CN111901899B

CN111901899B - Communication method and device

Info

Publication number: CN111901899B
Application number: CN201910373241.3A
Authority: CN
Inventors: 景昊; 宗在峰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-05-06
Filing date: 2019-05-06
Publication date: 2022-09-16
Anticipated expiration: 2039-05-06
Also published as: CN111901899A

Abstract

The application provides a communication method and device. According to the method, the SMF serving the terminal equipment can send first information to the management equipment and receive second information sent by the management equipment, wherein the second information can be used for indicating that the target SMF does not exist, or indicating that the source SMF reserves the first PDU session, or indicating that the redistribution of the SMF is not feasible, so that the source SMF can determine that the UE cannot be switched to the proper target SMF according to the second information, namely the target SMF meeting the condition does not exist, the UE can be prevented from trying to be switched to the target SMF in a continuous trial and error mode, and the signaling overhead is greatly saved.

Description

Communication method and device

Technical Field

The present application relates to the field of mobile communications technologies, and in particular, to a communication method and apparatus.

Background

The fifth generation (5) at present ^th generation, 5G) mobile communication technology, a Session Management Function (SMF) is responsible for managing a Protocol Data Unit (PDU) session. A PDU session is a channel for transmitting a PDU, and a terminal device needs to transfer the PDU to and from a Data Network (DN) through the PDU session.

Because terminal equipment (UE) has mobility, when the UE accesses a data network through a PDU session, if the UE moves out of the area served by the current SMF, the UE may try to access a new SMF, so that a new PDU session is established for the UE through the new SMF, and the UE still accesses the data network with the same Data Network Name (DNN).

However, if there is no SMF satisfying the condition in the area where the UE is currently located to establish the PDU session, so that the UE accesses the data network with the same DNN, the UE and the current SMF serving the UE cannot know that there is no SMF satisfying the condition, and in some scenarios, the UE can only try to make a trial and error to access the SMF satisfying the condition and establish a new PDU session, so that there is unnecessary signaling overhead. In other scenarios, the UE may reestablish the PDU session through an intervening intermediate SMF (I-SMF), but the user plane path of the PDU session reestablished through the intermediate SMF is not optimal, and thus there is unnecessary signaling overhead.

Disclosure of Invention

The application provides a communication method and device, which are used for optimizing the PDU session management problem of UE after the UE sends movement at the position of the UE.

In a first aspect, the present application provides a terminal management method, which may be performed by an SMF. According to the method, a source SMF sends first information to a management device, the source SMF provides service for a terminal device, and the terminal device is accessed to a data network DN through a first protocol data unit PDU session; the source SMF receives second information from the management device, wherein the second information is used for indicating that a target SMF of the terminal device does not exist, or indicating that the first PDU session is reserved, or indicating that the SMF cannot be reallocated; wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information (identities that a PDU Session re-establishes to the same DN) for indicating the PDU Session re-establishment; information indicating that a traffic and session continuity mode SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

By adopting the method, the SMF serving the terminal equipment can receive the second information sent by the management equipment, and the second information can be used for indicating that the target SMF does not exist, or indicating that the source SMF reserves the first PDU session, or indicating that the redistribution of the SMF is not feasible, so that the source SMF can determine that the UE cannot be switched to the proper target SMF according to the second information, namely, the target SMF meeting the condition does not exist, thereby avoiding that the UE tries to be switched to the target SMF in a continuous trial and error mode, greatly saving signaling cost, also avoiding inserting the middle SMF and establishing a user plane with non-optimal path, and saving the signaling cost.

In one possible design, the target SMF supports an identification of the DN and a location of the terminal device. By adopting the design, the target SMF can be used for the UE to access the same data network accessed before, and the session interruption between the UE and the data network is avoided. When the target SMF is not present, the source SMF may be made aware that there is no target SMF that enables the UE to access the same data network.

In one possible design, the second information includes information of the target SMF. With this design, the second information, when comprising information of the target SMF, may be used to indicate the presence of the target SMF.

In one possible design, the information indicating reallocation of SMFs for the terminal device is an SMF reallocation requested indication indicating that the source SMF is requested to be reallocated.

In one possible design, the source SMF may also reserve the first PDU session based on the second information. By adopting the design, the source SMF can reserve the first PDU session according to the second information, and the interruption of UE data service caused by the release of the first PDU session under the condition that the target SMF does not exist is avoided. In addition, the first PDU session is reserved, so that the UE can be prevented from trying to access the target SMF after the first PDU session is released, and the UE can continuously try and go wrong due to the fact that the target SMF does not exist, so that the design can save signaling overhead.

In one possible design, the source SMF may also determine a user plane function UPF to switch to providing service for the terminal device; and/or the source SMF can also determine the SMF switched to provide the service for the terminal equipment. With this design, before sending the first information, the source SMF needs to determine to switch to the UPF and/or SMF that provides the service for the terminal device.

In one possible design, the management device is an AMF or a network storage function NRF.

In one possible design, the first information is carried in a first message that also includes an identification of the first PDU session.

In addition, the above method may be implemented by a management apparatus. According to the method, a management device receives first information and sends second information to a source SMF according to the first information, the source SMF provides service for a terminal device, and the terminal device accesses a DN through a first PDU session; wherein the second information is used for indicating that a target SMF of the terminal equipment does not exist, or for indicating that the first PDU session is reserved, or for indicating that the re-allocation of the SMF is not feasible; wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the target SMF supports an identification of the DN and a location of the terminal device.

In one possible design, the sending, by the management device, second information to the source SMF according to the first information includes: the management equipment determines that the target SMF does not exist according to the first information; and the management equipment sends the second information to the source SMF.

In one possible design, the determining, by the management device according to the first information, that the target SMF does not exist includes: when the first information does not include the location information of the terminal device and the identifier of the DN, the management device acquires the location information of the terminal device and the identifier of the DN from the context of the first PDU session, and determines that the target SMF does not exist according to the SMF information stored by the management device, the location information of the terminal device and the identifier of the DN, wherein the SMF information includes the identifier of the DN supported by the SMF and the information of a service area; or when the first information includes the location information of the terminal device and the identifier of the DN, the management device determines that the target SMF does not exist according to the SMF information stored by the management device, the location information of the terminal device, and the identifier of the DN, where the SMF information includes the identifier of the DN supported by the SMF and information of a service area.

In one possible design, the management device is an AMF, and the sending, by the management device, second information to the source SMF according to the first information includes: the management equipment requests the target SMF from an NRF according to the first information; when the management device does not receive the information of the target SMF from the NRF, or the management device receives the information indicating that the target SMF does not exist from the NRF, the management device sends the second information to the source SMF.

In one possible design, the requesting, by the management device, the target SMF from an NRF according to the first information includes: when the first information comprises the position information of the terminal equipment and the identification of the DN, the management equipment sends the first information to the NRF; or, when the first information does not include the location information of the terminal device and the identifier of the DN, the management device obtains the location information of the terminal device and the identifier of the DN from the context of the first PDU session, and sends the location information of the terminal device and the identifier of the DN to the NRF.

In one possible design, the second information includes information of the target SMF.

In a possible design, the first information is carried in a first message, and the first message also carries an identifier of the first PDU session.

In a second aspect, the present application provides a method of terminal management, which may be implemented by a source SMF. The method comprises the following steps: a source SMF sends first information to a management device, the source SMF provides service for a terminal device, the terminal device accesses a data network through a first PDU session, the first information is used for determining whether a target SMF exists or not, and the target SMF supports the identifier of the data network and the position of the terminal device; and the source SMF receives third information from the management device, wherein the third information is used for indicating whether the target SMF exists or not.

By adopting the design, the source SMF can determine whether the target SMF exists according to the third information from the management equipment, and under the condition that the target SMF does not exist, the UE can be prevented from trying to switch to the target SMF in a continuous trial and error mode, so that the signaling overhead is greatly saved.

In one possible design, the source SMF reserves the first PDU session when the third information indicates that the target SMF is not present; or, when the third information is used to indicate that the target SMF exists, the source SMF triggers the release of the first PDU session.

In one possible design, the third information includes information of the target SMF.

In one possible design, before the sending, by the source SMF, the first information to the management device, the method further includes: the source SMF determines to switch to the UPF for providing the service for the terminal equipment; and/or the source SMF determines to switch to the SMF providing the service for the terminal equipment.

In one possible design, the first information includes at least one of the following information: information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; or, information for instructing the management device to determine whether the target SMF of the terminal device exists; or, the information is used for indicating to reallocate the SMF for the terminal equipment; or, information for indicating that the PDU session is reestablished to the same DN; or, the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the management device includes an AMF or an NRF.

In addition, the method may also be implemented by a management device. According to the method, a management device can receive first information and send third information to a source SMF according to the first information, wherein the third information is used for indicating whether a target SMF of a terminal device exists or not, the source SMF provides service for the terminal device, and the terminal accesses to the specified data network through a first PDU session; wherein the first information comprises at least one of: information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; or, information for instructing the management device to determine whether the target SMF of the terminal device exists; or, the information is used for indicating to reallocate the SMF for the terminal equipment; or, information for indicating that the PDU session is reestablished to the same DN; or, the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the sending, by the management device, third information to the source SMF according to the first information includes: the management equipment determines whether the target SMF exists or not according to the first information; when the management device determines that the target SMF exists, the management device sends the third information to the source SMF, wherein the third information is used for indicating that the target SMF exists; or, when the management device determines that the target SMF does not exist, the management device sends the third information to the source SMF, where the third information is used to indicate that the target SMF does not exist.

In one possible design, when the first information includes information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the management device determines whether the target SMF is present.

In one possible design, the determining, by the management device, whether the target SMF exists according to the first information includes: when the first information includes information indicating that the management device determines whether a target SMF of the terminal device exists, the management device determines whether the target SMF exists.

In one possible design, when the management device determines whether the target SMF exists according to the first information and includes information indicating to reallocate the SMF for the terminal device, the management device determines whether the target SMF exists.

In one possible design, when the management device determines whether the target SMF exists according to the first information and includes information indicating that the PDU session is reestablished to the same DN, the management device determines whether the target SMF exists.

In one possible design, when the first information does not include location information of the terminal device and an identification of the data network, the determining, by the management device, whether the target SMF exists includes: the management equipment acquires the position information of the terminal equipment and the identifier of the data network from the context of the first PDU session; and the management equipment determines whether the target SMF exists according to the SMF information, the position information of the terminal equipment and the identification of the data network, which are stored by the management equipment, wherein the SMF information comprises the identification of the data network supported by the SMF and the information of the service area of the SMF.

In one possible design, the first information includes location information of the terminal device and an identifier of the data network, and the determining, by the management device, whether the target SMF exists according to the first information includes: and the management equipment determines whether the target SMF exists according to the SMF information, the position information of the terminal equipment and the identification of the data network, which are stored by the management equipment, wherein the SMF information comprises the identification of the data network supported by the SMF and the information of the service area of the SMF.

In one possible design, the method further includes: and when the determination result is that the target SMF exists, the management equipment sends an NAS message to the terminal equipment.

In one possible design, the management device is an AMF, and the sending, by the management device to the source SMF, third information according to the first information includes:

the management device requests SMF information meeting the specific condition from an NRF according to the first information; when the management device receives SMF information which meets the specific condition from the NRF, the management device sends the third information to the source SMF, wherein the third information is used for indicating that the target SMF exists; or, when the management device does not receive the SMF information satisfying the specific condition from the NRF, or the management device receives indication information indicating that there is no SMF satisfying the specific condition from the NRF, the management device sends the third information to the source SMF, where the third information is used to indicate that there is no target SMF.

In one possible design, the requesting, by the management apparatus, the SMF information satisfying the specific condition from the NRF according to the first information includes: and the management equipment sends the position information of the terminal equipment and the identifier of the data network to the NRF according to the first information.

In one possible design, the sending, by the management device to the NRF, the location information of the terminal device and the identifier of the data network according to the first information includes: the first information comprises position information of the terminal equipment and an identifier of the data network, and the management equipment sends the first information to the NRF; or, the management device obtains the location information of the terminal device and the identifier of the data network from the context of the first PDU session, and sends the location information of the terminal device and the identifier of the data network to the NRF.

In one possible design, the third information includes information of the target SMF or information of one SMF of the target SMFs.

In a third aspect, the present application provides a communication device, which may be configured to perform the steps performed by the source SMF in any possible design of the above first aspect or first aspect, or in any possible design of the second aspect or second aspect, and may implement the functions in the above methods in the form of hardware structures, software modules, or hardware structures plus software modules. For example, when formed by software modules, the communication device may include a communication module and a processing module coupled to each other, wherein the communication module may be used to support the communication device for communication, and the processing module may be used to perform processing operations on the communication device, such as generating information/messages to be transmitted or processing received signals to obtain the information/messages. When formed by hardware components, the communication device may include a communication interface, a memory, and a processor, among others, coupled to each other.

In the implementation of the first aspect or any one of the possible designs of the first aspect, the communication module may be configured to send first information to the management device, where the communication device provides a service for a terminal device, and the terminal device accesses the data network DN through a first protocol data unit PDU session; the communication module may be further configured to receive second information from the management device, where the second information is used to indicate that there is no target SMF of the terminal device, or to indicate that the first PDU session is reserved, or to indicate that it is not feasible to reallocate SMFs; wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the communications apparatus further includes a processing module; the processing module is configured to reserve the first PDU session according to the second information.

In one possible design, the communication device further includes a processing module; the processing module is used for determining and switching a user plane function UPF for providing service for the terminal equipment; and/or the processing module is used for determining to switch the SMF for providing the service for the terminal equipment.

In carrying out any one of the above second aspects or possible designs of the second aspect, the communication module may be configured to send first information to the management device, the source SMF serving the terminal device, the terminal device accessing the data network through the first PDU session, the first information being used to determine whether a target SMF exists, the target SMF supporting an identity of the data network and a location of the terminal device; the processing module may determine whether the target SMF exists based on third information from the management device, the third information indicating whether the target SMF exists.

In one possible design, the processing module reserves the first PDU session when the third information indicates that the target SMF is not present; or, when the third information is used to indicate that the target SMF exists, the processing module triggers the release of the first PDU session.

In one possible design, before the communication module sends the first information to the management device, the processing module is further configured to: determining a UPF for switching to the terminal equipment to provide service; and/or determining the SMF for switching to provide the service for the terminal equipment.

In one possible design, the management device includes an AMF or an NRF.

In a fourth aspect, the present application provides a communication device, which may be used to execute the steps executed by the management apparatus in any possible design of the first aspect or the first aspect, or in any possible design of the second aspect or the second aspect, and the communication device may implement the functions in the methods through a hardware structure, a software module, or a hardware structure and a software module. For example, when formed by software modules, the communication device may include a communication module and a processing module coupled to each other, wherein the communication module may be used to support the communication device for communication, and the processing module may be used to perform processing operations on the communication device, such as generating information/messages to be transmitted or processing received signals to obtain the information/messages. When formed of hardware components, the communication device may include a communication interface 1501, memory, and a processor, among other components, coupled to each other.

In carrying out the first aspect or any possible design of the first aspect, the communication module is configured to receive first information; the communication module is also used for sending second information to a source SMF according to the first information, wherein the source SMF provides service for the terminal equipment, and the terminal equipment is accessed to the DN through a first PDU session; wherein the second information is used for indicating that a target SMF of the terminal equipment does not exist, or for indicating that the first PDU session is reserved, or for indicating that the re-allocation of the SMF is not feasible; wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the communication apparatus to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the communication device further includes a processing module; the processing module is used for determining that the target SMF does not exist according to the first information; the communication module is specifically configured to: and sending the second information to the source SMF.

In one possible design, the processing module is specifically configured to: when the first information does not comprise the position information of the terminal equipment and the identification of the DN, acquiring the position information of the terminal equipment and the identification of the DN from the context of the first PDU session, and determining that the target SMF does not exist according to the SMF information stored by the communication device, the position information of the terminal equipment and the identification of the DN, wherein the SMF information comprises the identification of the DN supported by the SMF and the information of a service area; or when the first information includes the location information of the terminal device and the identifier of the DN, determining that the target SMF does not exist according to SMF information stored by the communication device, the location information of the terminal device and the identifier of the DN, where the SMF information includes the identifier of the DN supported by the SMF and information of a service area.

In one possible design, the communication device is an AMF; the communication module is specifically configured to: requesting the target SMF from an NRF according to the first information; when the communication apparatus does not receive the information of the target SMF from the NRF, or the communication apparatus receives the information indicating that the target SMF does not exist from the NRF, the communication apparatus transmits the second information to the source SMF.

In one possible design, the communication module is specifically configured to: when the first information comprises the position information of the terminal equipment and the identification of the DN, the first information is sent to the NRF;

alternatively, the communication device further comprises a processing module; the processing module is used for: when the first information does not comprise the position information of the terminal equipment and the identification of the DN, acquiring the position information of the terminal equipment and the identification of the DN from the context of the first PDU session; the communication module is specifically configured to: and sending the position information of the terminal equipment and the DN identification to the NRF.

In executing the second aspect or any possible design of the second aspect, the communication module may be configured to receive first information, and send third information to a source SMF according to the first information, where the third information is used to indicate whether a target SMF of a terminal device exists, the source SMF provides a service for the terminal device, and the terminal accesses the specified data network through a first PDU session; wherein the first information comprises at least one of: information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; or, information for instructing the management device to determine whether the target SMF of the terminal device exists; or, the information is used for indicating to reallocate the SMF for the terminal equipment; or, information for indicating that the PDU session is reestablished to the same DN; or, the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

In one possible design, the processing module may be configured to determine whether the target SMF is present based on the first information; when the processing module determines that the target SMF exists, the communication module sends the third information to the source SMF, wherein the third information is used for indicating that the target SMF exists; or, when the processing module determines that the target SMF does not exist, the communication module sends the third information to the source SMF, where the third information is used to indicate that the target SMF does not exist.

In one possible design, when the first information includes information indicating that the SMF is to be reallocated for the terminal device, the processing module determines whether the target SMF is present.

In one possible design, when the first information includes information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the processing module determines whether the target SMF is present.

In one possible design, when the first information includes information for instructing the management device to determine whether a target SMF of the terminal device exists, the processing module determines whether the target SMF exists.

In one possible design, the processing module determines whether the target SMF is present when the first information includes information indicating that a PDU session is reestablished to the same DN.

In one possible design, the processing module determines whether the target SMF is present, including: the processing module acquires the position information of the terminal equipment and the identifier of the data network from the context of the first PDU session; and the processing module determines whether the target SMF exists according to the SMF information stored in the processing module, the position information of the terminal equipment and the identification of the data network, wherein the SMF information comprises the identification of the data network supported by the SMF and the information of the service area of the SMF.

In one possible design, the first information includes location information of the terminal device and an identifier of the data network, and the processing module determines whether the target SMF exists according to the first information, including: and the processing module determines whether the target SMF exists according to the SMF information stored in the processing module, the position information of the terminal equipment and the identification of the data network, wherein the SMF information comprises the identification of the data network supported by the SMF and the information of the service area of the SMF.

In one possible design, the method further includes: and when the determination result is that the target SMF exists, the communication module sends an NAS message to the terminal equipment.

In one possible design, the communication device is an AMF, and the sending, by the communication module, third information to the source SMF according to the first information includes:

the communication module requests SMF information meeting the specific condition from an NRF according to the first information; when the communication module receives SMF information satisfying the specific condition from the NRF, the communication module sends the third information to the source SMF, wherein the third information is used for indicating that the target SMF exists; or, when the communication module does not receive the SMF information satisfying the specific condition from the NRF, or the communication module receives indication information indicating that there is no SMF satisfying the specific condition from the NRF, the communication module sends the third information to the source SMF, where the third information is used to indicate that there is no target SMF.

In one possible design, the communication module requests, from the NRF, the SMF information satisfying the specific condition according to the first information, and includes: and the communication module sends the position information of the terminal equipment and the identifier of the data network to the NRF according to the first information.

In one possible design, the sending, by the communication module, the location information of the terminal device and the identifier of the data network to the NRF according to the first information includes: the first information comprises position information of the terminal equipment and identification of the data network, and the communication module sends the first information to the NRF; or, the first information includes an identifier of the first PDU session, the processing module obtains the location information of the terminal device and the identifier of the data network from the context of the first PDU session, and the communication module sends the location information of the terminal device and the identifier of the data network to the NRF.

In one possible design, the third information includes information of the target SMF or information of one of the target SMFs.

In a sixth aspect, the present application provides a communication system, which may include the communication apparatus of the third aspect and/or the fourth aspect.

In a seventh aspect, the present application provides a computer storage medium having instructions (or programs) stored therein, which when executed on a computer cause the computer to perform the method described in the first aspect or any one of the possible designs of the first aspect, or the second aspect, or any one of the possible designs of the second aspect.

In an eighth aspect, the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method as set forth in the first aspect or any one of the possible designs of the first aspect, or for performing the method as set forth in the second aspect or any one of the possible designs of the second aspect.

In a ninth aspect, the present application provides a chip or chip system comprising a chip, which chip may comprise a processor. The chip may also include a memory and/or a communication module. The chip may be adapted to perform a method as described in the first aspect or any one of the possible designs of the first aspect, or adapted to perform a method as described in the second aspect or any one of the possible designs of the second aspect. The chip system may be formed by the above chip, and may also include the above chip and other discrete devices, such as a communication module.

Advantageous effects in the third to ninth aspects and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the first aspect and any possible design thereof, or the second aspect and any possible design thereof.

Drawings

FIG. 1 is a block diagram of a wireless communication system;

FIG. 2 is a block diagram of another wireless communication system;

FIG. 3 is a block diagram of another wireless communication system;

fig. 4 is a flowchart illustrating a communication method according to the present application;

fig. 4A is a schematic flow chart of another communication method provided herein;

fig. 5 is a flow chart illustrating another communication method provided herein;

fig. 6 is a flow chart illustrating another communication method provided herein;

fig. 7 is a flow chart illustrating another communication method provided herein;

fig. 8 is a flow chart illustrating another communication method provided herein;

fig. 9 is a flow chart illustrating another communication method provided herein;

fig. 10 is a flow chart illustrating another communication method provided herein;

fig. 11 is a flow chart illustrating another communication method provided herein;

fig. 12 is a schematic structural diagram of a communication device provided in the present application;

fig. 13 is a schematic structural diagram of another communication device provided in the present application;

fig. 14 is a schematic structural diagram of another communication device provided in the present application;

fig. 15 is a schematic structural diagram of another communication device provided in the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings. The particular methods of operation in the method embodiments may also be applied to apparatus embodiments or system embodiments.

The following explains the present application with respect to terms:

at least one means one, or more than one, i.e., including one, two, three, and more than one.

Plural, refers to two, or more than two, that is, includes two, three and more than two.

Carrying may mean that a certain message is used to carry certain information or data, or that a certain message is composed of certain information.

Coupling refers to indirect coupling or communication connection between devices, units or modules, and may be electrical, mechanical or other forms for information interaction between the devices, units or modules.

In addition, it should be understood that in the embodiment of the present application, "and/or" describes an association relationship of associated objects, which means that three relationships may exist, for example, a and/or B may mean: a alone, both A and B, and B alone, where A, B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a and b, a and c, b and c, or a, b and c, wherein a, b and c can be single or multiple.

Hereinafter, embodiments of the present application will be described in detail with reference to the drawings. First, a wireless communication system to which the embodiment of the present application can be applied is introduced, then a communication method provided by the embodiment of the present application is introduced, and finally a communication apparatus provided by the embodiment of the present application is introduced.

As shown in fig. 1, a wireless communication system 100 is provided that may include a terminal device 101 and a network device 102.

It should be understood that the wireless communication system 100 may be applicable to both low frequency scenarios (sub 6G) and high frequency scenarios (above 6G). The application scenarios of the wireless communication system 100 include, but are not limited to, a global system for mobile communications (GSM) system, a Code Division Multiple Access (CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system, a General Packet Radio Service (GPRS), a Long Term Evolution (LTE) system, a Frequency Division Duplex (FDD) system, a Time Division Duplex (TDD), a Universal Mobile Telecommunications System (UMTS), a Worldwide Interoperability for Microwave Access (WiMAX) communication system, a future fifth generation system or a new Radio Network (NR) communication system, and the like.

The terminal device 101 shown above may be a user equipment, a terminal (terminal), a Mobile Station (MS), a mobile terminal (mobile terminal), and the like, and the terminal device 101 is capable of communicating with one or more network devices of one or more communication systems and accepting network services provided by the network devices, where the network devices include, but are not limited to, the illustrated network device 102. By way of example, the terminal equipment 101 may be a mobile phone (or "cellular" phone), a computer with mobile communication capabilities, etc., and the terminal equipment 101 may also be a portable, pocket, hand-held, computer-included, or vehicle-mounted mobile device. The terminal apparatus 101 may also be a communication chip having a communication module.

The network devices 102 shown above may include access network devices (or access network sites). The access network device refers to a device providing a network access function, such as a Radio Access Network (RAN) base station, and the like. The network device 102 may specifically include a Base Station (BS), or include a base station and a radio resource management device for controlling the base station, and the network device 102 may be a relay station (relay device), an access point, an in-vehicle device, a wearable device, a base station in a future 5G network, a base station in a future evolved Public Land Mobile Network (PLMN) network, or an NR base station. The network device 102 may also be a communication chip having a communication module.

In the execution process of the method described in the present application, the network device 102 may serve as a RAN base station to provide a wireless network connection to the terminal device 101, for example, the network device 102 may serve as an access network device in an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), which is a 4G access network, or the network device 102 may serve as an access network device in a 5G access network, which is a 5G access network, or the network device 102 may serve as an access network device in a future wireless communication system.

A wireless communication system to which the embodiments of the present application can be applied is described below with reference to a 5G core network as an example. As shown in fig. 2, an exemplary 5G wireless communication system is provided. The wireless communication system may include a 5G core network 201, and the wireless communication system may further include a 5G access network 202, where the 5G core network 201 and the 5G access network 202 may interact with each other via an interface. In the wireless communication system scenario, the functional entity for implementing the method according to the embodiment of the present application may be a network element and/or a terminal device in the 5G core network 201. Specifically, the terminal device according to the embodiment of the present application may include a terminal device connected to a base station in the 5G access network 202, for example, the UE 203 shown in fig. 2. The UE 203 is connected to the access network device 204 through a wireless link, and the access network device 204 may be a 5G base station in the 5G access network 202; the terminal device according to the embodiment of the present application may further include a UE connected to the relay station, for example, the UE 205 shown in fig. 2. Wherein, the UE 205 is connected with the relay station 206, and the relay station 206 is connected to the access network device 204 through the relay link. The network device 102 according to the embodiment of the present application may be an access network device 204 in a 5G access network 202 shown in fig. 2, or may be a relay station 206 connected to the access network device 204 shown in fig. 2.

Fig. 3 is a schematic diagram of a 5G network based on a service architecture. The network architecture shown in fig. 3 may include three parts: terminal equipment, Data Networks (DNs), and operator networks. Next, referring to fig. 3, the architecture of the 5G core network 201 and the 5G access network 202 shown in fig. 2 will be further described.

The operator network may include a Service Communication Proxy (SCP), a Network Slice Selection Function (NSSF), a network open function (NEF), a network storage function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), AN Application Function (AF), AN authentication server function (AUSF), AN AUSF, AN access and mobility management function (AMF), a Session Management Function (SMF), (radio) access network (R), and a User Plane Function (UPF), etc. In the operator network, a part other than the (radio) access network (e.g. the 5G access network 202 shown in fig. 2) may be referred to as a Core Network (CN) (e.g. the 5G core network 201 shown in fig. 2). For convenience of description, the (R) AN will be referred to as RAN as AN example.

The UE shown in fig. 3 may be a device with wireless transceiving function, which may be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on the water surface (such as a ship and the like); and may also be deployed in the air (e.g., airplanes, balloons, satellites, etc.). The UE may be a mobile phone (mobile phone), a tablet (pad), a computer with a wireless transceiving function, a Virtual Reality (VR) terminal, an Augmented Reality (AR) terminal, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medical), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety (transportation safety), a wireless terminal in smart city (smart city), a wireless terminal in smart home (smart home), and the like. The UE as shown in fig. 3 may comprise a terminal device 101.

The terminal device may establish a connection with the carrier network through an interface (e.g., N1, etc.) provided by the carrier network, and use data and/or voice services provided by the carrier network. The terminal device may also access the DN via an operator network, use operator services deployed on the DN, and/or services provided by a third party. The third party may be a service party other than the operator network and the terminal device, and may provide services such as data and/or voice for the terminal device. The specific expression form of the third party may be determined according to an actual application scenario, and is not limited herein.

Access network equipment, which refers to equipment providing a terminal with a wireless communication function, may be deployed in the RAN. Access network devices include, but are not limited to: next generation base station (G node B, gNB), evolved node B (eNB), Radio Network Controller (RNC), Node B (NB), Base Station Controller (BSC), Base Transceiver Station (BTS), home base station (e.g., home evolved node B, or home node B, HNB), Base Band Unit (BBU), transmission point (TRP), Transmission Point (TP), mobile switching center, etc. in 5G. The access network device as shown in fig. 3 may include network device 102.

The service communication proxy network element can be used for transmitting messages between control plane network elements and supporting the discovery of network elements and network function services. In 5G, the service communication proxy network element may be an SCP, and in future communication such as 6G, the network slice selecting device may still be an SCP, or have other names, which is not limited in this application.

The network slice selection device is used for realizing flexible selection of the network slices. For example, the network slice selection apparatus may support a slice selection policy based on a plurality of information, such as Network Slice Selection Assistance Information (NSSAI), location information, or slice load information, and may implement an intelligent slice selection scheme based on the slice selection policy. The network slice selection device can store slice selection strategy and other information configured by an operator. In 5G, the network slice selection element may be NSSF, and in future communications such as 6G, the network slice selection device may still be NSSF, or have another name, which is not limited in this application.

The mobility management network element shown above is a control plane network element provided by an operator network, and is responsible for access control and mobility management when the terminal device accesses the operator network, and includes functions of mobility state management, user temporary identity assignment, user authentication and authorization, and the like. In the 5G, the mobility management element may be an AMF, and in future communications such as the 6th generation (6G), the mobility management element may still be an AMF or have another name, which is not limited in this application.

The session management network element shown above is a control plane network element provided by an operator network, and is responsible for managing a Protocol Data Unit (PDU) session of the terminal device. A PDU session is a channel for transmitting PDUs, and a terminal device needs to transfer PDUs to and from the DN through the PDU session. The PDU session is responsible for establishment, maintenance, deletion, etc. by the SMF. SMF includes Session-related functions such as Session establishment, modification and release, including tunnel maintenance between UPF and RAN, UPF selection and control, Service and Session Continuity (SSC) mode selection, roaming, etc. The SMF may be used to select a UPF to serve a user, such as a UPF closer to the base station where the user is located, to reduce the user packet transmission and reception delay. In 5G, the session management network element may be an SMF, and in future communications such as 6G, the session management network element may still be an SMF, or have another name, which is not limited in this application.

The user plane network elements shown above are gateways provided by the operator, which are gateways for the operator's network to communicate with the DN. The UPF network element comprises user plane related functions such as data packet routing and transmission, packet detection, Service usage reporting, Quality of Service (QoS) processing, legal monitoring, uplink packet detection, downlink data packet storage and the like. In 5G, the user plane network element may be a UPF, and in future communications such as 6G, the user plane network element may still be a UPF, or have another name, which is not limited in this application.

The DN is a network located outside an operator network, and the operator network can access a plurality of DNs, and can deploy various services, and provide services such as data and/or voice for a terminal device. For example, the DN is a private network of a certain intelligent factory, a sensor installed in a workshop of the intelligent factory can be a terminal device, a control server of the sensor is deployed in the DN, and the control server can provide services for the sensor. The sensor can communicate with the control server, obtain the instruction of the control server, transmit the sensor data gathered to the control server, etc. according to the instruction. For another example, the DN is an internal office network of a company, the mobile phone or computer of the employee of the company may be a terminal device, and the mobile phone or computer of the employee may access information, data resources, and the like on the internal office network of the company.

In this application, the data management network element is a control plane network element provided by an operator, and is responsible for storing information such as a user permanent identifier (SUPI), a credential (trusted), a security context (security context), and subscription data of a subscription user in an operator network. These information stored by the UDM can be used for authentication and authorization of the terminal device to access the operator's network. The subscriber of the operator network may be specifically a user using a service provided by the operator network, for example, a user using a mobile phone core card of china telecommunications, or a user using a mobile phone core card of china mobile, and the like. The SUPI of the subscriber may be the number of the mobile phone core card. The credentials and security context of the subscriber may be a small file stored with an encryption key of the core card of the mobile phone or information related to encryption of the core card of the mobile phone, and used for authentication and/or authorization. The security context may be data (cookie) or token (token) stored on the user's local terminal (e.g., cell phone), etc. The subscription data of the subscriber may be a service associated with the mobile phone core card, such as a traffic package or a network using the mobile phone core card. It should be noted that the information related to the permanent identifier, the credentials, the security context, the authentication data (cookie), and the token equivalent authentication and authorization are not distinguished or limited in the present application for convenience of description. Unless otherwise specified, the embodiments of the present application will be described in the context of security, but the embodiments of the present application are also applicable to authentication, and/or authorization information in other expressions. In 5G, the data management network element may be a UDM, and in future communications such as 6G, the data management network element may still be a UDM, or have another name, which is not limited in this application.

In this application, the network element with the network open function is a control plane network element provided by an operator. The NEF opens the external interface of the operator network to third parties in a secure way. When the SMF communicates with a network element of a third party, the NEF may act as a relay for the SMF to communicate with the network element of the third party. When the NEF is used as a relay, it can be used as a translation of the identification information of the subscriber and a translation of the identification information of the network element of the third party. For example, when NEF sends the SUPI of a subscriber from the carrier network to a third party, the SUPI may be translated into its corresponding external Identity (ID). Conversely, when NEF sends an external ID (a network element ID of a third party) to the operator network, it can be translated into SUPI. In 5G, the network open network element may be NEF, and in future communications such as 6G, the network open network element may still be NEF, or have another name, which is not limited in this application.

In the present application, the authentication server function network element is a control plane network element provided by an operator. The AUSF may be used for access authentication for the terminal device. In 5G, the authentication server function network element may be an AUSF network element, and in future communications such as 6G, the network open network element may still be an AUSF or have another name, which is not limited in this application.

In this application, the network storage function network element may be configured to discover, for each Network Function (NF), a service provided by another network function, for example, to receive a function discovery request (NF discovery request) sent by the AMF or another NF, and then provide discovered network element information to a requesting network element. The network storage function network element may also maintain (e.g., store, manage, and update) features of an available network element instance and service capability related parameters supported by the available network element instance, such as a network element instance identifier, a network element type, a PLMN, and a network slice related identifier, such as a network slice selection assistance information (S-NSSAI) or a network slice instance identifier, an Internet Protocol (IP) address or domain name of the network element, capability information of the network element, a supported service capability name, and so on. In 5G, the network storage function network element may be NRF, and in future communication such as 6G, the network open network element may still be NRF, or have another name, which is not limited in this application.

In this application, the policy control network element is a control plane function provided by an operator, and is configured to provide a policy of a PDU session to the SMF. The policies may include charging related policies, QoS related policies, authorization related policies, and the like. In 5G, the policy control network element may be a PCF, and in future communications such as 6G, the policy control network element may still be a PCF, or have another name, which is not limited in this application.

In fig. 3, nssf, Nnef, Nausf, nrrf, Npcf, numm, Naf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface serial numbers. The meaning of these interface sequence numbers can be referred to as that defined in the 3GPP standard protocol, and is not limited herein.

For convenience of description, in the following of the present application, RAN equipment is referred to as RAN for short, and terminal equipment is referred to as UE.

It should be understood that the above network device 102 shown in fig. 1 may be used as AN access network device in AN (R) AN in a 5G wireless communication system shown in fig. 3, and the terminal device 101 may access the 5G network through the network device 102, such as accessing a 5G core network and/or accessing a DN. Taking the communication system shown in fig. 3 as AN example, the UE can access the data network via (R) AN, UPF through the PDU session. Wherein, the UPF can be selected by SMF, and the SMF is responsible for the establishment and maintenance of the PDU session. In a scenario where the UE is moving, the UE may select another SMF because it is moving out of the service area of the current SMF. At this time, the SMF that serves the UE before the UE moves may be referred to as a source SMF in this application, and the SMF that may serve the UE after the UE moves may be referred to as a target SMF in this application.

It should be noted that, unless otherwise specified, the same terms in the embodiments of the present application may have the same meaning, and the same steps may be referred to each other, so that no repeated description is provided. In addition, the "need to switch (need to be relocated)" mentioned in the embodiments of the present application may be replaced with "need to be relocated (need to be relocated)".

As shown in fig. 4, the present application provides a communication method, which may include the steps of:

s101: the source SMF sends the first information to the management device.

Here, the source SMF serves the UE, in other words, the source SMF refers to an SMF currently serving the UE. In addition, the UE accesses the DN through the first PDU session, in other words, the UE communicates with the DN through the first PDU session.

Wherein the first information may include at least one of: information indicating a reallocation of SMFs for the UE; information for instructing the management device to determine whether a target SMF of the UE exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the position information of the UE and the identification of the data network accessed by the UE through the first PDU session; or, an identification of the first PDU session.

It should be understood that the first PDU session described herein includes one or more PDU sessions, for example, when one or more PDU sessions may exist between the UPF serving the UE and the UE, which may be referred to as the first PDU session in this application.

Accordingly, the management device receives the first information.

S102: and the management equipment sends second information to the source SMF according to the first information.

Wherein the second information may be used to indicate that there is no target SMF for the UE, or to indicate that the first PDU session is reserved, or to indicate that a re-allocation (reallocation) SMF is not feasible.

Accordingly, the source SMF receives the second information.

By adopting the method provided by the above embodiment, the source SMF receives the second information from the management device, and the second information can be used for indicating that the target SMF does not exist, or indicating that the source SMF reserves the first PDU session, or indicating that the reallocation of the SMF is not feasible, so that the source SMF can determine that the UE cannot be switched to the appropriate target SMF according to the second information, thereby avoiding that the UE tries to switch to the target SMF in a continuous trial and error manner, greatly saving signaling overhead, and also avoiding inserting the intermediate SMF and establishing a user plane with non-optimal path, so as to save signaling overhead.

The above management device may be, for example, an AMF or an NRF in a 5G core network as shown in fig. 3. The above source SMF may be the SMF shown in fig. 3, which serves the UE.

The following is a detailed description of the content that the first information may include.

The above information for indicating the reallocation of the SMF for the UE may specifically be used for indicating that the source SMF is requested to be reallocated. For example, the information may be SMF reallocation requested indication (SMF reallocation requested indication) information. Alternatively, the information may be a specific value of a specific bit in a service message sent by the source SMF to the management device. Illustratively, when a particular bit in the service message is configured as 1 (or 0), the message may be used to indicate that the SMF is to be reallocated for the UE.

The above information indicating that the management apparatus determines whether the target SMF of the UE exists may be specific information. For example, the information may be a particular value of a particular bit in a servitization message sent by the source SMF to the management device. Illustratively, when a specific bit in the service message is configured as 1 (or 0), the message may be used to instruct the management device to determine whether the target SMF of the UE exists.

The above information indicating that a PDU session is reestablished to the same DN may include a cause (cause) value in a servitization message sent by the source SMF to the managing device. Illustratively, when the cause value in the message is configured to be 1 (or 0), the message may be used to indicate that the PDU session is reestablished to the same DN.

The above information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3 may include SSC mode information of the first PDU session. Specifically, when the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the source SMF may carry the SSC mode information in a servicing message sent to the management device. Accordingly, the management apparatus can perform the step shown in S102 after receiving the SSC mode information.

The location information of the UE may include a current PLMN ID, a cell (cell) ID, a Tracking Area Identity (TAI), and the like of the UE. Specifically, the location information of the UE may be used by the management device to determine the current location of the UE, and further determine whether there is a location where the target SMF can support the UE.

The identifier of the data network may be a DNN or an Access Point Name (APN) of the data network. The identification of the data network may be used by the management device to determine the data network currently accessed by the UE to determine whether the target SMF is capable of supporting the data network.

The above identification of the first PDU session may be used to manage the device querying the context of the first PDU session and/or other information related to the first PDU session.

Exemplarily, when the management device comprises the AMF, the above servitization message sent by the source SMF to the management device may be a Namf _ Communication _ N1N2MessageTransfer message. When the management device includes an NRF, the above servitization message sent by the source SMF to the management device may be an nrrf _ NFDiscovery _ Request message. Illustratively, the source SMF is in a service message sent to the managing device.

Optionally, the first information may be carried in a first message, such as a service message sent by the source SMF to the management device. When the first information does not include the identifier of the first PDU session, the first message may also carry the identifier of the first PDU session.

In one possible implementation, the source SMF may perform the steps described above in S101 after determining to switch to the UPF serving the UE and/or determining to switch to the SMF serving the UE. Specifically, when the first PDU session is SCC mode2, the source SMF may execute the step shown in S101 after determining to switch to the UPF providing the service for the UE. When the first PDU session is SCC mode 3, the source SMF may perform the step shown in S101 after determining to switch to the UPF providing the service for the UE and/or determining to switch to the SMF providing the service for the UE.

The second information related to S102 may be carried in a service message sent by the management device to the source SMF. Illustratively, when the management device includes the AMF, the servitization message may be a response message of the Namf _ Communication _ N1N2 MessageTransfer. When the management device includes an NRF, the service message may be a response message of nrrf _ NFDiscovery.

In addition, the second information may also include a positive (true) or negative (false) indication. E.g., cell configured to true, indicates that SMF is requested for reallocation. When the cell is configured as false, it indicates that the SMF does not need to be reallocated.

When the second information is used to indicate that the target SMF of the UE does not exist, a value of a specific bit in a serving message sent by the management device to the source SMF may be configured to be a specific value to indicate that the target SMF of the UE does not exist; or, in the specific indication information of the service message sent by the management device to the source SMF, the value of a specific bit is configured to be a specific value, so as to indicate that the target SMF of the UE does not exist. For example, when a specific bit of certain indication information in the serving message is configured as 1 (or 0), the message is used to indicate that the target SMF of the UE does not exist.

When the second information is used to indicate that the first PDU session is reserved, a value of a specific bit in a servitization message sent by a management device to a source SMF may be configured to be a specific value to indicate that the first PDU session is reserved; or, in the specific indication information of the servitization message sent by the management device to the source SMF, the value of a specific bit is configured to be a specific value to indicate that the first PDU session is reserved. For example, when a specific bit of some indication information in the servitization message is configured as 1 (or 0), the message is used to indicate that the first PDU session is reserved.

When the second information is used to indicate that the reallocation SMF is not feasible, a value of a specific bit in a servitization message sent by the management device to the source SMF may be configured as a specific value to indicate that the reallocation SMF is not feasible; or, in the specific indication information of the service message sent by the management device to the source SMF, the value of the specific bit is configured to be a specific value to indicate that it is not feasible to reallocate the SMF. For example, when a particular bit in the service message is configured to be 1 (or 0), the message is used to indicate that it is not feasible to reallocate SMF.

The target SMF of the UE referred to in S102 above may refer to an SMF of an identification of a data network supporting the UE access and a location of the UE. The identifier supporting the data network, which may also be referred to as a data network supporting the UE, refers to that the target SMF supports establishing a PDU session accessed to a specific data network, or that the target SMF supports the PDU session to be connected to a specific DN, where the specific data network is the data network accessed by the UE through the first PDU session. The location supporting the UE means that the service area of the target SMF contains the location where the UE is currently located.

In a possible implementation manner of S102, the management device may determine whether the target SMF exists according to the first information, and send the second information according to a determination result.

Specifically, if the management device determines that the target SMF does not exist, the management device may send the second information in S102 to the source SMF. If the management device determines that the target SMF exists, the management device may send second information to the source SMF, where the second information may include information of the target SMF, such as an identifier of the target SMF, and the AMF may carry the information of the target SMF in the second information and send the second information to the source SMF. Alternatively, if the management device determines that the target SMF exists, the management device may send second information indicating that the target SMF exists to the source SMF. Or, if the management device determines that the target SMF exists, the management device may not send the second information, and the source SMF does not receive the second information after sending the first information, or does not receive the second information within the first time period, and the source SMF determines that the target SMF exists. Specifically, the source SMF may start a timer after transmitting the first message, and perform timing for a first duration. The first duration may be configured by the network side, or defined by a protocol, or stored in the source SMF in a preconfigured manner.

For example, if the management device is an AMF, the management device may send a Non Access Stratum (NAS) message to the UE after determining that the target SMF exists. The NAS message may include a PDU session modification command (PDU session modification command).

For example, the management device may determine whether the target SMF exists according to the SMF information stored in the management device, the location information of the UE, and the identifier of the data network. Wherein the SMF information includes an identification of a data network supported by the SMF and information of a service area. Specifically, when the identifier of the data network supported by the SMF includes an identifier of the data network accessed by the UE through the first PDU session, and the service area supported by the SMF includes the location of the UE indicated by the location information of the UE, the management device may determine that the SMF supports the identifier of the data network and the location of the UE, and then the management device determines that the target SMF exists. And if the management equipment determines that the SMF supporting the identifier of the data network and the position of the UE does not exist, the management equipment judges that the target SMF does not exist. It should be understood that the management device described herein includes AMF or NRF.

Wherein the location information of the UE and the identity of the data network may be carried in the first information. Alternatively, when the first information does not include the location information of the UE and the identifier of the data network, the management device may obtain the location information of the UE and the identifier of the data network from the context of the first PDU session. Wherein the management device can look up the context of the first PDU session according to the identity of the first PDU session. The identifier of the first PDU session may be sent by the source SMF together with the first information in the same message or may be sent separately in different messages.

In another possible implementation manner of S102, if the management device is the AMF, the management device may further request the information of the target SMF from the NRF or the SCP according to the first information. In the following, a scheme in which the management device requests information of the target SMF will be specifically described by taking NRF as an example, and if the management device requests information of the target SMF from the SCP, the NRF in the following scheme may be replaced with the SCP.

When the AMF does not successfully receive information from the target SMF of the NRF or receives information from the NRF indicating that there is no target SMF, the AMF may send second information to the source SMF as shown at S102. In addition, if the AMF receives the information of the target SMF from the NRF, the AMF may carry the information of the target SMF in the second information and send the second information to the source SMF, or the AMF may send the second information indicating that the target SMF exists to the source SMF, or the AMF may not send the second information, and the source SMF determines that the target SMF exists within a second time period after sending the first information. Specifically, the source SMF may start a timer after sending the first message, and perform timing of the second duration. The second duration may be configured by the network side, or defined by a protocol, or stored in the source SMF in a preconfigured manner.

For example, when the management device requests the NRF for information of the target SMF according to the first information, the management device may send, to the NRF, the location information of the UE and the identifier of the data network, which are included in the first information. Alternatively, when the first information does not include the location information of the UE and the identity of the data network, the management device may acquire the location information of the UE and the identity of the data network from the context of the first PDU session. Wherein the management device can look up the context of the first PDU session according to the identity of the first PDU session. The identification of the first PDU session may be sent by the source SMF together with the first information in the same message or may be sent separately in different messages.

After receiving the location information of the UE and the identifier of the data network, the NRF may determine whether the target SMF exists according to SMF information stored in the NRF, the location information of the UE received from the AMF, and the identifier of the data network, where the SMF information includes the identifier of the data network and the information of the service area supported by the SMF. The method of the NRF determining whether the target SMF exists may refer to the aforementioned description of the method of the management apparatus determining whether the target SMF exists. If the NRF determines that the target SMF exists, information of the target SMF may be sent to the AMF, or the target SMF may be indicated to the AMF. If the NRF determines that the target SMF does not exist, the NRF may send information to the AMF indicating that the target SMF does not exist.

After the step shown in S102 above, the source SMF may reserve the first PDU session according to the second information. And specifically, when the second information is used for indicating that the target SMF of the UE does not exist, for indicating that the first PDU session is reserved or for indicating that the re-allocation of the SMF is not feasible, the source SMF reserves the first PDU session according to the second information.

The reserving of the first PDU session may refer to the source SMF not releasing session resources of the first PDU session. During the time that the first PDU session is reserved, the UE is not triggered to attempt to establish a new PDU session access through other SMFs to the same data network as the first PDU session access. In addition, if the source SMF determines that the feedback of the management device is not received within a third time period after the first message is sent, e.g., the second message sent by the management device is not received, the source SMF determines that the target SMF does not exist, and thereafter the source SMF may reserve the first PDU session.

Optionally, if the source SMF receives the second information in S102 and/or determines that the target SMF does not exist, the source SMF may further start the timer to time, and after the timer times out, the step shown in S101 is executed again. Alternatively, the source SMF may subscribe to the location information of the UE, and after determining that the UE moves to a new area or moves a threshold distance, re-execute the step shown in S101. Alternatively, when the management device includes an NRF, the source SMF may further subscribe to the NRF and notify the source SMF when the presence target SMF is registered with the NEF, and the source SMF determines that the target SMF is present after receiving the notification of the NRF.

If the SSC mode of the first PDU session is SSC mode2 and the management device determines that the target SMF is present, the management device may instruct the SMF and/or the UE to release the first PDU session.

In a possible implementation manner, when the management device is an AMF, and the management device determines that the target SMF exists, or the AMF serving as the management device receives information of the target SMF from an NRF, the information indicating that the SMF exists or the information of the target SMF may be carried in the second information, and the second information is sent to the source SMF. In response to the second information, the source SMF may trigger release of the first PDU session. It should be understood that the source SMF may trigger the release of the first PDU session immediately after receiving the second message, or may start the timing of the first timer after receiving the second message, and trigger after the timing of the first timer expires.

In addition, if the management device is the AMF, when determining that the target SMF exists, or the AMF serving as the management device receives information of the target SMF from the NRF, the management device may send a first indication to the UE, where the first indication is used to indicate that the target SMF exists, or carries the information of the target SMF, or is used to indicate the UE to trigger the release of the first PDU session, so that the UE triggers the release of the first PDU session in response to the first indication. It should be understood that the UE may trigger the release of the first PDU session immediately after receiving the first indication, or may start the timing of the second timer after receiving the first indication, and trigger after the timing of the second timer expires.

If the management device is an NRF, after determining that the target SMF exists, the management device may carry information indicating that the SMF exists or information of the target SMF in the second information, and send the second information to the source SMF. In response to the second information, the source SMF may trigger release of the first PDU session. It should be understood that the source SMF may trigger the release procedure of the first PDU session after receiving the second message, or may start the timing of the third timer after receiving the second message, and trigger after the timing of the third timer expires.

After the procedure of releasing the first PDU session is completed, the UE may initiate a process of re-establishing the PDU session connected to the same data network, that is, the data network to which the first PDU session is accessed, based on the re-establishment instruction sent by the AMF. For example, the UE may send a PDU session reestablishment request to the AMF, and the AMF selects an SMF meeting the condition for the UE to reestablish the PDU session, where the SMF selected by the AMF for the UE is the target SMF.

If the SSC mode of the first PDU session is SSC mode 3 and the management device determines that the target SMF is present, the management device may instruct the UE to reestablish the PDU session, the reestablished PDU session accessing the same data network as the first PDU session.

In one possible implementation, when the management device is an AMF, the management device determines that the target SMF exists, or the AMF as the management device receives information of the target SMF from an NRF, a second indication, such as a PDU session modification command, may be sent to the UE, where the second indication is used to instruct the UE to trigger re-establishment of the PDU session. Thereby triggering, by the UE in response to the second indication, re-establishment of a second PDU session, which is connected to the same data network as the first PDU session, after which the UE or the source SMF triggers release of the first PDU session. It should be understood that the AMF may also indicate a fourth timer to the UE, and the UE triggers the release of the first PDU session after the fourth timer expires.

If the management device is an NRF, after determining that the target SMF exists, the management device may carry information indicating that the SMF exists or information of the target SMF in the second information, and send the second information to the source SMF. In response to the second message, the source SMF sends a PDU session modification indication, such as a service message, to the AMF to indicate the presence of the target SMF, or to indicate to the AMF information of the target SMF, or to indicate to the AMF to perform session modification. And the AMF responds to the PDU session modification indication and sends a third indication, such as a PDU session modification command, to the UE, wherein the third indication is used for indicating that the target SMF exists or carrying the information of the target SMF or indicating that the UE triggers the reestablishment of the PDU session. Thereby triggering, by the UE, establishment of a second PDU session in response to the third indication. It should be understood that the AMF may also indicate a fifth timer to the UE, and the UE triggers the release of the first PDU session after the fifth timer expires.

As shown in fig. 4A, the present application provides another communication method that may include the following steps.

S101 a: the source SMF sends the first information to the management device.

The source SMF provides service for the UE, the UE accesses a data network through a first PDU session, the first information is used for determining whether a target SMF exists, and the target SMF supports the identification of the data network and the position of the UE.

Accordingly, the management device receives the first information.

S102 a: and the management equipment sends third information to the source SMF according to the first information.

Wherein the third information is used for indicating whether a target SMF of the UE exists.

Accordingly, the source SMF serving the UE may receive the third information transmitted by the management device, and based on the third information, the source SMF may determine whether the target SMF of the UE exists.

Accordingly, the source SMF receives the third information.

By adopting the method provided by the above embodiment, the source SMF receives the third information from the management device, and the third information can be used to indicate whether the target SMF exists, so that the source SMF can determine whether the UE can be switched to the appropriate target SMF according to the third information, and when the target SMF does not exist, the UE cannot be switched to the appropriate target SMF, so that the UE can be prevented from attempting to switch to the target SMF in a continuous trial and error manner, and signaling overhead is greatly saved.

The above management device may be, for example, AMF or NRF in a 5G core network as shown in fig. 3. The above source SMF may be the SMF shown in fig. 3, which serves the UE.

For the specific content of the first information, reference may be made to the description of the first information in the embodiments of the present application.

Prior to implementation at S101a, the source SMF may determine a UPF that needs to be switched to service the UE and/or determine an SMF that needs to be switched to service the UE.

Illustratively, the source SMF may also send an identification of the first PDU session to the managing device. Wherein the identifier of the first PDU session may be carried in the same message as the first information, for example, a service message.

For example, when the third information is used to indicate that the target SMF of the UE exists, the source SMF may release the first PDU session according to the existing flow of the relevant protocol, and perform a SMF handover or insert an intermediate SMF for re-establishing the first PDU session. When the third information is used for indicating that the target SMF of the UE does not exist, the source SMF can reserve the first PDU session, and service interruption of the UE caused by releasing the first PDU session is avoided.

In the implementation of S102a, if the management device is an AMF or an NRF, the management device may determine whether a target SMF of the UE exists according to the first information, and when the management device determines that the target SMF exists, the management device may send the third information to the source SMF, where the third information is used to indicate that the target SMF exists; or, when the management device determines that the target SMF does not exist, the management device sends the third information to the source SMF, where the third information is used to indicate that the target SMF does not exist.

In addition, when the target SMF of the UE exists, the third information may include information of the target SMF, and the source SMF may determine that the target SMF of the UE exists according to the information of the target SMF. The third information may include information of the target SMFs, or information of one of the target SMFs.

For example, the management device may determine whether a target SMF of the UE exists when determining that the first information includes information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, information indicating that the management device determines whether the target SMF exists, information indicating that the SMF is reallocated for the UE, or information indicating that the PDU session is reestablished to the same DN.

When the first information does not include the location information of the UE and the identifier of the data network, and when determining whether the target SMF of the UE exists, the management device may obtain the location information of the UE and the identifier of the data network from the context of the first PDU session, and determine whether the target SMF exists according to the SMF information stored by the management device, the location information of the UE, and the identifier of the data network, where the SMF information includes the identifier of the data network supported by the SMF and information of the service area of the SMF.

When the first information includes location information of the UE and an identifier of the data network, and when determining whether the target SMF of the UE exists, the management device may determine whether the target SMF exists according to the SMF information stored by the management device, the location information of the UE included in the first information, and the identifier of the data network included in the first information, where the SMF information includes an identifier of a data network supported by the SMF and information of a service area of the SMF.

In the implementation of S102a, if the management device is the AMF, the management device may further request the NRF for information of the SMF satisfying a specific condition according to the first information. When the management device receives information of the SMF satisfying the specific condition from the NRF, the management device transmits third information to the source SMF, wherein the third information is used for indicating that the target SMF exists or comprises information of the SMF satisfying the specific condition from the NRF. Or, when the management device does not receive the SMF information satisfying the specific condition from the NRF, or the management device receives indication information indicating that there is no SMF satisfying the specific condition from the NRF, the management device sends third information to the source SMF, where the third information indicates that there is no target SMF.

The above specific conditions may include: SMF supports UEs in specific locations and SMF supports specific DNs (or DNNs).

For example, if the management device is an AMF, when the management device may further request the NRF for information of an SMF that satisfies a specific condition according to the first information, the management device may send location information of the UE and an identifier of the data network to the NRF, so that the NRF determines whether there is an SMF that satisfies the specific condition according to the location information of the UE and the identifier of the data network. When there is location information supporting the UE and the SMF of the data network, i.e., there is a target SMF of the UE. The NRF may refer to the description in the embodiment of the present application, and may determine whether there is an SMF satisfying a specific condition according to the location information of the UE and the identifier of the data network.

For example, the AMF may send the location information of the UE and the identity of the data network, which are included in the first information, to the NRF. Alternatively, the AMF may acquire the location information of the UE and the identity of the data network from the context of the first PDU session, and transmit the location information of the UE and the identity of the data network to the NRF. Specifically, the AMF may obtain the context of the first PDU session according to the identifier of the first PDU session.

For example, if the management device is an AMF, the AMF may send an NAS message to the UE when determining that the target SMF of the UE exists. The NAS message may be configured as described in this application.

As shown in fig. 5, the present application provides another communication method, which takes the SCC mode of the first PDU session as SCCmode 2 and the management device as AMF for example. The method specifically comprises the following steps:

s201: the source SMF determines the UPF that needs to be switched to service the UE.

Wherein the source SMF serves the UE, and the UE accesses the data network through the first PDU session. The UPF1 serves the first PDU session, in other words, communications between the UPF1 and the UE are through the first PDU session.

S202: the source SMF sends first information to the AMF.

The first information can be carried in a service message.

The first information may include information indicating to reallocate an SMF for the UE, information indicating to the AMF to determine whether a target SMF of the UE exists, information indicating to the PDU session to be reestablished to the same DN, information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, location information of the UE and an identifier of the data network, or at least one of the identifier of the first PDU session.

S203: and the AMF judges whether the target SMF of the UE exists or not according to the first information.

Illustratively, the target SMF of the UE supports the location of the UE and the DNN of the data network that supports access of the UE over the first PDU session (or, alternatively, the data network that supports access of the UE over the first PDU session). When the first information includes the location information of the UE and the identifier of the data network, the AMF may determine whether the target SMF exists according to the SMF information stored in the AMF, the location information of the UE included in the first information, and the identifier of the data network. When the first information does not include the location information of the UE and the identifier of the data network, the AMF may query the context of the first PDU session, obtain the location information of the UE and the identifier of the data network from the context, and determine whether the target SMF exists according to the SMF information stored in the AMF, the location information of the UE and the identifier of the data network.

It should be noted that steps S204-S207 are optional steps, for example, when the AMF determines that there is no target SMF for the UE, steps S204 and S205 are executed; alternatively, when the AMF determines that the target SMF of the UE exists, steps S206-S207 are performed.

It should be noted that when the AMF determines that there is no target SMF of the UE, the AMF may not send the second information to save signaling, and S204 and S205 are optional steps. Correspondingly, if the source SMF does not receive the second information, the first PDU session is reserved.

S204: the AMF sends second information to the source SMF.

Wherein the second information may be used to indicate that there is no target SMF for the UE, or to indicate that the first PDU session is reserved, or to indicate that it is not feasible to reallocate SMFs.

In addition, the second information may be carried in a service message without limitation.

S205: the source SMF reserves the first PDU session according to the second information.

Wherein the second information may be used to indicate that there is no target SMF for the UE, or to indicate that the first PDU session is reserved, or to indicate that it is not feasible to reallocate SMFs. The remaining steps of the flow may not be performed thereafter.

S206: the AMF sends information of the target SMF or information indicating the presence of the target SMF to the source SMF.

The information of the target SMF may be used to indicate the target SMF, e.g., an identification of the SMF.

In addition, information of the target SMF or information indicating the presence of the target SMF may be carried in the servitization message.

S207: the source SMF triggers the release of the first PDU session based on information of the target SMF, or information indicating the presence of the target SMF.

Wherein, S207 is an optional step, and S207 may be replaced with: the UE triggers the release of the first PDU session. For example, a first indication is sent by the AMF to the UE, and a release of the first PDU session is triggered by the UE based on the first indication.

Optionally, the method further comprises steps S208-S209.

S208: in the release process of the first PDU session, the AMF sends a re-establishment indication to the UE.

S209: and the UE triggers the establishment process of the second PDU session according to the reestablishment indication.

Wherein the second PDU session is accessed to the same data network as the first PDU session.

The SMF serving the second PDU session may be the target SMF mentioned in step S203, or may be an SMF selected for the UE by the prior art, and the UPF serving the second PDU session may be a UPF2 different from the UPF1, or may be a UPF 1.

Illustratively, before the above step S201, if the source SMF has transmitted information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3 to the AMF, the first information may not include information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the first information may include an identification of the first PDU session, and the AMF may determine whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3 according to the identification of the first PDU session in S202. For example, in the setup process of the first PDU session, the AMF acquires the SSC mode information of the first PDU session from the SMF, and the AMF may query the SSC mode information of the first PDU session according to the identification of the first PDU session included in the first information received in step S202 to determine whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3. When determining whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the AMF may determine whether a target SMF of the UE exists.

The AMF involved in the above flow shown in fig. 5 may be, for example, the AMF in the 5G core network shown in fig. 3. The access network equipment involved in the above flow shown in fig. 5 may be a RAN in a 5G core network as shown in fig. 3. The UPFs 1 and 2 involved in the flow shown in fig. 5 above may be UPFs in a 5G core network as shown in fig. 3. The above source SMF, as well as the target SMF, may be the SMF shown in fig. 3.

As shown in fig. 6, the present application provides another communication method, and this method takes an SCC mode of a first PDU session as SCC mode2 and a management device as NRF as an example for description. The method specifically comprises the following steps:

s301: the source SMF determines the UPF that needs to be switched to service the UE.

S302: the source SMF sends the first information to the NRF.

Wherein the first information may be carried in a service message.

S303: and the NRF judges whether the target SMF of the UE exists or not according to the first information.

It should be noted that steps S304-S306 are optional steps, for example, when the NRF determines that there is no target SMF of the UE, steps S304 and S305 are executed; alternatively, when the NRF determines that the target SMF of the UE exists, step S306 is performed.

It should be noted that when the NRF determines that there is no target SMF for the UE, the NRF may not send the second information to save signaling, and S304 and S305 are optional steps. Correspondingly, if the source SMF does not receive the second information, the first PDU session is reserved.

S304: the NRF sends the second information to the source SMF.

S305: the source SMF reserves the first PDU session according to the second information.

S306: the NRF sends information of the target SMF or information indicating the presence of the target SMF to the source SMF.

S307: the source SMF triggers the release of the first PDU session based on information of the target SMF or information indicating the presence of the target SMF.

Optionally, the method further comprises steps S308-S309.

S308: in the release process of the first PDU session, the AMF sends a re-establishment indication to the UE.

S309: and the UE triggers the establishment flow of the second PDU session according to the reestablishment indication.

Wherein the second PDU session is accessed to the same data network as the first PDU session. The SMF serving the second PDU session may be the target SMF mentioned in step S203, or may be the SMF selected for the UE by the prior art, and the UPF serving the second PDU session may be a UPF2 different from the UPF1, or may be a UPF 1.

For example, the AMF involved in the above flow shown in fig. 6 may be an AMF in a 5G core network as shown in fig. 3. The NRF involved in the above flow shown in fig. 6 may be an NRF in a 5G core network as shown in fig. 3. The access network equipment involved in the above flow shown in fig. 6 may be a RAN in a 5G core network as shown in fig. 3. The UPFs 1 and 2 involved in the flow shown in fig. 6 above may be UPFs in a 5G core network as shown in fig. 3. The source SMF and the target SMF involved in the flow shown in fig. 6 above may be SMFs as shown in fig. 3.

As shown in fig. 7, the present application provides another communication method, which takes the SCC mode of the first PDU session as SCC mode 3, and takes the management device as AMF for example. The method specifically comprises the following steps:

s401: the source SMF determines a UPF which needs to be switched to provide service for the UE, and/or the source SMF determines an SMF which needs to be switched to provide service for the UE.

S402: the source SMF sends first information to the AMF.

The first information can be carried in the service message.

The first information may include information indicating to reallocate an SMF for a UE, information indicating to the AMF to determine whether a target SMF of the UE exists, information indicating to the same DN a PDU session re-establishment, information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3, location information of the UE and an identity of the data network, or at least one of the identity of the first PDU session.

S403: and the AMF judges whether the target SMF of the UE exists or not according to the first information.

It should be noted that steps S404-S407 are optional steps, for example, when the AMF determines that the target SMF of the UE does not exist, steps S404 and S405 are executed; alternatively, when the AMF determines that the target SMF of the UE exists, steps S406-S407 are performed.

It should be noted that when the AMF determines that there is no target SMF of the UE, the AMF may not send the second information to save signaling, and S404 and S405 are optional steps. Correspondingly, if the source SMF does not receive the second information, the first PDU session is reserved.

S404: the AMF sends the second information to the target SMF.

S405: and the source SMF reserves the first PDU session according to the second information.

S406: the AMF sends a second indication to the UE.

The second indication may be used to indicate the UE to trigger re-establishment of the PDU session, and then the steps shown in S407 are performed. The above second indication may be a PDU session modification command.

Optionally, the second indication is further used for indicating a fourth timer.

S407: and the UE triggers the establishment of the second PDU session according to the second indication.

Wherein the second PDU session is connected to the same data network as the first PDU session. The SMF serving the second PDU session may be the target SMF mentioned in step S203, or may be the SMF selected for the UE by the prior art, and the UPF serving the second PDU session may be a UPF2 different from the UPF1, or may be a UPF 1.

Optionally, the method further includes steps S408-S409.

S408: the UE triggers the release of the first PDU session.

For example, if the second indication is further used to indicate a fourth timer, the UE triggers the release of the first PDU session after the fourth timer expires.

This step is optional and is not performed when the second indication does not indicate the fourth timer.

S409: the source SMF triggers the release of the first PDU session.

For example, after the source SMF performs the step shown in S402, if the second information is not received within the first duration, the source SMF triggers the release of the first PDU session.

This step is an optional step.

It should be understood that S408 and S409 may be performed separately, and these two steps may not interfere with each other.

For example, before the above step S401, if the source SMF has transmitted information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3 to the AMF, in S402, the first information may not include information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the first information may include an identification of the first PDU session, and the AMF may determine whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3 according to the identification of the first PDU session. For example, in the setup process of the first PDU session, the AMF acquires SSC mode information of the first PDU session from the SMF, and the AMF may query the SSC mode information of the first PDU session according to the identification of the first PDU session included in the first information received in step S402 to determine whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3. When determining whether the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the AMF may determine whether there is a target SMF of the UE.

For example, the AMF involved in the above flow shown in fig. 7 may be an AMF in a 5G core network as shown in fig. 3. The access network equipment involved in the above flow shown in fig. 7 may be a RAN in a 5G core network as shown in fig. 3. The UPFs 1 and 2 involved in the flow shown in fig. 7 above may be UPFs in a 5G core network as shown in fig. 3. The source SMF and the target SMF involved in the flow shown in fig. 7 above may be SMFs as shown in fig. 3.

As shown in fig. 8, the present application provides another communication method, which takes an SCC mode of a first PDU session as SCC mode 3 and a management device as NRF for example. The method specifically comprises the following steps:

s501: the source SMF determines a UPF which needs to be switched to provide service for the UE, and/or the source SMF determines an SMF which needs to be switched to provide service for the UE.

S502: the source SMF sends the first information to the NRF.

S503: the NRF determines whether a target SMF of the UE exists according to the first information.

It should be noted that steps S504-S507 are optional steps, for example, when the NRF determines that there is no target SMF for the UE, steps S504 and S505 are executed; alternatively, when the NRF determines that the target SMF of the UE exists, steps S506 to S507 are performed.

It should be noted that when the NRF determines that there is no target SMF for the UE, the NRF may also not send the second information to save signaling, and S504 and S505 are optional steps. Correspondingly, if the source SMF does not receive the second information, the first PDU session is reserved.

S504: the NRF sends the second information to the source SMF.

S505: the source SMF reserves the first PDU session according to the second information.

S506: the NRF sends the source SMF information of the target SMF, or information indicating the presence of the target SMF.

S507: and the source SMF sends a PDU session modification indication to the AMF according to the information of the target SMF or the information for indicating the existence of the target SMF.

Wherein, the PDU session modification indication is used for indicating the modification process triggering the first PDU session.

Illustratively, after the SMF sends the PDU session modification indication to the AMF, the SMF receives a reception response sent by the AMF.

S508: and the AMF sends a third indication to the UE according to the PDU session modification indication.

S509: and the UE triggers the establishment of the second PDU session according to the third indication.

Wherein the second PDU session is connected to the same data network as the first PDU session.

The SMF serving the second PDU session may be the target SMF mentioned in step S203, or may be the SMF selected for the UE by the prior art, and the UPF serving the second PDU session may be the UPF2 different from the UPF1, or may be the UPF 1.

Optionally, the method further comprises steps S510-S511.

S510: the UE triggers the release of the first PDU session. For example, if the third indication is further used to indicate a fifth timer, the UE triggers the release of the first PDU session after the fifth timer expires.

This step is optional and is not performed when the third indication does not indicate the fifth timer.

S511: the source SMF triggers the release of the first PDU session. For example, after performing the step shown in S506, the source SMF starts the counting of the PDU session duration timer, and triggers the release of the first PDU session after the timer expires.

This step is an optional step, and when the step shown in S509 is performed, the step shown in S510 may not be performed.

For example, the AMF involved in the above flow shown in fig. 8 may be an AMF in a 5G core network as shown in fig. 3. The NRF involved in the above flow shown in fig. 8 may be an NRF in a 5G core network as shown in fig. 3. The access network equipment involved in the above flow shown in fig. 8 may be a RAN in a 5G core network as shown in fig. 3. The UPFs 1 and 2 involved in the flow shown in fig. 8 above may be UPFs in a 5G core network as shown in fig. 3. The source SMF and the target SMF involved in the flow shown in fig. 8 above may be SMFs as shown in fig. 3.

Illustratively, S203 or S403 above may also be replaced by the following steps shown in fig. 9:

s601: and the AMF sends the position information of the UE and the identification of the data network to the NRF according to the first information.

Accordingly, the NRF receives location information of the UE and an identification of the data network.

S602: the NRF determines whether a target SMF supporting the data network and the position exists according to the stored information of the SMF, the position information of the UE and the identification of the data network.

It should be noted that steps S603 and S604 are optional steps, for example, when the NRF determines that the target SMF exists, S603 is executed, and when the NRF determines that the target SMF does not exist, S604 is executed.

S603: the NRF sends information of the target SMF to the AMF, or the NRF indicates the AMF that the target SMF exists.

S604: NRF indicates AMF does not have the target SMF.

It should be understood that in the flow shown in fig. 9 above, NRF may be replaced with SCP.

In addition, the management device according to the embodiment of the present application may further include the UE.

For example, the UE may store information of the service area of the SMF supporting each data network, or the UE may obtain information of the service area of the SMF supporting each data network from a network side (e.g., a PCF network element), e.g., the UE updates a UE routing policy (URSP) according to an indication of the PCF, including obtaining information of the service area of the SMF supporting each data network. Specifically, the information of the service area of the SMF supporting each data network may be represented as a correspondence between the data network and the SMF supporting the data network and the service area of the SMF, for example, a correspondence between DNN, an identifier of the SMF, and the service area of the SMF. It should be understood that the UE may determine whether there is an SMF supporting the current location of the UE and each data network, based on the information of the service area of the SMF supporting each data network.

Illustratively, the information of the service area of the SMF supporting each data network may be obtained by updating a sub-entry of the SSC mode selection entries configured in the URSP. Alternatively, The information of The service area supporting The SMF of each data network may be obtained by updating an entry configured in parallel with an SSC mode selection (SSC mode selection) entry, such as adding The SMF service area of DNN parameter to The URSP for carrying The information.

As shown in fig. 10, the present application provides another communication method, which takes the SCC mode of the first PDU session as SCC mode2 and takes the management device as AMF for example. The method specifically comprises the following steps:

s701: the source SMF determines the UPF that needs to be switched to service the UE.

S702: the source SMF sends information to the AMF indicating the release of the first PDU session.

Wherein the information may be carried in a service message.

S703: the AMF transmits a PDU session release command (PDU session release command) to the UE.

S704: the UE determines whether the target SMF exists according to information of a service area supporting the SMF of each data network.

The information of the service area supporting the SMF of each data network may be stored in the UE, or before S704, the UE may update the URSP of the UE through a PCF policy association procedure or a UE configuration update procedure to obtain the information of the service area supporting the SMF of each data network. The target SMF supports the current location of the UE and supports the data network with the same DNN as the data network to which the first PDU session is accessed. In addition, the UE may also send a query request to the AMF and/or NRF to request the AMF and/or NRF to determine whether the target SMF is present.

Thereafter, the remaining steps of the first PDU session release procedure may be performed, specifically referring to the existing protocol.

It should be noted that steps S705-S707 are optional steps, for example, when the UE determines that the target SMF exists, step S705 is executed; alternatively, when the UE determines that the target SMF does not exist, steps S706-S707 are performed.

S705: the UE triggers the establishment of a second PDU session, which is connected to the same data network as the first PDU session.

S706: the UE sends a response message to the AMF.

Wherein the response message may carry information indicating that the target SMF is not present.

Wherein this step may be performed in the remaining steps of the first PDU session release procedure, in other words, the response message may be a response message in the remaining steps of the first PDU session release procedure.

This step is optional, and S707 may be executed when S706 is not executed.

S707: the UE initiates a session establishment procedure on the original path, that is, the UE initiates a PDU session establishment procedure of which the path includes the source SMF and the UPF 1.

The set-up flow may be inserted into an intermediate SMF, connected by the AMF to the I-SMF, and connected by the I-SMF to the source SMF.

For example, the AMF involved in the flow shown in fig. 10 above may be an AMF in a 5G core network as shown in fig. 3. The access network equipment involved in the above flow shown in fig. 10 may be a RAN in a 5G core network as shown in fig. 3. The UPFs 1 and 2 involved in the flow shown in fig. 10 above may be UPFs in a 5G core network as shown in fig. 3. The source SMF and the target SMF involved in the above flow shown in fig. 10 may be SMFs as shown in fig. 3.

As shown in fig. 11, the present application provides another communication method, which takes the SCC mode of the first PDU session as SCC mode 3, and takes the management device as AMF for example. The method specifically comprises the following steps:

s801: the source SMF determines a UPF which needs to be switched to provide service for the UE, and/or the source SMF determines an SMF which needs to be switched to provide service for the UE.

S802: the source SMF sends information to the AMF indicating the release of the first PDU session.

Wherein the information may be carried in a service message.

S803: the AMF sends a PDU session release command to the UE.

S804: and the UE judges whether the target SMF exists according to the information of the service area of the SMF supporting each data network.

Here, the information of the service area supporting the SMF of each data network may be stored in the UE, or the UE acquires the information of the service area supporting the SMF of each data network from the PCF before S804. The target SMF supports the current location of the UE and supports the data network with the same DNN as the data network to which the first PDU session is accessed. In addition, the UE may also send a query request to the AMF and/or NRF to request the AMF and/or NRF to determine whether the target SMF is present.

It should be noted that steps S805-S809 are optional steps, for example, when the UE determines that the target SMF exists, steps S805 and S806 are executed; alternatively, when the UE determines that the target SMF does not exist, steps S807-S809 are performed.

S805: and the UE initiates a second PDU session establishment flow and establishes a second PDU session through the target SMF.

S806: the first PDU session is released.

Wherein the first PDU session may be released by the UE or the source SMF.

S807: the UE sends indication information to the AMF.

For example, the indication information may be carried in a PDU session setup request message in the PDU session setup procedure, and the indication information may be used to indicate that the target SMF is not present or to indicate that the first PDU session is reserved.

S808: the AMF sends the indication to the source SMF.

S809: and the source SMF reserves the first PDU session according to the indication information.

Illustratively, if the indication information is carried in a PDU session establishment request message in the PDU session establishment procedure, the source SMF may also reject to establish the second PDU according to the PDU session establishment request according to the indication information.

For example, the AMF involved in the above flow shown in fig. 11 may be an AMF in a 5G core network as shown in fig. 3. The access network equipment involved in the above flow illustrated in fig. 11 may be a RAN in a 5G core network as illustrated in fig. 3. The UPFs 1 and 2 involved in the above flow shown in fig. 11 may be UPFs in a 5G core network as shown in fig. 3. The source SMF and the target SMF involved in the above flow shown in fig. 11 may be SMFs as shown in fig. 3.

Based on the same inventive concept as the above method embodiment, an embodiment of the present application further provides a communication apparatus, which may have the functions of one or more of the session management function network element (including the SMF described in the above method embodiment) or the management device (including the AMF or NRF described in the above method embodiment) in the above method embodiment, and may be configured to perform the corresponding steps provided by the above method embodiment. The functions can be realized by hardware, and can also be realized by software or hardware to execute corresponding software. The hardware or software includes one or more modules corresponding to the above-described functions.

As shown in fig. 12, a communication apparatus 1200 is provided, and the communication apparatus 1200 may be configured to execute the steps of the source SMF in the foregoing method embodiments. The communication apparatus 1200 may be an SMF, or a chip or a system on a chip on an SMF, or may be a functional module.

As shown in fig. 12, the communication apparatus 1200 includes: a communication module 1201 and a processing module 1202.

The communication module 1201 and the processing module 1202 are coupled to each other.

The communication module 1201 can be used to support the communication device 1200 for communication, and the processing module 1202 can be used to perform processing operations on the communication device 1200, such as generating information/message to be transmitted or processing the signal received by the communication module 1201 to obtain the information/message.

In executing the embodiment of the method shown in fig. 4, the communication module 1201 may be configured to send a first message to the management device, and the communication apparatus 1200 provides a service for a terminal device, where the terminal device accesses the data network DN through a first protocol data unit PDU session; the communication module 1201 may be further configured to receive second information from the management device, where the second information is used to indicate that there is no target SMF for the terminal device, or used to indicate that the first PDU session is reserved, or used to indicate that it is not feasible to reallocate SMFs;

wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode SSCmode of the first PDU session SSCmode 2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

The above target SMF supports the identification of the DN and the location of the terminal device.

The above second information includes information of the target SMF.

The above information for indicating the reallocation of the SMF to the terminal device is an SMF reallocation requested indication for indicating that the source SMF is requested to be reallocated.

The processing module 1202 may be configured to reserve the first PDU session according to the second information.

The processing module 1202 may be further configured to determine a user plane function UPF for switching to provide a service for the terminal device, and/or determine an SMF for switching to provide a service for the terminal device.

The above management device is an AMF or a network storage function NRF.

The first information is carried in a first message, and the first message further includes an identifier of the first PDU session.

In addition, when the flow shown in fig. 4A is executed, the communication module 1201 may be configured to send first information to a management device, where the source SMF provides a service for a terminal device, the terminal device accesses a data network through a first PDU session, and the first information is used to determine whether a target SMF exists, where the target SMF supports an identifier of the data network and a location of the terminal device; the communication module 1201 may also receive second information from the management device, the second information indicating whether the target SMF exists.

When the second information indicates that the target SMF is not present, the processing module 1202 may reserve the first PDU session; alternatively, the processing module 1202 may trigger the release of the first PDU session when the second information indicates that the target SMF exists.

The above second information may include information of the target SMF.

The processing module 1202 may determine to switch to the UPF providing the service for the terminal device, and/or determine to switch to the SMF providing the service for the terminal device, and before the communication module 1201 sends the first information to the management device, the method further includes:

the above first information may include at least one of the following information: information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; or, information for instructing the management device to determine whether the target SMF of the terminal device exists; or, the information is used for indicating to reallocate the SMF for the terminal equipment; or, information for indicating that the PDU session is reestablished to the same DN; or, the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

The above management device includes AMF or NRF.

It should be understood that the communication device 1200 described above may also be comprised of hardware components. When formed of hardware components, the communication device may include a communication interface 1501, memory, and a processor, among other components, coupled to each other.

As shown in fig. 13, another communication apparatus 1300 is provided. The communication device 1300 may be configured to perform the steps as the source SMF in the above-described method embodiments.

For ease of understanding, fig. 13 only shows the structure necessary to perform the method shown in the present application, which does not limit the communication apparatus to have more components. The communication apparatus 1300 includes a communication interface 1301, a memory 1302, and a processor 1303.

Communication interface 1301 may be used, among other things, for a communication device to communicate, such as to transmit or receive signals.

The memory 1302 is coupled to the processor 1303, and the memory 1302 stores programs and data necessary for the communication apparatus 1300 to implement the respective functions.

Processor 1303 is configured to enable communication apparatus 1300 to perform corresponding processing functions in the above-described methods, such as generating information and messages sent by communication interface 1301, and/or demodulating and decoding signals received by communication interface 1301, and so on. The memory 1302 and the processor 1303 may be integrated or independent.

Specifically, the communication interface 1301 may be an interface in a core network for communication between network elements.

It should be understood that the above memory 1302 may also be external to the communication device 1300, in which case the communication device 1300 may include the communication interface 1301 and the processor 1303.

It should be understood that the above communication interface 1301 may be external to the communication apparatus 1300, and in this case, the communication apparatus 1300 may include the memory 1302 and the processor 1303. When the communication interface 1301 and the memory 1302 are external to the communication apparatus 1300, the communication apparatus 1300 may include a processor 1303.

When the above communication apparatus is implemented by the structure shown in fig. 13, the steps performed by the above processing module 1202 may be executed by the processor 1303, and the steps performed by the above communication module 1201 may be executed by the communication interface 1301. When the communication device 1300 includes the memory 1302, the memory 1302 may be used to store programs for the processor 1303 to execute to perform the steps performed by the processing module 1202 above.

As shown in fig. 14, another communication device 1400 is provided. The communication apparatus 1400 may be configured to perform the steps of managing devices in the above method embodiments, or to perform the steps of AMF and/or NRF in the above method embodiments.

The communication apparatus 1400 includes: a communication module 1401 and a processing module 1402, wherein the communication module 1401 and the processing module 1402 are coupled to each other.

The communication module 1401 may be used to support communication for a communication device, among other things.

The processing module 1402 may be used by the communication device to perform processing operations such as generating information/messages to be transmitted or processing signals received by the communication module 1401 to obtain information/messages.

In performing the method embodiment as described in fig. 4, communications module 1401 may be used to receive first information; a communication module 1401, further configured to send, according to the first information, second information to a source SMF, where the source SMF provides a service for a terminal device, and the terminal device accesses a DN through a first PDU session; wherein the second information is used for indicating that a target SMF of the terminal equipment does not exist, or for indicating that the first PDU session is reserved, or for indicating that the re-allocation of the SMF is not feasible; wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the communication apparatus 1400 to determine whether the target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

The processing module 1402 may be configured to determine that the target SMF does not exist according to the first information, and the communication module 1401 may specifically be configured to: and sending the second information to the source SMF.

The processing module 1402 is specifically operable to: when the first information does not include the location information of the terminal device and the identifier of the DN, obtaining the location information of the terminal device and the identifier of the DN from the context of the first PDU session, and determining that the target SMF does not exist according to SMF information stored by the communication device 1400, the location information of the terminal device and the identifier of the DN, where the SMF information includes the identifier of the DN supported by the SMF and information of a service area; or, when the first information includes the location information of the terminal device and the identifier of the DN, determining that the target SMF does not exist according to the SMF information stored by the communication apparatus 1400, the location information of the terminal device, and the identifier of the DN, where the SMF information includes the identifier of the DN supported by the SMF and information of a service area.

The communications device 1400 is an AMF, and the communications module 1401 is specifically configured to: requesting the target SMF from an NRF according to the first information; when the communication apparatus 1400 does not receive the information of the target SMF from the NRF, or the communication apparatus 1400 receives the information indicating that the target SMF does not exist from the NRF, the second information is transmitted to the source SMF.

The communication module 1401 may specifically be used to: when the first information comprises the position information of the terminal equipment and the identification of the DN, the first information is sent to the NRF; alternatively, the processing module 1402 may be configured to: when the first information does not comprise the position information of the terminal equipment and the identification of the DN, acquiring the position information of the terminal equipment and the identification of the DN from the context of the first PDU session; the communication module 1401 may specifically be used to: and sending the position information of the terminal equipment and the DN identification to the NRF.

The above second information includes information of the target SMF.

The first information is carried in a first message, and the first message also carries an identifier of the first PDU session.

In executing the method shown in fig. 4A, the communication module 1401 is configured to receive first information, and send second information to a source SMF according to the first information, where the second information is used to indicate whether a target SMF of a terminal device exists, and the source SMF provides a service for the terminal device, and the terminal accesses the specified data network through a first PDU session.

The above includes at least one of: information indicating that an SSC mode of the first PDU session is SSC mode2 or SSC mode 3; or, information for instructing the management device to determine whether the target SMF of the terminal device exists; or, the information is used for indicating to reallocate the SMF for the terminal equipment; or, information for indicating that the PDU session is reestablished to the same DN; or, the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

The processing module 1402 may be configured to determine whether the target SMF is present based on the first information; when the processing module 1402 determines that the target SMF exists, the communication module 1401 sends the second information to the source SMF, where the second information indicates that the target SMF exists; alternatively, when the processing module 1402 determines that the target SMF does not exist, the communication module 1401 sends the second information to the source SMF, where the second information is used to indicate that the target SMF does not exist.

When the first information comprises information indicating that the SMF is to be reallocated for the terminal device, the processing module 1402 determines whether the target SMF is present.

When the first information includes information indicating that the SSC mode of the first PDU session is SSC mode2 or SSC mode 3, the processing module 1402 determines whether the target SMF exists.

When the first information includes information indicating that the management device determines whether the target SMF of the terminal device exists, the processing module 1402 determines whether the target SMF exists.

When the first information includes information indicating that a PDU session is reestablished to the same DN, the processing module 1402 determines whether the target SMF is present.

The processing module 1402, upon determining whether the target SMF exists, may obtain location information of the terminal device and an identifier of the data network from a context of the first PDU session; the processing module 1402 determines whether the target SMF exists according to the SMF information stored in the processing module, the location information of the terminal device, and the identifier of the data network, where the SMF information includes the identifier of the data network supported by the SMF and the information of the service area of the SMF.

The above first information may include location information of the terminal device and an identifier of the data network, and when determining whether the target SMF exists according to the first information, the processing module 1402 may determine whether the target SMF exists according to self-stored SMF information, the location information of the terminal device, and the identifier of the data network, where the SMF information includes an identifier of a data network supported by the SMF and information of a service area of the SMF.

The communication module 1401 may further transmit a NAS message to the terminal device when the determination result is that the target SMF exists.

The communication device 1400 is an AMF, and when the communication module 1401 sends the second information to the source SMF according to the first information, the communication module 1401 may request the NRF for the SMF information satisfying the specific condition according to the first information; when the communication module 1401 receives the SMF information satisfying the specific condition from the NRF, the communication module 1401 transmits the second information indicating that the target SMF exists to the source SMF; alternatively, when the communication module 1401 does not receive the SMF information satisfying the specific condition from the NRF, or the communication module 1401 receives the indication information indicating that there is no SMF satisfying the specific condition from the NRF, the communication module 1401 transmits the second information indicating that there is no target SMF to the source SMF.

The communication module 1401 may transmit the location information of the terminal device and the identifier of the data network to the NRF according to the first information when requesting the SMF information satisfying the specific condition from the NRF according to the first information.

When the communication module 1401 transmits the location information of the terminal device and the identifier of the data network to the NRF according to the first information, if the first information includes the location information of the terminal device and the identifier of the data network, the communication module 1401 may transmit the first information to the NRF; alternatively, if the first information includes the identifier of the first PDU session, the processing module 1402 may obtain the location information of the terminal device and the identifier of the data network from the context of the first PDU session, and the communication module 1401 sends the location information of the terminal device and the identifier of the data network to the NRF.

The second information includes information of the target SMF or information of one SMF of the target SMFs.

As shown in fig. 15, another communication apparatus 1500 is provided. The communications apparatus 1500 may be configured to perform the steps of managing devices (e.g., AMF and/or NRF) as in the above-described method embodiments.

For ease of understanding, fig. 15 shows only the structure necessary to perform the method shown in the present application, which does not limit the communication device to have more components. The communication device 1500 includes a communication interface 1501, a memory 1502, and a processor 1503.

The communication interface 1501 may be used for communication devices to communicate, such as for sending or receiving signals, among others.

A memory 1502 is coupled to the processor 1503, and the memory 1502 is used for storing programs and data necessary for the communication apparatus 1500 to realize each function.

The processor 1503 is used for supporting the communication device 1500 to perform corresponding processing functions in the above methods, such as generating information and messages sent by the communication interface 1501, and/or demodulating and decoding signals received by the communication interface 1501. The memory 1502 and the processor 1503 may be integrated or independent.

In particular, the communication interface 1501 may be a wireless transceiver, and may be configured to enable the communication device 1500 to receive and transmit signaling and/or data via wireless or wired means. The communication interface 1501 may also be referred to as a transceiving unit or a communication unit. In addition, the communication interface 1501 may be an interface in a core network for communication between network elements.

It should be understood that the above memory 1502 may also be external to the communication device 1500, in which case the communication device 1500 may include the communication interface 1501 and the processor 1503.

It is to be appreciated that the communication interface 1501 can also be external to the communication device 1500, in which case the communication device 1500 can include the memory 1502 and the processor 1503. The communication device 1500 may include a processor 1503 when the communication interface 1501 and the memory 1502 are external to the communication device 1500.

When the above communication apparatus is implemented by the configuration shown in fig. 15, the steps performed by the above processing module 1402 may be performed by the processor 1503, and the steps performed by the above communication module 1401 may be performed by the communication interface 1501. When the communication device 1500 includes storage 1502, the storage 1502 may be used to store programs for execution by the processor 1503 to perform the steps performed by the processing module 1402 above.

It should be understood that the above description of the components included in the communication device is illustrative, and is merely one possible example, and that the actual implementation may have another configuration. In addition, each component in the above communication apparatus may be integrated into one module, or may exist separately and physically. The integrated module may be implemented in the form of hardware or software functional module, and should not be construed as limited to the structure shown in the above drawings.

Based on the same concept as the method embodiments, embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the computer program causes the computer to perform the operations performed by the source SMF or the management device in any possible implementation manner of the method embodiments and the method embodiments.

Based on the same concept as the method embodiments, the present application also provides a computer program product, which when called by a computer, can enable the computer to implement the operations performed by the source SMF or the management device in any one of the possible implementations of the method embodiments and the method embodiments.

Based on the same concept as the method embodiments, the present application further provides a chip or a chip system, where the chip may be coupled to a transceiver, and is configured to implement the method embodiments and operations performed by the source SMF or the management device in any possible implementation manner of the method embodiments. The chip system may include the chip.

Based on the same concept as the method embodiment, the application also provides a communication system which can comprise the source SMF and/or the management device. The source SMF may be configured to implement the method embodiment and any possible implementation manner of the method embodiment, where the operation is performed by the source SMF. The management device may be used to implement the method embodiment, and the operation performed by the management device in any possible implementation manner of the method embodiment is exemplary, and the communication system has an architecture as shown in fig. 3.

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

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

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

Claims

1. A method of communication, comprising:

a source Session Management Function (SMF) sends first information to a management device, wherein the source SMF provides service for a terminal device, and the terminal device is accessed to a Data Network (DN) through a first Protocol Data Unit (PDU) session;

the source SMF receives second information from the management device, wherein the second information is used for indicating that a target SMF of the terminal device does not exist or indicating that the first PDU session is reserved;

wherein the first information comprises at least one of: information for indicating the reallocation of SMF for the terminal equipment; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session;

the method further comprises the following steps:

and the source SMF reserves the first PDU session according to the second information.

2. The method of claim 1, wherein the target SMF supports an identification of the DN and a location of the terminal device.

3. The method of claim 1 or 2, wherein the second information comprises information of the target SMF.

4. The method of claim 1 or 2, wherein the information indicating reallocation of SMFs for the terminal device is an SMF reallocation requested indication indicating that the source SMF is requested for reallocation.

5. The method of claim 1 or 2, wherein prior to the source SMF sending the first information to the managing device, the method further comprises:

the source SMF determines to switch to a user plane function UPF for providing service for the terminal equipment; and/or the presence of a gas in the atmosphere,

and the source SMF determines to switch to the SMF providing the service for the terminal equipment.

6. Method according to claim 1 or 2, wherein the management device is an access and mobility management function, AMF, or a network storage function, NRF.

7. The method of claim 1 or 2, wherein the first information is carried in a first message, the first message further comprising an identification of the first PDU session.

8. A method of communication, comprising:

the management equipment receives first information;

the management equipment sends second information to a source Session Management Function (SMF) according to the first information, the source SMF provides service for terminal equipment, and the terminal equipment is accessed to a Data Network (DN) through a first Protocol Data Unit (PDU) session;

wherein the second information is used for indicating that a target SMF of the terminal device does not exist or indicating that the first PDU session is reserved;

wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode, SSC mode, of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

9. The method of claim 8, wherein the target SMF supports an identification of the DN and a location of the terminal device.

10. The method of claim 8 or 9, wherein the managing device sending second information to the source SMF based on the first information, comprising:

the management equipment determines that the target SMF does not exist according to the first information;

and the management equipment sends the second information to the source SMF.

11. The method of claim 10, wherein the management device determining that the target SMF does not exist based on the first information, comprising:

when the first information does not include the location information of the terminal device and the identifier of the DN, the management device acquires the location information of the terminal device and the identifier of the DN from the context of the first PDU session, and determines that the target SMF does not exist according to the SMF information stored by the management device, the location information of the terminal device and the identifier of the DN, wherein the SMF information includes the identifier of the DN supported by the SMF and the information of a service area; alternatively, the first and second electrodes may be,

when the first information comprises the position information of the terminal device and the identifier of the DN, the management device determines that the target SMF does not exist according to the SMF information stored by the management device, the position information of the terminal device and the identifier of the DN, and the SMF information comprises the identifier of the DN supported by the SMF and the information of the service area.

12. The method according to claim 8 or 9, wherein the management device is an access and mobility management function, AMF, and wherein the management device sends second information to the source SMF according to the first information, including:

the management equipment requests the target SMF to a network storage function (NRF) according to the first information;

when the management device does not receive the information of the target SMF from the NRF, or the management device receives the information indicating that the target SMF does not exist from the NRF, the management device sends the second information to the source SMF.

13. The method of claim 12, wherein the managing device requesting the target SMF from an NRF based on the first information, comprising:

when the first information comprises the position information of the terminal equipment and the identification of the DN, the management equipment sends the first information to the NRF; alternatively, the first and second electrodes may be,

and when the first information does not comprise the position information of the terminal equipment and the identifier of the DN, the management equipment acquires the position information of the terminal equipment and the identifier of the DN from the context of the first PDU session, and sends the position information of the terminal equipment and the identifier of the DN to the NRF.

14. The method of any of claims 8, 9, 11 or 13, wherein the second information comprises information of the target SMF.

15. The method of any of claims 8, 9, 11 or 13, wherein the first information is carried in a first message, the first message also carrying an identification of the first PDU session.

16. A communications apparatus, comprising:

the communication device is used for providing service for terminal equipment, and the terminal equipment is accessed to a data network DN through a first protocol data unit PDU session;

the communication module is further configured to receive second information from the management device, where the second information is used to indicate that a target session management function SMF of the terminal device does not exist, or is used to indicate that the first PDU session is reserved;

wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the management device to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session;

the communication device further comprises a processing module;

the processing module is configured to reserve the first PDU session according to the second information.

17. The communications apparatus of claim 16, wherein the target SMF supports identification of the DN and a location of the terminal device.

18. The communications apparatus of claim 16 or 17, wherein the second information comprises information of the target SMF.

19. The communications apparatus of claim 16 or 17, wherein the information indicating to reallocate SMFs for the terminal device is an SMF reallocation requested indication, the SMF reallocation requested indication indicating that a source SMF is requested to be reallocated.

20. The communication apparatus according to claim 16 or 17, wherein the communication apparatus further comprises a processing module;

the processing module is used for determining and switching a user plane function UPF for providing service for the terminal equipment; and/or the presence of a gas in the atmosphere,

the processing module is used for determining the SMF for switching to provide service for the terminal equipment.

21. The communication apparatus according to claim 16 or 17, wherein the management device is an access and mobility management function, AMF, or a network storage function, NRF.

22. The communications apparatus of claim 16 or 17, wherein the first information is carried in a first message, the first message further comprising an identification of the first PDU session.

23. A communications apparatus, comprising:

the communication module is used for receiving first information;

the communication module is further configured to send second information to a source session management function SMF according to the first information, where the source SMF provides a service for a terminal device, and the terminal device accesses a data network DN through a first protocol data unit PDU session;

wherein the first information comprises at least one of: information for indicating a reallocation of SMFs for the terminal device; information for instructing the communication apparatus to determine whether a target SMF of the terminal device exists; information for indicating that a PDU session is reestablished to the same DN; information indicating that a traffic and session continuity mode SSC mode of the first PDU session is SSC mode2 or SSC mode 3; the location information of the terminal device and the identification of the DN; or, an identity of the first PDU session.

24. The communications apparatus of claim 23, wherein the target SMF supports an identification of the DN and a location of the terminal device.

25. The communication apparatus according to claim 23 or 24, wherein the communication apparatus further comprises a processing module;

the processing module is used for determining that the target SMF does not exist according to the first information;

the communication module is specifically configured to:

and sending the second information to the source SMF.

26. The communications apparatus as claimed in claim 25, wherein the processing module is specifically configured to:

when the first information does not comprise the position information of the terminal equipment and the identifier of the DN, acquiring the position information of the terminal equipment and the identifier of the DN from the context of the first PDU session, and determining that the target SMF does not exist according to the SMF information stored by the communication device, the position information of the terminal equipment and the identifier of the DN, wherein the SMF information comprises the identifier of the DN supported by the SMF and the information of a service area; alternatively, the first and second electrodes may be,

and when the first information comprises the position information of the terminal equipment and the identifier of the DN, determining that the target SMF does not exist according to the SMF information stored by the communication device, the position information of the terminal equipment and the identifier of the DN, wherein the SMF information comprises the identifier of the DN supported by the SMF and the information of the service area.

27. Communication device according to claim 23 or 24, wherein the communication device is an access and mobility management function, AMF;

the communication module is specifically configured to:

according to the first information, requesting the target SMF from a network storage function (NRF);

when the communication apparatus does not receive the information of the target SMF from the NRF, or the communication apparatus receives the information indicating that the target SMF does not exist from the NRF, the communication apparatus transmits the second information to the source SMF.

28. The communications apparatus as claimed in claim 27, wherein the communications module is specifically configured to:

when the first information comprises the position information of the terminal equipment and the identification of the DN, the first information is sent to the NRF;

alternatively, the first and second electrodes may be,

the communication device further comprises a processing module;

the processing module is used for:

when the first information does not comprise the position information of the terminal equipment and the identification of the DN, acquiring the position information of the terminal equipment and the identification of the DN from the context of the first PDU session;

the communication module is specifically configured to:

and sending the position information of the terminal equipment and the DN identification to the NRF.

29. The communications apparatus of any of claims 23, 24, 26 or 28, wherein the second information comprises information of the target SMF.

30. The communications apparatus of any of claims 23, 24, 26 or 28, wherein the first information is carried in a first message, the first message also carrying an identification of the first PDU session.