CN114079990A

CN114079990A - Communication method and device

Info

Publication number: CN114079990A
Application number: CN202011066441.3A
Authority: CN
Inventors: 朱强华; 吴问付
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-08-12
Filing date: 2020-09-30
Publication date: 2022-02-22

Abstract

The application provides a communication method and a device, so that the terminal equipment registered in a first network can establish a first PDU session associated with DNN and S-NSSAI in the first network, and the terminal equipment can also send a first registration request message to the first network equipment, wherein the first registration request message is used for requesting to register to a second network. The terminal device can also receive first information from the first network device, wherein the first information is determined according to the intercommunication mode between the first network and the second network. The terminal equipment can also establish a PDU session of the terminal equipment according to the first information, and the PDU session is associated with the DNN and the S-NSSAI, so that the switching efficiency of the UE in the non-public network can be improved.

Description

Communication method and device

The priority of the chinese patent application entitled "a method and apparatus for communication" filed by the intellectual property office of the people's republic of china at 8/12/2020, application No. 202010808903.8, is claimed and is incorporated herein by reference in its entirety.

Technical Field

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

Background

In a fifth generation (5G) wireless communication system, a non-public network (NPN) is supported as a non-public 5G network. The NPN includes a public network integrated NPN (public network integrated NPN) realized under support of a Public Land Mobile Network (PLMN) and an independent NPN (stand alone NPN) that can be realized independent of the PLMN.

In addition, there are two ways to support interworking between PLMN and SNPN. For example, as shown in fig. 1, interworking between the PLMN and the SNPN may be implemented by a non-third generation partnership project (non-3 GPP) interworking function network element (N3 IWF). Alternatively, interworking between PLMN and SNPN may be achieved through a roaming architecture as shown in fig. 2. Of course, both ways also support interworking between SNPN and SNPN.

Therefore, at present, the network may support the interworking between one SNPN and other SNPNs or PLMNs as follows: non-interworking, N3IWF architecture based interworking, and roaming architecture based interworking. Due to the difference of the interworking modes, when the UE moves between two networks, such as between an SNPN and a PLMN or between two SNPNs, the switching modes of the UE are different, but the UE cannot know the interworking mode supported by the current network and cannot reasonably select the switching mode, so that the switching efficiency of the UE switching between the two networks is not high or the UE cannot be correctly switched to maintain service continuity.

Disclosure of Invention

The application provides a communication method and a communication device, which are used for solving the problem that the switching efficiency of UE between cross-NPN networks is not high or the UE cannot be switched correctly.

In a first aspect, embodiments of the present application provide a communication method, which may be implemented by a terminal device or a component (e.g., a chip, a circuit, or the like) of the terminal device. The terminal device may be a UE.

Taking the execution subject as the terminal device as an example, according to the method, the terminal device registered in the first network may establish a first Protocol Data Unit (PDU) session associated with a Data Network Name (DNN) and single network slice selection assistance information (S-NSSAI) in the first network, and the terminal device may further send a first registration request message to the first network device. The first message is used to request registration to the second network, and the first message is taken as the first registration request message for the following description, but it should not be understood that the first message is limited to the registration request. The terminal device can also receive first information from the first network device, wherein the first information is determined according to the intercommunication mode between the first network and the second network. The terminal device may also establish a PDU session for the terminal device based on the first information, the PDU session being associated with the DNN and the S-NSSAI.

By adopting the method, after the UE is registered to the second network from the first network, the UE can receive the first information from the first network equipment in the second network, and due to the correlation between the first information and the intercommunication mode between the first network and the second network, the PDU session of the UE related to DNN and S-NSSAI can be recovered more efficiently according to the first information, so that the switching efficiency is improved, and the service continuity is ensured.

In a possible design, the first registration request message may include a handover across non-public networks indication, which is used to instruct the terminal device to perform handover across non-public networks.

In a possible design, the above interworking manner between the first network and the second network includes non-interworking between the first network and the second network, interworking between the first network and the second network based on N3IWF, or interworking between the first network and the second network based on roaming.

In one possible design, in a case that the interworking mode includes no interworking between the first network and the second network, the terminal device may send a second message to the first network device, where the second message includes a request type (request type) information element with an initial request (initial request) value, or the second message is used to request establishment of an initial PDU session. In the following, the second message is taken as the first PDU session request message for explanation, but it should not be understood that the second message is limited to the PDU session request message. The first PDU session request message may include information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI. Therefore, under the mode that the first network and the second network are not intercommunicated, the UE can establish the PDU session associated to the DNN and the S-NSSAI in the second network, the recovery of the PDU session associated to the DNN and the S-NSSAI is realized, and the switching efficiency is improved.

In a possible design, in a case that the interworking mode includes non-interworking between the first network and the second network, the first information is used to indicate that the first network and the second network do not interwork, or the first information is used to indicate that the terminal device sends the first PDU session request to the first network device. Accordingly, flexible indication of the interworking manner can be achieved.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the terminal device may send a third message to the first network device, the third message requesting establishment of the second PDU session. In the following, the third message is taken as the second PDU session request message for explanation, but it should not be understood that the third message is limited to the PDU session request message. The terminal device may also establish a connection with an N3IWF over a second PDU session, the N3IWF belonging to said first network. The terminal device may further send a fourth message to the second network device through the connection, where the fourth message is used to request registration in the first network in an N3GPP manner, and the second network device belongs to the first network. The fourth message is taken as the second registration request message for the following description, but it should not be understood that the fourth message is taken as the registration request message for the limitation. The terminal device may further send a fifth message to the second network device, where the fifth message includes a request type information element with a value of existing PDU session (existing PDU session), or the fifth message is used to request to establish the existing PDU session. In the following, the fifth message is taken as the third PDU session request message for explanation, but it should not be understood that the fifth message is limited to the PDU session request message. The third PDU session request message may carry information for the DNN and information for the S-NSSAI. Accordingly, in a mode that the first network and the second network are communicated based on the N3IWF, the UE can establish the information associated to the DNN and the third PDU session of the S-NSSAI through the N3IWF and the second network equipment, thereby realizing the recovery of the PDU session of the UE associated to the DNN and the S-NSSAI and improving the switching efficiency.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the first information may be used to instruct the first network and the second network to perform the N3 IWF-based interworking, or to instruct the terminal device to send the second PDU session request to the first network device, send the second registration request to the second network device through the N3IWF, and send the third PDU session request message to the second network device.

In a possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the terminal device may send a sixth message to the first network device, where the sixth message includes a request type cell having a value of existing PDU session, information of the DNN, and information of the S-NSSAI. In the following, the sixth message is taken as the fourth PDU session request message for explanation, but it should not be understood that the sixth message is limited to the PDU session request message. Therefore, in a roaming interworking mode between the first network and the second network, the UE can establish the information associated with the DNN and the fourth PDU session of the S-NSSAI through the first network device, thereby recovering the PDU sessions associated with the DNN and the S-NSSAI of the UE and improving the handover efficiency.

In a possible design, in a case that the interworking mode includes roaming interworking between the first network and the second network, the first information may be used to instruct roaming interworking between the first network and the second network, or to instruct the terminal device to send the fourth PDU session request message to the first network device.

In one possible design, the fourth PDU session request message includes a lossless handover indication. Therefore, in the case that the interworking mode includes roaming-based interworking between the first network and the second network, lossless network handover of the UE can be supported.

In a second aspect, embodiments of the present application provide a communication method, which may be performed by a first network device or a component thereof. The first network device may include a core network access and mobility management function (AMF).

Taking a first network device as an execution subject, according to the method, the first network device may receive a first registration request message from a terminal device, the first network device belongs to a second network, and the first registration request message is used to request registration to the second network. The first network device may also obtain a context of the terminal device and determine that the terminal device is registered in the first network according to the context. The first network device can also send the first information to the terminal device according to the intercommunication mode between the first network and the second network.

In a possible design, the first network device may determine that the terminal device performs handover between the non-public networks according to a handover between the non-public networks instruction included in the first registration request message, where the handover between the non-public networks instruction is used to instruct the terminal device to perform handover between the non-public networks. Or, the first network device may determine that the terminal device performs handover across non-public networks according to the identifier of the first network, where the identifier of the first network is included in the context. Or, the first network device may determine that the terminal device performs handover across the non-public network according to an identifier of the second network device, where the identifier of the second network device is included in the context of the terminal device. The second network device is a network device, such as an AMF, accessed by the terminal device at the time of registration with the first network.

In one possible design, a first network device may receive a context of a terminal device from a second network device deployed in a first network. The first network device may acquire information of the second network device from a Unified Data Management (UDM) and request a context of the terminal device.

Alternatively, the first network device receives a context of the terminal device from a data storage node, the data storage node being shared by the first network and the second network.

In one possible design, the data storage node includes a UDM or authentication, authorization, accounting (AAA) server.

In one possible design, in a case that the interworking mode includes no interworking between the first network and the second network, the first information may be used to indicate that the first network and the second network do not interwork, or the first information may be used to instruct the terminal device to send the first PDU session request message to the first network device. The first PDU session request message includes a request type cell with an initial request value, or the first PDU session request message is used to request the establishment of an initial PDU session. In addition, the first PDU session request message further includes DNN (or information of DNN) associated with the PDU session established by the terminal device in the first network and S-NSSAI (or information of S-NSSAI) associated with the PDU session, or the first information is further used to indicate that the UE carries the DNN information associated with the PDU session established by the terminal device in the first network and the S-NSSAI information associated with the PDU session in the first PDU session request message.

In one possible design, in a case that the interworking manner includes N3 IWF-based interworking between the first network and the second network, the first information may be used to indicate the N3 IWF-based interworking between the first network and the second network. Alternatively, the first information may be used to instruct the terminal device to send a second PDU session request message to the first network device, to send a second registration request message to the second network device through the N3IWF, and to send a third PDU session request message to the second network device. The second PDU session request message is used for requesting to establish a second PDU session, and the second PDU session is used for establishing the connection between the terminal equipment and the N3 IWF; the second registration request message is used for requesting to register in the first network in an N3GPP mode; the third PDU session request message includes a request type cell with a value of existing PDU session, information of DNN associated with the PDU session established by the terminal device in the first network, and information of S-NSSAI associated with the PDU session.

In one possible design, in a case that the interworking manner includes roaming-based interworking between the first network and the second network, the first information may indicate roaming-based interworking between the first network and the second network. Alternatively, the first information may instruct the terminal device to send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type cell with a value of existing PDU session, or the fourth PDU session request message is used to request to establish an existing PDU session. The fourth PDU session request message further includes information of DNN associated with the PDU session established by the terminal device in the first network and information of S-NSSAI associated with the PDU session, or the first information is further used to indicate that the terminal device carries the information of DNN associated with the PDU session established by the terminal device in the first network and the information of S-NSSAI associated with the PDU session in the fourth PDU session request message.

In a possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the first network device may further receive the fourth PDU session request message from the terminal device. The first network device may further send the fourth PDU session request message to the first SMF, where the first SMF is an intermediate SMF, the first SMF is connected to a second SMF, the second SMF maintains the first PDU session established by the terminal device in the first network and associated to the DNN and the S-NSSAI, and subsequently, the fourth PDU session request message may be forwarded by the first SMF to the second SMF, and the second SMF performs path switching. Or, the first SMF belongs to the first network, and the first SMF maintains the first PDU session established by the terminal device in the first network, associated to the DNN and the S-NSSAI.

In one possible design, the first network device may further send a non-public network crossing handover instruction to the first SMF, where the non-public network crossing handover instruction is used to instruct the terminal device to perform non-public network crossing handover.

In one possible design, the fourth PDU session request includes a lossless handover indication.

Advantageous effects in the second aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the first aspect and possible designs thereof.

In a third aspect, embodiments of the present application provide a communication method, which may be implemented by a terminal device or a component (e.g., a chip, a circuit, or the like) of the terminal device. The terminal device may be a UE.

Taking the implementation subject as the terminal device as an example, according to the method, the terminal device registered in the first network may establish the first PDU session associated with DNN and S-NSSAI in the first network, and may further send a first registration request message to the first network device, where the first registration request message is used to request registration to the second network. In addition, the end device establishes (or requests to establish) a PDU session for the end device according to the first order, the PDU session being associated with the DNN and S-NSSAI associated with the first PDU session. And the first sequence is used for indicating the terminal equipment to establish the sequence of the PDU conversation of the terminal equipment according to the sequence of the third mode, the second mode and the first mode. Or, the terminal device tries to establish the PDU session of the terminal device according to the third mode, the second mode and the first mode in sequence according to the first order until the PDU session is established.

For example, the first information may indicate priorities of the first mode, the second mode, and the third mode, where the priority of the third mode is highest, and the priority of the second mode is higher than the priority of the first mode, the UE may execute the third mode, the second mode, and the first mode in sequence according to the priorities, where if the PDU session is successfully established according to a certain mode, the terminal device does not attempt to establish the PDU session according to a mode with a later priority. The successful establishment of the PDU session here means that a PDU session establishment response message on the network side is received, and the PDU session establishment response message indicates the successful establishment of the PDU session.

By adopting the above process, the terminal device can recover the PDU session through the first mode, the second mode and/or the third mode according to the first sequence after registering from the first network to the second network, so as to improve the switching efficiency.

In a possible design, the first registration request message includes a non-public network crossing handover instruction, where the non-public network crossing handover instruction is used to instruct the terminal device to perform non-public network crossing handover.

In one possible design, when the PDU session of the terminal device is established according to the first manner, the terminal device may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI.

In one possible design, the terminal device may send a second PDU session request message to the first network device requesting establishment of a second PDU session. The terminal device may establish a connection with an N3IWF over a second PDU session, the N3IWF belonging to the first network. The terminal device sends a second registration request message to a second network device through the connection, wherein the second registration request message is used for requesting registration in the first network through an N3GPP mode, and the second network device belongs to the first network. When the PDU session is established according to the second method, the terminal device may send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with a value of existing PDU session, or the third PDU session request message may be used to request establishment of an existing PDU session. The third PDU session request message may include information of the DNN and information of the S-NSSAI.

In one possible design, when the PDU session of the terminal device is established according to the third method, the terminal device may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type cell with an existing PDU session value, or the fourth PDU session request message may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI. Therefore, the terminal equipment can establish the PDU session related to the DNN and the S-NSSAI through the fourth PDU session request message preferentially, and the switching efficiency is improved.

In one possible design, a lossless handover indication is included in the fourth PDU session request message to support lossless handover.

In one possible design, the first order is determined according to a local configuration. Alternatively, the terminal device may receive the indication of the first order from the first network device. Optionally, the indication information of the first order may be determined according to a local configuration of the first network device, or determined by the first network device according to an interworking manner between the first network and the second network. Alternatively, the terminal device may receive the indication of the first order from the second network device. Optionally, the indication information of the first order may be determined according to a local configuration of the second network device, or determined by the second network device according to an interworking manner between the first network and the second network. The first order can be flexibly determined.

In a fourth aspect, embodiments of the present application provide a communication method, which may be performed by a Session Management Function (SMF) or a component thereof.

Taking the execution subject as SMF as an example, according to the method, SMF may establish a first PDU session associated to DNN and S-NSSAI for a terminal device registered to the first network. The first PDU session is a PDU session between a first access network element and a first UPF, and the first access network element belongs to the first network. The SMF may receive a fourth PDU session request message including a request type cell having a value of existing PDU session, or may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated to the DNN and the S-NSSAI. The SMF may also send second information to the first UPF, where the second information is used to indicate that the first UPF sends an end mark to the first access network element after the path of the first PDU session is switched, and is used to indicate that the first UPF forwards downlink data from the terminal device of the first access network element to the terminal device through the switched path, where the downlink data includes the end mark. The SMF may further send third information to the first access network element, where the third information is used to instruct the first access network element to forward the downlink data of the terminal device cached by the first access network element to the first UPF until the end mark is received and forwarded.

By adopting the flow, the SMF can support the lossless path switching of the terminal equipment so as to maintain the service continuity.

In one possible design, the fourth PDU session request message includes a lossless handover indication, or the lossless handover may be determined by the SMF to be performed for the terminal device based on local configuration.

In one possible design, the SMF may also receive a non-public network handover indication.

In one possible design, the fourth PDU request message is from a first network device belonging to a second network, for example, when the SMF is connected to the second network, and the first network device is connected to the SMF. Or, the fourth PDU session request message is sent by the first network device to the intermediate SMF, and is forwarded by the intermediate SMF to the SMF, for example, at this time, the SMF does not belong to the second network, the first network device is not directly connected to the SMF, and the message forwarding needs to be performed through the intermediate SMF.

In a fifth aspect, an embodiment of the present application provides a communication apparatus, which may implement the method in the first aspect or any possible implementation manner of the first aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, a terminal device, or a chip, a chip system, a processor, or the like that can support the terminal device to implement the method.

In one possible design, the communication apparatus may include a communication module and a processing module, etc. in its structure, and these modules may perform the corresponding functions of the terminal device in the first aspect or each possible design example of the first aspect. For example, the communication module may be used for the communication device to perform receiving and transmitting of signals, data, information or messages, and the processing module may be used for processing the signals, data, information or messages received by the communication module or for generating the signals, data, information or messages transmitted by the communication module.

In carrying out the method of the first aspect, the communications apparatus may be registered with a first network, the communications module may establish a first PDU session associated with the DNN and S-NSSAI at the first network, and the communications module may further send a first registration request message to the first network device, the first registration request message requesting registration with a second network. The communication module can also receive first information from the first network device, wherein the first information is determined according to the intercommunication mode between the first network and the second network. The communication module may also establish a PDU session associated with the DNN and the S-NSSAI based on the first information.

In one possible design, the first registration request message may include a handover across non-public networks indication for instructing the communication device to perform handover across non-public networks.

In one possible design, in a case that the interworking mode includes no interworking between the first network and the second network, the communication module may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI. Therefore, under the mode that the first network and the second network are not intercommunicated, the UE can establish the PDU session associated to the DNN and the S-NSSAI in the second network, the recovery of the PDU session associated to the DNN and the S-NSSAI is realized, and the switching efficiency is improved.

In a possible design, in a case that the interworking mode includes non-interworking between the first network and the second network, the first information is used to indicate that the first network and the second network are not interworking, or the first information is used to indicate that the communication apparatus sends the first PDU session request to the first network device. Accordingly, flexible indication of the interworking manner can be achieved.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the communication module may send a second PDU session request message to the first network device, the second PDU session request requesting establishment of a second PDU session. The communication module may also establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication module may further send a second registration request message to a second network device through the connection, where the second registration request message is used to request registration in the first network in an N3GPP manner, and the second network device belongs to the first network. The communication module may further send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with a value of existing PDU session, or the third PDU session request message is used to request to establish an existing PDU session. The third PDU session request message may carry information for the DNN and information for the S-NSSAI. Accordingly, in a mode that the first network and the second network are communicated based on the N3IWF, the UE can establish the information associated to the DNN and the third PDU session of the S-NSSAI through the N3IWF and the second network equipment, thereby realizing the recovery of the PDU session of the UE associated to the DNN and the S-NSSAI and improving the switching efficiency.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the first information may be used to indicate the N3 IWF-based interworking between the first network and the second network, or to indicate sending the second PDU session request to the first network device, sending the second registration request to the second network device through the N3IWF, and sending the third PDU session request message to the second network device.

In one possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the communication module may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type cell having an existing PDU session value, information of the DNN, and information of the S-NSSAI. Therefore, in a roaming interworking mode between the first network and the second network, the UE can establish the information associated with the DNN and the fourth PDU session of the S-NSSAI through the first network device, thereby recovering the PDU sessions associated with the DNN and the S-NSSAI of the UE and improving the handover efficiency.

In one possible design, in a case that the interworking mode includes roaming interworking between the first network and the second network, the first information may be used to indicate roaming interworking between the first network and the second network, or to indicate sending of the fourth PDU session request message to the first network device.

In addition, the structure of the communication device may include a processor and optionally a communication interface (e.g., a transceiver) and memory. The communication interface may be used for transceiving information or data and for the communication device to communicatively interact with other communication devices (e.g., a first network device) in the network system. The processor is configured to enable the communication apparatus to perform the respective functions of the terminal device in the first aspect or each possible design example of the first aspect. The memory is coupled to the processor for storing program instructions and data necessary for the communication device. Illustratively, the transceiver may be configured to perform the steps performed by the communication module according to the fifth aspect, and the processor may be configured to perform the steps performed by the processing module according to the fifth aspect.

Advantageous effects in the fifth aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the first aspect and possible designs thereof.

In a sixth aspect, an embodiment of the present application provides a communication apparatus, which may implement the method in the second aspect or any possible implementation manner of the second aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, a first network device, or a chip, a system-on-chip, or a processor that may support the first network device to implement the second aspect or any one of the possible methods of the second aspect.

In one possible design, the communication apparatus may include a communication module and a processing module, etc. in its structure, and these modules may perform the corresponding functions of the first network device in the second aspect or each possible design example of the second aspect. For example, the communication module may be used for the communication device to perform receiving and transmitting of signals, data, information or messages, and the processing module may be used for processing the signals, data, information or messages received by the communication module or for generating the signals, data, information or messages transmitted by the communication module.

In performing the method of the second aspect, the communication module may receive a first registration request message from a terminal device, the communication apparatus belonging to a second network, the first registration request message requesting registration to the second network. The processing module may obtain a context of the terminal device and determine that the terminal device is registered with the first network based on the context. The communication module can also send first information to the terminal equipment according to the intercommunication mode between the first network and the second network.

In a possible design, the processing module may further determine that the terminal device performs handover between the non-public networks according to a handover between the non-public networks instruction included in the first registration request message, where the handover between the non-public networks instruction is used to instruct the terminal device to perform handover between the non-public networks. Or, the processing module may determine that the terminal device performs handover across non-public networks according to the identifier of the first network, where the identifier of the first network is included in the context. Alternatively, the processing module may determine that the terminal device performs handover across the non-public network according to an identifier of the second network device, where the identifier of the second network device is included in the context of the terminal device. The second network device is a network device, such as an AMF, accessed by the terminal device at the time of registration with the first network.

In one possible design, the communication module may receive a context of the terminal device from a second network device deployed in the first network. The communication module may obtain information of the second network device from the UDM and request a context of the terminal device.

Alternatively, the communication module may receive the context of the terminal device from a data storage node, the data storage node being shared by the first network and the second network.

In one possible design, the data storage node comprises a UDM or AAA server.

In one possible design, in a case that the interworking manner includes no interworking between the first network and the second network, the first information may be used to indicate no interworking between the first network and the second network, or the first information may be used to instruct the terminal device to send the first PDU session request message to the communication apparatus. The first PDU session request message includes a request type cell with an initial request value, or the first PDU session request message is used to request the establishment of an initial PDU session. In addition, the first PDU session request message further includes DNN (or information of DNN) associated with the PDU session established by the terminal device in the first network and S-NSSAI (or information of S-NSSAI) associated with the PDU session, or the first information is further used to indicate that the UE carries the DNN information associated with the PDU session established by the terminal device in the first network and the S-NSSAI information associated with the PDU session in the first PDU session request message.

In one possible design, in a case that the interworking manner includes N3 IWF-based interworking between the first network and the second network, the first information may be used to indicate the N3 IWF-based interworking between the first network and the second network. Alternatively, the first information may be used to instruct the terminal device to send a second PDU session request message to the communication apparatus, a second registration request message to the second network device through said N3IWF, and a third PDU session request message to the second network device. The second PDU session request message is used for requesting to establish a second PDU session, and the second PDU session is used for establishing the connection between the terminal equipment and the N3 IWF; the second registration request message is used for requesting to register in the first network in an N3GPP mode; the third PDU session request message includes a request type cell with a value of existing PDU session, information of DNN associated with the PDU session established by the terminal device in the first network, and information of S-NSSAI associated with the PDU session.

In one possible design, in a case that the interworking manner includes roaming-based interworking between the first network and the second network, the first information may indicate roaming-based interworking between the first network and the second network. Alternatively, the first information may instruct the terminal device to send a fourth PDU session request message to the communication apparatus, where the fourth PDU session request message includes a request type information element with a value of existing PDU session, or the fourth PDU session request message is used to request establishment of an existing PDU session. The fourth PDU session request message further includes information of DNN associated with the PDU session established by the terminal device in the first network and information of S-NSSAI associated with the PDU session, or the first information is further used to indicate that the terminal device carries the information of DNN associated with the PDU session established by the terminal device in the first network and the information of S-NSSAI associated with the PDU session in the fourth PDU session request message.

In a possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the communication module may further receive the fourth PDU session request message from the terminal device. The communication module may further send the fourth PDU session request message to the first SMF, where the first SMF is an intermediate SMF, the first SMF is connected to a second SMF, the second SMF maintains the first PDU session established by the terminal device in the first network and associated to the DNN and the S-NSSAI, and then the fourth PDU session request message may be forwarded by the first SMF to the second SMF, and the path switching may be performed by the second SMF. Or, the first SMF belongs to the first network, and the first SMF maintains the first PDU session established by the terminal device in the first network, associated to the DNN and the S-NSSAI.

In one possible design, the communication module may further send a non-public network crossing handover instruction to the first SMF, where the non-public network crossing handover instruction is used to instruct the terminal device to perform non-public network crossing handover.

In addition, the structure of the communication device may include a processor, and optionally a communication interface (e.g., a wired communication interface, etc.) and a memory. The communication interface can be used for transmitting and receiving information or data, and for the communication device to perform communication interaction with other communication devices (such as terminal equipment and the like) in the network system. The processor is configured to enable the communication apparatus to perform the respective functions of the first network device in the second aspect or each possible design example of the second aspect. The memory is coupled to the processor for storing program instructions and data necessary for the communication device. For example, the transceiver may be configured to execute the steps executed by the communication module of the above sixth aspect, and the processor may be configured to execute the steps executed by the processing module of the above sixth aspect.

Advantageous effects in the sixth aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the first aspect and possible designs thereof.

In a seventh aspect, an embodiment of the present application provides a communication apparatus, which may implement the third aspect or the method in any possible implementation manner of the third aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, a terminal device, or a chip, a chip system, a processor, or the like that can support the terminal device to implement the method.

In one possible design, the communication apparatus may include a communication module and a processing module, etc. in its structure, and these modules may perform the corresponding functions of the terminal device in the third aspect or each possible design example of the third aspect. For example, the communication module may be used for the communication device to perform receiving and transmitting of signals, data, information or messages, and the processing module may be used for processing the signals, data, information or messages received by the communication module or for generating the signals, data, information or messages transmitted by the communication module.

In performing the method of the third aspect, the communications device is registered with a first network, the communications module may establish a first PDU session associated with the DNN and the S-NSSAI at the first network, and the communications module may further send a first registration request message to the first network equipment, the first registration request message requesting registration with a second network. In addition, the communication module establishes a PDU session according to the first order, the PDU session being associated with the DNN and the S-NSSAI. The first sequence is used for indicating that the PDU conversation is established according to the third mode, the second mode and the first mode. Or, the processing module establishes (or requests to establish) the PDU sessions sequentially through the communication module according to the third mode, the second mode and the first mode according to the first sequence until the PDU sessions are established.

In one possible design, the first registration request message includes a handover across non-public networks indication, where the handover across non-public networks indication is used to indicate handover across non-public networks.

In one possible design, when establishing the PDU session according to the first manner, the communication module may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI.

In one possible design, the communication module may send a second PDU session request message to the first network device requesting establishment of a second PDU session. The communication module may establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication module sends a second registration request message to a second network device through the connection, wherein the second registration request message is used for requesting registration in the first network through an N3GPP mode, and the second network device belongs to the first network. When the PDU session is established according to the second manner, the communication module may send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with a value of existing PDU session, or the third PDU session request message may be used to request establishment of an existing PDU session. The third PDU session request message may include information of the DNN and information of the S-NSSAI.

In one possible design, when the PDU session is established according to the third manner, the communication module may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type information element with an existing PDU session value, or the fourth PDU session request message may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI.

In one possible design, the first order is determined according to a local configuration. Alternatively, the communication module may receive an indication of the first order from the first network device. Optionally, the indication information of the first order may be determined according to a local configuration of the first network device, or determined by the first network device according to an interworking manner between the first network and the second network. Alternatively, the communication module may receive the indication of the first order from the second network device. Optionally, the indication information of the first order may be determined according to a local configuration of the second network device, or determined by the second network device according to an interworking manner between the first network and the second network. The first order can be flexibly determined.

In addition, the structure of the communication device may include a processor, and optionally a communication interface and memory. The communication interface may be used for transceiving information or data and for the communication device to communicatively interact with other communication devices (e.g., a first network device) in the network system. The processor is configured to enable the communication apparatus to perform the corresponding functions of the terminal device in the third aspect or each possible design example of the third aspect. The memory is coupled to the processor for storing program instructions and data necessary for the communication device. For example, the transceiver may be configured to perform the steps performed by the communication module of the seventh aspect, and the processor may be configured to perform the steps performed by the processing module of the seventh aspect.

Advantageous effects in the seventh aspect and possible designs thereof described above, reference may be made to the description of advantageous effects of the method described in the third aspect and possible designs thereof.

In an eighth aspect, an embodiment of the present application provides a communication apparatus, which may implement the method in the fourth aspect or any possible implementation manner of the fourth aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, an SMF, or a chip, a system-on-chip, or a processor that may support an SMF to implement the fourth aspect or any possible method of the fourth aspect.

In one possible design, the communication device may include a communication module and a processing module, etc. in its structure, and these modules may perform the corresponding functions of the SMF in the fourth aspect or each possible design example of the fourth aspect. For example, the communication module may be used for the communication device to perform receiving and transmitting of signals, data, information or messages, and the processing module may be used for processing the signals, data, information or messages received by the communication module or for generating the signals, data, information or messages transmitted by the communication module.

In carrying out the method of the fourth aspect described above, the processing module may establish a first PDU session associated with DNN and S-NSSAI for a terminal device registered with the first network. The first PDU session is a PDU session between a first access network element and a first UPF, and the first access network element belongs to the first network. The communication module may receive a fourth PDU session request message including a request type cell having a value of existing PDU session, or the fourth PDU session request message may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated to the DNN and the S-NSSAI. The communication module may further send, to the first UPF, second information, where the second information is used to indicate that the first UPF sends an end mark to the first access network element after the path of the first PDU session is switched, and is used to indicate that the first UPF forwards downlink data from the terminal device of the first access network element to the terminal device through the switched path, where the downlink data includes the end mark. The communication module may further send third information to the first access network element, where the third information is used to instruct the first access network element to forward the downlink data of the terminal device cached by the first access network element to the first UPF until the end mark is received and forwarded.

In one possible design, the fourth PDU session request message includes a lossless handover indication, or the lossless handover may be determined by the processing module to be performed for the terminal device based on a local configuration.

In one possible design, the communication module may also receive a non-public network handover indication.

In one possible design, the fourth PDU request message is from a first network device belonging to a second network, for example, when the communication apparatus is connected to the second network, and the first network device is connected to the communication apparatus. Or, the fourth PDU session request message is sent by the first network device to the intermediate SMF, and is forwarded by the intermediate SMF to the communication module, for example, at this time, the communication apparatus does not belong to the second network, the first network device and the communication apparatus are not directly connected, and the message forwarding needs to be performed through the intermediate SMF.

In addition, the structure of the communication device may include a processor, and optionally a communication interface and memory. The communication interface may be used for transceiving information or data and for the communication device to communicatively interact with other communication devices (e.g., a first network device) in the network system. The processor is configured to enable the communication device to perform the respective functions of the SMF in the fourth aspect or each of the possible design examples of the fourth aspect. The memory is coupled to the processor for storing program instructions and data necessary for the communication device. For example, the transceiver may be configured to perform the steps performed by the communication module according to the above-mentioned eighth aspect, and the processor may be configured to perform the steps performed by the processing module according to the above-mentioned eighth aspect.

Advantageous effects in the above-mentioned eighth aspect and possible designs thereof may refer to the description of advantageous effects of the method in the fourth aspect and possible designs thereof.

In a ninth aspect, embodiments of the present application provide a communication method, which may be implemented by a terminal device or a component (e.g., a chip, a circuit, or the like) of the terminal device. The terminal device may be a UE.

Taking an execution subject as a terminal device as an example, according to the method, a terminal device registered in a first network establishes a first PDU session associated with DNN and S-NSSAI in the first network; the terminal equipment sends a first message to first network equipment, wherein the first message is used for requesting to register to the second network; the terminal equipment receives first information from the first network equipment, the first information is determined according to an interworking mode between a first network and a second network, and roaming interworking is not performed between the first network and the second network; and the terminal equipment determines to recover the PDU session of the terminal equipment in a mode of supporting N3WIF or determines not to establish the PDU session of the terminal equipment according to the first information, wherein the PDU session is associated with the DNN and the S-NSSAI.

By adopting the method, under the condition that roaming intercommunication is not carried out between the first network and the second network, the recovery of the PDU session of the terminal equipment is realized after the terminal equipment moves to the second network equipment, and the switching efficiency is improved; or the terminal device does not establish the PDU session any more to save signaling overhead.

In one possible design, the terminal device may send a third message to the first network device, the third message requesting establishment of a second PDU session; the terminal equipment establishes connection with an N3IWF through the second PDU session, wherein the N3IWF belongs to the first network; the terminal device sends a fourth message to a second network device through the connection, wherein the fourth message is used for requesting registration in the first network in an N3GPP mode, and the second network device belongs to the first network; the terminal device may send a fifth message to the second network device, where the fifth message is used to request establishment of an existing PDU session, and the fifth message includes the information of the DNN and the information of the S-NSSAI.

In one possible design, the first information may be used to indicate that non-roaming interworking is not supported between the first network and the second network.

In a tenth aspect, embodiments of the present application provide a communication method, which may be performed by a first network device or a component thereof. The first network device may include an AMF.

According to the method, a first network device can receive a first message from a terminal device, the first network device belongs to a second network, and the first message is used for requesting to register to the second network; the first network equipment acquires the identifier of the terminal equipment and determines the identifier of the first network; and the first network equipment sends first information to the terminal equipment according to the roaming intercommunication mode between the first network and the second network.

Advantageous effects in the tenth aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the ninth aspect and possible designs thereof.

In an eleventh aspect, an embodiment of the present application provides a communication apparatus, which can implement the method in the ninth aspect or any possible implementation manner of the ninth aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, a terminal device, or a chip, a chip system, a processor, or the like that can support the terminal device to implement the method.

When the method of the ninth aspect is executed, the terminal device communication module registered in the first network establishes a first PDU session associated with DNN and S-NSSAI in the first network; the communication module sends a first message to first network equipment, wherein the first message is used for requesting to register to the second network; the communication module receives first information from the first network equipment, the first information is determined according to an interworking mode between a first network and a second network, and roaming interworking is not performed between the first network and the second network; and the processing module determines to recover the PDU session in a mode of supporting N3WIF or determines not to establish the PDU session of the terminal equipment any more according to the first information, wherein the PDU session is associated with the DNN and the S-NSSAI.

In one possible design, the communication module may be to send a third message to the first network device, the third message to request establishment of a second PDU session; the communication module establishes connection with an N3IWF through the second PDU session, wherein the N3IWF belongs to the first network; the communication module sends a fourth message to a second network device through the connection, wherein the fourth message is used for requesting registration in the first network in an N3GPP mode, and the second network device belongs to the first network; the communication module may send a fifth message to the second network device, the fifth message requesting establishment of an existing PDU session, the fifth message including information of the DNN and information of the S-NSSAI.

In one possible design, the first information may be used to indicate that the first network does not support non-roaming interworking.

In a twelfth aspect, an embodiment of the present application provides a communication apparatus, which can implement the method of the tenth aspect or any possible implementation manner of the tenth aspect. The apparatus comprises corresponding units or means for performing the above-described method. The means comprising may be implemented by software and/or hardware means. The apparatus may be, for example, a first network device, or a chip, a chip system, or a processor that can support the first network device to implement any one of the possible methods of the tenth aspect or the tenth aspect.

When the method according to the tenth aspect is executed, the communication module may receive a first message from a terminal device, where the first network device belongs to a second network, and the first message is used to request registration to the second network; the first network equipment acquires the identifier of the terminal equipment and determines the identifier of the first network; the communication module sends first information to the terminal equipment according to a roaming intercommunication mode between a first network and a second network.

In a thirteenth aspect, an embodiment of the present application provides a communication system. The communication system may comprise the communication device provided in the fifth aspect above and the communication device provided in the sixth aspect.

Advantageous effects in the thirteenth aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the first aspect and possible designs thereof.

The communication system further comprises the communication device provided by the eighth aspect.

Where the communication apparatus provided by the eighth aspect is included, reference may be made to the description of advantageous effects of the method in the fourth aspect and its possible design.

The communication system may comprise the communication device provided in the above eleventh aspect and the communication device provided in the twelfth aspect.

In a fourteenth aspect, an embodiment of the present application provides a communication system. The communication system may comprise the communication apparatus and the first network device provided in the seventh aspect above.

Advantageous effects in the tenth aspect and possible designs thereof described above reference may be made to the description of advantageous effects of the method described in the third aspect and possible designs thereof.

The advantageous effects of the tenth aspect and possible designs thereof described above may refer to the description of the advantageous effects of the method described in the fourth aspect and possible designs thereof, when including the communication apparatus provided in the eighth aspect.

In a fifteenth aspect, the present application provides a computer storage medium having a program stored therein or, when invoked for execution on a computer, causing the computer to perform the method of any one of the above first aspect and its possible design, the second aspect and its possible design, the third aspect and its possible design, or the fourth aspect and its possible design, or the ninth aspect and its possible design, or the tenth aspect and its possible design.

In carrying out the method according to any one of the above first aspect and its possible designs or second aspect and its possible designs, reference may be made to the description of the advantageous effects of the method according to the above eleventh aspect and its possible designs. In carrying out the method according to any one of the above third aspect and its possible designs or fourth aspect and its possible designs, reference may be made to the description of advantageous effects of the method according to the above eleventh aspect and its possible designs.

In a sixteenth aspect, the present application provides a computer program product, which may contain a program or instructions, which, when run on a computer, causes the computer to perform the method of any one of the above first aspect and its possible design, the second aspect and its possible design, the third aspect and its possible design, or the fourth aspect and its possible design, or the ninth aspect and its possible design, or the tenth aspect and its possible design.

In carrying out the method according to any one of the above first aspect and its possible designs or second aspect and its possible designs, reference may be made to the description of the advantageous effects of the method according to the above twelfth aspect and its possible designs. In carrying out the method according to any one of the above third aspect and its possible designs, reference may be made to the description of advantageous effects of the method according to the above twelfth aspect and its possible designs. In carrying out the method according to any one of the above fourth aspect and its possible designs, reference may be made to the description of the advantageous effects of the method according to the above twelfth aspect and its possible designs.

In a thirteenth aspect, the present application provides a chip or a system of chips (or a circuit) including a chip, which may include a processor. The chip may also include a memory (or storage module) and/or a transceiver (or communication module). The chip may be adapted to perform the method as described in any of the first aspect and its possible design, the second aspect and its possible design, the third aspect and its possible design, or the fourth aspect and its possible design, or the ninth aspect and its possible design, or the tenth aspect and its possible design. The chip system may be formed by the above chip, and may also include the above chip and other discrete devices, such as a memory (or a storage module) and/or a transceiver (or a communication module).

A tenth aspect provides a communication system, which includes a first terminal device, a second terminal device, any one of the possible implementations of the third aspect and the third aspect, and a communication apparatus according to any one of the possible implementations of the fourth aspect and the fourth aspect.

Drawings

Fig. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application;

fig. 2 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 3 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 4 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 5 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 6 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 7a is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 7b is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 7c is a schematic structural diagram of another communication system according to an embodiment of the present application;

fig. 8 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 9 is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 10 is a flowchart illustrating a communication method according to an embodiment of the present application;

fig. 11 is a flowchart illustrating another communication method according to an embodiment of the present application;

fig. 12 is a flowchart illustrating another communication method according to an embodiment of the present application;

fig. 13 is a flowchart illustrating another communication method according to an embodiment of the present application;

fig. 14a is a schematic flowchart of another communication method provided in the embodiment of the present application;

fig. 14b is a flowchart illustrating another communication method according to an embodiment of the present application;

fig. 14c is a schematic flowchart of another communication method provided in the embodiment of the present application;

fig. 15 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 16 is a schematic structural diagram of another communication device according to an embodiment of the present application.

Detailed Description

In order to solve the problem that the switching efficiency of the UE between the cross-SNPN networks is not high or the UE cannot be switched correctly, the application provides a communication method. The present application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific methods of operation in the method embodiments described below may also be applied to either the apparatus embodiments or the system embodiments.

The next generation (i.e. 5G) mobile communication system architecture (NextGen/NG) is composed of UE (or called NextGen UE), (radio) access network (R) AN/NextGen (R) AN), core network (core/NextGen core), and Data Network (DN), wherein the UE, the access network, and the core network are main components constituting the architecture, and logically they can be divided into two parts, i.e. a user plane and a control plane, the control plane is responsible for management of the mobile network, and the user plane is responsible for transmission of service data. Wherein the NG2 reference point is located between the access network control plane and the core network control plane, the NG3 reference point is located between the access network user plane and the core network user plane, and the NG6 reference point is located between the core network user plane and the data network.

It should be understood that in the present application, the UE is a portal for the mobile user to interact with the network, and can provide basic computing power and storage capability, display a service window to the user, and accept user operation input. The NextGen UE will use the new air interface technology to establish signal connection and data connection with the AN, so as to transmit control signals and service data to the mobile network.

The access network is similar to a base station in a traditional network, is deployed at a position close to the UE, provides a network access function for authorized users in a specific area, and can determine transmission tunnels with different qualities according to the level of the users, the service requirements and the like to transmit user data. The AN can manage the resources of the AN, reasonably utilize the resources, provide access services for the UE as required, and is responsible for forwarding control signals and user data between the UE and the core network.

The core network is responsible for maintaining subscription data of the mobile network, managing network elements of the mobile network, and providing functions of session management, mobility management, policy management, security authentication and the like for the UE. When the UE is attached, network access authentication is provided for the UE; when the UE has a service request, network resources are distributed to the UE; updating network resources for the UE when the UE moves; when the UE is idle, a fast recovery mechanism is provided for the UE; when the UE is detached, releasing network resources for the UE; when the UE has service data, providing a data routing function for the UE, such as forwarding uplink data to a data network; or receiving UE downlink data from the data network, forwarding the UE downlink data to the AN, and then sending the UE downlink data to the AN.

The data network is a network for providing service for users, and generally, the client is located in the UE and the server is located in the data network. The data network may be a private network, such as a local area network, an external network that is not controlled by an operator, such as the internet, or a private network that is co-deployed by an operator, such as a network that provides an Internet Protocol (IP) multimedia network subsystem (IMS) service.

The UE is a device with a wireless transceiving function, and can be deployed on land, including indoors or outdoors, handheld, wearable or vehicle-mounted; can also be deployed on the water surface (such as a ship and the like); the terminal device may be a mobile phone (mobile phone), a tablet (Pad), a computer with wireless transceiving function, a Mobile Internet Device (MID), a wearable device, a Virtual Reality (VR) terminal device, an Augmented Reality (AR) terminal device, a wireless terminal in industrial control (industrial control), a wireless terminal in unmanned driving, a wireless terminal in remote medical (remote medical), a wireless terminal in smart grid, a wireless terminal in transportation security, a wireless terminal in smart city, a wireless terminal in home application field, etc . The embodiments of the present application do not limit the specific technologies, device forms, and names used by the terminal device.

The access network may include access network equipment. An access network device is a device in a network for accessing a terminal device to a wireless network. The access network device may be a node in a radio access network, which may also be referred to as a base station, and may also be referred to as a Radio Access Network (RAN) node (or device). The network device may include an evolved Node B (NodeB or eNB or e-NodeB) in a Long Term Evolution (LTE) system or an evolved LTE system (LTE-Advanced, LTE-a), such as a conventional macro base station eNB and a micro base station eNB in a heterogeneous network scenario, or may also include a next generation Node B (gNB) in a fifth generation mobile communication technology (5th generation,5G) New Radio (NR) system, or may also include a radio network controller (radio network controller, RNC), Node B (NB), a base station controller (base station controller, BSC), a base transceiver station (base transceiver station, BTS), a Transmission Reception Point (TRP), a home base station (e.g., a home base station, base station B, base station unit, HNB, BBU), a baseband pool BBU port, or a WiFi Access Point (AP), and further may further or may further include a Centralized Unit (CU) and a Distributed Unit (DU) in a cloud access network (cloudlen) system, which is not limited in the embodiment of the present application. In a scenario of separate deployment of an access network device including a CU and a DU, the CU supports Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Service Data Adaptation Protocol (SDAP), and other protocols; the DU mainly supports a Radio Link Control (RLC), a Medium Access Control (MAC) and a physical layer protocol.

The core network may comprise the following network elements or nodes:

an access management network element (also referred to as an access mobility management network element in this embodiment) is mainly used for attachment, mobility management, and tracking area update processes of a terminal in a mobile network, where the access management network element terminates a Non Access Stratum (NAS) message, completes registration management, connection management, reachability management, tracking area list (TA list) allocation, mobility management, and the like, and transparently routes a Session Management (SM) message to the session management network element. In a fifth generation (5G) communication system, the access management network element may be an access and mobility management function (AMF), and in a future communication system (e.g. a 6G communication system), the mobility management network element may still be an AMF network element, or may also have other names, which is not limited in this application.

The session management network element is mainly used for session management in a mobile network, such as session establishment, modification and release. The specific functions include allocating an Internet Protocol (IP) address to the terminal, selecting a user plane network element providing a message forwarding function, and the like. In the 5G communication system, the session management network element may be a Session Management Function (SMF), and in a future communication system (e.g. a 6G communication system), the session management network element may still be an SMF network element, or may also have another name, which is not limited in this application.

The user plane network element is mainly used for processing user messages, such as forwarding, charging, legal monitoring and the like. The user plane network element may also be referred to as a Protocol Data Unit (PDU) session anchor (PSA). In a 5G communication system, the user plane network element may be a User Plane Function (UPF), and in a future communication system (e.g., a 6G communication system), the user plane network element may still be a UPF network element, or may also have other names, which is not limited in this application.

The policy control network element includes a user subscription data management function, a policy control function, a charging policy control function, quality of service (QoS) control, and the like. In a 5G communication system, the policy control network element may be a Policy Control Function (PCF), and in a future communication system (e.g. a 6G communication system), the policy control network element may still be a PCF network element, or may also have other names, which is not limited in this application.

The network slice selection functional network element is mainly used for selecting a proper network slice for the service of the terminal equipment. In the 5G communication system, the network slice selection network element may be a Network Slice Selection Function (NSSF) network element, and in a future communication system (e.g., a 6G communication system), the network slice selection network element may still be an NSSF network element, or may also have other names, which is not limited in this application.

The network storage function network element is mainly used for providing registration and discovery functions of the network element or services provided by the network element. In the 5G communication system, the network storage function network element may be a Network Repository Function (NRF), and in a future communication system (e.g. a 6G communication system), the network storage function network element may still be an NRF network element, or may also have other names, which is not limited in this application.

The network data analysis network element may collect data from various Network Functions (NF), such as a policy control network element, a session management network element, a user plane network element, an access management network element, and an application function network element (through a network capability open function network element), and perform analysis and prediction. In the 5G communication system, the network data analysis network element may be a network data analysis function (NWDAF), and in a future communication system (e.g. a 6G communication system), the network data analysis network element may still be an NWDAF network element, or may also have other names, which is not limited in this application.

And the unified data management network element is mainly used for managing the subscription information of the terminal equipment. In the 5G communication system, the unified data management network element may be a Unified Data Management (UDM), and in a future communication system (e.g. a 6G communication system), the unified data management network element may still be a UDM network element, or may also have other names, which is not limited in this application.

The unified data storage network element is mainly used for storing structured data information, wherein the structured data information comprises subscription information, strategy information and network data or service data defined by a standard format. In the 5G communication system, the unified data storage network element may be a unified data storage (UDR), and in a future communication system (e.g. a 6G communication system), the unified data storage network element may still be a UDR network element, or may also have other names, which is not limited in this application.

And the authentication service function network element is mainly used for carrying out security authentication on the terminal equipment. In the 5G communication system, the authentication service function network element may be an authentication server function (AUSF), and in a future communication system (e.g., a 6G communication system), the authentication service function network element may still be an AUSF network element, or may also have other names, which is not limited in this application.

The network capability is opened, and part of the functions of the network can be exposed to the application in a controlled manner. In the 5G communication system, the network element with an open network capability may be a network capability open function (NEF), and in a future communication system (e.g., a 6G communication system), the network element with an open network capability may still be an NEF network element, or may also have another name, which is not limited in this application.

The application function network element may provide service data of various applications to a control plane network element of a communication network of an operator, or obtain data information and control information of the network from the control plane network element of the communication network. In the 5G communication system, the application function network element may be an Application Function (AF), and in a future communication system (e.g. a 6G communication system), the application function network element may still be an AF network element, or may also have other names, which is not limited in this application.

And the data network is mainly used for providing data transmission service for the terminal equipment. The data network may be a private network, such as a local area network, a Public Data Network (PDN) network, such as the Internet (Internet), or a private network co-deployed by an operator, such as an IP multimedia network subsystem (IMS) service.

It should be understood that the above network elements or functions may be network elements in a hardware device, or may be software functions running on dedicated hardware, or virtualization functions instantiated on a platform (e.g., a cloud platform). Optionally, the network element or the function may be implemented by one device, or may be implemented by multiple devices together, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application.

For convenience of description, in the following description, an access management network element is an AMF network element, and a network slice selection function network element is an NSSF network element. Further, the AMF network element is abbreviated as AMF, and the NSSF network element is abbreviated as NSSF. That is, AMFs described later in this application may be replaced with access management network elements, and NSSFFs may be replaced with network slice selection functional network elements.

As shown in fig. 3, taking a 5G architecture as an example, the user plane of the communication system provided in this embodiment may include a User Plane Function (UPF), and the core network control plane may include an authentication server function (AUSF), a core network access and mobility management function (AMF), a Session Management Function (SMF), a Network Slice Selection Function (NSSF), a network open function (NEF), a network function (NRF), a unified data management function (UDM), a Policy Control Function (PCF), and an Application Function (AF).

As shown in fig. 3, the core network control plane adopts a service architecture, and the interaction between the control plane network elements adopts a service invocation mode to replace a point-to-point communication mode in the conventional architecture. In the service architecture, the control plane network element opens service to other control plane network elements for other control plane network elements to call; in point-to-point communication, a communication interface between control plane network elements has a set of specific messages, and the control plane network elements at two ends of the interface can only use the messages during communication.

For example, the UPF may be configured to perform user packet forwarding according to routing rules of the SMF, such as sending upstream data to the DN or other UPF, and/or forwarding downstream data to other UPF or RAN. The AUSF may be used to perform security authentication of the UE. The AMF may be used for access management and Mobility Management (MM) of the UE, and is responsible for state maintenance of the UE, reachability management of the UE, forwarding of non-MM non-access-stratum (NAS) messages, and forwarding of SM N2 messages. The SMF can be used for UE session management, and resources are allocated and released for the session of the UE; the resources include session QoS, session path, forwarding rules, etc. The NSSF may be used to select a network slice for the UE. NEF may be used to open network functions to third parties in the form of an Application Programming Interface (API) interface. The NRF may be used to provide a storage function and a selection function of network function entity information for other network elements. UDMs may be used for user subscription context (or subscription data, UE context, etc.) storage and management. PCFs may be used for user policy management. The AF may be used for application management.

As shown in fig. 1 and 2, current NPN networks include PNI-NPN and SNPN.

Wherein, the PNI-NPN can be implemented using a network slice in the PLMN, and in order to prevent an unauthorized UE from attempting to access and select the PNI-NPN, a Closed Access Group (CAG) function is additionally used. The CAG may be used to identify a group of users that are allowed to access a cell associated with the CAG (i.e., a CAG cell). In order to prevent a UE which is not allowed to access a CAG cell from automatically selecting and accessing the CAG cell, the CAG cell broadcasts one or more CAG Identifiers (IDs), an available CAG directory (list) and an indication (for indicating whether the UE is allowed to access 5GS only through the CAG cell) are configured on the UE, and the UE subscription data on the UDM includes the available CAG list and the indication.

The SNPN network is deployed independently and independent of the PLMN network, and is identified by using a PLMN ID and a Network Identifier (NID), where the PLMN ID may be an inherent value reserved by a third-party operator or may be a specific value of the PLMN operator that deploys the SNPN. In the SNPN network, a cell broadcasts a PLMN ID and a NID, and the UE selects an accessed NPN network according to broadcast information and configured network selection information. If the UE finds that the configured network selection information comprises a combination of the PLMN ID and the NID1 which is different from the PLMN ID broadcasted by the network or the combination of the PLMN ID and the NID2, the UE does not select the access.

As shown in fig. 4, the PNI-NPN restricts access of the UE by broadcasting the CAG ID and configuring the CAG ID available to the UE, and the SNPN lets the UE select the cell and network correctly by broadcasting the PLMN ID and NID.

As shown in fig. 1, currently R16 supports interworking between SNPN and PLMN through N3IWF architecture, and UE can subscribe to SNPN and PLMN respectively. The UE can select the SNPN ID by using SNPN private network subscription, accesses the SNPN base station and carries out 3GPP registration in the SNPN network. And the UE can select the PLMN ID by using the public network subscription of the PLMN, select the PLMN N3IWF, establish the PDU session in the SNPN network to access the PLMN N3IWF, and perform the N3GPP registration in the PLMN network.

As shown in fig. 2, the SNPN under R17 needs to support the terminal to access the SNPN network using an "external subscription", that is, the user signature of the terminal is owned by an external entity (such as a Mobile Network Operator (MNO)) independent of the SNPN network, and the SNPN network allows such a terminal to access the SNPN using the external subscription. For example, when the UE accesses the SNPN network, the SNPN network entity (e.g., AMF/SMF) needs to interact with a PLMN network entity (e.g., UDM/AUSF), for example, to obtain a request for the PLMN network to perform authentication and authentication on the UE, to request the PLMN network to provide subscription information of the UE, to request the PLMN network to configure resources for a PDU session of the UE, and so on. In this case, the roaming architecture is used to support SNPN interworking with PLMNs, the UE only signs up on the PLMN, and the subscription data may be stored in the UDM of the PLMN, as shown in fig. 2: the UE uses public network subscription of PLMN to select SNPN ID, selects SNPN base station, registers in SNPN network, and establishes PDU session in SNPN, and SNPN network determines Local Break Out (LBO)/Home Route (HR) mode according to UE public network subscription.

In addition to the subscription of the terminal being provided by the PLMN, it may also be provided by the SNPN network of a third party, in which case the interworking of the two SNPNs is similar to that described above.

In addition, the user subscription may be provided by a third party AAA (authentication, authorization, accounting) server (AAA-server, AAA-S). As shown in fig. 5, the network elements of SNPN, such as AMF and SMF, need to authenticate the UE or obtain the stored subscription data from the AAA server, and interact with the AAA server through an AAA-proxy (AAA-proxy, AAA-P) (e.g., NSSAAF or AUSF).

When the UE's external subscription is provided by other PLMN, SNPN or AAA servers, the UE moves between two SNPNs, both of which may be connected to the PLMN, SNPN or AAA server holding the UE subscription as shown above. In another scenario, when the UE moves from SNPN #1 to SNPN #2, SNPN #2 may also be SNPN that holds the UE subscription. In addition, the UE may also move between SNPN and PLMN, and in one scenario, when the UE moves from SNPN #1 to PLMN, the PLMN may be VPLMN, or may be Home PLMN (HPLMN) storing the UE subscription.

Fig. 6 to 9 show several typical UE mobility scenarios across a private network.

In the scenario of fig. 6, the UE may move from SNPN #1 to SNPN # 2. Wherein the UE subscription is maintained by a third party AAA server to which SNPN #1 and SNPN #2 may connect. The roaming interworking mode shown in fig. 2 is supported between SNPN #1 and SNPN # 2.

In the scenario of fig. 7a, the UE may move from SNPN #1 to SNPN #2 or a Visited PLMN (VPLMN). Wherein the UE subscription is saved by the UDM of the HPLMN to which SNPN #1 and SNPN #2 or VPLMN can be connected. The N3IWF interworking mode shown in figure 1 is supported between SNPN #1 and SNPN #2 or VPLMN.

In the scenario of fig. 7b, the UE may move from SNPN #1 to SNPN #2 or to a visited PLMN. Wherein the UE subscription is saved by the UDM of the HPLMN to which SNPN #1 and SNPN #2 or VPLMN can be connected. Roaming interworking between SNPN #1 and HPLMN, and roaming interworking between SNPN #2 or VPLMN and HPLMN. The UE can establish an HR PDU session, namely a PDU session of an anchor UPF at the HPLMN, through SNPN #1, SNPN # 2/VPLMN.

In the scenario of fig. 7c, the UE may move between SNPN #1 and SNPN # 2. Wherein the UE subscription is saved by the UDM of the HPLMN to which SNPN #1 and SNPN #2 can be connected. Roaming intercommunication is carried out between SNPN #1 and HPLMN, and intercommunication is carried out between SNPN #2 and HPLMN through N3 IWF. The UE may establish an HR PDU session through SNPN #1, i.e. a PDU session at the HPLMN by the anchor UPF. The UE may establish a PDU session to the HPLMN in the manner shown in fig. 1.

In the scenario of fig. 8, the UE may move from SNPN #1 to the HPLMN. Wherein the UE subscription is saved by the UDM of the HPLMN. Roaming interworking as shown in fig. 2 is supported between SNPN #1 and the HPLMN.

In the scenario of fig. 9, the UE may move from SNPN #1 to the HPLMN. Wherein the UE subscription is saved by the UDM of the HPLMN. Core network elements such as AMF and SMF are shared between SNPN #1 and HPLMN. The UE may then continue to move from the HPLMN to the VPLMN, using the roaming interworking approach shown in fig. 2 between the HPLMN and the VPLMN.

The application provides a communication method for solving the problem that the switching efficiency of UE between cross NPN networks is not high or the UE cannot be switched correctly.

The communication method may be performed by a terminal device, a first network device, and the like. The terminal device is registered in a first network (or called a source network or a home network), and the first network device belongs to a second network (or called a destination network). The first network and/or the second network are/is an NPN network, so that when the terminal device is switched between the first network and the second network across non-public networks, the switching efficiency and the success rate can be improved according to the communication method provided by the embodiment of the application. It should be understood that the scenario in which the terminal device switches between the first network and the second network may refer to the scenarios shown in fig. 6-9.

Exemplarily, taking a terminal device as an example for explanation, a communication method provided in an embodiment of the present application may include the following steps shown in fig. 10:

s101: the UE establishes a first PDU session at a first network.

The first PDU session is associated with a Data Network Name (DNN) and a single network slice selection assistance information (S-NSSAI).

The process of establishing the first PDU session is not specifically limited in the present application.

S102: the UE sends a first registration request message to a first network device in a second network.

Accordingly, the first network device receives the first registration request message. The first registration request message may be used to request registration to a second network.

Illustratively, the first network device is an AMF deployed in the second network.

Optionally, the first registration request message may carry a non-public network handover crossing indication (or called private network handover crossing indication), where the non-public network handover crossing indication is used to indicate the terminal device to perform non-public network handover crossing.

S103: the first network device obtains a context of the UE.

The context of the UE may be stored in the second network device of the first network, or in a data storage node.

The second network device is, for example, an AMF deployed in the first network, and the AMF may manage registration requests of UEs in the first network. The first network device may obtain information, such as a temporary identifier, registered by the UE in the first network from the UDM, and further obtain information of the second network device, so as to obtain the context of the UE through the second network device.

The data storage node may be shared by the first network and the second network, and therefore may obtain the context of the UE previously registered in the first network by the first network device, for example, the data storage node may be deployed in the second network and shared by the first network and the second network (i.e., store the context of the UE registered in the first network and the second network), or the data storage node may be deployed in a third network other than the first network and the second network and shared by the first network and the second network. Such as UDM or AAA.

S104: the first network device determines that the UE is registered in the first network according to the context of the UE.

For example, the UE context may include an identifier of the first network or an identifier of the second network device, and the first network device may know that the UE is registered in the first network according to the identifier of the first network or the identifier of the second network device.

S105: the first network equipment determines the first information according to the intercommunication mode between the first network and the second network.

The first information may indicate how to switch PDU sessions during UE registration.

Specifically, the interworking method between the first network and the second network includes: the first network and the second network do not interwork, the first network and the second network interwork based on N3IWF as shown in fig. 1, and the first network and the second network interwork based on roaming.

It should be understood that in S105, if the interworking manner between the first network and the second network is different, the first information is different.

For example, in the case of no interworking between the first network and the second network, the first information may indicate that the first network and the second network do not interwork, for example, the first information is indication information of the non-interworking. Alternatively, the first information may instruct the UE to send a first PDU session request to the first network device. The first PDU session request includes a request type (request type information element) having a value of an initial request (initial request), or, the first PDU session request is for requesting establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI, or the first PDU session request message includes information of the DNN associated with the PDU session established by the UE in the first network and information of the S-NSSAI associated with the PDU session.

In the case of N3IWF interworking between the first network and the second network, the first information may indicate the N3IWF interworking between the first network and the second network, for example, the first information is indication information of the N3IWF interworking. Alternatively, the first information may instruct the UE to send a second PDU session request to the first network device, and send a second registration request to the second network device through the N3IWF, and send a third PDU session request message to the second network device. Wherein the second PDU session request is used for requesting to establish a second PDU session through which the UE can establish a connection with the N3 IWF. The second registration request may be for requesting registration with the first network by way of N3 GPP. The third PDU session request message includes a request type having a value of an existing PDU session (existing PDU session), or is used to establish the existing PDU session. The third PDU session request message includes the DNN information and the S-NSSAI information, or the third PDU session request message includes the DNN information associated with the PDU session established by the UE in the first network and the S-NSSAI information associated with the PDU session.

In the case of roaming interworking between the first network and the second network, the first information may indicate roaming interworking between the first network and the second network, for example, the first information is indication information based on roaming interworking. Alternatively, the first information may be used to instruct the UE to send a fourth PDU session request message to the first network device. The fourth PDU session request message includes a request type cell with a value of existing PDU session, or the fourth PDU session request message is used to request to establish an existing PDU session. The fourth PDU session request message includes the DNN information and the S-NSSAI information, or the fourth PDU session request message includes the DNN information associated with the PDU session established by the UE in the first network and the S-NSSAI information associated with the PDU session.

S106: the first network equipment sends first information to the UE.

Accordingly, the UE receives the first information from the AMF #2, which is determined according to the interworking manner between the SNPN #1 and the SNPN # 2.

S107: the UE establishes a PDU session of the UE according to the first information, wherein the PDU session is associated with the DNN and the S-NSSAI.

Specifically, in the case that the first network and the second network do not intercommunicate, or the first information indicates that the first network and the second network do not intercommunicate, or the UE sends the first PDU session request to the first network device, the UE may send the first PDU session request message to the first network device, where the first PDU session includes a request type cell with an initial request value, information of the DNN, and information of the S-NSSAI. Accordingly, under the mode that the first network and the second network are not in intercommunication, the UE can establish the PDU session associated to the DNN and the S-NSSAI in the second network, and the recovery of the PDU session associated to the DNN and the S-NSSAI is realized. Under the non-intercommunication mode, both the PDU session recovery mode based on the N3IWF intercommunication and the roaming intercommunication are not feasible, so that the UE executes the corresponding switching process according to the first information to improve the switching efficiency and avoid trial and error.

In the case of N3 IWF-based interworking between a first network and a second network, or in other words, in the case that the first information is used to indicate N3 IWF-based interworking between the first network and the second network, or to instruct the UE to send a second PDU session request to the first network device, send a second registration request to the second network device through N3IWF, and send a third PDU session request message to the second network device, the UE may send a second PDU session request message to the first network device, the second PDU session request being used to request establishment of a second PDU session. The UE may also establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. Thereafter, the UE may send a second registration request to the second network device over the connection, the second registration request requesting registration to the first network by the N3 GPP. The UE may also send a third PDU session request message to the second network device, the existing PDU session (which may be referred to as a third PDU session) having been established, which may include information of the DNN and information of the S-NSSAI. Accordingly, in a mode that the first network and the second network are intercommunicated based on the N3IWF, the UE can establish the information associated to the DNN and the third PDU session of the S-NSSAI through the N3IWF and the second network equipment, and the recovery of the PDU session associated to the DNN and the S-NSSAI of the UE is realized. Because the PDU session recovery mode based on the non-intercommunication and the roaming intercommunication is not feasible under the N3IWF intercommunication mode, the UE executes the corresponding switching process according to the first information to improve the switching efficiency and avoid trial and error.

In the case of roaming interworking between the first network and the second network, or in the case that the first information is used to indicate roaming interworking between the first network and the second network, or to indicate that the UE sends the fourth PDU session request message to the first network device, the UE may send the fourth PDU session request message to the first network device. The fourth PDU session request message includes a request type cell with a value of existing PDU session, or the fourth PDU session request message is used to request to establish an existing PDU session (the PDU session may be referred to as a fourth PDU session). And, the fourth PDU session request message includes information of the DNN and information of the S-NSSAI. Therefore, in a roaming interworking-based manner between the first network and the second network, the UE may establish the information associated with the DNN and the fourth PDU session of the S-NSSAI through the first network device, and implement recovery of the PDU session associated with the DNN and the S-NSSAI for the UE. Because the PDU session recovery mode based on the roaming intercommunication mode and the non-intercommunication mode and the N3IWF intercommunication mode are not feasible, the UE executes the corresponding switching process according to the first information to improve the switching efficiency and avoid trial and error.

Based on the above procedures, after registering from the first network to the second network, the UE may receive the first information from the first network device in the second network, and since the first information is related to the interworking manner between the first network and the second network, the PDU session associated to DNN and S-NSSAI of the UE can be recovered more efficiently according to the first information, so as to improve handover efficiency and ensure service continuity.

It should be understood that one of the above first and second networks is an NPN network. For example, at least one of the first network and the second network is an SNPN.

Under the condition of roaming interworking between the first network and the second network, the data lossless switching of the UE path can be supported. For example, the UE may carry a lossless handover indication in a fourth PDU session request message. Alternatively, the lossless handover indication may also be sent independently of the fourth PDU session request message. The first network device may send a lossless handover indication to an SMF, wherein the SMF is an SMF that manages the first PDU session; alternatively, the SMF is an intermediate SMF for connection to the SMF managing the first PDU session, after which the lossless handover indication may be forwarded by the intermediate SMF to the SMF managing the first PDU session.

The SMF managing the first PDU session may send, after receiving the lossless handover instruction, second information to the first UPF to indicate that the first UPF sends an end flag to the first access network element after the path of the first PDU session is handed over, and to indicate that the first UPF forwards downlink data from the UE in the first access network element to the UE through the handed over path, where the downlink data includes the end flag. And the SMF managing the first PDU session may send third information to the first access network element to instruct the first access network element to forward the downlink data of the UE buffered by the first access network element to the first UPF until receiving and forwarding the end flag. The first PDU session is a PDU session between the first access network element and the first UPF. Therefore, the first UPF and the first access network element can forward the downlink data of the UE before path switching to the UE through the switched path, and lossless path switching is realized.

In the following, the first network is SNPN #1, and the second network is SNPN #2, where SNPN #2 may be replaced by VPLMN #2 (i.e. a VPLMN).

As shown in fig. 11, a communication method provided in an embodiment of the present application may include the following steps:

s201: the UE registers with SNPN #1 and establishes a first PDU session. Wherein, the SMF and UPF of the first PDU session are SMF #1 and UPF #1, respectively. The first PDU session may be associated to a first DNN and a first S-NSSAI.

S202: SMF #1 sends an SMF registration message to the UDM or AAA server. The registration message may include a UE ID, an SNPN #1ID, an SMF #1ID, and an ID of the first PDU session. The UDM or AAA server may be deployed in the PLMN or the third network.

S203: the UE moves to the target network SNPN #2, and the UE sends a first registration request message to AMF #2 in SNPN #2 (AMF #2 is used as the first network device in fig. 11), carrying the UE ID.

Optionally, the first registration request message may carry an HO indication across a private network. Wherein the cross-private network HO indication is used for indicating that the AMF #2 registration aims to perform cross-private network handover, but not initial registration. The HO indication may be a location update registration or a new information element.

S204: if there is an interface between AMF #2 and AMF #1, AMF #2 may acquire a context of the UE including at least one information of a UE ID, SNPN #1ID, SMF #1ID, or an ID of the first PDU session from AMF # 1. Wherein, the information of AMF #1 can be obtained by AMF #2 from UDM or AAA server. Otherwise, if there is no interface between AMF #2 and AMF #1, AMF #2 may acquire the context of the UE from the UDM or the AAA.

S205: AMF #2 determines that the UE is switched across the private network according to the HO indication or the UE context of the UE across the private network, such as SNPN #1ID or SMF #1ID, and determines the switching mode according to the intercommunication mode (not intercommunication, intercommunication based on N3IWF mode or roaming intercommunication) of SNPN #2 and SNPN #1, such as determining that the UE is switched according to roaming intercommunication or not according to roaming intercommunication.

S206: the AMF #2 sends a registration response message to the UE, carrying the handover mode indication (i.e. the first information). If the SNPN #1 and the SNPN #2 do not intercommunicate, the switching mode information can indicate that the UE is switched in a non-intercommunicating mode or indicate that the SNPN #1 and the SNPN #2 do not intercommunicate; if the SNPN #1 and the SNPN #2 are intercommunicated based on the N3IWF mode, the switching mode information can indicate the UE to switch according to the mode of intercommunicating based on the N3IWF mode, or indicate the SNPN #1 and the SNPN #2 to be intercommunicated based on the N3IWF mode; the handover mode information may indicate that the UE performs handover in roaming interworking mode if roaming interworking is performed between SNPN #1 and SNPN #2, or indicate that roaming interworking is performed between SNPN #1 and SNPN # 2.

One of S207-S209 is then performed.

S207: if the SNPN #1 and the SNPN #2 do not intercommunicate, the UE reestablishes the PDU session, namely, sends a first PDU session request message with the request type of initial request to the AMF # 2. The first PDU session request message carries the first DNN and the first S-NSSAI, so that the newly established PDU session can be associated to the first DNN and the first S-NSSAI.

In this case, the handover mode indication may be used to indicate that there is no interworking between SNPN #1 and SNPN #2, or to indicate that the UE transmits the first PDU session request to AMF # 2.

S208: if the SNPN #1 and the SNPN #2 are intercommunicated based on the N3IWF mode, the UE firstly establishes a PDU session (namely a second PDU session) which is connected to the SNPN #1 and is based on the N3IWF in the SNPN #2 and establishes user plane connection; then UE initiates N3GPP registration at SNPN #1 through N3IWF, or sends a second registration request to AMF #1 through N3IWF to request to register to a first network in a N3GPP mode, and then UE can initiate a process of switching PDU session from 3GPP to N3GPP, namely a third PDU session request message with request type being existing PDU session is initiated, and the third PDU session request message carries first DNN and first S-NSSAI, so that the newly established PDU session of N3GPP can be associated to the first DNN and the first S-NSSAI.

In this case, the handover mode indication may be used to indicate N3IWF based mode interworking between SNPN #1 and SNPN #2, or to indicate that the UE first establishes an N3IWF based PDU session connected to SNPN #1 at SNPN #2 and initiates a handover procedure of the PDU session from 3GPP to N3 GPP.

S209: if the SNPN #1 and the SNPN #2 are based on roaming interworking, the UE initiates a switching process of the PDU session from SNPN #1 to SNPN #2 at SNPN #2, namely, a fourth PDU session request message with the request type of existing PDU session is sent to AMF #2, and then S210-S220 are executed. Wherein, the fourth PDU session request message carries the information of the DNN and the information of the S-NSSAI, so as to request to recover the PDU session related to the DNN and the S-NSSAI.

Optionally, if the UE needs lossless handover, a lossless handover indication may be additionally carried in the fourth PDU session request.

In this case, the handover mode indication may be used to indicate roaming interworking between SNPN #1 and SNPN #2, or to indicate that the UE initiates a handover procedure of a PDU session from SNPN #1 to SNPN #2 at SNPN # 2.

S210: and AMF #2 determines that the UE carries out cross-private network switching according to the cross-private network HO indication, the request type of the existing PDU session or the SMF #1ID, and determines to insert the I-SMF.

S211: AMF #2 sends an SMF discovery request message to the NRF.

S212: the NRF transmits the candidate SMF to AMF #2 according to the SMF discovery request message.

S213: AMF #2 selects SMF #2 as the I-SMF based on the candidate SMFs.

S214: the AMF #2 sends a fourth PDU session request message and a cross-private network HO indication to the SMF # 2.

S215: SMF #2 sends a fourth PDU session request message and an inter-private network HO indication to SMF # 1.

Alternatively, if SMF #2 receives a lossless handover indication sent by the UE, SMF #2 may forward the lossless handover indication to SMF # 1.

Alternatively, when SMF #2 is inserted as an I-UPF (e.g., UPF #2) according to the existing mechanism, SMF #2 may additionally configure the charging rules on the I-UPF based on the HO indication.

S216: the SMF #1 transmits a path switching instruction to the UPF #1 to instruct the UPF #1 to switch a path to the UE.

For example, the UPF #1 switches the path from the UPF #1 to the UE from the UPF #1 → RAN #1 → UE to the UPF #1 → UPF #2 → RAN #2 → UE.

In addition, the SMF indicates UPF #1 to maintain service continuity through the second information according to the cross-private network HO indication and the local configuration or lossless handover indication.

S217: the UPF #1 sends an end marker to the RAN #1 on the old path based on the second information of the SMF after switching to the new path.

The old path here refers to a path between UPF #1 and RAN # 1.

S218: SMF #1 (or AMF #1) sends a release request to RAN #1 to request RAN #1 to release the first PDU session.

In addition, after receiving the cross-private network HO indication, the SMF #1 (or AMF #1) may determine that a lossless handover is required according to local configuration, so as to send a third indication to the RAN #1 to instruct the RAN #1 to forward the buffered downlink data (including the end flag sent by the UPF #1) to the UPF #1 before releasing the context. Data from RAN #1 may subsequently be forwarded by UPF #1 to the UE over the new path.

Alternatively, the SMF #1/AMF #1 may instruct the RAN #1 to forward the buffered downlink data (including the end flag sent by the UPF #1) to the UPF #1 through the third information before releasing the context after receiving the lossless handover instruction from the SMF # 2. Data from RAN #1 may subsequently be forwarded by UPF #1 to the UE over the new path.

S219: RAN #1 forwards the buffered UE data, including the end marker, to UPF #1 and releases the resources of the first PDU session.

S220: UPF #1 forwards data from RAN #1 to the UE on a new path, i.e.: data is forwarded on the path of UPF #1 → UPF #2 → RAN #2 → UE. Data passing for subsequent UEs

Is forwarded.

If the UPF #1 receives the indication of the SMF switching path, it needs to forward the data from the RAN #1 first before forwarding the new data in the downlink direction, i.e. the UPF #1 forwards the message received from the original path first until receiving the end mark, and then forwards the new downlink data packet.

S221: the PDU session is resumed at SNPN # 2.

By adopting the method, the AMF #2 can indicate the mode of the cross-private network switching adopted by the UE, and the UE indicates to execute the cross-private network switching through the indicated switching mode, so that the UE is correctly switched to the target network, and the efficiency of the cross-private network switching is improved. In addition, when the switching of the private network is carried out based on the roaming mode, the data lossless switching can be provided for the UE.

As shown in fig. 12, another communication method provided in the embodiment of the present application is described by taking the first network as SNPN #1 and the second network as HPLMN #2 as an example. Here, HPLMN #2 may be replaced by home SNPN (H-SNPN) H-SNPN #2, and this scenario is shown in fig. 8.

As shown in fig. 12, another communication method provided in the embodiment of the present application may include the following steps:

s301: the UE registers with SNPN #1 through RAN #1 and establishes a first PDU session. Wherein, the SMF and UPF of the first PDU session are SMF #1 and UPF #1, respectively. The first PDU session may be associated to a first DNN and a first S-NSSAI.

S302: SMF #2 sends an SMF registration message to the UDM. The registration message may include a UE ID, an SNPN #1ID, an SMF #1ID, and an ID of the first PDU session. Wherein the UDM is deployed in HPLMN # 2.

S303: the UE moves to the target network HPLMN #2, and the UE sends a first registration request message to AMF #2 in HPLMN #2 (AMF #2 in fig. 12 is used as a first network device), carrying the UE ID. The first registration request message can also carry a cross-private network HO instruction. The cross-private network HO indication is used for indicating that the AMF #2 registration aims to perform cross-private network handover, but not initial registration, and the HO indication can be location update registration or a new cell.

S304: if there is an interface between AMF #2 and AMF #1, AMF #2 may acquire a context of the UE including at least one information of a UE ID, an SNPN #1ID, an SMF #1ID, or an ID of the first PDU session from AMF # 1; otherwise, if there is no interface between AMF #2 and AMF #1, AMF #2 acquires the context of the UE from the UDM.

S305: AMF #2 determines that the UE is switched across the private network according to the HO indication of the UE across the private network or the UE context, such as SNPN #1ID or SMF #2ID, and determines the switching mode according to the intercommunication mode of HPLMN #2 and SNPN #1, wherein the intercommunication mode of HPLMN #2 and SNPN #1 is roaming intercommunication.

S306: the AMF #2 sends a registration response message to the UE, carrying the handover mode indication (i.e. the first information). The handover mode information may indicate that the UE performs handover according to a roaming interworking mode, or indicate that the SNPN #1 and the HPLMN #2 perform roaming interworking.

S307: and the UE initiates a switching process of the PDU session from the SNPN #1 to the HPLMN #2 at the HPLMN #2, namely, a fourth PDU session request message with the request type of existing PDU session is sent to the AMF # 2. Wherein, the fourth PDU session request message carries the information of the DNN and the information of the S-NSSAI, so as to request to recover the PDU session related to the DNN and the S-NSSAI.

Optionally, if the UE needs lossless handover, a lossless handover indication may be additionally carried in the session request.

S308: and AMF #2 determines that the UE carries out cross-private network switching according to the cross-private network HO indication, the request type of the existing PDU session or the SMF #1ID, and determines to insert the I-SMF.

S309: AMF #2 sends an SMF discovery request to the NRF.

S310: the NRF transmits the candidate SMF to AMF #2 according to the SMF discovery request.

S311: AMF #2 selects SMF #2 as the I-SMF based on the candidate SMFs.

S312: the AMF #2 sends a fourth PDU session request message and a cross-private network HO indication to the SMF # 2.

S313: SMF #2 sends the fourth PDU session request message and the cross-private network HO instruction to SMF #2, and simultaneously sends the cross-private network HO instruction to SMF # 1.

S314: the SMF #1 transmits a path switching instruction to the UPF #1 to instruct the UPF #1 to switch a path to the UE.

S315: the UPF #1 may send an end marker to the RAN #1 on the old path according to the second information after the handover to the new path.

The old path here refers to a path between UPF #1 and RAN # 1.

S316: SMF #1 (or AMF #1) sends a release request to RAN #1 to request RAN #1 to release the first PDU session.

In addition, after receiving the cross-private network HO indication, the SMF #1 (or AMF #1) may determine that a lossless handover is required according to the local configuration, so as to instruct the RAN #1 to forward the buffered downlink data (including the end flag sent by the UPF #1) to the UPF #1 before releasing the context through the third information. Alternatively, the SMF #1/AMF #1 may instruct the RAN #1 to forward the buffered downlink data (including the end flag sent by the UPF #1) to the UPF #1 through the third information before releasing the context after receiving the lossless handover instruction from the SMF # 2. Data from RAN #1 may subsequently be forwarded by UPF #1 to the UE over the new path.

S317: RAN #1 forwards buffered UE data, including an end marker, to UPF #1 and releases the resources of the first PDU session.

S318: UPF #1 forwards data from RAN #1 to the UE over a new path, namely: data is forwarded on the path of UPF #1 → UPF #2 → RAN #2 → UE. Data passing for subsequent UEs

Is forwarded.

S318: the PDU session is resumed at HPLMN # 2.

By adopting the method, under the condition that the first network and the second network share the UDM, the core network can indicate the UE to adopt a roaming-based private network crossing switching mode so as to improve the private network crossing switching efficiency. In addition, data lossless handover may be provided for the UE.

For another example, in the scenario shown in fig. 9, the UE switches from SNPN #1 to HPLMN #2 (or H-SNPN #2), where SNPN #1 and HPLMN #2 (or H-SNPN #2) share a core network, and the communication method provided in the embodiment of the present application may include the following steps as shown in fig. 13:

s401: the UE registers with SNPN #1 through RAN #1 and establishes a first PDU session. Wherein, the SMF and UPF of the first PDU session are SMF #2 and UPF #2, respectively. The first PDU session may be associated to a first DNN and a first S-NSSAI.

S402: SMF #2 sends an SMF registration message to the UDM. The registration message may include a UE ID, an SNPN #1ID, an SMF #2ID, and an ID of the first PDU session.

S403: the UE moves to the target network HPLMN #2, and the UE sends a first registration request message to AMF #2 in HPLMN #2 (AMF #2 is used as the first network device in fig. 13), carrying the UE ID. The first registration request message can also carry a cross-private network HO instruction. Wherein, the cross-private network HO indication is used for indicating that the AMF #2 registration aims to perform cross-private network handover, but not initial registration, and the HO indication can be location updating registration or new information element.

S404: AMF #2 acquires the context of the UE from the UDM.

S405: AMF #2 determines that the UE is switched across the private network according to the HO indication or the UE context of the UE across the private network, such as SNPN #1ID, and determines the switching mode according to the intercommunication mode of HPLMN #2 and SNPN #1, wherein the intercommunication mode of HPLMN #2 and SNPN #1 is roaming intercommunication.

S406: the AMF #2 sends a registration response message to the UE, carrying the handover mode indication (i.e. the first information). The handover mode information may indicate that the UE performs handover according to a roaming interworking mode, or indicate that the SNPN #1 and the HPLMN #2 perform roaming interworking.

S407: and the UE initiates a switching process of the PDU session from the SNPN #1 to the HPLMN #2 at the HPLMN #2, namely, a fourth PDU session request message with the request type of existing PDU session is sent to the AMF # 2. Wherein, the fourth PDU session request message carries the information of the DNN and the information of the S-NSSAI, so as to request to recover the PDU session related to the DNN and the S-NSSAI.

S408: and the AMF #2 determines that the UE is switched across the private network according to the HO indication of the across private network, the request type of the existing PDU session or the SNPN #1 ID.

S409: the AMF #2 forwards the fourth PDU session request message and the cross private network HO indication to the SMF # 2.

S410: the first PDU session is resumed at HPLMN # 2.

S411: SMF #2 (or AMF #2) sends a release request to RAN #1 to request RAN #1 to release the first PDU session.

In addition, after receiving the cross-private network HO indication, the SMF #2/AMF #2 may determine that lossless handover is required according to local configuration, so as to instruct the RAN #1 to forward the buffered downlink data to the UPF #2 before releasing the context through the third information. Alternatively, the SMF #2/AMF #2 may instruct the RAN #1 to forward the buffered downlink data to the UPF #2 through the third information before releasing the PDU session after receiving the lossless handover instruction from the UE. Data from RAN #1 may subsequently be forwarded by UPF #2 to the UE over the new path.

S412: RAN #1 forwards the buffered UE data, including the end marker, to UPF #2 and releases the resources of the first PDU session.

S413: the UPF #2 forwards the data packet from the RAN #1 on the new path, that is: the data message is forwarded at UPF #2< - > RAN #2< - > UE; if the UPF #2 receives the indication of the SMF switching path, it needs to first forward the packet received from RAN #1, i.e. the original path, until receiving the end flag before forwarding the new downlink data packet.

By adopting the method, under the condition that the first network and the second network share the core network, the core network can indicate the UE to adopt a roaming-based private network crossing switching mode so as to improve the private network crossing switching efficiency. In addition, data lossless handover may be provided for the UE.

When the UE is registered in the home network, that is, the first network is the home network, the UE accesses the home network through the source network, and establishes a PDU session in the home network, the communication method provided in the embodiment of the present application may include the steps shown in fig. 14a and/or fig. 14 b. Here, the home network may be a HPLMN or a Home SNPN (HSNPN).

Fig. 14a shows another communication method provided in the embodiment of the present application when the first network is the HPLMN and the second network is the SNPN # 2. This method can be applied to the scenario shown in fig. 7b/7 c. Here, SNPN #2 can also be replaced with VPLMN #2 (i.e., one VPLMN).

The method may comprise the steps of:

s601: the UE registers in SNPN #1 and establishes a first PDU session, wherein the anchor UPF of the first PDU session is UPF #3 in the HPLMN, and the anchor SMF of the PDU session is SMF #3 in the HPLMN. The first PDU session may be associated to a first DNN and a first S-NSSAI.

The SNPN #1 and the HPLMN are intercommunicated based on a roaming mode.

S602: SMF #1 and SMF #3 transmit SMF registration messages to the UDM, respectively. The registration message may include a UE ID, an SNPN #1ID, an SMF #1ID (or an SMF #3ID), and an ID of the first PDU session. The UDM may be deployed at the HPLMN.

S603: the UE moves to a target network SNPN #2, and the UE sends a first registration request message to AMF #2 in the SNPN #2, wherein the UE ID is carried.

S604: AMF #2 determines that the UE is switched across the private network according to the HO indication of the UE across the private network, and determines the switching mode according to the intercommunication mode (based on non-roaming intercommunication or roaming intercommunication) of the SNPN #2 and the HPLMN, for example, determines that the UE is switched according to roaming intercommunication or not according to roaming intercommunication.

The AMF #2 may determine the ID of the home network of the UE, which may be the network ID of the HPLMN or the network ID of the SNPN #2, according to the UE ID (e.g., a user permanent identifier (SUPI) or a user hidden identifier (sui)) in the first registration request message of the UE. Meanwhile, AMF #2 can obtain the network ID of SNPN #2 from RAN, and then determine the intercommunication mode of SNPN #2 and HPLMN according to the ID of the home network.

S605: the AMF #2 sends a registration response message to the UE, carrying the handover mode indication (i.e. the first information).

If SNPN #2 and HPLMN are intercommunicated based on the non-roaming mode, the switching mode indication can indicate that SNPN #2 and HPLMN are intercommunicated based on the non-roaming mode. Alternatively, the handover mode indication may indicate to the UE: if the UE does not support N3IWF to HPLMN, e.g. no N3IWF configuration of HPLMN or does not support connection to N3IWF, then the first PDU session to HPLMN is not established after registration to SNPN # 2.

In addition, if SNPN #2 and HPLMN interwork based on non-roaming, the handover mode indication may also instruct the UE to: if the UE supports N3IWF to HPLMN, for example, the UE has N3IWF configuration of HPLMN or supports connection to N3IWF, the UE establishes PDU session of N3IWF connected to HPLMN, triggers flow of switching the first PDU session from 3GPP to N3GPP through the PDU session, and deletes SMF #1/UPF #1 of the first PDU session.

If SNPN #2 and HPLMN support the roaming-based interworking, the handover indication may indicate that SNPN #2 and HPLMN support the roaming-based interworking, or the handover indication may indicate that UE recovers the first PDU session in the following manner: AMF #2 triggers an I-SMF/I-UPF switching process of the PDU session in the existing mechanism, selects SMF #2/UPF #2 to replace the original SMF #1/UPF #1, and recovers the PDU session.

The UE then performs one of S606-S608 according to the handover mode indication.

S606: if SNPN #2 interworks with the HPLMN based on non-roaming, but the UE does not support N3IWF to the HPLMN, the UE does not attempt to establish the first PDU session to SNPN #2 any more.

S607: if SNPN #2 and HPLMN are intercommunicated based on a non-roaming mode and the UE supports N3IWF to the HPLMN, a PDU session (namely a second PDU session) of the N3IWF connected to the HPLMN is firstly established at SNPN #2, and user plane connection is established; then UE initiates the switching of the first PDU session from 3GPP to N3GPP at SNPN #1 through N3IWF, namely, a third PDU session request message with request type of existing PDU session is sent to SNPN #1, and the third PDU session request message carries first DNN and first S-NSSAI, so that the switched PDU session of N3GPP can be associated to the first DNN and the first S-NSSAI, and SMF #1 and UPF #1 of the first PDU session are deleted.

S608: if SNPN #2 and HPLMN are intercommunicated based on a roaming mode, UE can send a fourth PDU session request message with request type of existing PDU session to AMF #2, wherein the fourth PDU session request message carries the first DNN and the first S-NSSAI so as to request to recover the PDU session related to the DNN and the S-NSSAI. And after receiving the fourth session request, AMF #2 triggers an I-SMF/I-UPF switching process of the PDU session in the existing mechanism, selects SMF #2/UPF #2 to replace the original SMF #1/UPF #1, and recovers the first PDU session.

In this case, the handover mode indication may be used to indicate roaming interworking between SNPN #1 and SNPN #2, or to indicate that the UE initiates a handover procedure of a PDU session from SNPN #1 to SNPN #2 at SNPN # 2. The specific switching manner can refer to the steps shown in S210-S221.

Based on the above procedures, when the source SNPN #1 and the HPLMN are intercommunicated based on the roaming mode and the UE registered in the SNPN #1 establishes the HR PDU session of the HPLMN, the AMF in the SNPN #2 can instruct the UE to perform PDU session handover, thereby improving the PDU session handover efficiency.

It should be understood that the HPLMN may be replaced with Home SNPN (HSNPN) in the above flow.

Fig. 14b shows another communication method provided in the embodiment of the present application when the first network is the HPLMN and the second network is the SNPN # 2. This method can be applied to the scenario shown in fig. 7b/7 c. Here, SNPN #2 can also be replaced with VPLMN #2 (i.e., one VPLMN).

The method may comprise the steps of:

s701: the UE is connected to N3IWF of HPLMN through SNPN #1, and registers and establishes a first PDU session in the HPLMN through N3WIF, wherein the anchor UPF of the first PDU session is UPF #3 in the HPLMN, and the anchor SMF of the PDU session is SMF #3 in the HPLMN. The first PDU session may be associated to a first DNN and a first S-NSSAI.

Wherein, SNPN #1 and HPLMN are intercommunicated based on N3 IWF.

S702: SMF #3 sends an SMF registration message to the UDM. The registration message may include the UE ID, the network ID of the HPLMN, the SMF #3ID, and the ID of the first PDU session. The UDM may be deployed at the HPLMN.

S703: the UE moves to a target network SNPN #2, and the UE sends a first registration request message to AMF #2 in the SNPN #2, wherein the UE ID is carried.

S704: AMF #2 determines that the UE is switched across the private network according to the HO indication of the UE across the private network, and determines the switching mode according to the intercommunication mode (based on non-roaming sending intercommunication or roaming intercommunication) of the SNPN #2 and the HPLMN, for example, determines that the UE is switched according to roaming intercommunication or not according to roaming intercommunication.

Among them, the AMF #2 may determine the ID of the home network of the UE, which may be the network ID of the HPLMN or the network ID of the SNPN #2, according to the UE ID (e.g., SUPI or SUCI) in the first registration request message of the UE. Meanwhile, AMF #2 can obtain the network ID of SNPN #2 from RAN, and then determine the intercommunication mode of SNPN #2 and HPLMN according to the ID of the home network.

S705: the AMF #2 sends a registration response message to the UE, carrying the handover mode indication (i.e. the first information).

In addition, if SNPN #2 and HPLMN interwork based on non-roaming, the handover mode indication may also instruct the UE to: if the UE supports N3IWF to the HPLMN, e.g., the UE has N3IWF configuration of the HPLMN or supports connection to N3IWF, the UE establishes a PDU session for the N3IWF connected to the HPLMN over which a PDU session is established at the HPLMN through N3GPP, the PDU session being associated with the first DNN and the first S-NSSAI.

If SNPN #2 and HPLMN support the roaming-based interworking, the handover indication may indicate that SNPN #2 and HPLMN support the roaming-based interworking, or the handover indication may indicate that UE recovers the first PDU session in the following manner: AMF #2 triggers the I-SMF/I-UPF insertion process of the PDU session in the existing mechanism, SMF #2 and/or UPF #2 newly inserted into SNPN # 2.

The UE then performs one of S706-S708 according to the handover mode indication.

S706: if SNPN #2 interworks with the HPLMN based on a non-roaming manner, but the UE does not support N3IWF to the HPLMN, the UE no longer attempts to establish the first PDU session of SNPN # 2.

S707: if SNPN #2 and HPLMN are intercommunicated based on a non-roaming mode and the UE supports N3IWF to the HPLMN, a PDU session (namely a second PDU session) of the N3IWF connected to the HPLMN is firstly established at SNPN #2, and user plane connection is established; then the UE establishes an N3GPP PDU session with the request type of existing PDU session to the HPLMN through the N3IWF, and the PDU session is associated to the first DNN and the first S-NSSAI.

S708: if SNPN #2 and HPLMN are intercommunicated based on a roaming mode, UE can send a fourth PDU session request message with request type of existing PDU session to AMF #2, wherein the fourth PDU session request message carries the first DNN and the first S-NSSAI so as to request to recover the PDU session related to the DNN and the S-NSSAI. And after receiving the fourth session request, AMF #2 triggers an I-SMF/I-UPF insertion process of the PDU session in the existing mechanism, newly inserts SMF #2 and/or UPF #2 in SNPN #2, and is used for switching the first PDU session from N3GPP to 3 GPP.

Based on the above procedures, when the source SNPN #1 and the HPLMN are intercommunicated based on the N3IWF, and the UE registered in the SNPN #1 establishes the PDU session of the HPLMN through the N3IWF of the HPLMN, the AMF in the SNPN #2 can indicate the UE to carry out the PDU session switching, thereby improving the PDU session switching efficiency.

It should be understood that the HPLMN may be replaced with the home SNPN in the above flow.

As shown in fig. 14c, another communication method provided in the embodiment of the present application may include the following steps:

s501: the UE establishes a first PDU session at a first network.

The first PDU session is associated with DNN and S-NSSAI.

S502: the UE sends a first registration request message to a first network device in a second network.

Optionally, the first registration request message may carry a non-public network crossing handover instruction, where the non-public network crossing handover instruction is used to instruct the terminal device to perform non-public network crossing handover.

S503: a PDU session for the UE is established in a first order, the PDU session being associated with the DNN and the S-NSSAI. The first order may indicate an order of execution of a third manner, a second manner, and a first manner, respectively, wherein the third manner takes precedence over the second manner and the first manner, and the second manner takes precedence over the first manner.

It should be understood that the first order may only include a precedence order of two manners of the third manner, the second manner, and the first manner, and at this time, the terminal device does not execute a manner that the first order does not include any more, so as to further improve the handover efficiency.

The first order may indicate that the third manner is prior to the second manner, and the second manner is prior to the first manner, the UE may preferentially establish the PDU session in the third manner, and if successful establishment of the PDU session associated with the DNN and the S-NSSAI is successful, no attempt is made to establish the PDU session in the second manner and the first manner; otherwise, if the PDU session associated with the DNN and the S-NSSAI cannot be established according to the third approach, the UE may attempt to establish the PDU session associated with the DNN and the S-NSSAI according to the second approach; if a PDU session associated with the DNN and the S-NSSAI cannot be established according to the second manner, the UE may attempt to establish a PDU session associated with the DNN and the S-NSSAI according to the first manner.

By adopting the above procedures, the UE can recover the PDU session through the third mode, the second mode and/or the first mode according to the first sequence after registering from the first network to the second network, so as to improve the handover efficiency.

Optionally, the first mode, the second mode, and the third mode may be respectively related to an interworking mode between the first network and the second network. In other words, the first, second and third modes are respectively a mode for the UE to establish a PDU session associated to DNN and S-NSSAI in an interworking mode between the first network and the second network.

Illustratively, the first mode may comprise a non-interworking handover mode. The non-interworking handover mode may be used to implement handover of a PDU session of the UE when the first network and the second network are not interworking, and the non-interworking handover mode specifically includes that the terminal device sends a first PDU session request message to the first network device, where the first PDU session request message includes a request type cell with an initial request value, information of the DNN, and information of the S-NSSAI. Alternatively, the first manner may include a manner when the UE establishes the PDU session associated with the DNN and the S-NSSAI when the first network and the second network do not interwork, and the specific steps may be as described in the foregoing description.

The second mode may include an N3IWF interworking handover mode, where the N3IWF interworking handover mode may be used to implement PDU session handover of the UE when the first network and the second network are interworking based on N3 IWF. The N3IWF interworking handover scheme may include the steps of: UE sends a second PDU session request message to first network equipment, wherein the second PDU session request is used for requesting to establish a second PDU session, the UE establishes connection with an N3IWF through the second PDU session, and the N3IWF belongs to a first network; the UE sends a second registration request message to second network equipment through the connection, wherein the second registration request message is used for requesting registration in the first network in an N3GPP mode, and the second network equipment belongs to the first network; and the UE sends a third PDU session request message to the second network equipment, wherein the third PDU session request message comprises a request type cell with the value of existing PDU session, the information of DNN and the information of S-NSSAI. Alternatively, the second manner may include a manner when the UE establishes the PDU session associated with the DNN and S-NSSAI when the first network and the second network are interworking based on the N3IWF, and the specific steps may be referred to the foregoing description.

The third mode may include a roaming interworking handover mode, which may be used to implement a PDU session handover of the UE when performing roaming interworking between the first network and the second network. The roaming interworking handover mode may include the steps of: and the terminal equipment sends a fourth PDU session request message to the first network equipment, wherein the fourth PDU session request message comprises a request type cell with the value of existing PDU session, the information of DNN and the information of S-NSSAI. Optionally, the fourth PDU session request message may include a lossless handover indication to implement lossless handover, and the specific steps may refer to the lossless handover steps implemented based on SMF #1 (or UPF #2), UPF #1 (or UPF #2), and RAN #1 in fig. 11 to 13. Alternatively, the third manner may include a manner when the UE establishes the PDU session associated with the DNN and S-NSSAI when the first network and the second network are in roaming interworking, and the specific steps may be as described in the foregoing description. The third mode may be replaced by a roaming interworking handover mode, or may be referred to as a roaming interworking handover mode, and is used to implement PDU session handover of the UE when roaming interworking is performed between the first network and the second network.

Therefore, when the terminal equipment is switched from the first network to the second network, the PDU session related to the DNN and the S-NSSAI can be recovered preferentially by a roaming interworking switching mode, the PDU session related to the DNN and the S-NSSAI can be recovered by an N3IWF interworking switching mode in a suboptimal scheme, and the PDU session related to the DNN and the S-NSSAI can be recovered again by a non-interworking switching mode, so that the switching efficiency is improved.

For example, the first order may indicate that the third manner described above is preferred over the second manner, and the second manner is preferred over the first manner, the UE may preferentially establish the PDU session in the third manner, and if successful establishment of the PDU session associated with the DNN and the S-NSSAI is successful, no attempt may be made to establish the PDU session in the second manner and the first manner; otherwise, if the PDU session associated with the DNN and the S-NSSAI cannot be established according to the third approach, the UE may attempt to establish the PDU session associated with the DNN and the S-NSSAI according to the second approach; if a PDU session associated with the DNN and the S-NSSAI cannot be established according to the second manner, the UE may attempt to establish a PDU session associated with the DNN and the S-NSSAI according to the first manner.

Illustratively, the first order may be determined by a local configuration. Alternatively, the first order may be indicated by the first network device, for example, when the UE registers to the second network, the first network device sends the indication information of the first order to the UE. Alternatively, the first order may be indicated by a second network device deployed in the first network, for example, when the UE registers with the first network, the second network device sends information indicating the first order to the UE.

It should be understood that the indication information of the first order here may include priorities of the above first manner, second manner, and third manner, respectively. For example, the indication information may carry the priority of the first mode, the priority of the second mode, and the priority of the third mode.

Alternatively, the indication information may directly indicate that the UE performs in the order of the third manner, the second manner, and the first manner.

In addition, the indication information may further include information of the first manner, the second manner, and the third manner, respectively, to indicate the first manner, the second manner, and the third manner. For example, the indication information indicates the interworking mode between the first network and the second network corresponding to the first mode, the second mode, and the third mode, respectively, for example, indicates that the first mode is not interworking between the first network and the second network, indicates that the second mode is interworking between the first network and the second network based on N3IWF, and indicates that the third mode is interworking between the first network and the second network based on roaming. For another example, the indication information may further indicate respective handover manners of the first manner, the second manner and the third manner, for example, indicate that the first manner is a non-interworking handover manner, indicate that the second manner is an N3IWF interworking handover manner, and indicate that the third manner is a roaming interworking handover manner.

In addition, the UE may also determine the first mode, the second mode, and the third mode according to the local configuration, for example, determine the first mode as a non-interworking handover mode according to the local configuration, determine the second mode as an N3IWF interworking handover mode according to the local configuration, and determine the third mode as a roaming interworking handover mode according to the local configuration.

It should be understood that the above indication information of the first order is only an example, and the specific implementation can be implemented by a combination of several ways in the above various ways, and the specific implementation way should not be construed as being limited by the above examples.

In addition, the first network device and the second network device may indicate the order of the first mode, the second mode, and the third mode through other manners, for example, the indication information includes information about the first mode, the second mode, and the third mode (for example, information about intercommunication manners corresponding to the first mode, the second mode, and the third mode, or PDU session establishment manners corresponding to the first mode, the second mode, and the third mode), and the arrangement order of the intercommunication manners may represent the order of the first mode, the second mode, and the third mode.

In a possible implementation, on the basis of the flows shown in fig. 10 and fig. 14c, the embodiment of the present application supports that the UE determines the recovery manner of the PDU session according to the following method:

after the UE establishes the PDU session associated with the DNN and the S-NSSAI in the first network and the UE registers to the second network, if the UE receives first information from a first network device deployed in the second network, where the first information may refer to the description of the first information in the embodiment of the present application, the UE may establish the PDU session associated with the DNN and the S-NSSAI according to the first information; otherwise, if the UE does not receive the first information from the second network, the handover method may be performed in the order of the third manner, the second manner, and the first manner to attempt to establish the PDU session associated to the DNN and the S-NSSAI, where the order is the first order in the embodiment of the present application. The first order may be determined by the UE based on a local configuration or based on an indication of the first order from the second network device.

Based on the same concept, in order to implement each function in the method provided by the embodiment of the present application, the present application also provides a communication device. The communication device can be used for realizing the functions of the session management network element, the user plane network element, the policy management network element, the terminal equipment or the access network element. The communication means may comprise a hardware structure and/or a software module, and the functions described above are realized in the form of a hardware structure, a software module, or a hardware structure plus a software module. Whether any of the above-described functions is implemented as a hardware structure, a software module, or a hardware structure plus a software module depends upon the particular application and design constraints imposed on the technical solution.

As shown in fig. 15, a communication apparatus provided in an embodiment of the present application may include a communication module 1501 and a processing module 1502, where the communication module 1501 and the processing module 1502 are coupled to each other. The communication apparatus 1500 may be configured to perform the steps performed by the terminal device (UE), the first network device (AMF #2 shown in fig. 11 to 13), or the SMF (or a session management network element, such as SMF #1 in fig. 11 and 12 or SMF #2 in fig. 13) shown in fig. 3 to 8 above. The communication module 1501 may be used to support the communication device 1500 for communication, and the communication module 1501 may also be referred to as a communication unit, a communication interface, a transceiver module, or a transceiver unit. The communication module 1501 may have a wireless communication function and/or a wired communication function. The processing module 1502 may also be referred to as a processing unit, and may be configured to support the communication apparatus 1500 to perform the processing actions of the terminal device, the first network device, or the SMF in the foregoing method embodiments, including but not limited to: generate information, messages transmitted by the communication module 1501, and/or demodulate and decode signals received by the communication module 1501, and the like.

In performing the actions performed by the terminal device shown in fig. 10-13, communication module 1501 may establish a first PDU session associated with DNN and S-NSSAI at the first network, and communication module 1501 may also send a first registration request message to the first network device, the first registration request message requesting registration with the second network. The communication module 1501 may also receive first information from the first network device, where the first information is determined according to an interworking manner between the first network and the second network. The communication module 1501 may also establish a PDU session associated with the DNN and the S-NSSAI based on the first information.

In one possible design, in a case where the interworking manner includes no interworking between the first network and the second network, the communication module 1501 may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI. Therefore, under the mode that the first network and the second network are not intercommunicated, the UE can establish the PDU session associated to the DNN and the S-NSSAI in the second network, the recovery of the PDU session associated to the DNN and the S-NSSAI is realized, and the switching efficiency is improved.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the communication module 1501 may send a second PDU session request message to the first network device, the second PDU session request requesting establishment of a second PDU session. The communication module 1501 may also establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication module 1501 may further send a second registration request message to a second network device through a connection, where the second registration request message is used to request registration in the first network in an N3GPP manner, and the second network device belongs to the first network. The communication module 1501 may further send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with a value of existing PDU session, or the third PDU session request message is used to request to establish an existing PDU session. The third PDU session request message may carry information for the DNN and information for the S-NSSAI. Accordingly, in a mode that the first network and the second network are communicated based on the N3IWF, the UE can establish the information associated to the DNN and the third PDU session of the S-NSSAI through the N3IWF and the second network equipment, thereby realizing the recovery of the PDU session of the UE associated to the DNN and the S-NSSAI and improving the switching efficiency.

In one possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the communication module 1501 may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type cell having an existing PDU session value, information of the DNN, and information of the S-NSSAI. Therefore, in a roaming interworking mode between the first network and the second network, the UE can establish the information associated with the DNN and the fourth PDU session of the S-NSSAI through the first network device, thereby recovering the PDU sessions associated with the DNN and the S-NSSAI of the UE and improving the handover efficiency.

In performing the actions shown in fig. 10 to 13 performed by the first network device, the communication module 1501 may receive a first registration request message from the terminal device, the communication apparatus belongs to the second network, and the first registration request message is used to request registration to the second network. The processing module 1502 may obtain a context of the terminal device and determine that the terminal device is registered with the first network based on the context. The communication module 1501 may also send the first information to the terminal device according to an interworking manner between the first network and the second network.

In a possible design, the processing module 1502 may further determine that the terminal device performs handover between non-public networks according to a handover between non-public networks instruction included in the first registration request message, where the handover between non-public networks instruction is used to instruct the terminal device to perform handover between non-public networks. Alternatively, the processing module 1502 may determine that the terminal device performs handover across non-public networks according to the identifier of the first network, where the identifier of the first network is included in the context. Alternatively, processing module 1502 may determine that the terminal device performs handover across non-public networks according to an identifier of the second network device, where the identifier of the second network device is included in the context of the terminal device. The second network device is a network device, such as an AMF, accessed by the terminal device at the time of registration with the first network.

In one possible design, communication module 1501 may receive the context of the terminal device from a second network device deployed in the first network. The communication module 1501 may acquire information of the second network device from the UDM and request a context of the terminal device.

Alternatively, the communication module 1501 may receive the context of the terminal device from a data storage node shared by the first network and the second network.

In one possible design, the data storage node comprises a UDM or AAA server.

In one possible design, in a case that the interworking mode includes roaming interworking between the first network and the second network, the communication module 1501 may further receive the fourth PDU session request message from the terminal device. The communication module 1501 may further send the fourth PDU session request message to the first SMF, where the first SMF is an intermediate SMF, the first SMF is connected to a second SMF, and the second SMF maintains the first PDU session established by the terminal device in the first network and associated to the DNN and the S-NSSAI, and may subsequently forward the fourth PDU session request message to the second SMF by the first SMF, and perform path switching by the second SMF. Or, the first SMF belongs to the first network, and the first SMF maintains the first PDU session established by the terminal device in the first network, associated to the DNN and the S-NSSAI.

In one possible design, the communication module 1501 may further send a non-public network cross handover instruction to the first SMF, where the non-public network cross handover instruction is used to instruct the terminal device to perform non-public network cross handover.

In performing the actions performed by the SMF shown in fig. 10-13, processing module 1502 may establish a first PDU session associated with DNN and S-NSSAI for the terminal device registered with the first network. The first PDU session is a PDU session between a first access network element and a first UPF, and the first access network element belongs to the first network. The communication module 1501 may receive a fourth PDU session request message, which includes a request type cell having a value of existing PDU session, or may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated to the DNN and the S-NSSAI. The communication module 1501 may further send second information to the first UPF, where the second information is used to indicate that the first UPF sends an end flag to the first access network element after the path of the first PDU session is switched, and is used to indicate that the first UPF forwards downlink data from the terminal device of the first access network element to the terminal device through the switched path, where the downlink data includes the end flag. The communication module 1501 may further send third information to the first access network element, where the third information is used to instruct the first access network element to forward the downlink data of the terminal device cached by the first access network element to the first UPF until the end flag is received and forwarded.

In one possible design, the fourth PDU session request message includes a lossless handover indication, or the lossless handover may be determined by processing module 1502 to be performed for the terminal device based on local configuration.

In one possible design, communications module 1501 may also receive a non-public network handover indication.

In one possible design, the fourth PDU request message is from a first network device belonging to a second network, for example, when the communication apparatus is connected to the second network, and the first network device is connected to the communication apparatus. Or, the fourth PDU session request message is sent by the first network device to the intermediate SMF, and is forwarded by the intermediate SMF to the communication module 1501, for example, at this time, the communication apparatus does not belong to the second network, the first network device and the communication apparatus are not directly connected, and the message forwarding needs to be performed through the intermediate SMF.

In performing the actions performed by the terminal device shown in fig. 14c, the communication module 1501 may establish a first PDU session associated to DNN and S-NSSAI at the first network, and the communication module 1501 may further transmit a first registration request message to the first network device, the first registration request message requesting registration to the second network. In addition, communication module 1501 may establish (or request to establish) a PDU session associated with the DNN and the S-NSSAI according to a first order. The first sequence is used for indicating that the PDU conversation is established according to the third mode, the second mode and the first mode. In other words, the processing module 1502 establishes (or requests to establish) the PDU sessions sequentially through the communication module 1501 in the third manner, the second manner and the first manner according to the first order until the PDU sessions are established.

In one possible design, when establishing the PDU session according to the first manner, the communication module 1501 may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI.

In one possible design, communication module 1501 may send a second PDU session request message to the first network device requesting establishment of a second PDU session. The communication module 1501 may establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication module 1501 sends a second registration request message to a second network device through the connection, where the second registration request message is used to request registration in a first network in an N3GPP manner, and the second network device belongs to the first network. When the PDU session is established according to the second manner, the communication module 1501 may send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with an existing PDU session value, or the third PDU session request message may be used to request to establish an existing PDU session. The third PDU session request message may include information of the DNN and information of the S-NSSAI.

In one possible design, when the PDU session is established according to the third manner, the communication module 1501 may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type information element with an existing PDU session value, or the fourth PDU session request message may be used to request the establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI.

In one possible design, the first order is determined according to a local configuration. Alternatively, communication module 1501 may receive an indication of a first order from a first network device. Optionally, the indication information of the first order may be determined according to a local configuration of the first network device, or determined by the first network device according to an interworking manner between the first network and the second network. Alternatively, the communication module 1501 may receive the indication of the first order from the second network device. Optionally, the indication information of the first order may be determined according to a local configuration of the second network device, or determined by the second network device according to an interworking manner between the first network and the second network. The first order can be flexibly determined.

In addition, in another possible implementation manner, if the session management network element is implemented by a hardware component, the structure of the session management network element may also be as shown in fig. 16. For ease of understanding, fig. 16 shows only the structure necessary to perform the method shown in the present application, which does not limit the communication device to have more components. The communication device 1600 may include a communication interface 1601, a memory 1602, and a processor 1603. The communication interface 1601 may be used for communication by a communication device, such as for transmitting or receiving signals via wire and/or wirelessly, to thereby transmit and/or receive information, data, messages, and the like. The memory 1602 is coupled to the processor 1603 and is used for storing programs and data necessary for implementing the functions of the communication device 1600. The processor 1603 is configured to support the communication device 1600 to perform processing functions performed by the session management network element in the above-described method, such as determining to generate information, messages sent by the communication interface 1601, and/or to demodulate and decode signals received by the communication interface 1601, and the like. The memory 1602 and the processor 1603 may be integrated or may be independent of each other.

Illustratively, the communication interface 1601 may comprise a wired communication interface operable to enable the communication device 1600 to receive and transmit signaling and/or data via a wired connection. The communication interface 1601 may also be referred to as a transceiving unit or a communication unit. Alternatively, the communication interface 1601 can include a wireless transceiver (e.g., including a modem and/or antenna) that can be used to enable the communication device 1600 to receive and transmit signaling and/or data wirelessly. The communication interface 1601 may also be referred to as a wireless transceiver or a wireless communication unit.

The processor 1603 may be implemented by a processing chip or processing circuit.

In performing the actions illustrated in fig. 10-13 as being performed by the terminal device, the communication interface 1601 may establish a first PDU session associated with the DNN and the S-NSSAI at the first network, and the communication interface 1601 may further send a first registration request message to the first network device requesting registration with the second network. The communication interface 1601 is further capable of receiving a first message from the first network device, the first message being determined according to the interworking manner between the first network and the second network. The communication interface 1601 may also establish a PDU session based on the first information, the PDU session associated with the DNN and the S-NSSAI.

In one possible design, in a case where the interworking manner includes no interworking between the first network and the second network, the communication interface 1601 may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI. Therefore, under the mode that the first network and the second network are not intercommunicated, the UE can establish the PDU session associated to the DNN and the S-NSSAI in the second network, the recovery of the PDU session associated to the DNN and the S-NSSAI is realized, and the switching efficiency is improved.

In one possible design, where the interworking manner includes N3 IWF-based interworking between the first network and the second network, the communication interface 1601 may send a second PDU session request message to the first network device, the second PDU session request requesting establishment of a second PDU session. The communication interface 1601 may also establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication interface 1601 is further configured to send a second registration request message to a second network device through a connection, where the second registration request message is used to request registration in the first network by an N3GPP method, and the second network device belongs to the first network. The communication interface 1601 may further send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with a value of existing PDU session, or the third PDU session request message is used to request to establish an existing PDU session. The third PDU session request message may carry information for the DNN and information for the S-NSSAI. Accordingly, in a mode that the first network and the second network are communicated based on the N3IWF, the UE can establish the information associated to the DNN and the third PDU session of the S-NSSAI through the N3IWF and the second network equipment, thereby realizing the recovery of the PDU session of the UE associated to the DNN and the S-NSSAI and improving the switching efficiency.

In one possible design, in a case that the interworking mode includes roaming-based interworking between the first network and the second network, the communication interface 1601 may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type cell having an existing PDU session value, information of the DNN, and information of the S-NSSAI. Therefore, in a roaming interworking mode between the first network and the second network, the UE can establish the information associated with the DNN and the fourth PDU session of the S-NSSAI through the first network device, thereby recovering the PDU sessions associated with the DNN and the S-NSSAI of the UE and improving the handover efficiency.

In performing the actions shown in fig. 10 to 13, which are performed by the first network device, the communication interface 1601 may receive a first registration request message from a terminal device, which belongs to the second network, for requesting registration to the second network. Processor 1603 may obtain a context of the terminal device and determine, based on the context, that the terminal device is registered with the first network. The communication interface 1601 may also transmit first information to the terminal device according to an interworking manner between the first network and the second network.

In one possible design, the processor 1603 may further determine to perform handover across non-public network for the terminal device according to a handover across non-public network indication included in the first registration request message, where the handover across non-public network indication is used to indicate that the terminal device performs handover across non-public network. Alternatively, the processor 1603 may determine to perform handover across non-public networks of the terminal device according to the identity of the first network, which is included in the context. Alternatively, the processor 1603 may determine to perform handover across non-public networks for the terminal device according to an identifier of the second network device, which is included in the context of the terminal device. The second network device is a network device, such as an AMF, accessed by the terminal device at the time of registration with the first network.

In one possible design, the communication interface 1601 may receive a context of a terminal device from a second network device deployed in the first network. The communication interface 1601 may obtain information of the second network device from the UDM and request a context of the terminal device.

Alternatively, the communication interface 1601 may receive a context of a terminal device from a data storage node, which is shared by the first network and the second network.

In one possible design, the data storage node comprises a UDM or AAA server.

In one possible design, in a case that the interworking mode includes roaming interworking between the first network and the second network, the communication interface 1601 may further receive the fourth PDU session request message from the terminal device. The communication interface 1601 may further send the fourth PDU session request message to the first SMF, where the first SMF is an intermediate SMF, the first SMF is connected to a second SMF, and the second SMF maintains the first PDU session established by the terminal device in the first network and associated with the DNN and the S-NSSAI, and then the fourth PDU session request message may be forwarded by the first SMF to the second SMF, and the path switching may be performed by the second SMF. Or, the first SMF belongs to the first network, and the first SMF maintains the first PDU session established by the terminal device in the first network, associated to the DNN and the S-NSSAI.

In one possible design, the communication interface 1601 may further send a non-public network handover crossing indication to the first SMF, where the non-public network handover crossing indication is used to indicate that the terminal device performs non-public network handover crossing.

In performing the actions performed by the SMF shown in fig. 10-13, processor 1603 may establish a first PDU session associated with DNN and S-NSSAI for the terminal device registered with the first network. The first PDU session is a PDU session between a first access network element and a first UPF, and the first access network element belongs to the first network. The communication interface 1601 may receive a fourth PDU session request message that includes a request type information element having a value of existing PDU session, or may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated to the DNN and the S-NSSAI. The communication interface 1601 may further send, to the first UPF, second information, where the second information is used to instruct the first UPF to send an end flag to the first access network element after the path of the first PDU session is switched, and is used to instruct the first UPF to forward downlink data from the terminal device of the first access network element to the terminal device through the switched path, where the downlink data includes the end flag. The communication interface 1601 may further send third information to the first access network element, where the third information is used to instruct the first access network element to forward the downlink data of the terminal device cached by the first access network element to the first UPF until the end flag is received and forwarded.

In one possible design, the fourth PDU session request message may include a lossless handover indication, or the lossless handover may be determined by processor 1603 to be performed for the terminal device based on local configuration.

In one possible design, communication interface 1601 may also receive a non-public network switch indication.

In one possible design, the fourth PDU request message is from a first network device belonging to a second network, for example, when the communication apparatus is connected to the second network, and the first network device is connected to the communication apparatus. Alternatively, the fourth PDU session request message is sent by the first network device to the intermediate SMF, and forwarded to the communication interface 1601 by the intermediate SMF, for example, at this time, the communication apparatus does not belong to the second network, the first network device and the communication apparatus are not directly connected, and message forwarding needs to be performed through the intermediate SMF.

In performing the actions performed by the terminal device shown in fig. 14c, the communication interface 1601 may establish a first PDU session associated with the DNN and the S-NSSAI at the first network, and the communication interface 1601 may further send a first registration request message to the first network device, the first registration request message requesting registration with the second network. Further, the communication interface 1601 may establish (or request to establish) a PDU session according to the first order, the PDU session being associated with the DNN and the S-NSSAI. The first sequence is used for indicating that the PDU conversation is established according to the third mode, the second mode and the first mode. Alternatively, the processor 1603 establishes (or requests to establish) the PDU sessions sequentially in the third manner, the second manner and the first manner through the communication interface 1601 in the first order until the PDU sessions are established.

In one possible design, when establishing the PDU session according to the first manner, the communication interface 1601 may send a first PDU session request message to the first network device, where the first PDU session request message includes a request type information element with an initial request value, or the first PDU session request message is used to request establishment of an initial PDU session. The first PDU session request message includes information of the DNN and information of the S-NSSAI to request establishment of a PDU session associated with the DNN and the S-NSSAI.

In one possible design, the communication interface 1601 may send a second PDU session request message to the first network device requesting that a second PDU session be established. The communication interface 1601 may establish a connection with an N3IWF through a second PDU session, the N3IWF belonging to the first network. The communication interface 1601 sends a second registration request message to a second network device through the connection, the second registration request message being for requesting registration in the first network by the N3GPP, the second network device belonging to the first network. When the PDU session is established according to the second manner, the communication interface 1601 may send a third PDU session request message to the second network device, where the third PDU session request message includes a request type cell with an existing PDU session value, or the third PDU session request message may be used to request to establish an existing PDU session. The third PDU session request message may include information of the DNN and information of the S-NSSAI.

In one possible design, when the PDU session is established according to the third manner, the communication interface 1601 may send a fourth PDU session request message to the first network device, where the fourth PDU session request message includes a request type information element with an existing PDU session value, or the fourth PDU session request message may be used to request establishment of an existing PDU session. The fourth PDU session request message also includes information of the DNN and information of the S-NSSAI.

In one possible design, the first order is determined according to a local configuration. Alternatively, the communication interface 1601 may receive an indication of a first order from a first network device. Optionally, the indication information of the first order may be determined according to a local configuration of the first network device, or determined by the first network device according to an interworking manner between the first network and the second network. Alternatively, the communication interface 1601 may receive an indication of the first order from a second network device. Optionally, the indication information of the first order may be determined according to a local configuration of the second network device, or determined by the second network device according to an interworking manner between the first network and the second network. The first order can be flexibly determined.

Based on the same concept as the method embodiments, embodiments of the present application further provide a computer-readable storage medium, where a computer program (or instructions) is stored, and when the program is executed by a processor, the computer is enabled to perform the operations performed by the terminal device, the first network device, and/or the SMF in any possible implementation manner of the method embodiments and the method embodiments.

Based on the same concept as the method embodiments, the present application further provides a computer program product, which when being invoked by a computer, can enable the computer to implement the operations performed by the terminal device, the first network device and/or the SMF in any one of the possible implementations of the method embodiments.

Based on the same concept as the method embodiments, the present application further provides a chip or a chip system, where the chip is coupled to a transceiver and is configured to implement the operations performed by the terminal device, the first network device and/or the SMF in any possible implementation manner of the method embodiments and the method embodiments. The chip system may include the chip, as well as components including memory, communication interfaces, and the like.

Based on the same concept as the method embodiment, the present application further provides a communication system, which may be used to implement the operations performed by the terminal device, the first network device, and/or the SMF in any one of the possible implementations of the method embodiment and the method embodiment. Illustratively, the communication system has a structure as shown in any of fig. 6 to 9. The communication system may be used to perform the process shown in any of fig. 10 to 14 c.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

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

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

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

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A communication method is applied to a terminal device and comprises the following steps:

a terminal device registered with a first network establishes a first PDU session associated with a data network name DNN and single network slice selection assistance information S-NSSAI in the first network;

the terminal equipment sends a first message to first network equipment, wherein the first message is used for requesting to register to the second network;

the terminal equipment receives first information from the first network equipment, and the first information is determined according to an intercommunication mode between a first network and the second network;

and the terminal equipment establishes a Protocol Data Unit (PDU) session of the terminal equipment according to the first information, wherein the PDU session is associated with the DNN and the S-NSSAI.

2. The method of claim 1, wherein the first message includes a handover across non-public networks indication, and wherein the handover across non-public networks indication is used to indicate the terminal device to perform handover across non-public networks.

3. The method of claim 1 or 2, wherein the interworking manner comprises:

the first network and the second network do not intercommunicate; alternatively, the first and second electrodes may be,

the first network and the second network are intercommunicated based on a non-third generation partnership project interworking function network element N3 IWF; alternatively, the first and second electrodes may be,

the first network and the second network are based on roaming interworking.

4. The method of any of claims 1-3, wherein the interworking manner includes no interworking between the first network and the second network, and wherein the terminal device establishing the PDU session for the terminal device based on the first information comprises:

and the terminal equipment sends a second message to the first network equipment, wherein the second message is used for requesting to establish an initial PDU session and comprises the information of the DNN and the information of the S-NSSAI.

5. The method of claim 4, wherein the first information is used to indicate no interworking between the first network and the second network; alternatively, the first and second electrodes may be,

the first information is used for instructing the terminal device to send the first PDU session request to the first network device.

6. The method of any of claims 1-3, wherein the interworking manner comprises N3 IWF-based interworking between the first network and the second network, the method further comprising:

the terminal equipment sends a third message to the first network equipment, wherein the third message is used for requesting to establish a second PDU session;

the terminal equipment establishes connection with an N3IWF through the second PDU session, wherein the N3IWF belongs to the first network;

the terminal device sends a fourth message to a second network device through the connection, wherein the fourth message is used for requesting registration in the first network in an N3GPP mode, and the second network device belongs to the first network;

the terminal equipment establishes the PDU session of the terminal equipment according to the first information, and the PDU session comprises the following steps:

and the terminal equipment sends a fifth message to the second network equipment, wherein the fifth message is used for requesting the establishment of the existing PDU session, and the fifth message comprises the information of the DNN and the information of the S-NSSAI.

7. The method of claim 6, wherein the first information is used to indicate N3 IWF-based interworking between the first network and the second network; alternatively, the first and second electrodes may be,

the first information is used for instructing the terminal device to send the third message to the first network device, send the second registration request to the second network device through the N3IWF, and send the fifth message to the second network device.

8. The method of any of claims 1-3, wherein the interworking mode comprises roaming interworking between the first network and the second network, and wherein the terminal device recovers protocol data unit, PDU, sessions associated with the DNN and the S-NSSAI for the terminal device based on the first information, comprising:

and the terminal equipment sends a sixth message to the first network equipment, wherein the sixth message is used for requesting the establishment of the existing PDU session, and the sixth message comprises the information of the DNN and the information of the S-NSSAI.

9. The method of claim 8, wherein the first information is used to indicate roaming-based interworking between the first network and the second network; alternatively, the first and second electrodes may be,

the first information is used for instructing the terminal device to send the sixth message to the first network device.

10. The method of claim 8 or 9, wherein a lossless handover indication is included in the sixth message.

11. A method of communication, comprising:

a first network device receives a first message from a terminal device, wherein the first network device belongs to a second network, and the first message is used for requesting to register to the second network;

the first network equipment acquires the context of the terminal equipment;

the first network equipment determines that the terminal equipment is registered in a first network according to the context;

and the first network equipment sends first information to the terminal equipment according to the intercommunication mode between the first network and the second network.

12. The method of claim 11, further comprising:

the first network equipment determines that the terminal equipment carries out non-public network crossing switching according to a non-public network crossing switching instruction included in the first message, wherein the non-public network crossing switching instruction is used for indicating the terminal equipment to carry out non-public network crossing switching; alternatively, the first and second electrodes may be,

the first network equipment determines that the terminal equipment carries out cross-non-public network switching according to the identifier of the first network, wherein the identifier of the first network is included in the context; alternatively, the first and second electrodes may be,

and the first network equipment determines that the terminal equipment carries out cross-non-public network switching according to the identifier of second network equipment, wherein the identifier of the second network equipment is included in the context, and the second network equipment belongs to the first network.

13. The method of claim 12, wherein the first network device obtaining the context of the terminal comprises:

the first network device receiving a context of the terminal device from a second network device deployed in the first network; alternatively, the first and second electrodes may be,

the first network device receives a context of the terminal device from a data storage node, the data storage node being shared by the first network and the second network.

14. The method of claim 13, wherein the data storage node comprises a UDM or an authentication, authorization, accounting proxy, AAA, server.

15. The method of any of claims 11-14, wherein the interworking manner comprises:

the first network and the second network are communicated based on N3 IWF; alternatively, the first and second electrodes may be,

the first network and the second network are based on roaming interworking.

16. The method of any of claims 11-15, wherein the interworking manner comprises no interworking between the first network and the second network;

the first information is used for indicating that the first network and the second network do not intercommunicate; alternatively, the first and second electrodes may be,

the first information is used for instructing the terminal device to send a second message to the first network device, the second message is used for requesting to establish an initial PDU session, and the second message comprises information of DNN associated with the PDU session established by the terminal device in the first network and information of S-NSSAI associated with the PDU session.

17. The method of any of claims 11-15, wherein the interworking manner comprises N3 IWF-based interworking between the first network and the second network;

the first information is used for indicating the interworking between the first network and the second network based on N3 IWF; alternatively, the first and second electrodes may be,

the first information is used for indicating the terminal equipment to send a third message to the first network equipment, sending a fourth message to the second network equipment through the N3IWF, and sending a fifth message to the second network equipment;

wherein the third message is used for requesting to establish a second PDU session, and the second PDU session is used for establishing a connection between the terminal equipment and the N3 IWF; the fourth message is used for requesting to register in the first network in an N3GPP mode; the fifth message is used for requesting to establish an existing PDU session, and the fifth message includes information of DNN associated with the PDU session established by the terminal device in the first network and information of S-NSSAI associated with the PDU session.

18. The method of any of claims 11-15, wherein the interworking manner comprises roaming-based interworking between the first network and the second network;

the first information is used for indicating that roaming interworking is based between the first network and the second network; alternatively, the first and second electrodes may be,

the first information is used for instructing the terminal device to send a sixth message to the first network device, the sixth message is used for requesting the establishment of an existing PDU session, and the sixth message includes information of DNN associated with the PDU session established by the terminal device in the first network and information of S-NSSAI associated with the PDU session.

19. The method of claim 18, wherein the method further comprises:

the first network device receiving the sixth message;

the first network equipment sends the sixth message to a first Session Management Function (SMF);

the first SMF is an intermediate SMF, the first SMF is connected to a second SMF, the second SMF maintains a first PDU session established by the terminal device in the first network, the first PDU session is associated to the DNN and the S-NSSAI; alternatively, the first and second electrodes may be,

the first SMF belongs to the first network, and maintains a first PDU session established by the terminal device in the first network, the first PDU session being associated with the DNN and the S-NSSAI.

20. The method of claim 19, wherein the method further comprises:

and the first network equipment sends a non-public network crossing switching instruction to the first SMF, wherein the non-public network crossing switching instruction is used for indicating the terminal equipment to carry out non-public network crossing switching.

21. The method of any of claims 18-20, wherein a lossless handover indication is included in the sixth message.

22. A communication method is applied to a terminal device and comprises the following steps:

the terminal equipment registered in a first network establishes a first PDU session associated with DNN and S-NSSAI in the first network;

the terminal equipment establishes a PDU session of the terminal equipment according to a first sequence, wherein the PDU session is associated with the DNN and the S-NSSAI;

and the first sequence is used for indicating the terminal equipment to establish the PDU session of the terminal equipment according to the third mode, the second mode and the first mode.

23. The method of claim 22, wherein the first message includes a handover across non-public networks indication, and wherein the handover across non-public networks indication is used to indicate the terminal device to perform handover across non-public networks.

24. The method of claim 22 or 23, wherein the terminal device establishes the PDU session for the terminal device according to a first manner, comprising:

25. The method of any one of claims 22-24, wherein the method further comprises:

the terminal device sends a fourth message to a second network device through the connection, wherein the fourth message is used for requesting registration in a first network in an N3GPP mode, and the second network device belongs to the first network;

the terminal equipment establishes the PDU session of the terminal equipment according to a second mode, and the method comprises the following steps:

26. The method according to any of claims 22-25, wherein the terminal device establishes the PDU session for the terminal device according to a third approach comprising:

27. The method of claim 26, wherein the sixth message includes a lossless handover indication.

28. The method of claim 22 or 23, wherein the first order is determined according to a local configuration; alternatively, the first and second electrodes may be,

the method further comprises the following steps:

the terminal equipment receives indication information of the first sequence from the first network equipment; alternatively, the first and second electrodes may be,

the terminal device receives the indication information of the first order from the second network device.

29. A communication method is applied to a terminal device and comprises the following steps:

a terminal device registered in a first network establishes a first PDU session associated with DNN and S-NSSAI in the first network;

the terminal equipment receives first information from the first network equipment, the first information is determined according to an interworking mode between a first network and a second network, and roaming interworking is not performed between the first network and the second network;

and the terminal equipment determines to recover the PDU session of the terminal equipment in a mode of supporting N3WIF according to the first information, or determines not to establish the PDU session of the terminal equipment, wherein the PDU session is associated with the DNN and the S-NSSAI.

30. The method of claim 29, wherein the terminal device determining from the first information to resume the PDU session for the terminal device in a manner that supports N3WIF comprises:

31. The method of claim 30, wherein the first information indicates that roaming interworking is not supported between the first network and the second network.

32. A method of communication, comprising:

the first network equipment acquires the identifier of the terminal equipment and determines the identifier of the first network;

and the first network equipment sends first information to the terminal equipment according to whether a roaming intercommunication mode is supported between the first network and the second network.

33. A communication device comprising a processor and a communication interface;

the communication interface is operable to support the communication device for communication;

the processor is operable to execute instructions implementing the method of any of claims 1-10.

34. A communication device comprising a processor and a communication interface;

the processor is operable to execute instructions to implement the method of any of claims 11-20.

35. A communication device comprising a processor and a communication interface;

the processor is operable to execute instructions to implement the method of any of claims 21-28.

36. A communication device comprising a processor and a communication interface;

the processor is operable to execute instructions to implement the method of any of claims 29-31.

37. A communication device comprising a processor and a communication interface;

the processor is operable to execute instructions to implement the method of claim 32.

38. A communication system comprising a communication apparatus according to claims 29 and 30, or comprising a communication apparatus according to claim 31 and a first network device, or comprising a communication apparatus according to claims 36 and 35.

39. A computer-readable storage medium having instructions stored therein, which when invoked for execution on a computer, cause the computer to perform the method of any of claims 1-32.