Communication method and apparatus

Abstract

The present application relates to the technical field of communications, and provides a communication method and apparatus. A first device obtains first information, the first information being used by the first device to determine to establish a dual-oriented session. A first terminal in the first device may send an establishment request message for a first session (a dual-oriented session), and a second terminal in the first device may send an establishment request message for a second session (a dual-oriented session). The first device determines, on the basis of the first information, that the first device needs to establish a dual-oriented session. Hence, when service data of the first device switches between the first session and the second session, re-establishment of the communication connection is not required, thus reducing switching delay, and ensuring the service experience of a user.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on February 8, 2024, with application number 202410178193.3 and application name "A Communication Method and Device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present application relate to the field of communication technology, and in particular to a communication method and apparatus. Background Art

[0004] With the development of communication technology, future mobile communication devices may include two user equipment (UE) or two universal subscriber identity modules (USIM). The mobile communication device can connect to two radio access networks (RAN) through two UEs (or two USIMs) and transmit service data through the two RANs. Due to service transmission requirements, the service of the mobile communication device may need to be handed over between different UEs. During the handover process, the communication connection needs to be reestablished, which results in long delays and affects the user's service experience. Summary of the Invention

[0005] The present application provides a communication method and apparatus to reduce the UE switching delay and improve the user's service experience.

[0006] In a first aspect, the present application provides a communication method that can be performed by a first device, the first device comprising: a first terminal and a second terminal. The first terminal (or second terminal) can be the terminal itself, or a component in the terminal (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the terminal functions. This application does not specifically limit this.

[0007] This method can be applied to 5G communication systems or communication systems above 5G, and can also be applied to non-terrestrial communication systems, which is not specifically limited in this application. Execution is as follows:

[0008] Obtain first information, where the first information is used by the first device to determine whether to establish a bidirectional session; send a first message, where the first message includes a request message for establishing a first session, where the first session is a bidirectional session and is a session of the first terminal; and send a second message, where the second message includes a request message for establishing a second session, where session parameters of the second session are related to session parameters of the first session, where the second session is a bidirectional session and is a session of the second terminal.

[0009] It should be noted that a dual-directional session can also be referred to as an associated session between UEs. In the present application, the first terminal in the first device can send a request message to establish a first session (dual-directional session), and the second terminal in the first device can send a request message to establish a second session (dual-directional session). Since the first device determines that the first device needs to establish a dual-directional session based on the first information, the network controls the establishment of the dual-directional session. In addition, the session parameters of the second session can be determined with reference to the session parameters of the first session to ensure that the session parameters of the first session and the second session are related or the same, which facilitates session association. Since the session parameters of the second session are related or the same as the session parameters of the first session, when the second terminal creates the second session, there is no need to re-acquire the session parameters of the second session. Based on this, the creation delay of the second session can be reduced, the data processing efficiency can be improved, and the user's service experience can be guaranteed.

[0010] In an optional manner, the first information includes: a route selection descriptor (RSD) corresponding to the first service, the RSD including: indication information of a bidirectional session, session parameters of the first session, the indication information of the bidirectional session is used to indicate the establishment of a bidirectional session, and the first information is in the route selection policy of the first terminal.

[0011] In the present application, the first information may be a routing policy (from a core network device), which includes dual-directional session indication information corresponding to different services, for example, service 1 corresponds to dual-directional, and service 2 corresponds to non-dual-directional. When a service of the first device is triggered, the first device may query the RSD in the routing policy to determine the session indication information corresponding to the service, and based on this, determine whether to establish a dual-directional session. In addition, the session parameters of the first session may also be obtained based on the RSD. Based on this, the first device only needs to evaluate the routing policy and obtain the information for establishing a dual-directional session and the session parameters at the same time, thereby reducing the complexity of device processing.

[0012] In an optional manner, the first information is policy information of a bidirectional session, and the first terminal determines session parameters of the first session according to a routing policy of the first terminal.

[0013] In this application, the first information is policy information for a bidirectional session (from a core network device, such as a policy control function (PCF)). When a service of the first device is triggered, the first device may query the policy information for the bidirectional session to determine whether to establish the bidirectional session. Subsequently, the first terminal may obtain session parameters for the first session based on the first terminal's routing policy. Based on this, new policy information is introduced to reduce the impact on the routing policy.

[0014] In an optional manner, the policy information includes: service information allowing bi-directional sessions, and / or allowing the use of bi-directional sessions.

[0015] Based on this, the first device can determine which services allow the establishment of a bidirectional session and whether the first device itself allows the establishment of a bidirectional session. Based on this, the flexibility of the network in controlling the establishment of a bidirectional session is improved.

[0016] In an optional manner, obtaining the first information includes: receiving the first information from the first network element, where the first information is determined based on the bidirectional capability information and / or bidirectional subscription information of the first device.

[0017] Based on this, the network can control to which terminals the first information is sent.

[0018] In an optional manner, the second terminal determines the session parameters of the second session according to the session parameters of the first session.

[0019] In the present application, since the first device determines to establish a bidirectional session, the second terminal can determine the session parameters of the second session with reference to the session parameters of the first session, thereby reducing the creation delay of the second session and improving data processing efficiency. At the same time, it ensures that the session parameters of the first session and the second session are related or the same, facilitating session association.

[0020] In an optional manner, after acquiring the first information, the first device determines session parameters of the first session according to the routing policy of the first terminal; and determines session parameters of the second session according to the routing policy of the second terminal.

[0021] Based on this, two sessions are established in advance, which can improve transmission efficiency compared to obtaining session parameters of each session and establishing a session when UE switching occurs.

[0022] In an optional manner, before the second terminal sends the second message, the first terminal further receives a setup acceptance message for the first session.

[0023] It should be noted that the first session establishment acceptance message includes permission for the first terminal to establish a bidirectional session. Based on the first session establishment acceptance message, the first device can determine that the first session can be bidirectional (i.e., can be used as a bidirectional session). In addition, based on the first session establishment acceptance message, the second terminal determines that it can send the second message. This avoids triggering the establishment of a session for the second terminal when the first session establishment fails.

[0024] In an optional manner, the first message further includes at least one of the following parameters:

[0025] Bidirectional session request information, or a bidirectional identifier, where the bidirectional identifier is generated by the first device.

[0026] The dual-direction session request information may be referred to as a dual-direction session request type. Based on this information, a core network element can determine that the first session is dual-direction. A dual-direction identifier is generated by the first device upon obtaining the first information. Based on this, the first device generates a unique dual-direction identifier to facilitate the core network's association of the two sessions.

[0027] In an optional manner, the second message further includes at least one of the following parameters: bidirectional session request information, an identifier of the first session, or a bidirectional identifier.

[0028] Based on the above information, the network element of the core network can determine that the second session is used for dual-direction.

[0029] In an optional manner, the bidirectional identifier in the second message is generated by the first device; or the first device receives the bidirectional identifier, and the bidirectional identifier is allocated by a second network element, and the second network element is used to manage the first session.

[0030] In a second aspect, the present application provides a communication method that can be performed by a second network element, which is a session management network element. The second network element can be the second network element itself, or a component in the second network element (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the functions of the second network element. This application does not specifically limit this.

[0031] A third message is received, where the third message includes a request message for establishing a first session and an identifier of the first session, where the first session is a bidirectional session and is a session of the first terminal; a fourth message is received, where the fourth message includes a request message for establishing a second session, an identifier of the second session, and identifier information, where the second session is a bidirectional session and is a session of the second terminal; the identifier information is a bidirectional identifier or an identifier of the first session, where the bidirectional identifier is related to the first session; and a first association relationship between the first session and the second session is established based on the identifier information.

[0032] In the present application, after receiving the third and fourth messages, the second network element creates an association between the first and second sessions based on the bidirectional identifier (or the identifier of the first session), for example by sharing the same Internet Protocol (IP) address, to ensure service continuity during the switching of service data between the two sessions. This ensures a guaranteed user experience.

[0033] In an optional manner, the identification information is a bidirectional identification, and the third message also includes the bidirectional identification, which is generated by the first terminal or the second terminal. Based on this, the first terminal or the second terminal generates a unique bidirectional identification to facilitate the core network to associate the two sessions.

[0034] In one optional embodiment, the identification information is a bidirectional identifier, and the third message also includes bidirectional session request information. The second network element generates the bidirectional identifier based on the bidirectional session request information and sends a setup acceptance message for the first session, the setup acceptance message including the bidirectional identifier. Based on this, the second network element generates a unique bidirectional identifier to facilitate core network association of the two sessions.

[0035] In one optional embodiment, the second network element stores a second association between the bidirectional identifier and the first session. Exemplarily, the second association may be stored in the context of the first session. Based on this, when the second network element receives the bidirectional identifier from the second terminal, it may determine the first session based on the second association and the bidirectional identifier, thereby facilitating association between the first session and the second session.

[0036] In an optional manner, when the identification information is a bidirectional identification and the third message further includes the bidirectional identification, the second network element creates a first association relationship between the first session and the second session based on the bidirectional identification, thereby facilitating the core network to associate the two sessions.

[0037] In an optional manner, the identification information is the identifier of the first session, and the second network element creates a first association relationship between the first session and the second session based on the identifier of the first session and the identifier of the second session, thereby facilitating the core network to associate the two sessions.

[0038] In an optional manner, the second network element also sends a sixth message, which includes: the identifier of the first session, bidirectional information and the identifier of the second network element. The second network element is used to manage the first session. The bidirectional information is a bidirectional identifier or a bidirectional session type.

[0039] Based on this, the fifth network element can easily learn which second network element can handle bidirectional directionality.

[0040] In a third aspect, the present application provides a communication method that can be performed by a fourth network element, which is an access management network element of a second terminal. The fourth network element can be the fourth network element itself, or a component in the fourth network element (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the functions of the fourth network element. This application does not specifically limit this.

[0041] Receive a fifth message, the fifth message includes an identifier of a second network element and a bidirectional identifier, the second network element is used to manage the first session, the bidirectional identifier is related to the first session, and the first session is a session of the first terminal; receive a second message, the second message includes a request message to establish a second session and a bidirectional identifier, the second session is a session of the second terminal; determine the second network element based on the bidirectional identifier, the second network element is also used to manage the second session; send a fourth message to the second network element, the fourth message includes a request message to establish the second session; or, send a fourth message to a third network element, the fourth message includes a request message to establish the second session and the identifier of the second network element, the third network element is used to manage the second session in the roaming network of the second terminal.

[0042] In the present application, the fourth network element receives the identifier of the second network element and the bidirectional identifier, so as to determine the second network element based on the bidirectional identifier in the second message from the second terminal. In this way, the same second network element manages the first session and the second session, facilitating the association of the first session and the second session.

[0043] In an optional manner, after receiving the fifth message, the fourth network element further stores the third association relationship between the identifier of the second network element and the bidirectional identifier, so as to determine the second network element based on the third association relationship after receiving the bidirectional identifier.

[0044] In an optional manner, the fourth network element determines the second network element according to the bidirectional identifier and the third association relationship.

[0045] In one optional manner, the second message also includes bidirectional session request information. Upon determining that the second session establishment request message is a bidirectional session request message, the fourth network element determines the second network element based on the bidirectional identifier. Therefore, it can be seen that the fourth network element determines the second network element based on the bidirectional identifier only when a bidirectional session is being established. In other cases, the second network element does not need to determine the second network element.

[0046] In an optional manner, the fifth message also includes a bidirectional session type, so that the fourth network element can determine that the second network element can manage the bidirectional session.

[0047] In an optional manner, the fourth message further includes: an identifier and identification information of the second session, where the identification information is a bidirectional identifier or an identifier of the first session, and the bidirectional identifier is related to the first session. The present application creates an association between the first session and the second session based on the bidirectional identifier (or the identifier of the first session), for example, by sharing the same IP address, to ensure service continuity during the switching of service data between the two sessions.

[0048] In a fourth aspect, the present application provides a communication method that can be performed by a fourth network element, which is an access management network element of a second terminal. The fourth network element can be the fourth network element itself, or a component in the fourth network element (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the fourth network element's functions. This application does not specifically limit this.

[0049] Receive a fifth message, the fifth message includes an identifier of the second network element and an identifier of the first session, the second network element is used to manage the first session, and the first session is a session of the first terminal; receive a second message, the second message includes a request message to establish the second session and an identifier of the first session, and the second session is a session of the second terminal; determine the second network element based on the identifier of the first session, and the second network element is also used to manage the second session; send a fourth message to the second network element, the fourth message includes a request message to establish the second session; or, send a fourth message to a third network element, the fourth message includes a request message to establish the second session and the identifier of the second network element, and the third network element is used to manage the second session in the roaming network of the second terminal.

[0050] In the present application, the fourth network element receives the identifier of the second network element and the identifier of the first session, so as to determine the second network element based on the identifier of the first session in the second message from the second terminal. In this way, the same second network element manages the first session and the second session, facilitating the association of the first session and the second session.

[0051] In an optional manner, after receiving the fifth message, the fourth network element further stores the fourth association relationship between the identifier of the second network element and the identifier of the first session, so as to determine the second network element based on the third association relationship after receiving the identifier of the first session.

[0052] In an optional manner, the fourth network element determines the second network element according to the identifier of the first session and the fourth association relationship.

[0053] In an optional manner, the second message further includes bidirectional session request information. The fourth network element determines the second network element according to the identifier of the first session under the condition that the second session establishment request message is determined to be bidirectional session request information.

[0054] In an optional manner, the fifth message further includes a bidirectional session type.

[0055] In an optional manner, the fourth message further includes: an identifier and identification information of the second session, where the identification information is a bidirectional identifier, or an identifier of the first session, where the bidirectional identifier is related to the first session.

[0056] In a fifth aspect, the present application provides a communication method that can be performed by a fifth network element, where the fifth network element is a data management network element, configured to manage data information of a first terminal and a second terminal. The fifth network element can be the fifth network element itself, or a component in the fifth network element (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the functions of the fifth network element. This application does not specifically limit this.

[0057] Receive a sixth message, the sixth message including: the identifier of the first session, bidirectional information and the identifier of the second network element, the first session is a session of the first terminal, the second network element is used to manage the first session, the bidirectional information is a bidirectional identifier, or a bidirectional session type; according to the association relationship between the first terminal and the second terminal, send a fifth message to the fourth network element, the fifth message including the identifier of the second network element, and the fourth network element is the access management network element of the second terminal.

[0058] In the present application, the fifth network element sends the identifier of the second network element so that the fourth network element that receives the second message from the second terminal determines to which second network element to send the fourth message, thereby improving data processing efficiency.

[0059] In an optional manner, when the bidirectional information is a bidirectional identifier, the fifth message further includes the bidirectional identifier; or when the bidirectional information is a bidirectional session type, the fifth message further includes the identifier of the first session.

[0060] In an optional manner, the fifth network element sends a fifth message to the fourth network element according to the association relationship between the first terminal and the second terminal and the bi-directional information.

[0061] In an optional manner, the fifth message further includes a bidirectional session type.

[0062] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a first device (a first terminal and a second terminal), a second network element, a fourth network element, or a fifth network element. The communication device has the functions of implementing the first to fifth aspects above. For example, the communication device includes modules or units or means corresponding to the steps involved in the first to fifth aspects above. The functions or units or means may be implemented by software, or by hardware, or may be implemented by hardware executing the corresponding software.

[0063] In one possible design, the communication device includes a processing unit and a transceiver unit, wherein the transceiver unit can be used to send and receive signals to achieve communication between the communication device and other devices, for example, the transceiver unit is used to receive a first message; the processing unit can be used to perform some internal operations of the communication device. The transceiver unit can be called an input / output unit, a communication unit, etc., and the transceiver unit can be a transceiver; the processing unit can be a processor. When the communication device is a module (such as a chip) in a communication device, the transceiver unit can be an input / output interface, an input / output circuit, or an input / output pin, etc., and can also be called an interface, a communication interface, or an interface circuit, etc.; the processing unit can be a processor, a processing circuit, or a logic circuit, etc.

[0064] In another possible design, the communication device includes a processor and may also include a transceiver, the transceiver is used to send and receive signals, and the processor executes program instructions to complete the method in any possible design or implementation of the first to fifth aspects above. The communication device may also include one or more memories, the memory is used to couple with the processor, and the memory can store the necessary computer programs or instructions for implementing the functions involved in the first to fifth aspects above. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first to fifth aspects above.

[0065] In another possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of the first to fifth aspects described above. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design or implementation of the first to fifth aspects described above.

[0066] In another possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first to fifth aspects above.

[0067] It can be understood that in the sixth aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory and the processor can be set separately. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0068] In a seventh aspect, an embodiment of the present application provides a communication system, which includes the above-mentioned first device (first terminal and second terminal), a first network element, a second network element, a third network element, a fourth network element and a fifth network element.

[0069] In an eighth aspect, the present application provides a chip system, which includes a processor and may also include a memory, for implementing the methods described in aspects 1 to 5. The chip system may be composed of a chip or may include a chip and other discrete devices.

[0070] In a ninth aspect, the present application further provides a computer-readable storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed on a computer, the computer executes the methods in the first to fifth aspects.

[0071] In a tenth aspect, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the methods of the embodiments of the first to fifth aspects above.

[0072] For the technical effects that can be achieved in the above-mentioned second to tenth aspects, please refer to the description of the technical effects that can be achieved by the corresponding possible design schemes in the above-mentioned first aspect, and this application will not repeat them here. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] FIG1 shows a schematic diagram of a communication system provided by an embodiment of the present application;

[0074] FIG2 shows a schematic diagram of a scenario of a bidirectional conversation;

[0075] FIG3 shows a flow chart of a communication method provided in an embodiment of the present application;

[0076] FIG4 shows a schematic diagram of a scenario for determining the second session parameters provided by an embodiment of the present application;

[0077] FIG5 is a schematic diagram showing a scenario of determining the second session parameters provided by an embodiment of the present application;

[0078] FIG6 shows a flow chart of a communication method provided in an embodiment of the present application;

[0079] FIG7 shows a flow chart of a communication method provided in an embodiment of the present application;

[0080] FIG8 shows a flow chart of a communication method provided in an embodiment of the present application;

[0081] FIG9 shows a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0082] FIG10 shows a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0083] FIG11 shows a schematic structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0084] In order to make the purpose, technical solutions and advantages of this application clearer, the present application will be further described in detail below with reference to the accompanying drawings. The specific operating methods in the method embodiments can also be applied to the device embodiments or system embodiments. In the description of this application, unless otherwise specified, "multiple" means two or more. Therefore, the implementation of the device and method can refer to each other, and the repeated parts will not be repeated.

[0085] Figure 1 shows a schematic diagram of a mobile communication network architecture, which includes a terminal, access network equipment, access and mobility management functions, session management functions, user plane functions, policy control functions, network slice selection functions, network slice specific authentication and authorization functions, network warehouse functions, network data analysis functions, unified data management functions, unified data storage functions, authentication service functions, network capability exposure functions, terminal wireless capability management functions, binding support functions, application functions, and a data network (DN) connected to the operator's network. The terminal can access the wireless network through the access node at its current location. The terminal can send service data to the data network and receive service data from the data network through the access network equipment and user plane functions.

[0086] The access and mobility management function is mainly used for terminal attachment, mobility management, tracking area update procedures, etc. in the mobile network. In the 5G communication system, the access and mobility management function can be the access and mobility management function (AMF). In future communication systems (such as 6G communication systems), the access and mobility management function can still be AMF, or it can have other names, which is not limited in this application.

[0087] The session management function is mainly used for session management in mobile networks, such as session establishment, modification, and release. Specific functions include allocating Internet Protocol addresses to terminals, selecting user plane functions that provide message forwarding functions, etc. In 5G communication systems, the session management function may be a session management function (SMF). In future communication systems (such as 6G communication systems), the session management function may still be SMF, or may have other names, which is not limited in this application. This application also involves a multicast / broadcast session management network element, which may be a multicast / broadcast-session management function (MB-SMF), which is mainly used for session management in mobile networks, such as session establishment, modification, and release.

[0088] The user plane function is mainly used to process user messages, such as forwarding and billing. In the 5G communication system, the user plane function can be the user plane function (UPF). In future communication systems (such as 6G communication systems), the user plane function can still be UPF, or it can have other names, which is not limited in this application.

[0089] Policy control function, including policy control function, charging policy control function, QoS control, etc. In 5G communication systems, the policy control function may be a policy control function (PCF). In future communication systems (such as 6G communication systems), the policy control function may still be PCF, or may have other names, which is not limited in this application.

[0090] The network slice selection function is mainly used to select a suitable network slice for the terminal's service. In a 5G communication system, the network slice selection function may be a network slice selection function (NSSF). In future communication systems (such as a 6G communication system), the network slice selection function may still be NSSF, or may have other names, which is not limited in this application.

[0091] The network slice-specific authentication and authorization function (NSSAAF) is mainly used for authentication and authorization of terminals accessing specific network slices.

[0092] The network repository function is mainly used to provide registration and discovery of network functions or services provided by network functions. In 5G communication systems, the network repository function can be a network repository function (NRF). In future communication systems (such as 6G communication systems), the network repository function can still be NRF, or it can have other names, which are not limited by this application.

[0093] The network data analysis function can collect data from various network functions, such as the policy control function, session management function, user plane function, access management function, and application function (through the network capability exposure function), and perform analysis and prediction. In the 5G communication system, the network data analysis function can be the network data analysis function (NWDAF). In future communication systems (such as 6G communication systems), the network data analysis function can still be NWDAF, or it can have other names, which is not limited by this application.

[0094] The unified data management function is mainly used to manage the contract information of the terminal. In the 5G communication system, the unified data management function can be a unified data management (UDM) function. In future communication systems (such as 6G communication systems), the unified data management function can still be the UDM function, or it can have other names, which is not limited by this application.

[0095] The unified data storage function is mainly used to store structured data information, including contract information, policy information, and network data or business data defined in a standard format. In the 5G communication system, the unified data storage function can be a unified data repository (UDR) function. In future communication systems (such as 6G communication systems), the unified data storage function can still be a UDR function, or it can have other names, which is not limited by this application.

[0096] The authentication service function is mainly used to perform security authentication on the terminal. In the 5G communication system, the authentication service function can be the authentication server function (AUSF). In future communication systems (such as 6G communication systems), the authentication service function can still be AUSF, or it can have other names, which is not limited by this application.

[0097] The network capability exposure function can controllably expose some network functions to applications. In 5G communication systems, the network capability exposure function can be NEF. In future communication systems (such as 6G communication systems), the network capability exposure function can still be NEF, or it can have other names, which are not limited by this application.

[0098] The terminal radio capability management function is used to store and manage the radio capabilities of terminals within the network. In 5G communication systems, the terminal radio capability management function may be the user equipment radio capability management function (UCMF). In future communication systems (such as 6G communication systems), the terminal radio capability management function may still be UCMF, or may have other names, which are not limited by this application.

[0099] The binding support function is used to maintain the correspondence between the protocol (Internet protocol, IP) addresses and service functions of the interconnected user networks. In the 5G communication system, the binding support function can be the binding support function (BSF). In future communication systems (such as 6G communication systems), the binding support function can still be BSF, or it can have other names, which is not limited by this application.

[0100] The application function can provide service data of various applications to the control plane function of the operator's communication network, or obtain network data information and control information from the control plane function of the communication network. In the 5G communication system, the application function can be an application function (AF). In future communication systems (such as 6G communication systems), the application function can still be AF, or it can have other names, which is not limited by this application.

[0101] Data networks are primarily used to provide data transmission services to terminals. They can be private networks, such as local area networks (LANs), public data networks (PDNs), such as the Internet, or proprietary networks deployed by operators, such as those configured with the Internet Protocol Multimedia Core Network Subsystem (IMS) service.

[0102] It should be noted that in the embodiments of the present application, functions may also be referred to as network elements, network functions, functional entities, devices, etc. For example, the access and mobility management function may also be referred to as an access and mobility management network element, an access and mobility management network function, or an access and mobility management functional entity, etc. The names of the various functions are not limited in this application. Those skilled in the art may replace the names of the aforementioned functions with other names while still performing the same functions, and all such changes fall within the scope of protection of this application.

[0103] To facilitate understanding of the embodiments of the present application, the following briefly describes the terms or processing procedures involved in the embodiments of the present application.

[0104] 1) First device

[0105] The first device includes: at least two terminals and / or at least two user identification modules (e.g., USIM cards). For example, the first device includes terminal 1 and terminal 2; or, the first device includes USIM card 1 and USIM card 2; or, the first device includes terminal 1, terminal 2, and terminal 3; or, the first device includes USIM card 1, USIM card 2, and USIM card 3. These are merely exemplary and not limiting. Optionally, the first device includes at least two protocol stacks, with terminal 1 replaced by protocol stack 1 and terminal 2 replaced by protocol stack 2.

[0106] In the embodiment of the present application, the two terminals included in the first device are taken as an example for illustration. The two terminals can be two devices / apparatuses. Alternatively, the two UEs included in the first device can be two USIMs, for example, the first UE can be a first USIM and the second UE can be a second USIM. Alternatively, the first device is a terminal, and the terminal includes two USIMs, the first UE corresponds to the first USIM, and the second UE corresponds to the second USIM. Accordingly, in the embodiment of the present application, the first device can be replaced by a terminal, the UE is replaced by a USIM, the first UE is replaced by the first USIM, and the second UE is replaced by the second USIM. Alternatively, the first device is a dual-directional device, and the dual-directional device includes two USIMs, the first UE corresponds to the first USIM, and the second UE corresponds to the second USIM. Accordingly, in the embodiment of the present application, the first device can be replaced by a dual-directional device, the UE is replaced by a USIM, the first UE is replaced by the first USIM, and the second UE is replaced by the second USIM. Alternatively, the first device is a terminal, and the terminal includes two protocol stacks (Stacks), the first UE is replaced by the first protocol stack of the terminal, and the second UE is replaced by the second protocol stack of the terminal.

[0107] 2) Dual Direction

[0108] The first device includes terminal 1 and terminal 2. The first device can be dual-directed, that is, the service data of the first device can be directed to be transmitted through terminal 1 or terminal 2, or switched from being transmitted through terminal 1 to being transmitted through terminal 2. Alternatively, terminal 1 and terminal 2 belong to the same user, and the service data of the user can be directed to be transmitted through terminal 1 or terminal 2, or switched from being transmitted through terminal 1 to being transmitted through terminal 2.

[0109] 3) DualSteer Session (also known as Session for DualSteer)

[0110] Here, the example in which the first device includes two UEs (UE1 and UE2) or two USIM cards (USIM card 1 and USIM card 2) is used for illustration. Figure 2 shows that the PDU session of UE1 (PDU Session ID#1) and the PDU session of UE2 (PDU Session ID#2) share the same IP address. UE1 creates PDU Session ID#1 through RAN1, and UE2 creates PDU Session ID#2 through RAN2. RAN1 and RAN2 are 3GPP access types (3GPP Access Type). RAN1 and RAN2 may have the same (or different) radio access technology type (RAT Type). RAT Type may be 5G NR, 5G NR (satellite), or 6G RAT. For example, RAN1 is 5G NR and RAN2 is 6G RAT. RAN1 and RAN2 may belong to the same Public Land Mobile Network (PLMN) or different PLMNs.

[0111] Before the service is switched between UE1 and UE2, the service data corresponding to the IP is transmitted through UE1's PDU Session ID#1 (that is, the PDU layer is associated with UE1's transmission channel (UE1—RAN1—UPF)). After the service is switched between UE1 and UE2, the service data corresponding to the IP is transmitted through UE2's PDU Session ID#2 (that is, the PDU layer is associated with UE2's transmission channel (UE2—RAN2—UPF)). Before and after the service is switched between UE1 and UE2, the connection between the PDU layer and the application layer (App layer) (such as the socket connection) does not change, that is, the IP address used by the application does not change, and service continuity is not affected. Furthermore, the activation of UE2's PDU Session ID#2 may also trigger the deactivation or release of UE1's PDU Session ID#1.

[0112] Bidirectionality can indicate the attributes or usage of a PDU session, for example, the type of the PDU session is bidirectionality or the PDU session is used to provide a bidirectionality function. The service data carried by the PDU session can be directed to the first terminal or the second terminal.

[0113] By creating a bidirectional PDU session, the latency of service handoffs between different UEs can be reduced, improving the user experience. Based on this, the present application provides a communication method, which is illustrated using data interaction between a first terminal, a second terminal, a second network element, a fourth network element, a fifth network element, and a sixth network element as an example. The first terminal and the second terminal may be terminals or SIM cards in a first device. The first terminal and the second terminal may also be different devices that can share an IP address. For example, if user A's mobile phone and car are in the same spatial location (the mobile phone is in the car, or the distance between the mobile phone and the car is within a distance threshold), the mobile phone and the car can share the same IP address. In this case, the mobile phone can be considered the first terminal, and the car can be considered the second terminal. Alternatively, if user A's mobile phone and tablet are in the same spatial location (the distance between the mobile phone and the tablet is within a distance threshold), the mobile phone and the tablet can share the same IP address. In this case, the mobile phone can be considered the first terminal, and the tablet can be considered the second terminal. This application does not specifically limit whether the first terminal and the second terminal are in the same device or in different devices. In specific applications, other terminals may also be involved. This application does not limit the number of terminals; all terminals can share the same IP address. This application is described by taking the first terminal and the second terminal as examples.

[0114] The second network element is an access management network element for the terminal, for example, the second network element is an SMF. The fourth and sixth network elements are used for terminal attachment, mobility management, and tracking area update procedures in the mobile network, for example, the fourth network element is an AMF. The fifth network element is used to manage the terminal's subscription information, for example, the fifth network element is an UDM.

[0115] In Figure 3, the first terminal and the second terminal are located in the first device, the second network element is SMF, the fourth network element is the access management network element AMF2 of the second terminal, the fifth network element is UDM, and the sixth network element is the access management network element AMF1 of the first terminal. Figure 3 uses the example of switching from the session of the first terminal to the session of the second terminal. In specific applications, it is not limited to switching from the session of the first terminal to the session of the second terminal, or from the session of the second terminal to the session of the first terminal. Execution is as follows:

[0116] Step 301: A first device obtains first information, where the first information is used by the first device to determine to establish a bidirectional session.

[0117] Optionally, the first information is used to trigger the first device to establish a bi-directional session.

[0118] It should be noted that the first device can receive the first information from the first network element (such as the policy control function), and the first information is determined by the policy control function based on the dual-directional capability information and / or the dual-directional contract information of the first device. Exemplarily, when the first device (the first terminal and / or the second terminal) registers to join the network, it reports the dual-directional capability information, and the policy control function obtains the dual-directional capability information from the registration network element of the first device (for example, AMF1 and / or AMF2) to generate the first information; or, the policy control function obtains the contract information of the first device (i.e., the dual-directional contract information), and generates the first information based on the contract information, and the contract information indicates that the first terminal or the second terminal allows dual-directional; or, the policy control function obtains the dual-directional capability information from the registration network element of the first device, and generates the first information based on the dual-directional capability information and the contract information of the first device. In addition, the first information can be understood as being obtained by any one of the first terminal and the second terminal in the first device, or both the first terminal and the second terminal. The first information can be shared between the first terminal and the second terminal, and the specific sharing method is not specifically limited in this application.

[0119] It should also be noted that if the first terminal and the second terminal are not in the same device (ie, in the first device), the first terminal and the second terminal may obtain the first information separately.

[0120] Exemplarily, the first information may be in the routing policy, and the first information may also be policy information for a dual-directional session, which is not specifically limited in this application. Wherein, when the first information is in the first terminal routing policy (for example, UE route selection policy 1, URSP1), the first information includes: the RSD corresponding to the first service, and the RSD includes: indication information of the dual-directional session (or called cross-UE session indication, DualSteer session indication), session parameters of the first session (for example, data network name (DNN) #1, single network slice selection assistance information (S-NSSAI) #1, etc.). The indication information of the dual-directional session is used to indicate the establishment of a dual-directional session or the transmission of the first service through the dual-directional session. In this application, the first information may be a routing policy, which includes dual-directional session indication information corresponding to different services. When the service of the first device is triggered, the first device can query the RSD corresponding to the first service in the routing policy to determine the session indication information corresponding to the service, and based on this, determine whether to establish a dual-directional session. In addition, the session parameters of the first session can also be obtained based on the RSD corresponding to the first service. Based on this, the first device only needs to evaluate the routing strategy and obtain the information and session parameters for establishing a bidirectional session, thereby reducing the processing complexity of the device.

[0121] Indicate information about a dual-directional session is added to the RSD corresponding to the first service in URSP1 of the first terminal. The dual-directional session indication information can be indicated by a parameter, such as DualSteer, or by other methods, which are not specifically limited here. In Table 1 below, the first service can be indicated by an application description of the first service, an identifier of the first service, or address information for transmitting the first service.

[0122] Table 1 Examples of RSD

[0123] Wherein, when the first information is the policy information of a bidirectional session, the policy information includes: service information that allows bidirectional sessions, and / or, allows the use of bidirectional sessions. For example, the policy information includes: service 1, service 2, or the policy information includes: service 1 allows the use of bidirectional sessions, then when service 1 is triggered, the first device can determine to establish a bidirectional session according to the policy information. Alternatively, the policy information includes: allowing the use of bidirectional sessions, then the first device can determine to establish a bidirectional session according to the policy information. In addition, the policy information can also include service information that does not allow bidirectional sessions, for example, the policy information includes: service 1 allows the use of bidirectional sessions, service 2 allows the use of bidirectional sessions, service 3 does not allow the use of bidirectional sessions, then when service 3 is triggered, the first device can determine not to establish a bidirectional session according to the policy information. Allowing the use of bidirectional sessions means that the first device allows the use of bidirectional sessions or that any service of the first device allows the use of bidirectional sessions.

[0124] In step 302, the first terminal sends a first message, which includes a request message to establish a first session. The first session is a bidirectional session, and the first session is a session of the first terminal. Accordingly, AMF1 receives the first message.

[0125] Exemplarily, if the first session is a dual-directional session (or a dual-directional service is provided for the first session), then AMF1 obtains the establishment request message of the first session (for example, a PDU session establishment request message) and determines that dual-directional communication is to be performed. The first message can be a new type of message that is associated with dual-directional communication, and based on the first message, it can be determined that dual-directional communication is to be performed. Alternatively, the first message reuses an existing NAS message, and by carrying the establishment request message of the first session in the NAS message, the network element of the core network determines that dual-directional communication is to be performed. This is not specifically limited here.

[0126] In order to facilitate AMF1 to determine that the first session is used for bidirectional communication, the first message may also include at least one of the following parameters: bidirectional session request information, or a bidirectional identifier, where the bidirectional identifier is generated by the first device (generated by the first terminal or the second terminal).

[0127] The dual-directional session request information can be referred to as a dual-directional session request type, or DualSteer Session Request Type. The dual-directional session request information can be indicated by a parameter (e.g., Request Type). Request Type indicates that the establishment of the first session is a request for a dual-directional session, such as Request Type 1 indicating a dual-directional session request information, and Request Type 2 indicating a non-dual-directional session request information. Based on this information, AMF1 can determine that the first session is dual-directional. The dual-directional identifier can also be referred to as the dual-directional session identifier. The dual-directional identifier is generated by the first device upon obtaining the first information (i.e., upon executing step 301 above). When the first device generates the dual-directional identifier, its uniqueness within the first device must be guaranteed. The dual-directional identifier can be generated based on the dual-directional session request information and the identifier of the first device. Different first devices can generate different dual-directional identifiers, and the construction of the dual-directional identifier is not specifically limited herein. Based on this, the first device generates a unique dual-directional identifier to facilitate the SMF's association of the two sessions. For example, when the first device determines to establish a dual-directional session, it generates the dual-directional identifier. If the first terminal and the second terminal are not in the same device, the bidirectional identifier can be generated by the first terminal or the second terminal, or the first terminal and the second terminal can share the bidirectional identifier after negotiation. It should be understood that the bidirectional identifier is used to associate the first session of the first terminal with the second session of the second terminal.

[0128] It should be noted that, in addition to the above information, the first message may also include the identifier of the first session and the session parameters of the first session (for example, DNN#1, S-NSSAI#1, etc.). Exemplarily, the identifier of the first session and the session parameters of the first session may be carried in the establishment request message of the first session. Based on the description in step 301 above, if the first information is in the routing selection policy of the first terminal (for example, URSP1), then the session parameters of the first session can be obtained from the RSD corresponding to the first service, that is, the session parameters of the first session are determined directly based on the first information. If the first information is the policy information of a bidirectional session, the first terminal can obtain the session parameters of the first session according to the routing selection policy of the first terminal, that is, the first information is used as the execution condition for obtaining the session parameters of the first session, and the session parameters of the first session are obtained by querying the routing selection policy of the first terminal.

[0129] In step 303, AMF1 sends a third message including a request message to establish the first session and an identifier of the first session. Accordingly, SMF receives the third message.

[0130] Exemplarily, if the first session is a dual-directional session (or a dual-directional service is provided for the first session), then the SMF obtains the establishment request message of the first session (for example, a PDU session establishment request message) and determines that dual-directional communication is to be performed. The third message can be a new type of message that is associated with dual-directional communication, and based on the third message, it can be determined that dual-directional communication is to be performed. Alternatively, the third message is a Create Session Management Context Request message, which carries the establishment request message of the first session so that the network element of the core network determines that dual-directional communication is to be performed. This is not specifically limited here.

[0131] Optionally, the third message may further include a bidirectional identifier and / or bidirectional session request information. The bidirectional identifier may be generated by the first device (generated by the first terminal or the second terminal). For example, AMF1 selects an SMF that supports the bidirectional function based on the bidirectional identifier or the bidirectional session request information, and the SMF manages the first session.

[0132] Optionally, the third message also carries the identity of the first terminal, such as SUPI 1. Based on this, the SMF can determine which terminal device requests to establish a bidirectional session.

[0133] In addition, the third message also carries the session parameters of the first session. AMF1 selects an SMF according to the session parameters of the first session.

[0134] In step 304, the SMF sends a sixth message. The sixth message includes the identifier of the first session, bidirectional information, and the identifier of the SMF. The SMF is used to manage the first session. The bidirectional information includes the bidirectional identifier, the bidirectional session type, or an indication that the session is bidirectional. Accordingly, the UDM receives the sixth message.

[0135] The SMF is used to manage the first session, which can be understood as the SMF is used to manage the first session of the first terminal.

[0136] The bidirectional session type indicates that the first session is bidirectional or provides bidirectional services. The SMF identifier may be the address information of the SMF or the fully qualified domain name (FQDN) information of the SMF.

[0137] Exemplarily, the first session is a dual-directional session (or a dual-directional service is provided for the first session), then the UDM obtains dual-directional information and determines to execute dual-directional. The sixth message can be a new type of message, and the sixth message is associated with dual-directional, and based on the sixth message, it can be determined to execute dual-directional. Alternatively, the sixth message is a terminal context management registration (UE Context Management Registration message, which carries dual-directional information in the message so that the network element of the core network can determine to execute dual-directional. It is not specifically limited here.

[0138] In specific applications, the sixth message also carries the identity of the first terminal, such as SUPI1.

[0139] Step 305: The UDM sends a fifth message to the AMF2 based on the association between the first terminal and the second terminal. The fifth message includes the SMF identifier. Accordingly, the AMF2 receives the fifth message.

[0140] For example, the fifth message is a UE Context Management Update message.

[0141] It should be noted that AMF1 registers with the UDM that it is responsible for managing the first terminal, and reports the identity of the first terminal, such as SUPI1, to the UDM. Optionally, AMF1 also reports the dual-directional capability information of the first terminal to the UDM (for example, the first terminal supports dual-directional operations, or the first terminal supports the creation of dual-directional sessions, or the first terminal supports cross-terminal sessions). AMF2 registers with the UDM that it is responsible for managing the second terminal, and reports the identity of the second terminal, such as SUPI2, to the UDM. Optionally, AMF2 also reports the dual-directional capability information of the second terminal to the UDM (for example, the second terminal supports dual-directional operations, or the second terminal supports the creation of dual-directional sessions, or the second terminal supports cross-terminal sessions).

[0142] The UDM stores the association between the first terminal and the second terminal, namely, the association between SUPI1 and SUPI2. It should be understood that when the operator creates subscription data for the user of the first device, the association between the user's first terminal and the second terminal exists. For example, the subscription data of the first terminal includes the identifier of the second terminal (SUPI2). For another example, the subscription data of the second terminal includes the identifier of the first terminal (SUPI1). For another example, the UDM stores the subscription data of the first terminal, the subscription data of the second terminal, and the association between SUPI1 and SUPI2.

[0143] Optionally, the association between the first terminal and the second terminal can be replaced by the information that the first terminal and the second terminal allow bidirectional communication (or the first terminal and the second terminal are in bidirectional mode). Accordingly, the UDM stores information that the first terminal and the second terminal allow bidirectional communication (or the UDM stores information that the first terminal and the second terminal are in bidirectional mode). Based on the information that the first terminal and the second terminal allow bidirectional communication (or the first terminal and the second terminal are in bidirectional mode), the UDM sends a fifth message to the AMF2. It is understood that the UDM sends the fifth message to the AMF2 when it determines that the first terminal and the second terminal allow bidirectional communication (or the first terminal and the second terminal are in bidirectional mode). Alternatively, the UDM sends the fifth message to the AMF2 based on the association between the first terminal and the second terminal and the information that the first terminal and the second terminal allow bidirectional communication (or the first terminal and the second terminal are in bidirectional mode). For example, before step 305, the UDM receives a request from the first terminal and the second terminal to execute bidirectional communication, the UDM determines that the first terminal and the second terminal allow bidirectional communication, and then the UDM stores information that the first terminal and the second terminal allow bidirectional communication (or the first terminal and the second terminal are in bidirectional mode).

[0144] Exemplarily, if in step 304 above, the bidirectional information is a bidirectional identifier, and the fifth message also includes the bidirectional identifier, AMF2 may store a third association between the bidirectional identifier and the SMF identifier, so that after receiving the bidirectional identifier from the second terminal, AMF2 can determine the SMF based on the bidirectional identifier and the third association. Optionally, AMF2 stores the third association between the bidirectional identifier and the SMF identifier in the context of the second terminal.

[0145] Exemplarily, if in step 304 above, the bidirectional information is a bidirectional session type or indicates that the session is for bidirectional use, and the fifth message also includes the identifier of the first session, AMF2 may store the fourth association between the identifier of the first session and the identifier of the SMF, so that after receiving the identifier of the first session from the second terminal, AMF2 can determine the SMF based on the identifier of the first session and the fourth association. Optionally, AMF2 stores the fourth association between the identifier of the first session and the identifier of the SMF in the context of the second terminal.

[0146] In addition, the UDM may send a fifth message to the AMF2 based on the association relationship between the first terminal and the second terminal and the bidirectional information. That is, the sending of the fifth message is triggered only when the sixth message includes bidirectional information (or when it is understood that the first session is a bidirectional session).

[0147] Optionally, the fifth message may also include a bidirectional session type or indicate that the session is used for bidirectional purposes, so that AMF2 can determine that SMF can manage bidirectional sessions.

[0148] Optionally, the fifth message may also include the identity of the first terminal, and AMF2 may store the association between the identity of the first terminal, the identifier of the first session, and the identifier of the SMF, so that after AMF2 receives the identity of the first terminal and the identifier of the first session from the second terminal, it can determine the SMF based on the identity of the first terminal, the identifier of the first session, and the association.

[0149] Optionally, the fifth message may also include the identity of the first terminal, and AMF2 may store the association between the identity of the first terminal and the identifier of the first session (i.e., indicating that the first session is the session of the first terminal), so that after AMF2 determines the SMF, it sends the identity of the first terminal, the identifier of the first session, the identity of the second terminal, and the identifier of the second session to the SMF, so that SMF2 can determine the association between the first session of the first terminal and the second session of the second terminal.

[0150] In step 307, the second terminal sends a second message, which includes a request message to establish a second session. The session parameters of the second session are related to the session parameters of the first session. The second session is a bidirectional session and is a session for the second terminal. Accordingly, AMF2 receives the second message.

[0151] Exemplarily, the second session is a dual-directional session (or a dual-directional service is provided for the second session), then AMF2 obtains the establishment request message of the second session (for example, a PDU session establishment request message) and determines that dual-directional is to be performed. The second message can be a new type of message, which is associated with dual-directional, and based on the second message, it can be determined that dual-directional is to be performed. Alternatively, the second message reuses an existing NAS message, and by carrying the establishment request message of the second session in the NAS message, the network element of the core network determines that dual-directional is to be performed. This is not specifically limited here.

[0152] In order to facilitate AMF2 to determine that the second session is used for bidirectional communication, the second message may also include at least one of the following parameters: bidirectional communication session request information, the identifier of the first session, or the bidirectional communication identifier.

[0153] Among them, the bidirectional session request information can be understood with reference to the description of step 302 above, and will not be repeated here. In step 307, the bidirectional identifier can be generated by the first device obtaining the first information (that is, under the premise of executing step 301 above). The bidirectional identifier can be generated based on the bidirectional session request information and the identifier of the first device. Different first devices can generate different bidirectional identifiers. How the bidirectional identifier is constructed is not specifically limited here. If the first terminal and the second terminal are not in the same device, the bidirectional identifier can be generated by the first terminal or the second terminal, and the bidirectional identifier can be shared between the first terminal and the second terminal. If the first message does not carry the bidirectional identifier, the bidirectional identifier in the second message can also be the bidirectional identifier received by the first device (for example, the bidirectional identifier received from the SMF), and the bidirectional identifier is allocated by the SMF. Exemplarily, the SMF can generate the bidirectional identifier based on the bidirectional session request information carried in the first message.

[0154] In addition, since the first terminal has sent a dual-direction session establishment request message (that is, a first session establishment request message) through the first message, the second terminal can carry the identifier of the first session in the second message so that AMF2 can determine to perform dual-direction.

[0155] It should be noted that, in addition to the aforementioned information, the second message may also include an identifier for the second session and session parameters for the second session. The identifier for the second session is different from the identifier for the first session. When the first device assigns the session identifier, the uniqueness of the session identifiers for the first and second terminals can be guaranteed. Based on the description in step 301 above, if the first message follows the first terminal's routing policy (e.g., URSP1) and the second terminal performs dual-direction with the first terminal, the first device or the second terminal may determine the session parameters for the second session based on the session parameters for the first session. If the first message follows the first terminal's routing policy (e.g., URSP1) and the second terminal performs dual-direction with the first terminal, the first terminal may determine the session parameters for the first session based on the first terminal's routing policy, and the second terminal may also determine the session parameters for the second session based on the second terminal's routing policy. Exemplarily, the session parameters for the second session may be the same as those for the first session. For example, the session parameters for the first session may include DNN#1 and S-NSSAI#1. The session parameters for the second session may also include DNN#1 and S-NSSAI#1. The session parameters of the second session may also be determined with reference to the session parameters of the first session. For example, the session parameters of the first session include DNN#1 and S-NSSAI#1. The session parameters of the second session include DNN#1, S-NSSAI#1, and S-NSSAI#2 of the roaming PLMN. When the second terminal is roaming, the second terminal may determine S-NSSAI#2 of the roaming PLMN based on S-NSSAI#1.

[0156] Optionally, the session parameters of the second session are related to the session parameters of the first session, which may be replaced by the session parameters of the second session being the same as the session parameters of the first session, or the session parameters of the second session being determined based on the session parameters of the first session.

[0157] Referring to Figure 4(a), when service 1 is triggered on the first device, the first device determines that the first terminal and the second terminal are to perform bidirectional communication (or establish a bidirectional session) based on the bidirectional session indication information in the first terminal's URSP1. Furthermore, the first device determines session parameters for the first session based on the first terminal's URSP1 (which corresponds one-to-one with the first terminal), and the first device creates the first session based on the session parameters of the first session. The first device may use the session parameters of the first session to create a second session for the second terminal. Referring to Figure 4(b), when service 1 is triggered on the first device, the first device determines that the first terminal and the second terminal are to perform bidirectional communication (or establish a bidirectional session) based on the bidirectional session indication information in the first terminal's URSP1. Furthermore, the first device determines session parameters for the first session based on the first terminal's URSP1, and the first terminal creates the first session based on the session parameters of the first session. The first device determines session parameters for the second session based on the second terminal's URSP2 (which corresponds one-to-one with the second terminal), and the second terminal creates the second session based on the session parameters of the second session. In Figure 4(b), the session parameters of the first session and the second session are the same.

[0158] Based on the description of step 301 above, if the first information is policy information for a bidirectional session, and the second terminal is performing bidirectional communication with the first terminal, the first device may determine the session parameters for the second session based on the session parameters for the first session. The first device may also determine the session parameters for the second session based on the routing policy of the second terminal.

[0159] Referring to FIG5(a), when service 1 is triggered on the first device, the first device determines that the first terminal and the second terminal perform bidirectional communication (or establish a bidirectional session) based on the bidirectional session policy information. The first device determines the session parameters of the first session based on the first terminal's URSP1 (which corresponds one-to-one with the first terminal), and the first terminal creates the first session based on the session parameters of the first session. The second terminal can use the session parameters of the first session to create a second session for the second terminal. It should be understood that the first device first evaluates the bidirectional session policy information and then evaluates URSP1, without evaluating URSP2. Referring to FIG5(b), when service 1 is triggered on the first device, the first device determines that the first terminal and the second terminal perform bidirectional communication (or establish a bidirectional session) based on the bidirectional session policy information. The first device determines the session parameters of the first session based on the first terminal's URSP1, and the first terminal creates the first session based on the session parameters of the first session. The first device determines the session parameters of the second session based on the second terminal's URSP2 (which corresponds one-to-one with the second terminal), and the second terminal creates the second session based on the session parameters of the second session. In Figure 5(b), the session parameters of the first session are the same as the session parameters of the second session. It should be understood that the first device first evaluates the policy information of the bi-directional session, and then evaluates URSP1 and URSP2 respectively.

[0160] Optionally, before executing step 307, step 306 is also executed.

[0161] Step 306: SMF sends a setup acceptance message for the first session.

[0162] Based on the first session establishment acceptance message, the first device can determine that the first session can perform bidirectional communication (i.e., can be used as a bidirectional session). Step 307 is performed only when the first session is successfully established, or when the first session allows bidirectional communication, or when the first session allows bidirectional communication. The first session establishment acceptance message may include a bidirectional identification, the IP address of the first device, bidirectional session acceptance information (e.g., the first session allows bidirectional communication, or the first session allows bidirectional communication), etc. For example, step 307 is performed only when the first session establishment acceptance message includes bidirectional session acceptance information.

[0163] Step 308: AMF2 determines SMF.

[0164] It should be noted that if the second message includes a bidirectional identifier, AMF2 can determine the SMF based on the bidirectional identifier. Exemplarily, AMF2 can determine the SMF based on the bidirectional identifier and the third association relationship (the association relationship between the bidirectional identifier and the SMF identifier) ​​stored after it receives the fifth message. If the second message includes the identifier of the first session, AMF2 can determine the SMF based on the identifier of the first session. Exemplarily, AMF2 can determine the SMF based on the identifier of the first session and the fourth association relationship (the association relationship between the identifier of the first session and the identifier of the SMF) stored after it receives the fifth message.

[0165] In addition, when the second message includes bidirectional session request information, AMF2 determines the SMF based on the bidirectional identifier or the identifier of the first session, only under the condition that the establishment request message of the second session is bidirectional session request information. Otherwise, AMF2 selects the SMF based on the session parameters of the second session (for example, DNN#1 and S-NSSAI#1).

[0166] Step 309: AMF2 sends a fourth message to SMF, where the fourth message includes a request message to establish the second session. Accordingly, SMF receives the fourth message.

[0167] In addition, the fourth message also includes the identity of the second terminal.

[0168] Exemplarily, if the second session is a dual-directional session (or a dual-directional service is provided for the second session), then AMF2 obtains the establishment request message of the second session (for example, a PDU session establishment request message) and determines that dual-directional communication is to be performed. The fourth message can be a new type of message that is associated with dual-directional communication, and based on the second message, it can be determined that dual-directional communication is to be performed. Alternatively, the fourth message is a create session management context request message, which carries the establishment request message of the second session in the NAS message so that the network element of the core network determines that dual-directional communication is to be performed. This is not specifically limited here.

[0169] If the second terminal is in a roaming network, AMF2 sends a fourth message to a third network element (which manages the second session in the roaming network of the second terminal, such as V-SMF), where the fourth message includes the SMF identifier so that the third network element determines the SMF based on the SMF identifier.

[0170] In addition, the fourth message also includes: an identifier and identification information of the second session. The identification information is a bidirectional identifier, or an identifier of the first session. The bidirectional identifier is associated with the first session, so that the first association relationship between the first session and the second session can be determined based on the identification information. It should also be noted that if the identification information is a bidirectional identifier, the third message sent by AMF1 to SMF also includes the bidirectional identifier. In this case, the bidirectional identifier is generated by the first device (or the first terminal or the second terminal). If the identification information is a bidirectional identifier, the third message also includes a bidirectional session request message (excluding the bidirectional identifier). The SMF can generate the bidirectional identifier based on the bidirectional session request information and carry the bidirectional identifier in the first session establishment accept message so that the second terminal can obtain the bidirectional identifier. The second message sent by the second terminal to AMF2 includes the bidirectional identifier. Based on this, the fourth message sent by AMF2 to SMF includes the bidirectional identifier.

[0171] Optionally, the SMF may store the bidirectional identifier and the second association relationship of the first session. For example, the bidirectional identifier is stored in the context of the first session. When the fourth message includes the bidirectional identifier and the identifier of the second session, the SMF may create a first association relationship between the first session and the second session based on the bidirectional identifier, i.e., the following step 310. Exemplarily, the SMF may search for the second association relationship based on the bidirectional identifier, determine the identifier of the first session based on the second association relationship, and create the first association relationship based on this. This application does not specifically limit this.

[0172] If the identification information is the identifier of the first session, the SMF may establish a first association relationship based on the identifier of the first session and the identifier of the second session when executing step 310 below. This is not specifically limited in this application. For example, the fourth message also includes the identity of the first terminal, the identifier of the first session, the identity of the second terminal, and the identifier of the second session. In this way, SMF2 can determine the association between the first session of the first terminal and the second session of the second terminal.

[0173] Step 310: The SMF creates a first association relationship between the first session and the second session according to the identification information.

[0174] Exemplarily, when the first session is associated with the second session, the first session and the second session may share the same N4 Session ID and / or the same IP address.

[0175] Based on this, the present application can create an association between the first session of the first terminal and the second session of the second terminal to ensure that when the user's business data or the business data of the first device is switched between different terminals, the IP address of the transmitted business data remains unchanged, and the first device or terminal does not need to re-establish a connection with the server, thereby reducing the switching delay or reducing the switching interruption time, improving data processing efficiency, and ensuring the user's business experience.

[0176] It should be noted that the message / information transmission between the terminals and network elements, and between network elements, may be direct transmission or indirect transmission via other network elements or devices, and this application does not specifically limit this. For example, the transmission of a first message between a first terminal and AMF1 can be understood as the first terminal transmitting the first message to AMF1 via RAN1, or as the first terminal transmitting the first message directly to AMF1. The transmission of a fifth message between AMF2 and UDM can be understood as the UDM transmitting a third message to AMF1 via SMF, or as the UDM transmitting the third message directly to AMF1. This is for illustrative purposes only.

[0177] The following is a combination of UE1 (ie, the first terminal), UE2 (ie, the second terminal), AMF1 (ie, the sixth network element), AMF2 (ie, the fourth network element), SMF (ie, the second network element) and UDM (ie, the fifth network element) (or PCF) data interaction to illustrate the solution of the present application. The following is explained in detail. In addition, the following messages that are the same as those in the embodiment of Figure 3 above can be understood with reference to the description of the messages in the relevant steps in Figure 3. For example, the first message can be understood with reference to step 302 in Figure 3 above, which is not repeated here. The details are as follows:

[0178] Case 1: UE1 and / or UE2 generates a dual-directional identifier

[0179] Referring to Figure 6, the execution is as follows:

[0180] In step 600A, UE1 and UE2 register to join the network respectively.

[0181] AMF1 is responsible for UE1's access and mobility management, as well as UE1's registration management. AMF1 stores SUPI1 (UE1's identity) and registers its responsibility for UE1 with the UDM. AMF1 reports SUPI1 to the UDM. AMF1 also reports UE1's bidirectional capability information to the UDM (for example, whether UE1 supports bidirectional operations, supports the creation of bidirectional sessions, or supports cross-UE sessions).

[0182] AMF2 is responsible for UE2's access and mobility management, as well as UE2's registration management. AMF2 stores SUPI2 (UE2's identity) and registers its responsibility for UE2 with the UDM. AMF2 reports SUPI2 to the UDM. AMF2 also reports UE2's bidirectional capability information to the UDM (e.g., whether UE2 supports bidirectional operations, supports the creation of bidirectional sessions, or supports cross-UE sessions).

[0183] Step 600B: UDM stores the association relationship between UE1 and UE2.

[0184] For example, the association between SUPI1 and SUPI2. It should be understood that when the operator opens an account for the UE, the association between the two UEs exists (for example, UE1 and UE2 both belong to the same user), so the UDM can store the association between SUPI1 and SUPI2.

[0185] In step 601, UE1 sends a first message to AMF1, where the first message includes: a PDU session establishment request message of UE1 (ie, a first session establishment request message) and a bidirectional identifier. Accordingly, AMF1 receives the first message.

[0186] It should be noted that the dual-directional identifier in step 601 is generated after UE1 obtains the first information. The specific method of obtaining the first information can be understood by referring to step 301 in FIG. 3 , which will not be described in detail here.

[0187] Optionally, the first message may be a NAS message. The first message may further include: an identifier of PDU session 1 (i.e., an identifier of the first session), and session parameters (DNN and S-NSSAI) of PDU session 1 (i.e., session parameters of the first session). The PDU session establishment request message of UE1 also includes an identifier of PDU session 1.

[0188] Optionally, the first message may also include bidirectional session request information.

[0189] In addition, the PDU session establishment request message of UE1 may also include a bidirectional identifier.

[0190] After receiving the first message, AMF1 can obtain the identity SUPI1 of UE1. Exemplarily, AMF1 searches the registration information of UE1 to determine SUPI1.

[0191] When executing step 601, UE1 may forward the first message to AMF1 through RAN1.

[0192] Step 601 can be understood with reference to the above-mentioned step 302 and will not be described in detail here.

[0193] Step 602: AMF1 sends a third message to SMF, which includes: UE1's PDU session establishment request message and a bidirectional identifier. Correspondingly, SMF receives the third message.

[0194] When the first message includes the identifier of PDU session 1 and the session parameters of PDU session 1, the third message may also include the identifier of the PDU session and the session parameters of the PDU session. The third message may also be a Create Session Management Context Request message, which carries the establishment request message of the first session so that the core network element determines to perform dual-direction.

[0195] When the first message includes the bidirectional session request information, the third message may further include the bidirectional session request information. In addition, the third message may further include the identity SUPI1 of UE1.

[0196] Optionally, the third message also carries the identity of the first terminal, such as SUPI 1. Based on this, the SMF can determine which terminal device requests to establish a bidirectional session.

[0197] Optionally, AMF1 selects an SMF that supports bidirectionality based on the bidirectionality identifier or bidirectionality session request information.

[0198] In addition, AMF1 performs step 603 only if it determines that UE1 supports dual-directional operation according to step 600A, otherwise it sends a rejection message to UE1.

[0199] Step 602 can be understood with reference to the above-mentioned step 303 and will not be described in detail here.

[0200] Step 603: The SMF sends a sixth message to the UDM, the sixth message including: a bidirectional identifier and an SMF identifier. Correspondingly, the UDM receives the sixth message.

[0201] When the sixth message includes the identifier of the PDU session, the session parameters of the PDU session, and SUPI1, the sixth message may further include: the identifier of the PDU session 1, the session parameters of the PDU session 1, and SUPI1.

[0202] When the third message includes the bidirectional session request information, the sixth message may further include the bidirectional session request information.

[0203] In addition, the SMF performs step 603 only if it determines according to step 600A that UE1 supports the dual-directional operation; otherwise, a rejection message is sent to UE1.

[0204] Step 604A: The SMF stores the association between the bi-directional identifier and the PDU session of UE1 (ie, the second association relationship).

[0205] Exemplarily, the second association relationship may indicate an association among SUPI1, the identifier of PDU session 1, and the bidirectional identifier.

[0206] In addition, SMF also selects UPF for UE1's PDU session, allocates an IP address to UE1, and allocates N4 Session ID for UE1's PDU session, where N4 Session ID is used for interaction between SMF and UPF.

[0207] Step 604B: The UDM stores the association between the bidirectional identifier and the SMF identifier.

[0208] Exemplarily, the UDM may store an association between SUPI1, an identifier of the PDU session 1, session parameters of the PDU session 1, an identifier of the SMF, and an identifier of the bidirectional direction.

[0209] Step 605: UDM sends a fifth message to AMF2, where the fifth message includes the SMF identifier. Accordingly, AMF2 receives the fifth message.

[0210] Exemplarily, the UDM may determine UE2 based on the association relationship between UE1 and UE2 in step 600B, and determine AMF2 based on the registration information of UE2 in step 600A.

[0211] Optionally, the fifth message also includes a bidirectional identifier and a bidirectional session type. AMF2 may store a third association between the SMF identifier and the bidirectional identifier. The third association may indicate an association between SUPI2 (UE2's identity), the SMF identifier, and the bidirectional identifier. Exemplarily, AMF2 may store the third association in the context of UE2.

[0212] In addition, UDM only sends the PDU session information of UE1 related to bidirectional to AMF2, such as the SMF identifier and the bidirectional identifier. If UE1 does not support bidirectional, step 605 may not be performed.

[0213] Step 605 can be understood by referring to the above-mentioned step 305 and will not be described in detail here.

[0214] Step 606: SMF sends UE1's PDU session establishment acceptance message to UE1.

[0215] Exemplarily, the PDU session establishment acceptance message of UE1 includes the IP address allocated by the SMF to UE1. Optionally, the establishment acceptance message includes DualSteer Session allowed, indicating that the PDU session 1 of UE1 is allowed to be a dual-directional session. Optionally, the establishment acceptance message also includes: dual-directional session request information.

[0216] Optionally, the following step 607 is performed only if the PDU session establishment acceptance message of UE1 in step 606 allows UE1's PDU session 1 to be a bidirectional session.

[0217] In addition, after step 606 is executed, other processing procedures of UE2's PDU session are also included (N3 establishment, DRB configuration, etc.), which can be understood with reference to the existing technology and will not be explained in detail here.

[0218] In step 607, UE2 sends a second message, which includes: UE2's PDU session establishment request message (i.e., the second session establishment request message) and a bidirectional identifier (the same as the bidirectional identifier in step 601). Accordingly, AMF2 receives the second message.

[0219] Optionally, the second message may be a NAS message. The first message may also include: an identifier of PDU session 2 (i.e., an identifier of the second session), and session parameters of PDU session 1 (i.e., session parameters of the first session. Based on the description of step 301 above, it can be seen that the session parameters of the second session are related to the session parameters of the first session. It is assumed here that the session parameters of the first session are the same as the session parameters of the second session). UE2's PDU session establishment request message also includes the identifier of PDU session 2.

[0220] Optionally, the second message may further include bidirectional session request information.

[0221] In addition, the PDU session establishment request message of UE2 may also include a bidirectional identifier.

[0222] After receiving the second message, AMF2 may obtain the identity SUPI2 of UE2. Exemplarily, AMF2 searches the registration information of UE2 to determine SUPI2.

[0223] When executing step 607, UE2 may forward the second message to AMF2 through RAN2.

[0224] Step 607 can be understood by referring to the above-mentioned step 307 and will not be described in detail here.

[0225] Step 608: AMF2 determines the SMF according to the third association relationship between the bidirectional identifier and the SMF identifier.

[0226] Exemplarily, AMF2 may search for the SMF identifier from the context of UE2.

[0227] Step 609: AMF2 sends a fourth message to SMF, where the fourth message includes UE2's PDU session establishment request message and a bidirectional identifier. Accordingly, SMF receives the fourth message.

[0228] If UE2 is in a roaming network, AMF2 sends a fourth message to the third network element (managing the second session in the roaming network of UE2), where the fourth message includes the SMF identifier so that the third network element determines the SMF based on the SMF identifier.

[0229] Optionally, the fourth message further includes: an identifier of PDU session 2, SUPI2, bidirectional session request information, and session parameters of PDU session 1.

[0230] This can be understood by referring to the description of step 309 above, which will not be elaborated here.

[0231] Step 610: The SMF creates a first association relationship between the PDU session of UE1 and the PDU session of UE2 according to the bi-directional identifier.

[0232] Exemplarily, the above step 609 includes the identifier of PDU session 2, or the SMF parses the PDU session establishment request message of UE2 to obtain the identifier of PDU session 2. The SMF searches the second association relationship stored in step 604A based on the bidirectional identifier received in step 609, obtains the identifier of PDU session 1, and creates a first association relationship between the identifier of PDU session 1 and the identifier of PDU session 2.

[0233] UE2's PDU session and UE1's PDU session share the same N4 Session ID and IP address. The SMF does not need to select a new UPF for UE2's PDU session, allocate an IP address for UE2, or allocate an N4 Session ID for UE2's PDU session.

[0234] Optionally, the SMF may send a PDU session establishment accept message of UE2 to UE2. Optionally, the PDU session establishment accept message of UE2 includes DualSteer Session allowed, indicating that the PDU session 2 of UE2 is allowed to be a dual-directional session.

[0235] Based on this, both UE1's PDU session and UE2's PDU session request carry the same dual-directional identifier, which is used by the network to associate the identifier of UE1's PDU session 1 with the identifier of UE2's PDU session 2.

[0236] Case 2: SMF generates a dual-directional identifier

[0237] Referring to Figure 7, the execution is as follows:

[0238] The execution process of step 700A is the same as that of step 600A, which will not be described in detail here. You can refer to it for understanding.

[0239] The execution process of step 700B is the same as that of step 600B, which will not be described in detail here. You can refer to it for understanding.

[0240] In step 701, UE1 sends a first message to AMF1, where the first message includes: UE1's PDU session establishment request message (i.e., the first session establishment request message) and bidirectional session request information. Accordingly, AMF1 receives the first message.

[0241] Optionally, the first message may be a NAS message. The first message may further include: an identifier of PDU session 1 (i.e., an identifier of the first session), and session parameters (DNN and S-NSSAI) of PDU session 1 (i.e., session parameters of the first session). The PDU session establishment request message of UE1 also includes an identifier of PDU session 1.

[0242] Optionally, the first message may also include bidirectional session request information.

[0243] After receiving the first message, AMF1 may obtain the identity SUPI1 of UE1. Exemplarily, AMF1 searches the registration information of UE1 to determine SUPI1.

[0244] When executing step 701, UE1 may forward the first message to AMF1 through RAN1.

[0245] Step 701 can be understood with reference to the above-mentioned step 302 and will not be described in detail here.

[0246] Step 702: AMF1 sends a third message to SMF, which includes: UE1's PDU session establishment request message and bidirectional session request information. Correspondingly, SMF receives the third message.

[0247] When the first message includes the identifier of the PDU session 1 and the session parameters of the PDU session 1, the third message may further include: the identifier of the PDU session and the session parameters of the PDU session.

[0248] In addition, the third message may also include the identity SUPI1 of UE1. Optionally, AMF1 selects an SMF that supports bidirectionality according to the bidirectional session request information.

[0249] In addition, AMF1 performs step 703 only if it determines, according to step 700A, that UE1 supports the dual-directional operation; otherwise, it sends a rejection message to UE1.

[0250] Step 702 can be understood with reference to the above-mentioned step 303 and will not be described in detail here.

[0251] Step 703: The SMF generates a bidirectional identifier according to the bidirectional session request information.

[0252] Optionally, the SMF obtains from the UDM or PCF whether the PDU session of the UE1 is allowed to be a bidirectional session. The SMF determines that the PDU session of the UE1 is allowed to be a bidirectional session and then generates a bidirectional identifier.

[0253] The execution process of step 704 is the same as that of step 603, which will not be described in detail here. You can refer to it for understanding.

[0254] The execution process of step 705A is the same as that of step 604A, which will not be described in detail here. You can refer to it for understanding.

[0255] The execution process of step 705B is the same as that of step 604B, which will not be described in detail here. You can refer to it for understanding.

[0256] The execution process of step 706 is the same as that of step 605, which will not be described in detail here. You can refer to it for understanding.

[0257] Step 707: SMF sends UE1's PDU session establishment acceptance message to UE1.

[0258] Exemplarily, the establishment acceptance message includes the IP address and dual-directional identifier assigned by the SMF to UE1. Optionally, the establishment acceptance message includes DualSteer Session allowed, indicating that the PDU session 1 of UE1 is allowed to be a dual-directional session. Optionally, the establishment acceptance message also includes: dual-directional session request information.

[0259] Optionally, the following step 708 is performed only if the acceptance message in step 707 is that the PDU session 1 of UE1 is allowed to be a bidirectional session.

[0260] In step 708, UE2 sends a second message, which includes: UE2's PDU session establishment request message (i.e., the second session establishment request message) and a bidirectional identifier (the same as the bidirectional identifier in step 703, which is carried in step 707). Accordingly, AMF2 receives the second message.

[0261] Optionally, the second message may be a NAS message. The first message may also include: an identifier of PDU session 2 (i.e., an identifier of the second session), and session parameters of PDU session 1 (i.e., session parameters of the first session. Based on the description of step 301 above, it can be seen that the session parameters of the second session are related to the session parameters of the first session. It is assumed here that the session parameters of the first session are related to the session parameters of the second session). The PDU session establishment request message of UE2 also includes the identifier of PDU session 2.

[0262] Optionally, the second message may further include bidirectional session request information.

[0263] In addition, the PDU session establishment request message of UE2 may also include a bidirectional identifier.

[0264] After receiving the second message, AMF2 can obtain the identity identifier SUPI2 of UE2. Exemplarily, AMF2 searches the registration information of UE2 to determine SUPI2.

[0265] When executing step 708, UE2 may forward the second message to AMF2 through RAN2.

[0266] Step 708 can be understood by referring to the above-mentioned step 307 and will not be described in detail here.

[0267] Step 709: AMF2 determines the SMF according to the third association relationship between the bidirectional identifier and the SMF identifier.

[0268] Exemplarily, AMF2 may search for the SMF identifier from the context of UE2.

[0269] Step 710: AMF2 sends a fourth message to SMF, where the fourth message includes UE2's PDU session establishment request message and a bidirectional identifier. Accordingly, SMF receives the fourth message.

[0270] If UE2 is in a roaming network, AMF2 sends a fourth message to the third network element (managing the second session in the roaming network of UE2), where the fourth message includes the SMF identifier so that the third network element determines the SMF based on the SMF identifier.

[0271] Optionally, the fourth message further includes: an identifier of PDU session 2, SUPI2, bidirectional session request information, and session parameters of PDU session 1.

[0272] Step 711: SMF creates a first association relationship between the PDU session of UE1 and the PDU session of UE2 according to the bidirectional identifier.

[0273] Exemplarily, the above step 710 includes the identifier of PDU session 2, or the SMF parses the PDU session establishment request message of UE2 to obtain the identifier of PDU session 2. The SMF searches the second association relationship stored in step 604A based on the bidirectional identifier received in step 710, obtains the identifier of PDU session 1, and creates a first association relationship between the identifier of PDU session 1 and the identifier of PDU session 2.

[0274] UE2's PDU session and UE1's PDU session share the same N4 Session ID and IP address. The SMF does not need to select a new UPF for UE2's PDU session, allocate an IP address for UE2, or allocate an N4 Session ID for UE2's PDU session.

[0275] Optionally, the SMF may send a PDU session establishment accept message of UE2 to UE2. Optionally, the PDU session establishment accept message of UE2 includes DualSteer Session allowed, indicating that the PDU session 2 of UE2 is allowed to be a dual-directional session.

[0276] Based on this, SMF generates a dual-directional identifier when UE1 requests a PDU session, and UE2 carries a dual-directional identifier when requesting a PDU session, which is used by the network to associate the identifier of UE1's PDU session 1 with the identifier of UE2's PDU session 2.

[0277] Case 3: No dual-directional identification is generated

[0278] Referring to Figure 8, the execution is as follows:

[0279] The execution process of step 800A is the same as that of step 600A, which will not be described in detail here. You can refer to it for understanding.

[0280] The execution process of step 800B is the same as that of step 600B, which will not be described in detail here. You can refer to it for understanding.

[0281] In step 801, UE1 sends a first message to AMF1. The first message includes: UE1's PDU session establishment request message (i.e., the first session establishment request message), the identifier of PDU session 1 (i.e., the identifier of the first session), and bidirectional session request information. Accordingly, AMF1 receives the first message.

[0282] Optionally, the first message may be a NAS message. The first message may also include: session parameters (DNN and S-NSSAI) of PDU session 1 (i.e., session parameters of the first session). The PDU session establishment request message of UE1 also includes an identifier of PDU session 1.

[0283] Optionally, the first message may also include bidirectional session request information.

[0284] After receiving the first message, AMF1 can obtain the identity SUPI1 of UE1. Exemplarily, AMF1 searches the registration information of UE1 to determine SUPI1.

[0285] When executing step 801, UE1 may forward the first message to AMF1 through RAN1.

[0286] Step 802: AMF1 sends a third message to SMF, which includes: UE1's PDU session establishment request message, the identifier of PDU session 1, and bidirectional session request information. Accordingly, SMF receives the third message.

[0287] When the first message includes the session parameters of the PDU session 1, the third message may further include: an identifier of the PDU session and the session parameters of the PDU session.

[0288] In addition, the third message may also include the identity SUPI1 of UE1. Optionally, AMF1 selects an SMF that supports bidirectionality according to the bidirectional session request information.

[0289] In addition, AMF1 determines according to step 800A that UE1 supports dual-directional operation before executing step 803, otherwise it sends a rejection message to UE1.

[0290] Step 803: The SMF sends a sixth message to the UDM, where the sixth message includes: the SMF identifier, the bidirectional session type, and the identifier of PDU session 1. Accordingly, the UDM receives the sixth message.

[0291] When the sixth message includes the identifier of the PDU session 1, the session parameters of the PDU session, and SUPI1, the sixth message may further include: the session parameters of the PDU session 1 and SUPI1.

[0292] In addition, the SMF performs step 803 only if it determines according to step 800A that UE1 supports the dual-directional operation; otherwise, it sends a rejection message to UE1.

[0293] Step 804A: The SMF stores the association between the identifier of the PDU session 1 and the bidirectional session type, that is, the PDU session 1 is used for bidirectional.

[0294] Exemplarily, the second association relationship may indicate an association between SUPI1, the identifier of PDU session 1, and a bidirectional session type.

[0295] In addition, SMF also selects UPF for UE1's PDU session, allocates an IP address to UE1, and allocates N4 Session ID for UE1's PDU session, where N4 Session ID is used for interaction between SMF and UPF.

[0296] Step 804B: UDM stores the association between the identifier of PDU session 1 and the identifier of SMF (ie, the fourth association relationship).

[0297] Exemplarily, the UDM may store SUPI1, the identifier of the PDU session 1, the session parameters of the PDU session 1, the identifier of the SMF, and the association of the bidirectionality.

[0298] Step 805: UDM sends a fifth message to AMF2, where the fifth message includes the SMF identifier and the identifier of PDU session 1. Accordingly, AMF2 receives the fifth message.

[0299] Exemplarily, the UDM may determine UE2 based on the association relationship between UE1 and UE2 in step 600B, and determine AMF2 based on the registration information of UE2 in step 600A.

[0300] Optionally, the fifth message also includes a bidirectional session type. AMF2 may store a fourth association relationship between the SMF identifier and the PDU session 1 identifier. The fourth association relationship may indicate an association between SUPI2 (UE2's identity), the SMF identifier, and the PDU session 1 identifier. Exemplarily, AMF2 may store the fourth association relationship in the context of UE2.

[0301] In addition, UDM only sends the PDU session information of UE1 related to bidirectional, such as the SMF identifier, to AMF2. If UE1 does not support bidirectional, step 805 may not be performed.

[0302] Step 806: SMF sends UE1's PDU session establishment acceptance message to UE1.

[0303] Exemplarily, the establishment acceptance message includes the IP address allocated by the SMF to UE1. Optionally, the establishment acceptance message includes DualSteer Session allowed, indicating that the PDU session 1 of UE1 is allowed to be a dual-directional session. Optionally, the establishment acceptance message also includes: dual-directional session acceptance information.

[0304] Optionally, the following step 807 is performed only if the acceptance message in step 806 is that the PDU session 1 of UE1 is allowed to be a bidirectional session.

[0305] In addition, after step 806 is executed, other processing procedures of UE2's PDU session are also included (N3 establishment, DRB configuration, etc.), which can be understood with reference to the existing technology and will not be explained in detail here.

[0306] In step 807, UE2 sends a second message, which includes: UE2's PDU session establishment request message (i.e., the second session establishment request message), the identifier of PDU session 1, and the identifier of PDU session 2 (i.e., the identifier of the second session). Accordingly, AMF2 receives the second message.

[0307] Optionally, the second message may be a NAS message. The second message may also include: session parameters of PDU session 1 (i.e., session parameters of the first session. Based on the description of step 301 above, it can be seen that the session parameters of the second session are related to the session parameters of the first session. It is assumed here that the session parameters of the first session are related to the session parameters of the second session). The PDU session establishment request message of UE2 also includes the identifier of PDU session 2.

[0308] Optionally, the second message may further include bidirectional session request information.

[0309] After receiving the second message, AMF2 may obtain the identity SUPI2 of UE2. Exemplarily, AMF2 searches the registration information of UE2 to determine SUPI2.

[0310] When executing step 807, UE2 may forward the second message to AMF2 through RAN2.

[0311] Step 808: AMF2 determines the SMF based on the fourth association relationship between the identifier of PDU session 1 and the identifier of SMF.

[0312] Exemplarily, AMF2 may search for the SMF identifier from the context of UE2.

[0313] Step 809: AMF2 sends a fourth message to SMF, where the fourth message includes UE2's PDU session establishment request message and the identifier of PDU session 1. Accordingly, SMF receives the fourth message.

[0314] If UE2 is in a roaming network, AMF2 sends a fourth message to the third network element (managing the second session in the roaming network of UE2), where the fourth message includes the SMF identifier so that the third network element determines the SMF based on the SMF identifier.

[0315] Optionally, the fourth message further includes: an identifier of PDU session 2, SUPI2, bidirectional session request information, and session parameters of PDU session 1.

[0316] Step 810: The SMF creates a first association relationship between the PDU session of UE1 and the PDU session of UE2 according to the identifier of the PDU session 1.

[0317] Exemplarily, the above step 809 includes the identifier of PDU session 2 or the SMF parses the PDU session establishment request message of UE2 to obtain the identifier of PDU session 2. The SMF creates a first association relationship between the identifier of PDU session 1 and the identifier of PDU session 2.

[0318] UE2's PDU session and UE1's PDU session share the same N4 Session ID and IP address. The SMF does not need to select a new UPF for UE2's PDU session, allocate an IP address for UE2, or allocate an N4 Session ID for UE2's PDU session.

[0319] Optionally, the SMF may send a PDU session establishment accept message of UE2 to UE2. Optionally, the PDU session establishment accept message of UE2 includes DualSteer Session allowed, indicating that the PDU session 2 of UE2 is allowed to be a dual-directional session.

[0320] Based on this, both UE1's PDU session and UE2's PDU session request carry it.

[0321] Based on this, without constructing a dual-directional identifier, reusing UE1's PDU session identifier can associate UE1's PDU session 1 identifier with UE2's PDU session 2 identifier, thereby reducing data processing complexity.

[0322] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of device interaction. It is understandable that, in order to implement the above functions, each device may include a hardware structure and / or software module that performs each function. Those skilled in the art should easily appreciate that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven hardware manner depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0323] In the embodiments of the present application, the functional units of the device can be divided according to the above method examples. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or software functional units.

[0324] In the case of adopting an integrated unit, Figure 9 shows a possible exemplary block diagram of the communication device involved in the embodiments of the present application. As shown in Figure 9, the communication device 900 may include: a processing unit 901 and a transceiver unit 902. The processing unit 901 is used to control and manage the actions of the communication device 900. The transceiver unit 902 is used to support communication between the communication device 900 and other devices. Optionally, the transceiver unit 902 may include a receiving unit and / or a sending unit, which are used to perform receiving and sending operations respectively. Optionally, the communication device 900 may also include a storage unit for storing program code and / or data of the communication device 900. The transceiver unit can be called an input / output unit, a communication unit, etc., and the transceiver unit can be a transceiver; the processing unit can be a processor. When the communication device is a module (such as a chip) in a communication device, the transceiver unit can be an input / output interface, an input / output circuit or an input / output pin, etc., and can also be called an interface, a communication interface or an interface circuit, etc.; the processing unit can be a processor, a processing circuit or a logic circuit, etc. Exemplarily, the apparatus may be the aforementioned first device (the first terminal and the second terminal), the first network element, the second network element, the third network element, the fourth network element, and the fifth network element.

[0325] In one embodiment, the communication device 900 is a first device, the processing unit 901 is used to obtain first information, and the first information is used by the first device to determine to establish a bidirectional session; the transceiver unit 902 of the first terminal sends a first message, the first message includes a request message to establish a first session, the first session is a bidirectional session, and the first session is a session of the first terminal; the transceiver unit 902 of the second terminal sends a second message, the second message includes a request message to establish a second session, the session parameters of the second session are related to the session parameters of the first session, the second session is a bidirectional session, and the second session is a session of the second terminal.

[0326] In an optional manner, the first information includes: RSD corresponding to the first service, the RSD includes: indication information of the bidirectional session, session parameters of the first session, the indication information of the bidirectional session is used to indicate the establishment of a bidirectional session, and the first information is in the routing selection policy of the first terminal.

[0327] In an optional manner, the first information is policy information of a bidirectional session, and the processing unit 901 of the first terminal is configured to determine session parameters of the first session according to a routing policy of the first terminal.

[0328] In an optional manner, the policy information includes: service information allowing bi-directional sessions, and / or allowing the use of bi-directional sessions.

[0329] In an optional manner, the transceiver unit 902 (which can be the first terminal or the second terminal) is used to receive first information from the first network element, and the first information is determined based on the dual-directional capability information and / or dual-directional subscription information of the first device.

[0330] In an optional manner, the processing unit 901 of the second terminal is configured to determine the session parameters of the second session according to the session parameters of the first session.

[0331] In an optional manner, after the first device obtains the first information, the processing unit 901 of the first terminal is used to determine the session parameters of the first session according to the routing selection policy of the first terminal; the processing unit 901 of the second terminal is used to determine the session parameters of the second session according to the routing selection policy of the second terminal.

[0332] In an optional manner, before the second terminal sends the second message, the transceiver unit 902 of the first terminal further receives a setup acceptance message of the first session.

[0333] In an optional manner, the first message further includes at least one of the following parameters:

[0334] Bidirectional session request information, or a bidirectional identifier, where the bidirectional identifier is generated by the first device.

[0335] In an optional manner, the second message further includes at least one of the following parameters: bidirectional session request information, an identifier of the first session, or a bidirectional identifier.

[0336] In an optional manner, the bidirectional identifier in the second message is generated by the first device; or the first device receives the bidirectional identifier, and the bidirectional identifier is allocated by a second network element, and the second network element is used to manage the first session.

[0337] In another embodiment, the communication device 900 is a second network element, and the transceiver unit 902 is used to receive a third message, the third message including a request message for establishing a first session and an identifier of the first session, the first session is a bidirectional session, and the first session is a session of the first terminal; receive a fourth message, the fourth message including a request message for establishing a second session, an identifier and identification information of the second session, the second session is a bidirectional session, and the second session is a session of the second terminal, the identification information is a bidirectional identifier, or an identifier of the first session, and the bidirectional identifier is related to the first session; the processing unit 901 is used to create a first association relationship between the first session and the second session based on the identification information.

[0338] In an optional manner, the identification information is a bidirectional identification, and the third message further includes the bidirectional identification, which is generated by the first terminal or the second terminal.

[0339] In an optional manner, the identification information is a bidirectional identification, the third message also includes a bidirectional session request information, and the processing unit 901 is further used to generate a bidirectional identification based on the bidirectional session request information; the transceiver unit 902 is also used to send an establishment acceptance message for the first session, and the establishment acceptance message includes the bidirectional identification.

[0340] In an optional manner, the processing unit 901 is configured to store a second association relationship between the bi-directional identifier and the first session.

[0341] In an optional manner, when the identification information is a bidirectional identification and the third message further includes the bidirectional identification, the processing unit 901 is configured to create a first association relationship between the first session and the second session according to the bidirectional identification.

[0342] In an optional manner, the identification information is an identifier of the first session, and the processing unit 901 is configured to create a first association relationship between the first session and the second session according to the identifier of the first session and the identifier of the second session.

[0343] In an optional manner, the second network element also sends a sixth message, which includes: the identifier of the first session, bidirectional information and the identifier of the second network element. The second network element is used to manage the first session. The bidirectional information is a bidirectional identifier or a bidirectional session type.

[0344] In another embodiment, the communication device 900 is a fourth network element, and the transceiver unit 902 is used to receive a fifth message, the fifth message including an identifier of a second network element and a bidirectional identifier, the second network element is used to manage a first session, the bidirectional identifier is related to the first session, and the first session is a session of the first terminal; receive a second message, the second message including a request message to establish a second session and a bidirectional identifier, the second session is a session of the second terminal; the processing unit 901 is used to determine the second network element according to the bidirectional identifier, and the second network element is also used to manage the second session; the transceiver unit 902 is also used to send a fourth message to the second network element, the fourth message including a request message to establish a second session; or, send a fourth message to a third network element, the fourth message including a request message to establish a second session and the identifier of the second network element, and the third network element is used to manage the second session in the roaming network of the second terminal.

[0345] In an optional manner, after the fourth network element receives the fifth message, the processing unit 901 is further configured to store a third association relationship between the identifier of the second network element and the bi-directional identifier.

[0346] In an optional manner, the processing unit 901 is further configured to determine the second network element according to the bi-directional identifier and the third association relationship.

[0347] In an optional manner, the second message further includes bidirectional session request information, and the processing unit 901 is further configured to determine the second network element according to the bidirectional identifier under the condition that it is determined that the second session establishment request message is bidirectional session request information.

[0348] In an optional manner, the fifth message further includes a bidirectional session type.

[0349] In an optional manner, the fourth message further includes: an identifier and identification information of the second session, where the identification information is a bidirectional identifier, or an identifier of the first session, where the bidirectional identifier is related to the first session.

[0350] In another embodiment, the communication device 900 is a fourth network element, and the transceiver unit 902 is used to receive a fifth message, the fifth message includes an identifier of the second network element and an identifier of the first session, the second network element is used to manage the first session, and the first session is a session of the first terminal; receive a second message, the second message includes a request message to establish a second session and an identifier of the first session, and the second session is a session of the second terminal; the processing unit 901 is used to determine the second network element according to the identifier of the first session, and the second network element is also used to manage the second session; the transceiver unit 902 is also used to send a fourth message to the second network element, the fourth message includes a request message to establish a second session; or, send a fourth message to a third network element, the fourth message includes a request message to establish a second session and the identifier of the second network element, and the third network element is used to manage the second session in the roaming network of the second terminal.

[0351] In an optional manner, after the fourth network element receives the fifth message, the processing unit 901 is further configured to store a fourth association relationship between the identifier of the second network element and the identifier of the first session.

[0352] In an optional manner, the processing unit 901 is further configured to determine the second network element according to the identifier of the first session and the fourth association relationship.

[0353] In an optional manner, the second message further includes bidirectional session request information, and the processing unit 901 is further configured to determine the second network element according to the identifier of the first session under the condition that it is determined that the establishment request message of the second session is bidirectional session request information.

[0354] In an optional manner, the fifth message further includes a bidirectional session type.

[0355] In an optional manner, the fourth message further includes: an identifier and identification information of the second session, where the identification information is a bidirectional identifier, or an identifier of the first session, where the bidirectional identifier is related to the first session.

[0356] In one embodiment, the communication device 900 is a fifth network element, and the transceiver unit 902 is used to receive a sixth message, which includes: an identifier of the first session, bidirectional information and an identifier of the second network element, the first session is a session of the first terminal, the second network element is used to manage the first session, and the bidirectional information is a bidirectional identifier, or a bidirectional session type; the processing unit 901 is used to send a fifth message to the fourth network element based on the association relationship between the first terminal and the second terminal, the fifth message includes the identifier of the second network element, and the fourth network element is the access management network element of the second terminal.

[0357] In an optional manner, when the bidirectional information is a bidirectional identifier, the fifth message further includes the bidirectional identifier; or when the bidirectional information is a bidirectional session type, the fifth message further includes the identifier of the first session.

[0358] In an optional manner, the processing unit 901 is configured to send a fifth message to the fourth network element according to the association relationship between the first terminal and the second terminal and the bi-directional information.

[0359] In an optional manner, the fifth message further includes a bidirectional session type.

[0360] As shown in Figure 10, this application also provides a communication device 1000. The communication device 1000 can be a chip or a chip system. The communication device can be located in the device involved in any of the above method embodiments, such as an access network device or a first core network device, to perform the corresponding actions of the device.

[0361] Optionally, the chip system may consist of the chip, or may include the chip and other discrete devices.

[0362] The communication device 1000 includes a processor 1010 .

[0363] The processor 1010 is configured to execute the computer program stored in the memory 1020 to implement the actions of each device in any of the above method embodiments.

[0364] The communication device 1000 may further include a memory 1020 for storing computer programs.

[0365] Optionally, memory 1020 and processor 1010 are coupled. Coupling is an indirect coupling or communication connection between devices, units, or modules, and can be electrical, mechanical, or other forms, for information exchange between devices, units, or modules. Optionally, memory 1020 and processor 1010 are integrated.

[0366] The processor 1010 and the memory 1020 can be one or more without limitation.

[0367] Optionally, in actual applications, the communication device 1000 may or may not include a transceiver 1030, as illustrated by a dashed box in the figure. The communication device 1000 can exchange information with other devices via the transceiver 1030. The transceiver 1030 can be a circuit, a bus, a transceiver, or any other device capable of exchanging information.

[0368] In a possible implementation, the communication device 1000 may be an access network device or a first core network device in the implementation of the above methods.

[0369] The specific connection medium between the transceiver 1030, processor 1010, and memory 1020 is not limited in the embodiments of the present application. In FIG10 , the memory 1020, processor 1010, and transceiver 1030 are connected via a bus. The bus is represented by a bold line in FIG10 . The connection between other components is for illustrative purposes only and is not intended to be limiting. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, FIG10 uses only a single bold line, but this does not imply that there is only one bus or a single type of bus. In the embodiments of the present application, the processor can be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of the present application can be directly executed by a hardware processor or by a combination of hardware and software modules within the processor.

[0370] In an embodiment of the present application, the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), etc., or a volatile memory (volatile memory), such as a random-access memory (RAM). The memory may also be any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in an embodiment of the present application may also be a circuit or any other device that can implement a storage function, for storing computer programs, program instructions and / or data.

[0371] Based on the above embodiments, referring to FIG11 , the embodiment of the present application also provides another communication device 1100, including: an interface circuit 1110 and a logic circuit 1120; the interface circuit 1110 can be understood as an input and output interface, which can be used to execute the receiving and sending steps of each device in any of the above method embodiments, and the logic circuit 1120 can be used to run code or instructions to execute the method executed by each device in any of the above embodiments, which will not be repeated.

[0372] Based on the above embodiments, embodiments of the present application further provide a computer-readable storage medium storing instructions that, when executed, cause the method executed by each device in any of the above method embodiments to be implemented. The computer-readable storage medium may include any medium capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk.

[0373] Based on the above embodiments, an embodiment of the present application provides a communication system, which includes the first device (first terminal and second terminal), first network element, second network element, third network element, fourth network element and fifth network element mentioned in any of the above method embodiments, and can be used to execute the method executed by each device in any of the above method embodiments.

[0374] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0375] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0376] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0377] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

Claims

1. A communication method, characterized in that: Applied to a first device, the first device including: a first terminal and a second terminal, the method including: Acquire first information, where the first information is used by the first device to determine to establish a bi-directional session; Sending a first message, where the first message includes a request message for establishing a first session, where the first session is a bidirectional session and is a session of the first terminal; A second message is sent, where the second message includes a request message for establishing a second session, session parameters of the second session are related to session parameters of the first session, the second session is a bidirectional session, and the second session is a session of the second terminal.

2. The method according to claim 1, characterized in that The first information includes: a routing descriptor corresponding to the first service, the routing descriptor includes: indication information of the bidirectional session, session parameters of the first session, the indication information of the bidirectional session is used to indicate the establishment of the bidirectional session, and the first information is in the routing policy of the first terminal.

3. The method according to claim 1, characterized in that The first information is policy information of the bi-directional session, and the method further includes: Determine session parameters of the first session according to the routing policy of the first terminal.

4. The method according to claim 3, characterized in that The policy information includes: service information allowing the bi-directional session, and / or information allowing the use of the bi-directional session.

5. The method according to any one of claims 1 to 4, characterized in that: The obtaining of the first information includes: The first information is received from a first network element, where the first information is determined based on the bidirectional capability information and / or bidirectional subscription information of the first device.

6. The method according to any one of claims 1 to 5, characterized in that: The method further comprises: The session parameters of the second session are determined according to the session parameters of the first session.

7. The method according to any one of claims 1 to 5, characterized in that The method further comprises: determining session parameters of the first session according to a routing policy of the first terminal; The session parameters of the second session are determined according to the routing policy of the second terminal.

8. The method according to any one of claims 1 to 7, characterized in that: Before sending the second message, the method further includes: Receive a setup acceptance message for the first session.

9. The method according to any one of claims 1 to 8, characterized in that: The first message also includes at least one of the following parameters: The bidirectional session request information, or the bidirectional identifier, where the bidirectional identifier is generated by the first device.

10. The method according to any one of claims 1 to 9, characterized in that: The second message further includes at least one of the following parameters: The bidirectional session request information, the identifier of the first session, or the bidirectional identifier.

11. The method according to claim 10, characterized in that The dual-directional identifier is generated by the first device; or The bi-directional identifier is received, where the bi-directional identifier is allocated by a second network element, and the second network element is used to manage the first session.

12. A communication method, characterized in that: Applied to a second network element, the method includes: receiving a third message, the third message including a first session establishment request message and an identifier of the first session, the first session being a bidirectional session and being a session of the first terminal; receiving a fourth message, the fourth message including a second session establishment request message, an identifier of the second session, and identification information, wherein the second session is a bidirectional session, the second session is a session of the second terminal, and the identification information is the bidirectional identifier or the identifier of the first session, wherein the bidirectional identifier is related to the first session; A first association relationship between the first session and the second session is created according to the identification information.

13. The method according to claim 12, characterized in that The identification information is the bi-directional identification, and the third message further includes the bi-directional identification, which is generated by the first terminal or the second terminal.

14. The method according to claim 12, characterized in that The identification information is the bidirectional identification, the third message further includes the bidirectional session request information, and the method further includes: generating the bi-directional identifier according to the bi-directional session request information; Sending a setup acceptance message for the first session, where the setup acceptance message includes the bi-directional identifier.

15. The method according to claim 13 or 14, characterized in that The method further comprises: A second association relationship between the bi-directional identifier and the first session is stored.

16. The method according to any one of claims 13 to 15, characterized in that: The creating a first association relationship between the first session and the second session according to the identification information includes: A first association relationship between the first session and the second session is created according to the bi-directional identifier.

17. The method according to claim 12, wherein: The identification information is an identifier of the first session, and the creating a first association relationship between the first session and the second session according to the identification information includes: A first association relationship between the first session and the second session is created according to the identifier of the first session and the identifier of the second session.

18. The method according to any one of claims 12 to 17, characterized in that: The method further comprises: Send a sixth message, the sixth message including: the identifier of the first session, bidirectional information and the identifier of the second network element, the second network element is used to manage the first session, the bidirectional information is the bidirectional identifier, or the bidirectional session type.

19. A communication method, characterized in that: Applied to a fourth network element, the method includes: receiving a fifth message, the fifth message including an identifier of a second network element and a bi-directional identifier, the second network element being configured to manage a first session, the bi-directional identifier being associated with the first session, the first session being a session of the first terminal; receiving a second message, where the second message includes a second session establishment request message and the bidirectional identifier, where the second session is a session of the second terminal; determining the second network element according to the bi-directional identifier, where the second network element is further configured to manage the second session; sending a fourth message to the second network element, where the fourth message includes a request message for establishing the second session; or, A fourth message is sent to a third network element, where the fourth message includes a request message for establishing the second session and an identifier of the second network element. The third network element is used to manage the second session in the roaming network of the second terminal.

20. The method according to claim 19, characterized in that After receiving the fifth message, the method further includes: A third association relationship between the identifier of the second network element and the bi-directional identifier is stored.

21. The method according to claim 20, characterized in that The determining the second network element according to the dual-directional identifier includes: The second network element is determined according to the bi-directional identifier and the third association relationship.

22. The method according to any one of claims 19 to 21, characterized in that: The second message further includes the bi-directional session request information, and the method further includes: Under the condition that the establishment request message of the second session is the bi-directional session request information, the second network element is determined according to the bi-directional identifier.

23. The method according to any one of claims 19 to 22, characterized in that: The fifth message further includes the bi-directional session type.

24. The method according to any one of claims 19 to 23, characterized in that: The fourth message further includes: an identifier and identification information of the second session, where the identification information is the bidirectional identifier or the identifier of the first session, and the bidirectional identifier is related to the first session.

25. A communication method, characterized in that: Applied to a fourth network element, the method includes: receiving a fifth message, the fifth message including an identifier of a second network element and an identifier of a first session, the second network element being configured to manage the first session, the first session being a session of the first terminal; receiving a second message, where the second message includes a request message for establishing a second session and an identifier of the first session, where the second session is a session of a second terminal; determining the second network element according to the identifier of the first session, where the second network element is further used to manage the second session; sending a fourth message to the second network element, where the fourth message includes a request message for establishing the second session; or, A fourth message is sent to a third network element, where the fourth message includes a request message for establishing the second session and an identifier of the second network element. The third network element is used to manage the second session in the roaming network of the second terminal.

26. The method according to claim 25, characterized in that After receiving the fifth message, the method further includes: A fourth association relationship between the identifier of the second network element and the identifier of the first session is stored.

27. The method according to claim 26, characterized in that The determining the second network element according to the identifier of the first session includes: The second network element is determined according to the identifier of the first session and the fourth association relationship.

28. The method according to any one of claims 25 to 27, characterized in that: The second message further includes the bi-directional session request information, and the method further includes: Under the condition that the establishment request message of the second session is the bi-directional session request information, the second network element is determined according to the identifier of the first session.

29. The method according to any one of claims 25 to 28, characterized in that: The fifth message also includes a bi-directional session type.

30. The method according to any one of claims 25 to 29, characterized in that: The fourth message further includes: an identifier and identification information of the second session, where the identification information is the bidirectional identifier or the identifier of the first session, and the bidirectional identifier is related to the first session.

31. A communication method, characterized in that: Applied to a fifth network element, the method includes: receiving a sixth message, the sixth message including: an identifier of a first session, bidirectional information, and an identifier of a second network element, wherein the first session is a session of the first terminal, the second network element is configured to manage the first session, and the bidirectional information is the bidirectional identifier or the bidirectional session type; According to the association relationship between the first terminal and the second terminal, a fifth message is sent to a fourth network element, where the fifth message includes an identifier of the second network element, and the fourth network element is an access management network element of the second terminal.

32. The method according to claim 31, characterized in that When the bidirectional information is the bidirectional identifier, the fifth message further includes the bidirectional identifier; or When the bi-directional information is the bi-directional session type, the fifth message further includes an identifier of the first session.

33. The method according to claim 31 or 32, characterized in that The sending a fifth message to a fourth network element according to the association relationship between the first terminal and the second terminal includes: A fifth message is sent to the fourth network element according to the association relationship between the first terminal and the second terminal and the bi-directional information.

34. The method according to any one of claims 31 to 33, characterized in that The fifth message further includes the bi-directional session type.

35. A communication device, characterized in that: include: A functional module for implementing the method according to any one of claims 1 to 34.

36. A communication device, characterized in that include: at least one processor and memory; The memory is used to store computer programs or instructions; The at least one processor is configured to execute the computer program or instructions so that the method according to any one of claims 1 to 34 is performed.

37. A chip system, characterized in that: The chip system includes: a processing circuit; the processing circuit is coupled to a storage medium; The processing circuit is used to execute part or all of the computer programs or instructions in the storage medium, and when the part or all of the computer programs or instructions are executed, it is used to implement the method according to any one of claims 1 to 34.

38. A computer-readable storage medium, characterized in that The computer-readable storage medium stores instructions, which, when executed by a computer, cause the method according to any one of claims 1 to 34 to be performed.

39. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is run on a computer, the method according to any one of claims 1 to 34 is performed.

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