home location when the PDN connection is switched to the 5G network, and determine, according to the network slice information of the home location when the PDN connection is switched to the 5G network and a mapping relationship between the home location network slice information and the visited location network slice information, network slice information of the visited location when the PDN connection is switched to the 5G network.

In another possible design, when the mobility management entity is an MME, the sending unit 92 is specifically configured to carry, in the first message, the corresponding network slice information when the PDN connection is switched to the 5G network, and send the information to the MME; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network.

In another possible design, when the mobility management entity is an AMF entity, the sending unit 92 is specifically configured to carry, in the registration request, the corresponding network slice information when the PDN connection is switched to the 5G network, and send the information to the AMF entity.

It should be noted that all relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again. The terminal device provided by the embodiment of the application is used for executing the session switching method, so that the same effect as the session switching method can be achieved.

In case of an integrated unit, the terminal device may comprise a processing module and a communication module, the processing module being configured to control and manage the actions of the terminal device. The communication module is used for supporting communication between the terminal device and other network entities, for example, the functional module or the network entity shown in fig. 1. The terminal device may further comprise a storage module for storing program codes and data of the server.

The processing module may be a processor or a controller. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The communication module may be a transceiver, a transceiving circuit or a communication interface, etc. The storage module may be a memory.

When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the server according to the embodiment of the present application may be the communication device shown in fig. 4.

In the case of dividing each functional module by corresponding functions, fig. 10 shows a possible composition diagram of the MME involved in the above embodiment, as shown in fig. 10, the MME may include: receiving section 101 and transmitting section 102.

A receiving unit 101, configured to receive, from a terminal device, network slice information corresponding to a PDN connection determined by the terminal device when the PDN connection is switched to a fifth generation 5G network; the sending unit 102 is further configured to send a context of the terminal device to the access and mobility management function AMF entity, where the context of the terminal device includes network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network and information of the PDN connection, and the information of the PDN connection includes address information of a control plane function entity corresponding to the PDN connection.

In another possible design, the receiving unit 101 is specifically configured to receive a first message sent by the terminal device and carrying network slice information corresponding to when the PDN connection is switched to the 5G network; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network.

It should be noted that all relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again. The MME provided in the embodiment of the present application is configured to execute the session handover method, so that the same effect as the session handover method can be achieved.

In the case of an integrated unit, the MME may include a processing module for controlling and managing the actions of the MME and a communication module. The communication module is used to support communication between the MME and other network entities, such as the functional modules or network entities shown in fig. 1. The MME may also include a storage module to store program codes and data for the server.

In the case of dividing each function module by corresponding functions, fig. 11 shows a possible composition diagram of the AMF involved in the above embodiment, as shown in fig. 11, the AMF may include: a receiving unit 111, an acquiring unit 112, a transmitting unit 113, and a determining unit 114.

A receiving unit 111, configured to receive network slice information corresponding to when a PDN connection of a packet data network determined by a terminal device is switched to a fifth generation 5G network, address information of a control plane functional entity corresponding to the PDN connection, and network slice information signed by the terminal device;

an obtaining unit 112, configured to obtain, according to network slice information corresponding to when the PDN connection is switched to the 5G network and network slice information signed by the terminal device, network slice information corresponding to when the PDN connection allowed to be switched in the PDN connection is switched to the 5G network;

a sending unit 113, configured to send a session switching request to the home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection, where the session switching request is used to request to switch the PDN connection to a protocol data unit PDU session.

In yet another possible design, the receiving unit 111 is specifically configured to obtain, from the mobility management entity MME, network slice information corresponding to when the PDN connection is switched to the fifth-generation 5G network; or acquiring network slice information corresponding to the switching of the PDN connection to the fifth generation 5G network from the terminal equipment.

In another possible design, when the AMF entity obtains, from the terminal device, network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network, the receiving unit 111 is specifically configured to receive, from the terminal device, a registration request carrying the network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network, and obtain, from the registration request, network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network.

In yet another possible design, the determining unit 114 is configured to, when the terminal is roaming in the home route home router, determine the visited control plane function entity according to a network slice indicated by the corresponding network slice information when a PDN connection that can be switched among the PDN connections is switched to the 5G network, and a corresponding data network name DNN when the PDN connection is switched to the 5G network;

the sending unit 113 is specifically configured to send, to the visited control plane functional entity, a session establishment request carrying network slice information corresponding to when the PDN connection that can be switched in the PDN connection is switched to the 5G network and address information of a control plane functional entity corresponding to the PDN connection, where the session establishment request is used to instruct the visited control plane functional entity to send a session switching request to the home control plane functional entity.

It should be noted that all relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again. The AMF entity provided in the embodiment of the present application is configured to execute the session handover method, so that the same effect as the session handover method can be achieved.

In case of an integrated unit, the AMF entity may include a processing module for controlling and managing the actions of the AMF entity and a communication module. The communication module is used for supporting communication between the AMF entity and other network entities, for example, communication between the functional module or the network entity shown in fig. 1. The AMF entity may further include a storage module for storing program codes and data of the server.

An embodiment of the present application further provides a session switching method, as shown in fig. 12, the method may include:

step 1201: the terminal device registers with the 4G network and requests establishment of a PDN connection.

Optionally, the terminal device is registered in the 4G network through the MME, and after the terminal device is registered in the 4G network, the terminal device determines that a PDN is to be accessed by an application, at this time, the terminal device sends a PDN connection establishment request carrying an APN corresponding to the PDN to the MME, where the PDN connection establishment request is used to request establishment of a PDN connection, and after receiving the PDN connection establishment request, the MME sends a PDN connection establishment request to the control plane functional entity, and the control plane functional entity establishes a PDN connection according to the APN corresponding to the PDN. One PDN connection may correspond to one or more applications, one PDN connection corresponds to one APN, and multiple PDN connections may be established under one APN, without limitation.

After the terminal device establishes the PDN connection, the control plane functional entity may send information of the PDN connection to the MME, so that the MME stores it in the context of the terminal device. At least one of the address information of the control plane functional entity corresponding to the PDN connection and the APN corresponding to the PDN connection may be referred to as information of the PDN connection. The information of the PDN connection is used to indicate a certain PDN connection corresponding to the control plane function entity or the APN. Optionally, the information of the PDN connection further includes a PDN type corresponding to the PDN connection, a PDN address corresponding to the PDN connection, an S-NSSAI set supported by a control plane functional entity corresponding to the PDN connection, and other information.

In each embodiment of the present application, the control plane functional entity may refer to the SMF entity + PGW-C entity in fig. 1, fig. 2, or fig. 3, and a process of establishing a PDN connection according to an APN corresponding to a PDN by the control plane functional entity may refer to the prior art and is not described again. The address information of the control plane functional entity may be used to identify the control plane functional entity, and the address information of the control plane functional entity may be information of a PLMN where the control plane functional entity is located, or an IP address of the control plane functional entity, or an FQDN.

Step 1202: and the control plane functional entity determines corresponding network slice information when the PDN connection is switched to the 5G network.

Wherein, the network slice information may refer to the S-NSSAI of the network slice.

In the process of establishing the PDN connection, the control plane functional entity may determine whether the PDN connection needs to be subsequently handed over to the 5G network by: in a possible manner, the terminal device determines that the PDN connection is to be subsequently switched to the 5G network in the manner described in step 502, where the sent PDN connection establishment request carries indication information for indicating whether the PDN connection is to be switched to the 5G network, and when the control plane functional entity receives the PDN connection establishment request, the control plane functional entity determines whether the PDN connection needs to be switched to the 5G network according to the indication information carried in the PDN connection establishment request. In yet another possible manner, the control plane functional entity determines whether the PDN connection needs to be switched to 5G according to a self-configured switching policy, where the switching policy is used to indicate that the PDN connection needs to be switched to a 5G network. For example, the handover policy may be used to indicate that a PDN connection carrying a specified APN needs to be handed over to the 5G network. In another possible manner, the control plane functional entity determines whether the PDN connection needs to be switched to 5G according to APN subscription information, where the APN subscription information may be obtained from the UDM, and the APN subscription information is used to indicate an APN that needs to be switched to a 5G network, and when the APN corresponding to the PDN connection is included in the APN subscription information, it indicates that the PDN connection needs to be switched to the 5G network, and otherwise, the PDN connection is not switched. For example, the APN subscription information includes APNs 1-2, and if the APN corresponding to the PDN connection 1 established by the user is APN1, it is determined that the PDN connection 1 needs to be switched to a 5G network according to the APN subscription information; and if the APN corresponding to the PDN connection 2 established by the user is the APN4, determining that the PDN connection 2 does not need to be switched to the 5G network according to the APN subscription information.

The control plane functional entity determines that the PDN connection is switched to the 5G network subsequently, the control plane functional entity can determine corresponding network slice information when the PDN connection is switched to the 5G network according to a corresponding relationship between the information of the PDN connection and the network slice information, the corresponding relationship can be configured in the control plane functional entity in advance or stored in NSSP of other network elements (such as terminal equipment) in advance, and the control plane functional entity can acquire the corresponding relationship from the other network elements. Such as: the information of the PDN connection comprises an APN corresponding to the PDN connection, and the control plane functional entity can determine corresponding network slice information when the PDN connection is switched to the 5G network according to the corresponding relation between the APN and the network slice information. For example, the correspondence between the APN and the network slice information is shown in table five, and when the APN corresponding to the PDN connection switched to the 5G network is APN3, the control plane function entity may determine, through table five, that the S-NSSAI of the network slice corresponding to the PDN connection switched to the 5G network is S-NSSAI3 and S-NSSAI 4.

Watch five

APN	Network slicing information
		APN1	S-NSSAI1
APN2	S-NSSAI2
		APN3	S-NSSAI3
……	……

In another example, the information of the PDN connection includes address information of a control plane functional entity, and the control plane functional entity may determine, according to a correspondence between the address entity of the control plane functional entity and the network slice information, corresponding network slice information when the PDN connection is switched to the 5G network. For example, the correspondence between the information of the SMF entity + PGW-C entity and the network slice information is shown in table six, and when the information of the SMF entity + PGW-C entity corresponding to the PDN connection is IP address 1, it can be determined by looking up table six that the S-NSSAI of the corresponding network slice is S-NSSAI1 or S-NSSAI2 when the PDN connection is switched to the 5G network.

Watch six

SMF entity + PGW-C entity information	Network slicing information
		IP address 1	S-NSSAI1、S-NSSAI2
IP address 2	S-NSSAI2
		IP address 3	S-NSSAI3、S-NSSAI4
……	……

It should be noted that, this embodiment of the present application only exemplarily provides specific implementations of several control plane function entities for determining network slice information corresponding to when a PDN connection is switched to a 5G network, and of course, the control plane function entity may also obtain the network slice information corresponding to when the PDN connection is switched to the 5G network in other manners, such as: if the control plane functional entity only supports one S-NSSAI, the control plane functional entity determines that the S-NSSAI corresponding to the PDN connection is the S-NSSAI supported by the control plane functional entity. Or the control plane functional entity configures a corresponding relationship between the PDN type and the S-NSSAI, and further, the control plane functional entity determines the S-NSSAI of the network slice corresponding to the PDN connection according to the PDN type corresponding to the PDN connection and the corresponding relationship. The embodiment of the present application does not limit a specific implementation manner of determining, by a control plane function entity, the S-NSSAI of the network slice corresponding to the PDN connection. When the information of the PDN connection is other information, only the information of the PDN connection in table five or table six needs to be replaced with other information, and the control plane functional entity determines, according to the correspondence between the other information and the S-NSSAI, network slice information corresponding to when the PDN connection is switched to the 5G network, which is not described in detail herein.

In addition, when the terminal device is in home router roaming, the network slice information determined by the control plane functional entity in step 1202 is the network slice information of the visited place when the PDN connection is switched to the 5G network, and at this time, the control plane functional entity may determine the network slice information of the home place when the PDN connection is switched to the 5G network according to the corresponding relationship between the information of the PDN connection and the network slice information, and then determine the network slice information of the visited place when the PDN connection is switched to the 5G network according to the determined network slice information of the home place when the PDN connection is switched to the 5G network and the mapping relationship between the network slice information of the home place and the network slice information of the visited place; or, when the terminal device is in home router roaming, the network slice information determined by the control plane function entity in step 1202 is the network slice information corresponding to the location where the PDN connection is switched to the 5G network when the PDN connection is switched to the 5G network, and in the subsequent step, when the AMF entity receives the network slice information of the location where the PDN connection is switched to the 5G network, the AMF entity determines the network slice information of the visited location when the PDN connection is switched to the 5G network according to the mapping relationship between the network slice information of the home location and the network slice information of the visited location, which is not limited.

Step 1203: and the control plane functional entity sends corresponding network slice information when the PDN connection is switched to the 5G network to the MME, and the MME receives the corresponding network slice information when the PDN connection is switched to the 5G network.

Wherein, the MME may be the MME in fig. 1, fig. 2, or fig. 3.

Optionally, the control plane functional entity carries the corresponding network slice information when the PDN connection is switched to the 5G network in the first message, and sends the first message to the MME. The first message may be a session establishment response message for notifying the terminal device that the PDN connection is established, where the session establishment response message may carry an identifier of the terminal device.

The first message may be used to instruct the MME to only store the network slice information corresponding to the PDN connection handover to the 5G network, without parsing the network slice information corresponding to the PDN connection handover to the 5G network included in the first message. In one possible design, the first message carries indication information, which may be used to instruct the MME to only store the corresponding network slice information when the PDN connection is switched to the 5G network, without parsing the corresponding network slice information when the PDN connection is switched to the 5G network, such as: the first message may be an information element, which may be a transparent container (transparent container), and may include a header and a payload, where the header carries indication information and the payload carries corresponding network slice information when the PDN connection is switched to the 5G network. In yet another possible design, the first message is a message of a special message type, where the message type is used to instruct the MME to only store the corresponding network slice information when the PDN connection is switched to the 5G network, without parsing the corresponding network slice information when the PDN connection is switched to the 5G network, and after receiving the message of the message type, the MME stores the content carried in the first message in the context of the terminal device.

Under the condition that the control plane functional entity and the SGW are combined, the control plane functional entity can directly send a first message to the MME; and under the condition that the control plane functional entity is separated from the SGW, the control plane functional entity sends a first message to the SGW, and the SGW forwards the first message to the MME after receiving the first message.

Optionally, when the control plane functional entity sends, to the MME, network slice information corresponding to when the PDN connection is switched to the 5G network, address information of the control plane functional entity may also be sent to the MME, where the address information of the control plane functional entity may be carried in the first message or may not be carried in the first message. Further, after receiving the network slice information request and the address information of the control plane functional entity corresponding to the PDN connection being switched to the 5G network, the MME may store the network slice information request and the address information of the control plane functional entity corresponding to the PDN connection being switched to the 5G network in the context of the terminal device.

In addition, the control plane functional entity may send, to the MME, network slice information corresponding to when the PDN connection is switched to the 5G network, and may also send, to the MME, priority information of the network slice information corresponding to when the PDN connection is switched to the 5G network. The priority information of the corresponding network slice information when the PDN connection is switched to the 5G network is used to indicate the priority of the a-NSSAI of the network slice or the priority of the PDN connection, which is not limited. The control plane functional entity may determine priority information of the corresponding network slice information when the PDN connection is switched to the 5G network, according to at least one of importance of the PDN connection and a load condition of the network slice indicated by the corresponding network slice information when the PDN connection is switched to the 5G network.

It should be noted that step 1202 and step 1203 are completed in a PDN connection establishment procedure, where the PDN connection establishment procedure may be a PDN connection establishment procedure initiated after the terminal device registers in the network, or a PDN connection establishment procedure initiated by the terminal device in an attach procedure or a tracking area update procedure.

Step 1204: and the MME receives the HO request sent by the source access network equipment and sends the context of the terminal equipment to the AMF entity.

Wherein, the source access network device may be an E-UTRAN device in fig. 1 or fig. 2 or fig. 3. The context of the terminal device includes information of the PDN connection and corresponding network slice information when the PDN connection is switched to the 5G network. Optionally, after determining that the terminal device moves from the 4G network to the 5G network according to the cell measurement information reported by the terminal device, the source access network device sends an HO request to the MME through an S1-MME interface, where the HO request may carry an identifier of the terminal device, and after receiving the HO request, the MME sends the context of the terminal device to the AMF entity according to the identifier of the terminal device.

The AMF entity may be a default AMF entity corresponding to the MME, or the HO request carries information of the current area of the terminal device, the MME determines an AMF entity set according to the current area of the terminal device and a correspondence between the target area and the AMF entity set, and then selects one AMF entity from the selected AMF entity set as the AMF entity in step 1204 according to a corresponding policy; or, the MME determines the AMF entity set according to the correspondence between the MME and the AMF entity set, and selects one AMF entity from the selected AMF entity set as the AMF entity in step 1204 according to the corresponding policy; or the MME selects an AMF from multiple AMFs configured by itself or pre-configured by an operator, without limitation. The policy may specifically be a method for determining one AMF entity from the AMF entity set based on information such as priority, capacity, or load of each AMF entity in the AMF entity set.

Step 1205: and the AMF entity receives the context of the terminal equipment from the MME and acquires the corresponding network slice information when the PDN connection is switched to the 5G network.

Optionally, in step 1205, the AMF also obtains other information, such as: and network slice information signed by the terminal equipment. The network slice information signed by the terminal device is included in the subscription data of the terminal device, and the AMF may obtain the network slice information signed by the terminal device from a user data management entity (e.g., UDM), such as: and the AMF sends a request message carrying the identifier of the terminal equipment to the UDM to request the subscription data of the terminal equipment, and the UDM sends the subscription data of the terminal equipment to the AMF through the Nudm interface after receiving the request message.

It should be noted that, when the terminal device is in a roaming scenario and the network slice information determined by the control plane function entity in step 1202 when the PDN connection is switched to the 5G network is the network slice information of the home location when the PDN connection is switched to the 5G network, in step 1205, after the AMF entity obtains the network slice information corresponding to the PDN connection when the PDN connection is switched to the 5G network, it is further required to determine the network slice information of the visited location when the PDN connection is switched to the 5G network according to a mapping relationship between the network slice information of the home location and the network slice information of the visited location, and use the network slice information of the visited location when the PDN connection is switched to the 5G network as the network slice information corresponding to the PDN connection in step 1206 when the PDN connection is switched to the 5G network.

Step 1206: and the AMF entity acquires network slice information corresponding to the PDN connection which can be switched in the PDN connection when the PDN connection is switched to the 5G network according to the network slice information corresponding to the PDN connection which can be switched when the PDN connection is switched to the 5G network, and determines a target AMF entity supporting the network slice corresponding to the PDN connection which can be switched when the PDN connection is switched to the 5G network.

In a possible implementation manner, in step 1205, the AMF further obtains network slice information signed by the terminal device, the AMF entity takes, as candidate network slice information, the S-NSSAI corresponding to each PDN connection in the network slice information corresponding to when the multiple PDN connections are switched to the 5G network, and takes network slice information in an intersection of the candidate network slice information and the signed network slice information as network slice information corresponding to when the PDN connections that can be switched in the PDN connections are switched to the 5G network; after determining the network slice information corresponding to the switching of the switched PDN connection in the PDN connection to the 5G network, the AMF entity determines whether the AMF entity supports the corresponding network slice when the switched PDN connection in the PDN connection is switched to the 5G network according to the configuration capability of the AMF entity, if so, the AMF entity is determined to be a target AMF entity, if not, the AMF entity determines a target AMF entity set according to the capability of the network slice supported by other AMF sets configured by the AMF entity, and one AMF entity is selected from the target AMF entity set to serve as the target AMF entity.

In another possible implementation manner, in step 1205, the AMF further obtains network slice information signed by the terminal device, the AMF entity sends a slice selection request carrying the network slice information corresponding to the PDN connection switched to the 5G network and the signed network slice information to the NSSF entity, the NSSF determines, according to the network slice information corresponding to the PDN connection switched to the 5G network and the network slice information signed by the terminal device, the network slice information corresponding to the PDN connection capable of being switched in the PDN connection switched to the 5G network, and determining a target AMF entity supporting a corresponding network slice when the switched PDN connection is switched to the 5G network, the NSSF returning a determination result to the AMF entity, the AMF entity obtaining corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network according to the determination result, and determining a target AMF entity supporting a corresponding network slice when the PDN connection capable of being switched is switched to the 5G network.

Step 1207: and when the target AMF entity is self, the AMF entity sends a session switching request to the control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection.

In a possible implementation manner, when the AMF entity determines that the terminal device is in non-roaming or LBO roaming shown in fig. 2, the AMF entity directly sends a session handover request to the ground control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection in the context of the terminal device in step 1205.

In another possible implementation manner, when the AMF entity determines that the terminal device is in the home router roaming shown in fig. 3, the AMF entity determines a visited control plane function entity (e.g., a vSMF entity in fig. 3), the AMF entity sends, to the vSMF entity, a session establishment request carrying network slice information and address information of the control plane function entity corresponding to a PDN connection that can be switched in the PDN connection and is switched to the 5G network, and the vSMF entity sends, to the control plane function entity, the session switching request according to the address information of the control plane function entity. That is, in the scenario shown in fig. 3, after receiving the context including the information of the PDN connection from the MME, the AMF entity sends, to the vSMF, address information of the control plane function entity and network slice information corresponding to the case where the PDN connection is switched to the 5G network, and the vSMF sends, according to the address information of the control plane function entity, a session switching request to the SMF entity + PGW-C entity, and requests to switch the PDN connection to the 5G network.

The vSMF may be a default vSMF, or the AMF entity may select, according to the S-NSSAI indicated by the corresponding network slice information when the PDN connection that can be switched in the PDN connection is switched to the 5G network, a control plane functional entity that can access the S-NSSAI from control plane functional entities included in the S-NSSAI as the vSMF. For example, when a switched PDN connection in the PDN connection is switched to a 5G network, the corresponding network slice information is S-NSSAI1, and the S-NSSAI1 corresponds to a network slice 1, and the network slice 1 includes a plurality of control plane function entities, and the terminal device may select one control plane function entity in the network slice 1 as a vSMF. It is to be understood that, when there are multiple control plane functional entities capable of accessing the S-NSSAI, the AMF entity may use the control plane functional entity with a low load as the vSMF according to the load condition of the control plane functional entity, or select the vSMF according to other conditions of the control plane functional entity, which is not limited.

In another possible implementation manner, when the AMF entity determines that the terminal device is in home router roaming as shown in fig. 3 and the AMF entity cannot select vSMF, the AMF entity sends a selection request to the NRF, where the selection request carries network slice information corresponding to when a PDN connection capable of being switched in the PDN connection is switched to the 5G network, the NRF switches to a network slice indicated by network slice information corresponding to when a PDN connection capable of being switched in the PDN connection is switched to the 5G network, selects a control plane functional entity from the control plane functional entities included in the network slice as vSMF, and feeds back address information of the vSMF to the AMF entity, and the AMF entity sends a session establishment request to the vSMF, where the session establishment request carries network slice information corresponding to when a PDN connection capable of being switched in the PDN connection is switched to the 5G network and address information of the control plane functional entity corresponding to the PDN connection, according to a feedback result of the NRF, and the vSMF sends a session switching request to the control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection.

It should be noted that, when the target AMF entity is another AMF entity, the AMF entity sends a redirection instruction to the target AMF entity; and the target AMF entity receives the redirection indication from the AMF entity, and sends a session switching request to the control plane functional entity according to the redirection indication. The redirection instruction may carry network slice information corresponding to the PDN connection that can be switched in the PDN connection determined by the AMF entity when the PDN connection is switched to the 5G network, and address information of a control plane function entity corresponding to the PDN connection in the context of the terminal device received by the AMF entity from the MME. Such as: after the AMF entity 1 performs step 1206, it determines that the target AMF entity is the AMF entity 2, and then the AMF entity 1 sends a redirection indication carrying address information of the control plane function entity to the AMF entity 2, and the AMF entity 2 sends a session handover request to the control plane function entity.

Step 1208: and the control plane functional entity receives the session switching request and updates the PDU session according to the corresponding network slice information when the switched PDN connection in the PDN connection is switched to the 5G network.

Wherein, the control plane function entity updating PDU session may refer to: the control plane functional entity updates the user plane path of the session to pass through the target access network device (i.e. the NG-RAN device in fig. 1 or fig. 2 or fig. 3). Specifically, the process of updating the PDU session may refer to the existing flow, which is not described herein.

At this point, the PDN connection is switched into a PDU session. It should be noted that, steps 1201 to 1208 only exemplarily illustrate a process of switching one PDN connection to a PDU session, and other processes of switching multiple PDN connections to PDU sessions may refer to this process, which is not described herein again.

Based on the session switching method provided in fig. 12, the control plane functional entity determines network slice information corresponding to the PDN connection, and sends the determined network slice information corresponding to the PDN connection switched to the 5G network to the AMF entity through the MME, so that the AMF entity determines, according to the network slice information corresponding to the PDN connection switched to the 5G network and the network slice information signed, network slice information corresponding to the PDN connection switched to the 5G network in the PDN connection, and sends the network slice information corresponding to the PDN connection switched to the 5G network in the PDN connection to the control plane functional entity, and the control plane functional entity establishes a PDU session in the network slice corresponding to the PDN connection according to the network slice information, thereby implementing the switching of the PDN connection to the PDU session. That is to say, the scheme solves the problem that the network slice supporting the PDN connection slice cannot be determined in the prior art, and realizes the switching between the PDN connection and the PDU session.

Fig. 13 shows a schematic diagram of a possible composition of the control plane functional entity involved in the above embodiment, and as shown in fig. 13, the control plane functional entity may include: determination unit 131, sending unit 132.

A determining unit 131, configured to determine network slice information corresponding to when the PDN connection of the packet data network is switched to a fifth generation 5G network; a sending unit 132, configured to send, to the MME, network slice information corresponding to when the PDN connection is switched to the 5G network.

In a possible design, the determining unit 131 is specifically configured to determine, according to a correspondence between information of the PDN connection and network slice information, corresponding network slice information when the PDN connection is switched to the 5G network; and the information of the PDN connection comprises an access point name APN corresponding to the PDN connection.

In yet another possible design, the sending unit 132 is further configured to send, to the MME, information of priority of corresponding network slice information when the PDN connection is switched to the 5G network.

In another possible design, the sending unit 92 is specifically configured to carry, in the first message, the corresponding network slice information when the PDN connection is switched to the 5G network, and send the information to the MME; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network.

It should be noted that all relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again. The control plane functional entity provided by the embodiment of the application is used for executing the session switching method, so that the same effect as the session switching method can be achieved.

In case of an integrated unit, the control plane functional entity shown in fig. 13 may include a processing module and a communication module, and the processing module is used for performing control management on the actions of the control plane functional entity. The communication module is configured to support communication between the control plane functional entity and other network entities, for example, the functional module or the network entity shown in fig. 1. The control plane functional entity may also include a storage module for storing program codes and data of the server.

The processing module may be a processor or a controller. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The communication module may be a transceiver, a transceiving circuit or a communication interface, etc. The storage module may be a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the server according to the embodiment of the present application may be the communication device shown in fig. 4.

In the case of dividing each functional module by corresponding functions, fig. 14 shows a possible schematic composition diagram of the MME involved in the above embodiment, as shown in fig. 14, the MME may include: receiving section 141 and transmitting section 142.

A receiving unit 141, configured to receive, from a control plane function entity, network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network; a sending unit 142, configured to send a context of the terminal device to the AMF entity, where the context of the terminal device includes network slice information corresponding to when the PDN connection is switched to the fifth generation 5G network and information of the PDN connection, and the information of the PDN connection includes address information of a control plane function entity corresponding to the PDN connection.

In another possible design, the receiving unit 141 is specifically configured to receive a first message sent by the terminal device and carrying network slice information corresponding to when the PDN connection is switched to the 5G network; the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network.

In the case of an integrated unit, the MME may include a processing module for controlling and managing the actions of the MME and a communication module. The communication module is used to support communication between the MME and other network entities, such as the functional modules or network entities shown in fig. 1. The MME may also include a storage module to store program codes and data for the server. The processing module may be a processor or a controller. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The communication module may be a transceiver, a transceiving circuit or a communication interface, etc. The storage module may be a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the server according to the embodiment of the present application may be the communication device shown in fig. 4.

In the case of dividing each function module by corresponding functions, fig. 15 shows a possible composition diagram of the AMF involved in the above embodiment, as shown in fig. 15, the AMF may include: a receiving unit 151, an acquiring unit 152, a transmitting unit 153, and a determining unit 154.

A receiving unit 151, configured to receive, from an MME, network slice information corresponding to switching of a PDN connection to a fifth generation 5G network and address information of a control plane functional entity corresponding to the PDN connection;

an obtaining unit 152, configured to obtain, according to network slice information corresponding to when the PDN connection is switched to the 5G network, network slice information corresponding to when the PDN connection allowed to be switched in the PDN connection is switched to the 5G network;

a sending unit 153, configured to send a session switching request to the control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection, where the session switching request is used to request to switch the PDN connection to a protocol data unit PDU session.

In one possible design, the receiving unit 151 is further configured to receive network slice information signed by the terminal device; an obtaining unit 152, configured to obtain network slice information corresponding to a PDN connection allowed to be switched in the PDN connection and switched to the 5G network according to network slice information corresponding to the PDN connection switched to the 5G network and network slice information signed by the terminal device

In yet another possible design, the determining unit 154 is configured to determine, when the terminal device that establishes the PDN connection is in the home router roaming, a visited control plane function entity according to a network slice indicated by network slice information when a PDN connection that can be switched in the PDN connection is switched to the 5G network;

the sending unit 153 is specifically configured to send, to the visited control plane functional entity, a session establishment request carrying network slice information corresponding to when the PDN connection that can be switched in the PDN connection is switched to the 5G network and address information of the control plane functional entity corresponding to the PDN connection, where the session establishment request is used to instruct the visited control plane functional entity to send a session switching request to the home control plane functional entity.

In case of an integrated unit, the AMF entity may include a processing module for controlling and managing the actions of the AMF entity and a communication module. The communication module is used for supporting communication between the AMF entity and other network entities, for example, communication between the functional module or the network entity shown in fig. 1. The AMF entity may further include a storage module for storing program codes and data of the server. The processing module may be a processor or a controller. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The communication module may be a transceiver, a transceiving circuit or a communication interface, etc. The storage module may be a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the server according to the embodiment of the present application may be the communication device shown in fig. 4.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented using a software program, 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. The procedures or functions described in accordance with the embodiments of the present application are all or partially generated upon loading and execution of computer program instructions on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or can comprise one or more data storage devices, such as a server, a data center, etc., that can be integrated with the medium. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

While the present application has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A method for session handoff, the method comprising:

the method comprises the steps that the first equipment determines corresponding network slice information when PDN connection of the packet data network is switched to a fifth generation 5G network;

the first equipment sends corresponding network slice information when the PDN connection is switched to a 5G network to a mobility management entity;

wherein, the first device is a terminal device, and before the first device determines the corresponding network slice information when the PDN connection of the packet data network is handed over to the fifth generation 5G network, the method further includes:

the first equipment determines PDN connection switched to a 5G network in the established PDN connection according to the applied strategy information corresponding to the PDN connection; alternatively, the first and second electrodes may be,

when the first equipment supports the 5G network communication capability, the first equipment determines that all established PDN connections are switched to the 5G network.

2. The method of claim 1, wherein the determining, by the first device, corresponding network slice information when the PDN connection is handed over to a 5G network comprises:

the first equipment determines corresponding network slice information when the PDN connection is switched to the 5G network according to the corresponding relation between the information of the PDN connection and the network slice information;

and the information of the PDN connection comprises an access point name APN corresponding to the PDN connection.

3. The method according to any one of claims 1-2, further comprising:

and the first equipment sends the information of the priority of the corresponding network slice information when the PDN connection is switched to the 5G network to the mobility management entity.

4. The method of claim 3, wherein when the terminal device establishing the PDN connection is roaming; the network slice information when the PDN connection is switched to the 5G network is network slice information of a visited place when the PDN connection is switched to the 5G network, and the determining, by the first device, of the corresponding network slice information when the PDN connection is switched to the fifth-generation 5G network includes:

the first equipment determines network slice information of a home location when the PDN connection is switched to a 5G network according to applied strategy information corresponding to the PDN connection;

and the first equipment determines the network slice information of the visited place when the PDN connection is switched to the 5G network according to the network slice information of the home place when the PDN connection is switched to the 5G network and the mapping relation between the network slice information of the home place and the network slice information of the visited place.

5. The method of claim 4,

the mobility management entity is a mobility management entity MME or an access and mobility management function AMF entity.

6. The method of claim 5, wherein when the mobility management entity is the MME, the first device sends, to the mobility management entity, network slice information corresponding to the PDN connection being switched to a 5G network, and wherein the network slice information comprises:

the first equipment carries corresponding network slice information in a first message when the PDN connection is switched to the 5G network and sends the first message to the MME;

wherein the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal equipment when the PDN connection is switched to the 5G network.

7. The method of claim 5, wherein when the mobility management entity is the AMF entity, the first device is a terminal device, and the first device sends, to the mobility management entity, network slice information corresponding to the PDN connection handover to a 5G network, where the network slice information includes:

and the first equipment carries the corresponding network slice information in a registration request when the PDN connection is switched to the 5G network and sends the information to the AMF entity.

8. A method for session handoff, the method comprising:

a mobile management entity MME receives corresponding network slice information when the PDN connection of the packet data network is switched to a fifth generation 5G network from first equipment;

and the MME sends the context of the terminal equipment to an access and mobility management function (AMF) entity, wherein the context of the terminal equipment comprises network slice information corresponding to the PDN connection when the PDN connection is switched to a fifth generation 5G network and PDN connection information, and the PDN connection information comprises address information of a control plane function entity corresponding to the PDN connection.

9. The method of claim 8, wherein the mobility management entity MME receives network slice information corresponding to the packet data network PDN connection handover to a fifth generation 5G network from the first device, and comprises:

the MME receives a first message which is sent by the terminal equipment and carries corresponding network slice information when the PDN connection is switched to a 5G network;

wherein the first message is used for instructing the MME to store corresponding network slice information in the context of the terminal device when the PDN connection is switched to a 5G network.

10. The method according to claim 8 or 9,

the information of the PDN connection also comprises an access point name APN corresponding to the PDN connection.

11. A method for session handoff, the method comprising:

an access and mobility management function (AMF) entity acquires corresponding network slice information when a Packet Data Network (PDN) connection is switched to a fifth generation 5G network, address information of a control plane function entity corresponding to the PDN connection and network slice information signed by terminal equipment;

the AMF entity selects the corresponding network slice information when the PDN connection of the PDN connection allowed to be switched is switched to the 5G network from the intersection of the candidate network slice information corresponding to the PDN connection and the network slice information signed by the terminal equipment;

and the AMF entity sends a session switching request to a home control plane function entity according to the address information of the control plane function entity corresponding to the PDN connection, wherein the session switching request is used for requesting to switch the PDN connection of the PDN connection which is allowed to be switched in the PDN connection to a Protocol Data Unit (PDU) session.

12. The method of claim 11, wherein the obtaining, by the AMF entity, network slice information corresponding to the PDN connection handover for the fifth generation 5G network comprises:

the AMF entity acquires corresponding network slice information when the PDN connection is switched to a fifth generation 5G network from a Mobile Management Entity (MME); alternatively, the first and second electrodes may be,

and the AMF entity acquires corresponding network slice information when the PDN connection is switched to a fifth generation 5G network from terminal equipment.

13. The method of claim 12, wherein when the AMF entity obtains, from a terminal device, corresponding network slice information when the PDN connection is switched to a fifth generation 5G network, the access and mobility management function (AMF) entity obtains corresponding network slice information when a Packet Data Network (PDN) connection is switched to the fifth generation 5G network, and wherein the method comprises:

and the AMF entity receives a registration request which is sent by the terminal equipment and carries the network slice information corresponding to the PDN connection switched to the 5G network, and acquires the network slice information corresponding to the PDN connection switched to the 5G network from the registration request.

14. The method according to any of claims 11-13, wherein the AMF entity sends a session handover request to a home control plane function entity according to address information of a control plane function entity corresponding to the PDN connection, including:

when the AMF entity determines that the terminal equipment for establishing the PDN connection is in home router roaming, the AMF entity determines a visited control plane function entity according to a network slice indicated by corresponding network slice information when the PDN connection capable of being switched in the PDN connection is switched to a 5G network and a corresponding data network name DNN when the PDN connection is switched to the 5G network;

and the AMF entity sends a session establishment request carrying corresponding network slice information when a switched PDN connection in the PDN connection is switched to a 5G network and address information of a control surface function entity corresponding to the PDN connection to the visited control surface function entity, wherein the session establishment request is used for indicating the visited control surface function entity to send a session switching request to the home control surface function entity.

15. A first device, characterized in that the first device comprises:

the determining unit is used for determining corresponding network slice information when the PDN connection of the packet data network is switched to a fifth generation 5G network;

a sending unit, configured to send, to a mobility management entity, network slice information corresponding to the PDN connection being switched to the 5G network;

wherein the first device is a terminal device,

the determining unit is further configured to determine, according to policy information of an application corresponding to the PDN connection, a PDN connection switched to the 5G network in the PDN connections established by the terminal device before the determining unit determines network slice information corresponding to when the PDN connection of the packet data network is switched to the fifth-generation 5G network; or, when the terminal device itself supports the 5G network communication capability, the determining unit determines that all established PDN connections are switched to the 5G network.

16. The first apparatus of claim 15,

the determining unit is specifically configured to determine, according to a correspondence between PDN connection information and network slice information, corresponding network slice information when the PDN connection is switched to a 5G network;

17. The first apparatus according to any one of claims 15 to 16,

the sending unit is further configured to send, to the mobility management entity, information of priority of corresponding network slice information when the PDN connection is switched to the 5G network.

18. The first apparatus of claim 17, wherein when a terminal device establishing the PDN connection is roaming; the network slice information when the PDN connection is switched to the 5G network is network slice information of a visited place when the PDN connection is switched to the 5G network, and the determining unit is specifically configured to:

determining network slice information of a home location when the PDN connection is switched to a 5G network according to applied strategy information corresponding to the PDN connection;

and determining the network slice information of the visited place when the PDN connection is switched to the 5G network according to the network slice information of the home place when the PDN connection is switched to the 5G network and the mapping relation between the network slice information of the home place and the network slice information of the visited place.

19. The first apparatus of claim 18,

20. The first apparatus of claim 19, wherein when the mobility management entity is the MME, the sending unit is specifically configured to carry, in a first message, corresponding network slice information when the PDN connection is switched to a 5G network, and send the first message to the MME;

21. The first device of claim 19, wherein when the mobility management entity is the AMF entity, the first device is a terminal device, and the sending unit is specifically configured to carry, in a registration request, the corresponding network slice information when the PDN connection is switched to a 5G network, and send the network slice information to the AMF entity.

22. A Mobility Management Entity (MME), wherein the MME comprises:

the receiving unit is used for receiving corresponding network slice information when the PDN connection of the packet data network is switched to a fifth generation 5G network from the first equipment;

and the sending unit is further configured to send a context of the terminal device to an access and mobility management function (AMF) entity, where the context of the terminal device includes network slice information corresponding to when the PDN connection is switched to a fifth-generation 5G network and information of the PDN connection, and the information of the PDN connection includes address information of a control plane function entity corresponding to the PDN connection.

23. The MME of claim 22,

the receiving unit is specifically configured to receive, from the first device, a first message carrying network slice information corresponding to the PDN connection being switched to the 5G network;

24. The MME of claim 22 or 23,

25. An access and mobility management function, AMF, entity, characterized in that the AMF entity comprises:

a receiving unit, configured to receive network slice information corresponding to when a packet data network PDN connection is switched to a fifth-generation 5G network, address information of a control plane function entity corresponding to the PDN connection, and network slice information signed by a terminal device;

an obtaining unit, configured to select, from an intersection of candidate network slice information corresponding to the PDN connection and network slice information signed by the terminal device, network slice information corresponding to a PDN connection that is allowed to be switched in the PDN connection when the PDN connection is switched to a 5G network;

and a sending unit, configured to send a session switching request to a home control plane function entity according to address information of a control plane function entity corresponding to the PDN connection, where the session switching request is used to request to switch, to a protocol data unit PDU session, a PDN connection of a PDN connection that allows switching in the PDN connection.

26. The AMF entity of claim 25,

the receiving unit is specifically configured to receive, from a mobility management entity MME, network slice information corresponding to when the PDN connection is switched to a fifth generation 5G network; or receiving the corresponding network slice information when the PDN connection is switched to the fifth generation 5G network from the terminal equipment.

27. The AMF entity of claim 26, wherein when the AMF entity receives, from a terminal device, network slice information corresponding to when the PDN connection is handed over to a fifth-generation 5G network, the receiving unit is specifically configured to:

and receiving a registration request which is sent by the terminal equipment and carries the corresponding network slice information when the PDN connection is switched to the 5G network.

28. The AMF entity according to any one of claims 25-27, further comprising:

a determining unit, configured to determine, when the terminal device that establishes the PDN connection is in home router roaming, a visited control plane function entity according to a network slice indicated by network slice information when a PDN connection that can be switched in the PDN connection is switched to a 5G network, and a data network name DNN corresponding to the PDN connection when the PDN connection is switched to the 5G network;

the sending unit is specifically configured to send, to the visited control plane function entity, a session establishment request carrying network slice information corresponding to when a PDN connection that can be switched in the PDN connection is switched to a 5G network, and address information of a control plane function entity corresponding to the PDN connection, where the session establishment request is used to instruct the visited control plane function entity to send a session switching request to the home control plane function entity.