Data transmission method, communication device, and communication system

Abstract

To provide a data transmission method, a communication device, and a communication system that correctly determine the validity of system information of a non-public network (NPN) stored in a terminal device.SOLUTION: A terminal device receives first system information broadcast by a wireless access network device. The first system information includes an NPN identification information list and first related information, and the NPN identification information list includes at least one piece of NPN identification information. If first NPN identification information in the NPN identification information list is the same as second NPN identification information stored in the terminal device, and the first related information is the same as second related information stored in the terminal device, the terminal device determines that second system information including the second NPN identification information and the second related information is valid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001]

[0002] Technical Field The present application relates to the field of communication technologies, and in particular to a data transmission method, a communication device, and a communication system. [Background technology]

[0002]

[0003] A non-public network (NPN) or private network is a type of network that is part of the 5th generation (5G) standard of the third generation partnership project (3GPP). th It is a network that is being discussed in the 5G (5th generation) mobile communication standard. Unlike traditional cellular networks, NPNs only allow access to some users with certain rights. NPNs are classified into standalone NPNs (SNPNs) and non-standalone NPNs. Non-standalone NPNs are also called public network integrated NPNs (PNI-NPNs). In a standalone NPN, the NPN and the public land mobile network (PLMN) have a standalone radio access network (RAN) and a standalone core network (CN), respectively. The network elements are connected between the core network of the NPN and the core network of the PLMN by using a non-3GPP interworking function (N3IWF). Specifically, the N3IWF may be used to realize networking between the user plane of the standalone NPN and the PLMN, and between the control plane of the standalone NPN and the PLMN.

[0003]

[0004] Due to the movement of a user equipment (UE), there exists a scenario where a terminal device is handed over between networks. For example, the terminal device is initially located in an original network and then moves to a target network. In order to ensure the continuity of a protocol data unit (PDU) session in the target network, after the terminal device is handed over to the target network, it is necessary for the PDU session in the target network to be re-established.

[0004]

[0005] Also, currently, a shared-access network is used in a communication system to set cells of different networks in one access network. A terminal device can access different networks via one shared access network. For example, it can access networks with different public land mobile network (PLMN) identifiers (IDs). However, in a stand-alone non-public network (NPN) scenario and a shared access network scenario, when a terminal device moves from a cell of an original network to a cell of a target network, based on relatively little packet loss or even no packet loss, the way of transferring data of the original network to the target network has become a research trend attracting much attention.

SUMMARY OF THE INVENTION

[0005]

[0006] Embodiments of the present application provide a data transmission method, a communication device, and a communication system, and solve the problem of service discontinuity caused by serious packet loss in the data transfer process between different networks in a shared access network scenario.

[0006]

[0007] According to a first aspect, a data transmission method is provided. The method includes: a step in which a first access network device transmits first indication information and first cause information to a second access network device, where the first indication information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device, the first cause information is used to indicate the reason why the first access network device needs to transfer data, the transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored transmitted by the terminal device and received by the first access network device, one of the first access network device and the second access network device is an access network device shared by a first network and a second network, the first access network device and the second access network device respectively belong to the first network and the second network, core network elements of the first network and the second network are independently deployed, there is a first interface between the first access network device and the second access network device, and the first interface is configured to perform user plane data communication and control plane data communication; a step in which the first access network device receives first information transmitted from the second access network device, where the first information includes transport network layer information set by the second access network device for a data transfer path, and the data transfer path is configured to transmit the transfer data information; and The step in which the first access network device transmits the transfer data information to the second access network device based on the first information is included.

[0007]

[0008] Regarding the first aspect, in some implementations of the first aspect, the step in which the first access network device transmits the first indication information to the second access network device is: The step in which the first access network device receives a first request message transmitted from a first access mobility management function network element AMF, where the first request message is used to inquire whether the first access network device has the transfer data, and the first AMF is the AMF in the first network; and The step in which the first access network device transmits the first indication information to the second access network device based on the first request message is included.

[0008]

[0009] Regarding the first aspect, in some implementations of the first aspect, the step in which the first access network device transmits the first indication information to the second access network device is: The step in which the first access network device receives a second request message transmitted from the second access network device, where the second request message is used to inquire about the context of the terminal device regarding the first access network device; and The step in which the first access network device transmits the first indication information to the second access network device based on the second request message is included.

[0009]

[0010] Regarding the first aspect, in some implementations of the first aspect, the first network is a stand-alone non-public network SNPN, and the second network is a public land mobile network PLMN; Is the first network a PLMN and the second network an SNPN? Is the first network a PNI-NPN and the second network an SNPN? Or The first network is an SNPN and the second network is a PNI-NPN.

[0010]

[0011] Regarding the first aspect, in some implementations of the first aspect, the step in which the first access network device transmits the transfer data information to the second access network device based on the first information is: The step includes the first access network device transmitting the transfer data information to the second access network device via the interface.

[0011]

[0012] Regarding the first aspect, in some implementations of the first aspect, the first request message and the second request message include the following information: At least one of the reason for transmitting the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, the PDU session identifier, the PDU session type, the QoS flow identifier, and the identifier of the terminal device.

[0012]

[0013] Regarding the first aspect, in some implementations of the first aspect, the first indication information includes the following information: At least one of the protocol data unit PDU session identifier, the quality of service QoS flow identifier, the data radio bearer DRB identifier, the mapping list between the DRB and the QoS flow, the data transfer status information in the DRB, and the data transfer cause.

[0013]

[0014] The data transfer reason may include at least one of the following: movement beyond the network of the terminal device, handover beyond the network of the terminal device, cell reselection beyond the network performed by the terminal device, or cell selection beyond the network performed by the terminal device, which should be understood.

[0014]

[0015] Regarding the first aspect, in some implementations of the first aspect, the first indication information is further used to indicate that the transfer data can be transferred by the first access network device to the second access network device via the first interface.

[0015]

[0016] According to a second aspect, a data transmission method is provided. The method includes: a step in which a second access network device receives first instruction information and first cause information transmitted from a first access network device, where the first instruction information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device, and the first cause information is used to indicate a reason why the first access network device needs to transfer data, and the transfer data is data that has been transmitted by the first access network device but not successfully received by a terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device and received by the first access network device, and one of the first access network device and the second access network device is an access network device shared by a first network and a second network, the first access network device and the second access network device belong to the first network and the second network respectively, core network elements of the first network and the second network are independently deployed, a first interface exists between the first access network device and the second access network device, and the first interface is configured to perform user plane data communication and control plane data communication; a step in which the second access network device transmits first information to the first access network device based on the first instruction information, where the first information includes transport network layer information set by the second access network device for a data transfer path, and the data transfer path is used to transmit the transfer data information; and including the step that the second access network device receives the transfer data sent from the first access network device.

[0016]

[0017] Regarding a second aspect, in some implementations of the second aspect, the method includes: the step that the second access network device receives a first message sent by the terminal device, where the first message is used to indicate the location information of the first network where the terminal device was located before the terminal device moved to the second network; and the step that the second access network device sends a second request message to the first access network device based on the first message, where the second request message is used to query the context of the terminal device regarding the first access network device.

[0017]

[0018] Regarding a second aspect, in some implementations of the second aspect, the step that the second access network device sends first information to the first access network device based on the first indication information includes: the step that the second access network device directly sends the first information to the first access network device through the interface.

[0018]

[0019] Regarding a second aspect, in some implementations of the second aspect, the second request message includes at least one of the following information: the reason for sending the first request message, the location information of the terminal device after the terminal device moves, the location information of the terminal device before the terminal device moves, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0019]

[0020] Regarding the second aspect, in some implementations of the second aspect, the first network is an SNPN, and the second network is a PLMN; Is the first network a PLMN and the second network an SNPN? Is the first network a PNI-NPN and the second network an SNPN? Or The first network is an SNPN and the second network is a PNI-NPN.

[0020]

[0021] Regarding the second aspect, in some implementations of the second aspect, the first indication information is the following information: At least one of a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, data transfer status information in the DRB, and a data transfer cause.

[0021]

[0022] It should be understood that the data transfer cause may include at least one of the following: movement of the terminal device across networks, handover of the terminal device across networks, cell reselection of the terminal device across networks, or cell selection of the terminal device across networks.

[0022]

[0023] According to the third aspect, a data transmission method is provided. The method includes: a step in which a first AMF receives a second message transmitted from a terminal device, where the second message includes location information of the first network where the terminal device was located before the terminal device moved and location information of the second network where the terminal device is located after the terminal device moved, and core network elements of the first network and the second network are independently deployed, and the first AMF is an AMF in the first network; and The step in which the first AMF sends a first request message to a first access network device based on the second message, where the first request message is used to inquire whether the first access network device has transfer data, and the transfer data is data that has been sent by the first access network device but not successfully received by the terminal device, out-of-order data that has been sent by the terminal device and received by the first access network device, or data to be restored that has been sent by the terminal device and received by the first access network device, and the first access network device is an access network device in a first network.

[0023]

[0024] Regarding the third aspect, in some implementations of the third aspect, the first network is an SNPN, and the second network is a PLMN; Is the first network a PLMN and the second network an SNPN? Is the first network a PNI-NPN and the second network an SNPN? Or The first network is an SNPN and the second network is a PNI-NPN.

[0024]

[0025] Regarding the third aspect, in some implementations of the third aspect, the first request message includes at least one of the following information: The reason for sending the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0025]

[0026] Regarding the third aspect, in some implementations of the third aspect, the second message includes the following information: The terminal device further includes at least one of the reason for the terminal device to send the second message to the first AMF, the location information of the terminal device after the terminal device moves, the location information of the terminal device before the terminal device moves, the PDU session identifier, the reason for setting the PDU session of the first network, the type of the PDU session of the first network, and the identifier of the terminal device.

[0026]

[0027] Regarding the third aspect, in some implementations of the third aspect, the first indication information is the following information: It includes at least one of the protocol data unit (PDU) session identifier, the quality of service (QoS) flow identifier, the data radio bearer (DRB) identifier, the mapping list between the DRB and the QoS flow, the data transfer status information in the DRB, and the data transfer cause.

[0027]

[0028] It should be understood that the data transfer cause may include at least one of the following: movement of the terminal device across the network, handover of the terminal device across the network, cell reselection across the network performed by the terminal device, or cell selection across the network performed by the terminal device.

[0028]

[0029] According to a fourth aspect, a data transmission method is provided. The method includes: a step in which a first access network device transmits first indication information and first cause information to a second access network device, where the first indication information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device, the first cause information is used to indicate the reason why the first access network device needs to transfer data, the transfer data is data that has been transmitted by the first access network device but not successfully received by a terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored transmitted by the terminal device and received by the first access network device, one of the first access network device and the second access network device is an access network device shared by a first network and a second network, the first access network device and the second access network device belong to the first network and the second network respectively, core network elements of the first network and the second network are independently deployed, a first interface exists between the first access network device and the second access network device, and the first interface is configured to perform user plane data communication; a step in which the first access network device receives first information transmitted from the second access network device, where the first information includes transport network layer information set by the second access network device for a data transfer path, and the data transfer path is configured to transmit the transfer data information; and a step in which the first access network device transmits the transfer data to the second access network device based on the first information.

[0029]

[0030] Regarding the fourth aspect, in some implementations of the fourth aspect, the step in which the first access network device transmits the first indication information to the second access network device is: The step in which the first access network device transmits the first indication information to the first AMF; then, the step in which the first AMF transfers the first indication information to the second access network device via the non-3GPP interworking function N3IWF and the terminal device, where the N3IWF is used for control plane data transmission and user plane data transmission between the first network and the second network, step; or The step in which the first access network device transmits the first indication information to the first AMF; then, the step in which the first AMF transfers the first indication information to the second access network device via the N3IWF, the terminal device, and the second AMF, where the N3IWF is used for control plane data transmission and user plane data transmission between the first network and the second network, and the second AMF is the AMF in the second network, step; is included.

[0030]

[0031] Regarding the fourth aspect, in some implementations of the fourth aspect, the step in which the first access network device transmits the transfer data to the second access network device based on the first information is: The step in which the first access network device transmits the transfer data to the first AMF; then, the step in which the first AMF transfers the transfer data to the second access network device via the N3IWF and the terminal device; or The step in which the first access network device transmits the transfer data to the first AMF; then, the step in which the first AMF transfers the transfer data to the second access network device via the N3IWF, the terminal device, and the second AMF, where the second AMF is the AMF in the second network; is included.

[0031]

[0032] Regarding the fourth aspect, in some implementations of the fourth aspect, the step in which the first access network device transmits the first indication information to the second access network device is: The step in which the first access network device receives a first request message transmitted from the first AMF, where the first request message is used to inquire whether the first access network device has the transfer data; and The step in which the first access network device transmits the first indication information to the second access network device based on the first request message is included.

[0032]

[0033] Regarding the fourth aspect, in some implementations of the fourth aspect, the first network is a stand-alone non-public network SNPN, and the second network is a public land mobile network PLMN; Is the first network a PLMN and the second network an SNPN? Is the first network a PNI-NPN and the second network an SNPN? Or The first network is an SNPN and the second network is a PNI-NPN.

[0033]

[0034] Regarding the fourth aspect, in some implementations of the fourth aspect, the first request message and the second request message are the following information: It includes at least one of the reason for sending the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0034]

[0035] Regarding the fourth aspect, in some implementations of the fourth aspect, the first indication information is the following information: It includes at least one of a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, data transfer status information in the DRB, and a data transfer cause.

[0035]

[0036] It should be understood that the data transfer cause may include at least one of the following: movement of the terminal device across the network, handover of the terminal device across the network, cell reselection across the network performed by the terminal device, or cell selection across the network performed by the terminal device.

[0036]

[0037] Regarding the fourth aspect, in some implementations of the fourth aspect, the first indication information is further used to indicate that the transferred data can be transferred by the first access network device to the second access network device via the first interface.

[0037]

[0038] According to the fifth aspect, a data transmission method is provided. The method includes: a step in which a second access network device receives first instruction information and first cause information transmitted from a first access network device, where the first instruction information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device, the first cause information is used to indicate the reason why the first access network device needs to transfer data, the transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored transmitted by the terminal device and received by the first access network device, one of the first access network device and the second access network device is an access network device shared by a first network and a second network, the first access network device and the second access network device belong to the first network and the second network respectively, core network elements of the first network and the second network are independently deployed, there is a first interface between the first access network device and the second access network device, and the first interface is configured to perform user plane data communication; a step in which the second access network device transmits first information to the first access network device based on the first instruction information, where the first information includes transport network layer information set by the second access network device for a data transfer path, and the data transfer path is used to transmit the transfer data; and The step that the second access network device receives the transfer data sent from the first access network device is included.

[0038]

[0039] Regarding the fifth aspect, in some implementations of the fifth aspect, the step that the second access network device sends the first information to the first access network device based on the first indication information is: The step that the second access network device sends the first information to the terminal device; then, the step that the terminal device transfers the first information to the first access network device via the N3IWF and the first AMF, where the N3IWF is used for control plane data transmission and user plane data transmission between the first network and the second network, and the first AMF is the AMF in the first network; or The step that the second access network device sends the first information to the AMF; then, the step that the second AMF transfers the first information to the first access network device via the terminal device, the N3IWF, and the first AMF, where the N3IWF is used for control plane data transmission and user plane data transmission between the first network and the second network, and the second AMF is the AMF in the second network, includes the step.

[0039]

[0040] Regarding the fifth aspect, in some implementations of the fifth aspect, the first network is an SNPN, and the second network is a PLMN; The first network is a PLMN and the second network is an SNPN; The first network is a PNI-NPN and the second network is an SNPN; or The first network is an SNPN and the second network is a PNI-NPN.

[0040]

[0041] Regarding the fifth aspect, in some implementations of the fifth aspect, the first indication information is the following information: At least one of a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, data transfer status information in the DRB, and a data transfer cause.

[0041]

[0042] It should be understood that the data transfer cause may include at least one of the following: movement of the terminal device beyond the network, handover of the terminal device beyond the network, cell reselection of the terminal device beyond the network, or cell selection of the terminal device beyond the network.

[0042]

[0043] According to the sixth aspect, a data transmission method is provided. The method includes: a step in which the first AMF transmits a first request message to a first access network device, where the first request message is used to inquire whether the first access network device has transfer data to be transmitted to a second access network device, and the transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device and received by the first access network device; one of the first access network device and the second access network device is an access network device shared by a first network and a second network, the first access network device and the second access network device belong to the first network and the second network respectively, core network elements of the first network and the second network are independently deployed, a first interface exists between the first access network device and the second access network device, and the first interface is configured to perform user plane data communication; a step in which the first AFM receives a first indication message transmitted from the first access network device, where the first indication message is used to indicate that the first access network device has the transfer data; a step in which the first AMF transfers first indication information to the second access network device via the N3IWF, the second AMF, and the terminal device; The step in which the first AMF receives the first information sent from the second access network device via the terminal device and the N3IWF, where the first information includes transport network layer information set by the second access network device for a data transfer path, and the data transfer path is used to transmit the transfer data information; and The step in which the first AMF includes sending the first information to the first access network device.

[0043]

[0044] Regarding the sixth aspect, in some implementations of the sixth aspect, the first network is an SNPN, and the second network is a PLMN; Is the first network a PLMN and the second network an SNPN? Is the first network a PNI-NPN and the second network an SNPN? Or The first network is an SNPN and the second network is a PNI-NPN.

[0044]

[0045] Regarding the sixth aspect, in some implementations of the sixth aspect, the first request message includes the following information: At least one of the reason for sending the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0045]

[0046] According to a seventh aspect, a data transmission method is provided. The data transmission method is applicable to a process in which a first access network device transmits transfer data to a second access network device after a terminal device moves from a cell of a first network to a cell of a second network. The first access network device and the second access network device belong to the first network and the second network, respectively. One of the first access network device and the second access network device is an access network device shared by the first network and the second network. Core network elements of the first network and the second network are independently deployed, and a first interface exists between the first access network device and the second access network device. The first interface is configured to perform user plane data communication and / or control plane data communication. The transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device and received by the first access network device.

[0046] After the terminal device autonomously determines to move to the cell of the second access network device, the method requires the terminal device to establish an IPsec tunnel configured to transmit NAS signaling to the N3IWF; the step of the terminal device sending a PDU session establishment request message to the first AMF, where the first AMF is the AMF in the first network; the step of the first AMF sending the PDU session establishment request message to the N3IWF; the step of the N3IWF determining to establish an IPsec tunnel for the PDU session based on the PDU session establishment request message; the step of the N3IWF sending the PDU session establishment request message to the terminal device and instructing the terminal device to establish the IPsec tunnel; the step of the terminal device sending the PDU session establishment request message to the second AMF; the step of the second AMF instructing an element such as the second access network device, the second UPF, or the terminal device to set the corresponding bearer of the PUD session based on the PDU session establishment request message; the step of the second access network device setting the PDU session resource (e.g., DRB resource or SRB resource) of the terminal device; and the step of setting the parameter to notify the terminal device correspondingly, where the terminal device is set using the corresponding PDU session resource (e.g., DRB resource or SRB resource).

[0047]

[0047] It should be understood that the process in which the terminal device sends a PDU session establishment request message to the second AMF, and the second AMF instructs an element such as the second access network device, the second UPF, or the terminal device to set the corresponding bearer resource of the PDU session based on the PDU session establishment request message may be executed before the terminal device is required to establish an IPsec tunnel configured to send NAS signaling to the N3IWF.

[0048]

[0048] It should be understood that the PDU session establishment request message may include information such as a PDU session identifier, a QFI, a DRB identifier, PDU session / QoS flow / DRB resources and the reason for establishing an IPsec tunnel, and the type of the PDU session. Further, when data transfer is performed at the DRB granularity, the PDU session establishment request message may further include information regarding the data to be transferred at the DRB granularity.

[0049]

[0049] For example, when the PDU session establishment request message is transmitted between different network elements, the PDU session establishment request message may be of different message types. For example, the PDU session establishment request message transmitted from the terminal device to the first AMF may be specifically carried by, for example, a PDU session establishment request message / initial UE message / UL information transfer message, etc., and the PDU session establishment request message transmitted from the first AMF to the N3IWF may be a PDU resource setting request / initial UE context setting message, etc., and the PDU session establishment request message transmitted by the N3IWF to the terminal device may be an IKE_creat_child_SA request message, etc., and the PDU session establishment request message transmitted from the terminal device to the second access network device may be specifically a UL information transfer message, etc. It should be understood that all of the foregoing various specific types of messages may be used to establish a PDU session or an IPsec tunnel, and the message may carry information such as a PDU session identifier, a QFI, a DRB identifier, PDU session / QoS flow / DRB resources and the reason for establishing an IPsec tunnel, the type of the PDU session, and information regarding the data to be transferred at the DRB granularity.

[0050] It should be further understood that the process by which the terminal device transmits the PDU session establishment request message to the second AMF may be as follows: After the terminal device transmits the PDU session establishment request message to the second access network device, the second access network device transfers the PDU session establishment request message to the second AMF. The second AMF parses the PDU session establishment request message and transmits the parsed message to the second access network device. The second access network device configures the bearer resources for the corresponding PDU session of the terminal device based on the parsed message.

[0051]

[0051] According to an eighth aspect, a communication system for data transmission is provided. The communication system includes at least one terminal device, a first access network device, a second access network device, and a first AMF. The first access network device is configured to execute a method according to any implementation of the first aspect, the second access network device is configured to execute a method according to any implementation of the second aspect, and the first AMF is configured to execute a method according to any implementation of the third aspect.

[0052]

[0052] According to a ninth aspect, a communication system for data transmission is provided. The communication system includes at least one terminal device, a first access network device, a second access network device, and a first AMF. The first access network device is configured to execute a method according to any implementation of the fourth aspect, the second access network device is configured to execute a method according to any implementation of the fifth aspect, and the first AMF is configured to execute a method according to any implementation of the sixth aspect.

[0053] According to the tenth aspect, an access network device is provided. The access network device includes a module configured to execute a method according to any implementation of the first aspect or the second aspect, or any implementation of the fourth aspect or the fifth aspect.

[0054] According to the eleventh aspect, an AMF device is provided. The AMF device includes a module configured to execute a method according to any implementation of the third aspect or the sixth aspect.

[0055] According to the twelfth aspect, a communication device for data transmission is provided. The communication device includes at least one processor and a communication interface. The communication interface is used by the communication device to exchange information with other communication devices. When program instructions are executed in at least one processor, the communication device can implement the functions of any one of the following devices in the method according to any implementation of the first aspect to the sixth aspect: the first access network device, the second access network device, and the first AMF.

[0056] According to the thirteenth aspect, a computer storage medium is provided. The computer program storage medium includes program instructions. When the program instructions are executed directly or indirectly, the function of the first access mobility management function network element AMF in the method according to any implementation of the first aspect to the sixth aspect is realized.

[0057] According to the data transmission method, according to the data transmission method provided in the embodiments of the present application, when the terminal device autonomously moves between different types of networks, the corresponding data transfer path is designed based on the interface capabilities between different networks, reducing cross-network handover, or even realizing cross-network handover without packet loss, thereby ensuring service continuity.

Brief Description of the Drawings

[0058]

Figure 1

[0058] FIG. 1 is a schematic diagram of a network architecture for providing PLMN services to a terminal device using NPN.

Figure 2

[0059] FIG. 2 is a schematic flowchart for configuring PLMN PDU session resources for a terminal device by using NPN.

Figure 3

[0060] FIG. 3 is a schematic diagram of a network architecture for providing PLMN services to a terminal device by using PLMN.

Figure 4

[0061] FIG. 4 is a schematic diagram of a network architecture for providing NPN services to a terminal device by using PLMN.

Figure 5

[0062] FIG. 5 is a schematic flowchart for providing NPN services to a terminal device by using PLMN.

Figure 6

[0063] FIG. 6 is a schematic diagram of a network architecture for providing NPN services to a terminal device by using NPN.

Figure 7

[0064] FIG. 7 is a schematic diagram of cross-network handover of a terminal device.

Figure 8

[0065] FIG. 8 is a schematic diagram for guaranteeing service continuity by using a data transfer technology during network switching.

Figure 9

[0066] FIG. 9 is a schematic diagram of a shared access network architecture.

Figure 10

[0067] FIG. 10 is a schematic flowchart of a data transmission method according to an embodiment of the present application.

Figure 11

[0068] Figure 11 is a schematic flowchart of the data transmission method according to the embodiment of the present application.

Figure 12

[0069] Figure 12 is a schematic flowchart of another data transmission method according to the embodiment of the present application.

Figure 13

[0070] Figure 13 is a schematic flowchart of another data transmission method according to the embodiment of the present application.

Figure 14

[0071] Figure 14 is a schematic diagram of an application scenario of the data transmission method according to the embodiment of the present application.

Figure 15

[0072] Figure 15 is a schematic diagram of an application scenario of another data transmission method according to the embodiment of the present application.

Figure 16

[0073] Figure 16 is a schematic diagram of an application scenario of the data transmission method according to the embodiment of the present application.

Figure 17

[0074] Figure 17 is a schematic diagram of an application scenario of the data transmission method according to the embodiment of the present application.

Figure 18

[0075] Figure 18 is a schematic structural diagram of an access network device according to the embodiment of the present application.

Figure 19

[0076] Figure 19 is a schematic structural diagram of another access network device according to the embodiment of the present application.

Figure 20

[0077] Figure 20 is a schematic structural diagram of the AMF according to the embodiment of the present application.

Figure 21

[0078] Figure 21 is a schematic structural diagram of a communication device according to the embodiment of the present application.

Embodiments for Carrying Out the Invention

[0059]

[0079] Hereinafter, with reference to the accompanying drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described. Obviously, the described embodiments are part of but not all of the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall be included in the protection scope of the present application.

[0060]

[0080] In the embodiments of the present application, the terminal device (or terminal apparatus) may also be referred to as a user equipment (UE), a mobile station (MS), a mobile terminal, a station (STA), etc. The terminal device can communicate with one or more core networks by using a radio access network (RAN). For example, the terminal device may be a mobile phone (or a so-called "cellular" phone) or a computer having a mobile phone. For example, the terminal device may be a portable, pocket-sized, handheld, computer-integrated, or in-vehicle mobile device, a terminal device in a 5G network, or a terminal device in a future developed PLMN.

[0061]

[0081] In the embodiment of the present application, the first network may be referred to as a source network or an original network, which is a network corresponding to a cell in which the terminal device was located before the terminal device moved. For example, the first network may be a non-public network (NPN). The second network may be referred to as a target network, which is a network corresponding to a cell in which the terminal device is located after the terminal device moved. For example, the second network may be a public land mobile network (PLMN). Furthermore, the movement of the terminal device in this embodiment of the present application may be a handover of the terminal device from a cell of the first network to a cell of the second network, or a reselection of the terminal device from a cell of the first network in which the terminal device was previously located to a cell of the second network.

[0062]

[0082] For ease of understanding, the NPN and PLMN services relevant to the embodiments of the present application are first briefly described in the present application.

[0063]

[0083] NPN is a 3rd Generation Partnership Project (3 rd 5th Generation Partnership Project (3GPP) th NPNs are networks discussed in the 5G (5G) wireless communication standard. Unlike conventional cellular networks, NPNs only allow access to some users with specific rights. NPNs are classified into standalone NPNs and non-standalone NPNs. The embodiments of this application relate only to standalone NPNs.

[0064]

[0084] Figure 1 is a schematic diagram of a stand-alone network.

[0065]

[0085] In a Standalone NPN, the NPN and the PLMN each have a Standalone Radio Access Network and a Standalone Core Network (CN). The Standalone NPN is considered a non-3GPP network. Therefore, the core networks of the NPN and the PLMN may be connected to each other by using a non-3GPP interworking function (N3IWF) network element, and user plane interworking and control plane interworking may be realized by using the N3IWF network element.

[0066]

[0086] Figure 2 is a schematic flowchart for setting up PLMN PDU session resources for a terminal device by using an NPN.

[0067]

[0087] Also, setting up PLMN PDU session resources for a terminal device by using an NPN may be referred to as providing PLMN services to the terminal device by using the NPN. Specifically, this is a process of setting up PLMN PDU session resources for a terminal device within the NPN. The PDU session resource setup process is a process of setting up wireless and wired resources for user plane data transmission. PDU session establishment involves multiple network elements between the user and the data network (DN), such as the access and mobility management function (AMF), the session management function (SMF), and the user plane function (UPF). The PDU session resource setup process is an end-to-end setup process.

[0068]

[0088] Referring to FIG. 2, it can be seen that the process of setting up PLMN PDU session resources for the terminal device by using NPN may include the following.

[0069]

[0089] S101. The terminal device sends a PDU session establishment request message to the PLMN-AMF.

[0070]

[0090] Before sending the PDU session establishment request message to the PLMN-AMF, the terminal device may first establish an Internet Protocol Security (IPsec) security association (SA) tunnel for control signaling transmission using the PLMN-N3IWF. Specifically, the terminal device uses an NPN-3GPP access device (such as a base station) and the PLMN-N3IWF to request setting up the PLMN's PDU session resources, thereby sending non-access stratum (NAS) signaling to the PLMN-AMF. The NAS signaling may carry information such as a PDU session identifier (ID).

[0071]

[0091] S102a is the related setup step of the control plane and the user plane between the PLMN-AMF and the related network elements of the PLMN core network. For the related setup steps of the control plane and the user plane, please refer to the existing procedures. Details are not described in this case.

[0072]

[0092] S102b. The PLMN-AMF sends the PDU session establishment request message to the PLMN-N3IWF.

[0073]

[0093] The PLMN-AMF is capable of sending a PDU session establishment request message to the PLMN-N3IWF, and the message can further include information such as a PDU session ID, service quality (QoS) flow-related information included in the PDU session, and a QoS flow identifier (QFI).

[0074]

[0094] S103. The PLMN-N3IWF determines the number of IPsec SA tunnels to be established.

[0075]

[0095] The PLMN-N3IWF determines the number of IPsec SA tunnels that need to be established for user plane data transmission based on the number of QoS flows of the PDU session that need to be established in step 102. For example, if the PLMN-N3IWF determines to establish an IPsec SA tunnel for user plane data transmission of the PDU session, all QoS flows of the PDU session in step 102 are bound to the IPsec SA tunnel. During the binding, the data is transmitted through the IPsec SA tunnel.

[0076]

[0096] S104a. The PLMN-N3IWF sends an IPsec SA tunnel establishment request to the terminal device.

[0077]

[0097] An IPsec SA tunnel is established between the PLMN-N3IWF and the terminal device. Specifically, the PLMN-N3IWF can send an IPsec SA tunnel establishment request message to the terminal device, and the request message can be used to indicate that the IPsec SA tunnel established by the terminal device may be configured to send any one or more of the following information: (a) PDU session ID, (b) QoS flow identifier, (c) differentiated services code point (DSCP) value. When the PLMN-N3IWF notifies the DSCP value to the terminal device, it should be understood that each IP packet transmitted between the terminal device and the PLMN-N3IWF is subsequently required to carry the corresponding DSCP value. DSCP is used to guarantee the QoS of communication, encoded in the identifier byte of the IP header of the data packet to identify the service type and service priority.

[0078]

[0098] S104b. The terminal device sends an IPsec SA tunnel establishment response to the PLMN-N3IWF.

[0079]

[0099] S105. The PLMN-N3IWF may send a PDU session establishment success notification to the terminal device to indicate that the PDU session has been successfully established.

[0080]

[0100] S106. The PLMN-N3IWF sends a PDU session establishment confirmation message such as an N2 PDU session request ACK to the PLMN-AMF to indicate that the PDU session has been successfully established.

[0081]

[0101] S107 is a related setup step for the control plane and user plane between the PLMN-AMF and the relevant network elements of the PLMN core network. For the setup process of the control plane and user plane, please refer to the existing procedures. Details are not described in this case.

[0082]

[0102] S108. The PLMN-N3IWF performs user plane data transmission with the terminal device.

[0083]

[0103] Specifically, when the terminal device needs to transmit an uplink (UL) PDU session to the PLMN-N3IWF via an IPsec SA tunnel, the UL PDU packet needs to carry QFI information. When the PLMN-N3IWF receives downlink (DL) PDU data from a PLMN core network element, the UPF, the PLMN-N3IWF uses the PDU ID and QFI to determine the IPsec tunnel to be used for transmission to the terminal device and adds the QFI to the DL PDU packet to be transmitted.

[0084]

[0104] With reference to FIG. 3, the process of providing a PLMN service to a terminal device by using a PLMN will be described below.

[0085]

[0105] FIG. 3 is a schematic diagram of a network architecture for setting up PLMN PDU session resources for a terminal device by using a PLMN.

[0086]

[0106] Providing a PLMN service to a terminal device by using a PLMN means that the terminal device is located in the PLMN and PLMN PDU session resources are set for the terminal device. The process of providing an NPN service to a terminal device by using an NPN (i.e., the terminal device is located in the NPN and NPN PDU session resources are set for the terminal device) is similar to the process of providing a PLMN service to a terminal device by using a PLMN, and the details are not described in this case.

[0087]

[0107] The process of providing PLMN services to a terminal device by using a PLMN may be as follows: When the terminal device is located in a cell of the PLMN, the radio resources (such as DRBs) configured for the PLMN PDU session of the terminal device are carried in the access network device of the PLMN (such as the PLMN NG-RAN), and the wired resources (data transmission tunnels of the core network) are carried in the core network device of the PLMN (such as a UPF). In this case, the process of configuring PLMN PDU session resources for the terminal device is the same as the conventional process of establishing the PDU session resources, which will not be described in detail in this case.

[0088]

[0108] Hereinafter, with reference to FIGS. 4 and 5, the manner of providing NPN services to a terminal device by using a PLMN network will be described.

[0089]

[0109] FIG. 4 is a schematic diagram of a network architecture for providing NPN services to a terminal device by using a PLMN network.

[0090]

[0110] FIG. 5 is a schematic flowchart of providing NPN services to a terminal device by using a PLMN.

[0091]

[0111] S201. The terminal device sends a PDU session establishment request message to the NPN-AFM.

[0092]

[0112] Before sending the PDU session establishment request message to the NPN-AMF, the terminal device first establishes an IPsec SA tunnel for control signaling transmission by using the PLMN-N3IWF.

[0093]

[0113] Specifically, the terminal device sends NAS signaling to the NPN-AMF by requesting to configure the PDU session resources of the NPN using a PLMN-3GPP access device (such as a base station) and the NPN-N3IWF. The NAS signaling may carry information such as a PDU ID.

[0094]

[0114] S202a is a related setup step for the control plane and the user plane between the NPN-AMF and the related network elements of the NPN core network. For the related setup steps of the control plane and the user plane, please refer to the existing procedures. Details are not described in this case.

[0095]

[0115] S202b. The NPN-AMF sends a PDU session establishment request message to the NPN-N3IWF.

[0096]

[0116] The PLMN-AMF can send a PDU session establishment request message to the PLMN-N3IWF, and the message can further include information such as a PDU session ID, QoS flow related information included in the PDU session, and a QFI.

[0097]

[0117] S203. The NPN-N3IWF determines the IPsec SA tunnel to be established.

[0098]

[0118] The NPN-N3IWF determines the IPsec SA tunnel that needs to be established for user plane data transmission based on the QoS flows of the PDU session that need to be established in step 202. For example, if the NPN-N3IWF determines to establish an IPsec SA tunnel for user plane data transmission of the PDU session, all QoS flows of the PDU session in step 202 are bound to the IPsec SA tunnel. During the binding, the data is sent through the IPsec SA tunnel.

[0099]

[0119] S204a. The NPN-N3IWF sends an IPsec SA tunnel establishment request to the terminal device.

[0100]

[0120] An IPsec SA tunnel is established between the NPN-N3IWF and the terminal device. Specifically, the NPN-N3IWF can send an IPsec SA tunnel establishment request message to the terminal device, and the request message can be used to indicate that the IPsec SA tunnel established by the terminal device is configured to send data corresponding to any one or more of the following information: (a) PDU session ID, (b) QoS flow identifier, (c) differentiated services code point (DSCP) value. When the NPN-N3IWF notifies the DSCP value to the terminal device, it should be understood that each IP packet transmitted between the terminal device and the NPN-N3IWF is then required to carry the corresponding DSCP value. DSCP is used to guarantee the QoS of communication and is encoded in the identifier byte of the IP header of the data packet to identify the service type and service priority.

[0101]

[0121] S204b. The terminal device sends an IPsec SA tunnel establishment response to the PLMN-N3IWF.

[0102]

[0122] S205. The PLMN-N3IWF may send a PDU session establishment success notification to the terminal device to indicate that the PDU session has been successfully established.

[0103]

[0123] S206. The PLMN-N3IWF sends a PDU session establishment confirmation message (N2 PDU session request ACK) to the NPN-AMF to indicate that the PDU session has been successfully established.

[0104]

[0124] S207 is a configuration step related to the control plane and user plane between the NPN-AMF and network elements related to the NPN core network. For the configuration processes of the control plane and user plane, please refer to the existing procedures. Details are not described in this case.

[0125] S208. The NPN-N3IWF executes user plane data transmission together with the terminal device.

[0105]

[0126] Specifically, when the terminal device needs to transmit the UL PDU session to the NPN-N3IWF via the IPsec SA tunnel, the UL PDU packet needs to carry QFI information. When the NPN-N3IWF receives downlink (DL) PDU data from the NPN core network element, the UPF, the PLMN-N3IWF uses the PDU ID and QFI to determine the IPsec tunnel to be used for transmission to the terminal device and adds the QFI to the DL PDU packet to be transmitted.

[0106]

[0127] FIG. 6 is a schematic diagram of a network architecture that provides NPN services to a terminal device by using NPN.

[0107]

[0128] Providing NPN services to the terminal device by using NPN means that the terminal device is located in the NPN and NPN PDU session resources are configured for the terminal device.

[0108]

[0129] Specifically, the process of configuring NPN PDU session resources is a process of configuring radio and wired resources for user plane data transmission. PDU session establishment involves multiple network elements between the terminal and the DN and is an end-to-end configuration process. The process of providing NPN services for the terminal device by using NPN may include the following: When the terminal device is located in an NPN cell, the radio resources (such as DRB) configured for the NPN PDU session of the terminal device are carried in the NPN access network device, and the wired resources (data transmission tunnels of the core network) are carried in the NPN core network device (such as UPF). In this case, the process of configuring NPN PDU session resources for the terminal device is the same as the conventional process of configuring PDU session resources. Details are not described in this case.

[0109]

[0130] Embodiments of the present application are related to the process of the terminal device moving from the original network to the target network. In other words, it should be understood that the present application is related to the cross-network handover of the terminal device. Hereinafter, the cross-network handover process of the terminal device will be described with reference to the drawings.

[0110]

[0131] FIG. 7 is a schematic diagram of the cross-network handover of the terminal device. The drawings are also applicable to the cross-network movement of the terminal device, the cross-network handover of the terminal device, the cross-network cell reselection of the terminal device, or the cross-network cell selection of the terminal device. It should be understood that "handover" in the specification may be replaced by "movement", "cell reselection", or "cell selection". The following content is included.

[0111]

[0132] S301. The terminal device autonomously triggers a handover from NPN to PLMN.

[0112]

[0133] Before the terminal device is handed over, it should be understood that first, the PLMN PDU session resource and / or the NPN PDU session resource are set in the NPN. For the specific process of the terminal device setting the PLMN PDU session resource and / or the NPN PDU session resource in the NPN, please refer to the corresponding description above.

[0113]

[0134] S302. By using the PLMN, reset the PLMN PDU session resource and / or the NPN PDU session resource again.

[0114]

[0135] After the terminal device is handed over to the target network, i.e., the PLMN, the PLMN PDU session resource and / or the NPN PDU session resource can be reset again by using the PLMN.

[0115]

[0136] Hereinafter, with reference to the accompanying drawings, the service continuity during network switching will be described.

[0116]

[0137] FIG. 8 is a schematic diagram for guaranteeing service continuity by using a data transfer technique during network switching. The schematic diagram on the left side of FIG. 8 shows a network architecture based on the NG interface, and the schematic diagram on the right side of FIG. 8 shows a network architecture based on the Xn interface.

[0117]

[0138] As shown in the left figure of FIG. 8, in a network switching scenario, when a terminal device is handed over from an original base station (or source base station S-RAN) to a target base station (or target RAN, T-RAN), the source base station notifies the target base station of the PDU session resources that need to be set for the terminal device by using the AMF, and guarantees the continuity of the PDU session when the terminal device is handed over. The notification message sent from the source base station to the target base station can carry information such as PDU ID, QoS flow ID, DRB ID, and QoS flow mapping table. After the target base station sets the corresponding PDU session resources for the terminal device based on the notification message from the source base station, the network side may instruct the terminal device to execute the handover.

[0118]

[0139] In the handover process, in order to guarantee service continuity, data that has been sent to the source base station but not sent from the source base station to the terminal device or the core network may be sent from the source base station to the target base station via the data transfer path by using the data transfer method; then, the target base station sends the data to the target device or the core network.

[0119]

[0140] Specifically, the data transfer path may be at the PDU session granularity or the DRB session granularity. When the data transfer path is at the DRB session granularity, the source base station can notify the target base station of the transmission status of the data in the corresponding DRB by using the AMF. For example, the uplink / downlink RAN status transfer is used to carry the uplink packet data convergence protocol (PDCP) sequence number (SN) and hyper frame number (HFN) receiver status information, and the downlink PDCP SN and HFN transmitter status information. The status information may include the UL / DL count value of information elements such as the UL / DL PDCP SN or the HFN of the PDCP SN; and the receive status of the UL PDCP service data units. The information regarding the receive status of the UL PDCP service data units can reflect whether the receiver has successfully received a specific UL PDCP SDU. For example, 0 indicates that the corresponding PDCP has not been received normally, and 1 indicates that the corresponding PDCP has been received normally.

[0120]

[0141] Similarly, the handover process of the network structure based on the Xn interface shown on the right side of FIG. 8 may include the following: When the terminal device is handed over from the source base station to the target base station, the source base station notifies the target base station of the PDU session resources that need to be set for the terminal device by using the Xn interface. The notification message sent from the source base station to the target base station further carries the PDU ID, QoS flow ID, DRB, and the mapping list between QoS flows, and can guarantee the continuity of the PDU session when the terminal device is handed over. After the target base station sets the corresponding PDU session resources for the terminal device, the network side instructs the terminal device to execute the handover.

[0121]

[0142] In the handover process, in order to guarantee service continuity, data that has been sent to the source access network device but has not been sent from the source access network device to the terminal device or the core network can be sent from the source access network device to the target access network device via the data transfer path by using the data transfer method; then, the target access network device sends the data to the terminal device or the core network. The data transfer path may be such that the source access network device directly sends the data that needs to be transferred to the target access network device via the Xn interface between the source access network device and the target access network device. In this case, the source access network device and the target access network device can each assign a port address to the data transfer path.

[0122]

[0143] When the terminal device is to be handed over within the network, it can be understood that the network side determines whether the terminal device should be handed over and when the handover should occur. The target network sets up PDU session resources for the terminal device before the target device is handed over to ensure the continuity of the PDU session within the target network. However, in actual applications, there can be scenarios where the terminal device is handed over across networks, for example, from a private network to a public network or from a public network to a private network. In this case, the terminal device itself determines whether to perform the handover and when to perform the handover, or the terminal device itself determines whether to perform cross-network cell reselection or cross-network cell selection and when to perform cross-network cell reselection or cross-network cell selection, and the network side does not know whether the terminal device will perform a handover, cross-network cell reselection, or cross-network cell selection, and when the handover, cross-network cell reselection, or cross-network cell selection will be performed. Therefore, the target network cannot pre-configure PDU session resources for the terminal device before the terminal device is handed over, and cannot guarantee the continuity of the PDU session after the terminal device has moved.

[0123]

[0144] To solve the above problems, embodiments of the present application provide a data transmission method. The data transfer path is designed according to whether the interface between the source base station and the target base station can transmit control plane data. As a result, the data that needs to be transferred in the source network is transferred to the target network based on the interface between the source base station and the target base station, thereby guaranteeing the continuity of the service.

[0124]

[0145] Further, it should be understood that the data transmission method provided in this embodiment of the present application may be applicable to a network architecture including a shared access network device. Specifically, the application scenario of the data transmission method provided in this embodiment of the present application may be as follows: After moving from a source network to a target network, the target device transmits, via a data transfer path, data that needs to be transferred by a source access network device to a target access network device. The source access network device may be an access network device in the source network, the target access network device may be an access network device in the target network, and any one of the source access network device and the target access network device may be a shared access network device. The shared access network device means that cells of different networks may be set for one access network device, and the terminal device can access different networks by using one shared access network device. In the embodiment of the present application, the shared access network device may be an access network device shared by a cell of a first network and a cell of a second network.

[0125]

[0146] To facilitate the understanding of the shared access network architecture, the shared access network architecture is described using an example related to FIG. 9. As shown in FIG. 9, in a scenario where access network devices are shared, the access network devices within the NPN may be shared access network devices and are configured together with the cells of the PLMN and NPN. Different from the case of FIG. 1 where the PLMN PDU session resources are carried in the terminal device, NPN access network device, NPN-UPF, DN, PLMN-N3IWF, PLMN-UPF, or DN, the PLMN session resources of the terminal device may be directly configured by the terminal device, shared access network device, PLMN UPF, and data network DN. Also, when the access network device in one of the two networks is a shared access network device, there may be an Xn interface between the shared access network device and the access network devices in other networks. The Xn interface can perform user plane data transmission and control plane data transmission, or can perform only user plane data transmission.

[0126]

[0147] For various data transmission capabilities supported by interfaces between access network devices in various networks, various data transfer methods are provided in the following embodiments of the present application. The first method is applicable to a scenario where the interface between a first access network device and a second access network device can only perform user plane data transmission and cannot perform control plane data transmission (this method is also applicable to a scenario where the interface between the first access network device and the second access network device can perform both user plane data transmission and control plane data transmission): After moving to the second network, the terminal device sends NAS information to the first AMF (for example, notifies the AMF of the location information of the terminal device before the terminal device moves and the location information of the terminal device after the terminal device moves), as a result, the AMF notifies that information (for example, location information) to the first access network device, and the first access network device uses the first AMF, the terminal device, etc. to send related information to the second access network device based on that information (for example, the location information of the terminal device).

[0127] The second method is applicable to a scenario where the interface between the first access network device and the second access network device can perform both user plane data transmission and control plane data transmission: After moving to the second network, the terminal device transmits RRC information to the second access network device (for example, the terminal device notifies the second access network device of the location information of the terminal device before the terminal device moves and the location information of the terminal device after the terminal device moves; or the terminal device may first transmit the information to the second AMF by using NAS information, and then the second AMF notifies the second access network device of the information). The second access network device transmits the relevant information to the first access network device based on the information (for example, the location information of the terminal device).

[0128] It is to be understood that it is necessary to determine a specific scenario before the terminal device transmits NAS information to the first AMF, or transmits RRC information to the second access network device, or transmits a NAS message to the second AMF, that is, it is necessary to determine whether the interface can perform both user plane data communication and control plane data communication, or whether the interface can only perform user plane data communication and cannot perform control plane data communication.

[0129] The specific determination method may be as follows: The terminal device can first send a radio resource control (RRC) message to the second access network device (or the terminal device may first send NAS information to the second AMF, and then the second AMF notifies the second access network device of the NAS information). If the feedback message of the second access network device indicates that the interface between the second access network device and the first access network device cannot perform control plane data transmission, the terminal device sends NAS signaling to the first AMF. Specifically, taking the transmission of the RRC message as an example. When the terminal device sends an RRC message to the second access network device, the second access network device can send a notification message to the terminal device, notifying the terminal device that the interface between the second access network device and the first access network device cannot perform control plane data transmission. For example, indication information (indicator) is carried to indicate that the interface between the second access network device and the first access network device cannot perform control plane data transmission and / or user plane data transmission. Also, the notification message may carry a cause value indicating the reason why control plane data transmission cannot be performed, and the cause value may be that the interface is not constructed, the constructed interface has only some functions, etc.

[0130] Furthermore, the second access network device can first notify the terminal device whether the interface between the second access network device and the first access network device, another access network device, or an access network device having an interface connected to the second access network device can perform control plane data transmission and / or user plane data transmission by broadcasting MAC CE signaling or another RRC message (e.g., by broadcasting system information). For example, the second access network device broadcasts capability information by using system information to notify the terminal device of the above information and scenarios. It should also be understood that the standard can also specify the method that the terminal device first uses by default to send a message. For example, the standard may specify that after a handover, the terminal device may use the first method by default to send a message.

[0131]

[0148] When the UE obtains the MIB, SIB1, or other system information messages in a cell, if the UE needs to store the obtained SIB, the UE needs to store the area scope related to the system information, which is the area scope indicated by the si-SchedulingInfo of SIB1, the system information area identifier, the value tag, the first PLMN ID in the PLMN identification information list of SIB1, and the cell identity. The stored information is used to verify whether the stored system information is valid. The UE can use a valid stored version of system information other than MIB, SIB1, SIB6, SIB7, or SIB8. For example, after cell reselection or after receiving a system information change instruction, it can return from out of coverage.

[0132]

[0149] In order for the UE to be able to reuse the stored system information, SIBs (other than SIB1, SIB6, SIB7, and SIB8) in NR are associated with association information. The association information includes one or more of an area scope, a system information area identifier, a value tag, the first PLMN ID in the PLMN identification information list of SIB1, and a cell identity. If the stored SIB is obtained within 3 hours and the stored corresponding association information matches the association information (a value tag) provided for the SIB in the SIB1 of the new cell, the stored SIB is considered valid. The SIB may also be associated with a zone marker (e.g., an area scope), and one SIB is allowed to be reused in multiple cells.

[0133]

[0150] As described above, when determining whether the system information stored locally in the terminal device is still valid, the terminal device compares whether the system information stored locally is consistent with the system information broadcast by the cell. When comparing, the network identified by the first PLMN ID broadcast by the cell is used as the primary PLMN. In the case of an access network device shared by the RAN, in the system information (e.g., SIB1 system information) broadcast by the cell of the access network device, the network identification information of the NPN (e.g., PLMN ID, network identifier (NID), closed access group (CAG), cell identification) and the network identification information of the PLMN (e.g., PLMN ID, cell identification) may be included in the same list entry (e.g., PLMN identification information list (PLMN-IdentityInfoList)), or the network identification information of the NPN and the network identification information of the PLMN may be included in two different list entries. When the network identification information of the NPN and the network identification information of the PLMN are included in two different list entries, if the network identified by the first PLMN ID of the second list entry is the primary PLMN, the terminal device may erroneously analyze that the network identified by the first PLMN ID in the first list entry is the primary PLMN. Therefore, an error occurs when the validity of the stored system information is determined. Thus, the following solutions are provided:

[0151] Solution 1: In order to identify whether the network identified by the corresponding PLMN ID is the primary PLMN, indication information is added to the first PLMN ID in each of the two list entries.

[0134]

[0152] Solution 2: In order to indicate whether the network identified by the corresponding PLMN ID is the primary PLMN, the indication information is added only to the first PLMN ID of the first list entry or the first PLMN ID of the second list entry. For example, if it is indicated only in the indication information of the first PLMN ID in the second list entry that the network identified by the corresponding PLMN ID is not the primary PLMN, and not in the indication information of the first PLMN ID of the first list entry, it means that the network identified by the first PLMN ID of the first list entry is the primary PLMN; If it is indicated only in the indication information of the first PLMN ID in the second list entry that the network identified by the corresponding PLMN ID is the primary PLMN, and not in the indication information of the first PLMN ID of the first list entry, it means that the network identified by the first PLMN ID of the second list entry is the primary PLMN; If it is indicated only in the indication information of the first PLMN ID in the first list entry that the network identified by the corresponding PLMN ID is not the primary PLMN, and not in the indication information of the first PLMN ID of the second list entry, it means that the network identified by the first PLMN ID of the second list entry is the primary PLMN; or If it is indicated only in the indication information of the first PLMN ID in the first list entry that the network identified by the corresponding PLMN ID is the primary PLMN, and not in the indication information of the first PLMN ID of the second list entry, it means that the network identified by the first PLMN ID of the first list entry is the primary PLMN.

[0135]

[0153] Solution 3: In order to indicate that the network identified by the PLMN ID is the primary PLMN, indication information is added to the set primary PLMN ID (for example, the non-first PLMN ID in the first list entry or the non-first PLMN ID in the second list entry).

[0136]

[0154] Solution 4: In order to indicate whether the network identified by the first PLMN ID of the first list entry or the network identified by the first PLMN ID of the second list entry is the primary PLMN, indication information is added at a location other than the locations in Solutions 1, 2, and 3, and within the system information (for example, SIB1), at a location (for example, at a location within the PLMN-IDInforList or PLMN-ID List information element of SIB1 other than the locations in Solutions 1, 2, and 3).

[0137]

[0155] The indication information may also be used to indicate whether the corresponding PLMN ID should be used as a type of related information for verifying the validity of the SIB, or whether network identification information such as the NID and / or CAG ID corresponding to the corresponding PLMN ID should be used as a type of related information for verifying the validity of the SIB.

[0138]

[0156] If the NPN network identification information and the PLMN network identification information are included in the same list entry, the NPN network identification information and the PLMN identification information are listed in different sequences. For example, in the SIB1 information of the cell, the network identification information of all PLMNs supported by the cell is listed first, and then the network identification information of all NPNs supported by the cell is listed; or the network identification information of all NPNs supported by the cell is listed first, and then the network identification information of all PLMNs supported by the cell is listed. Similarly, if the network identified by the PLMN ID corresponding to the first NPN is the primary PLMN, the terminal device may misinterpret that the network identified by the PLMN ID corresponding to the first PLMN is the primary PLMN, resulting in a determination error. Therefore, the following solution is provided: In order to indicate that the network identified by the PLMN ID is the primary PLMN, indication information is provided to the PLMN ID corresponding to the primary PLMN.

[0139]

[0157] Alternatively, the operating specifications of the terminal device in different versions are redefined. For example, in the R16 standard, it is stipulated that the cellReservedForOtherUse information element of SIB1 is set to true, and when the network identification information list (PLMN-IDInforList) used to indicate the SIB1 of the cell is used for NPN (for example, SNPN), the terminal device in R15 should consider that the cell is prohibited, and the terminal device no longer compares the PLMN ID corresponding to the stored SIB with the PLMN ID broadcast by the cell, and regards the stored SIB as invalid in that cell.

[0140]

[0158] In another example, when the SIB1 of a cell that supports only SNPN contains only one network identification information list, the first PLMN ID of the SIB1 may be a special PLMN identifier used for SNPN (for example, MCC = 999), or the same PLMN ID as that of the public network, which is Case 1; or when the SIB1 of a cell that supports only SNPN contains two or more network identification information lists, the first PLMN ID of the first network identification information list may be set to a dummy value, which is Case 2. The first PLMN ID of the SIB1 is not unique in either case. Therefore, there is a risk that the terminal device may erroneously determine that the stored SIB is valid. To solve this problem, the terminal device needs to use the first network identification information (for example, PLMN ID, NID, and / or CAG ID) instead of the first PLMN identifier when verifying the SIB. As another example, in the case of Case 1, for terminal devices after Release 16, it is stipulated that they use the first network identification information (for example, PLMN ID, NID, and / or CAG ID) instead of the first PLMN identifier to verify the validity of the SIB. As another example, in the case of Case 2, for terminal devices before Release 15, it is stipulated that they invalidate the SIB stored in the current cell, and for terminal devices after Release 16, they compare identification information such as the first PLMN ID and / or NID and / or CAG ID in the second network identification information list.

[0141]

[0159] As another example, the terminal stores a PLMN ID (the PLMN ID is a network identifier of a public network or a network identifier of an NPN). The first PLMN ID in the SIB1 of the verified cell is the network ID of the NPN (i.e., the NID and / or CAG ID are also provided together with the first PLMN ID in the SIB1). The PLMN ID stored in the terminal device is the same as the first PLMN ID in the SIB1 of the cell to be verified. When the PLMN ID stored in the terminal device is a network identifier of a public network and after receiving the SIB1 information of the cell to be verified, the terminal device only compares the PLMN ID and does not compare the NID and / or CAG ID corresponding to the PLMN ID. Therefore, the terminal device may erroneously determine that the stored SIB is valid in the cell to be verified. Alternatively, if the PLMN ID stored in the terminal device is a network identifier of an NPN but the terminal device does not store the NID and / or CAG ID corresponding to the PLMN ID, after receiving the SIB1 information of the cell to be verified, the terminal device compares the PLMN ID with the NID and / or CAG ID corresponding to the PLMN ID, and the terminal device may erroneously determine that the stored SIB is invalid in the cell to be verified. Therefore, the following regulations need to be set for the terminal device: Regulation 1: If information such as the NID and / or CAG ID corresponding to the PLMN ID is stored, when verifying the validity of the SIB, it is necessary to verify information such as the NID and / or CAG ID corresponding to the PLMN ID; Regulation 2: Only the PLMN ID is verified (for example, only the PLMN ID is stored), and in order to facilitate verification, indication information of the aforementioned solution is required; Regulation 3: The terminal device compares more than one stored PLMN ID with more than one PLMN ID in the SIB1 of the cell to be verified (for example, the first two or more PLMN IDs in the stored SIB1); Rule 4: The terminal device compares the identification information of the first network instead of the first PLMN ID; or Rule 5: If the PLMN ID in the first network identification information list in the SIB1 of the cell to be verified is a dummy, the terminal device compares the first PLMN ID or the network identification information in the second network identification information list.

[0142]

[0160] It should be understood that providing indication information by the PLMN ID may mean that the PLMN ID itself has an indication function, or that while another indication information element is provided, the PLMN ID is provided for the SIB1.

[0143]

[0161] First, a scenario where the interface between different access network devices can support both user plane data transmission and control plane data transmission is described. For ease of understanding, the data transmission method provided in the embodiments of the present application is described by using NPN and PLMN as examples.

[0144]

[0162] FIG. 10 is a schematic flowchart of a data transmission method according to an embodiment of the present application. The method includes the following steps:

[0163] S401. The first access network device sends the first instruction information and the first cause information to the second access network device. The first instruction information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data. The first access network device and the second access network device belong to the first network and the second network respectively. The core network elements of the first network and the second network are independently deployed. There is a first interface between the first access network device and the second access network device. The first interface is configured to perform user plane data communication and control plane data communication.

[0145]

[0164] S402. The first access network device receives the first information sent from the second access network device. The first information includes the transport network layer information set by the second access network device for the data transfer path. The data transfer path is configured to transmit transfer data information.

[0146]

[0165] S403. The first access network device sends the transfer data to the second access network device based on the first information.

[0147]

[0166] Hereinafter, the data transmission method provided in the embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0148]

[0167] FIG. 11 is a schematic flowchart of the data transmission method according to the embodiment of the present application.

[0149]

[0168] Specific application scenarios of the data transmission method provided in this embodiment may be, for example, as follows: The terminal device sets up NPN PDU session resources in an NPN cell having an NPN shared access network device (shared-RAN). Then, the terminal device moves to the PLMN and accesses the PLMN access network device. In this case, there is an Xn interface between the shared access network device and the PLMN access network device, and the Xn interface can be used for user plane transmission and can also be used for control plane signaling transmission. In this scenario, the process in which the access network device of the network where the terminal device was located before the terminal device moved sends the data to be transferred to the access network device of the network where the terminal device is located after the terminal device moved includes the following content.

[0150]

[0169] S501. The terminal device requests the first AMF to establish a PDU session.

[0151]

[0170] The first AMF is the AMF in the first network, and the first network is the network corresponding to the cell where the terminal device was located before the terminal device moved. For example, the first network may be an NPN.

[0152]

[0171] It should be understood that the terminal device may be located in the first network before it moves, access the cell of the first network, and set up the PDU session resources of the first network. When the terminal device autonomously decides to move to the cell of the second network, the terminal device needs to re - establish the PDU session using the first network in order to execute the subsequent data transfer process. Specifically, the terminal device first establishes an IPsec path to the N3IWF to transmit NAS signaling, and then requests the AMF (shown as the first AMF) in the first network to establish the PDU session. It should be understood that the "movement" in this application may be replaced by "handover", "cell reselection", "cell selection", etc.

[0153]

[0172] In implementation, after an IPsec path is established between the terminal device and the N3IWF, the terminal device can send NAS signaling (e.g., PDU session establishment request message / initial UE message) to the first AMF to request the establishment of a PDU session in the first network. When requesting the first AMF to establish a PDU session in the first network, the terminal device can further add to the PDU session establishment request message sent by the first AMF information such as the reason for establishing the PDU session, the type of the PDU session, information about the newly re-accessed cell, and information about the cell of the first network where the terminal device was located before the terminal device re-selected the second network. For example, the reason for establishing the PDU session may be any of the following: cross-network handover of the terminal device, cross-network cell reselection, or cross-network cell selection (e.g., reselection from a cell of an SNPN to a cell of a PLMN or PNI-NPN, i.e., SNPNtoPLMN or SNPN-NPN). The type of the PDU session may be an NPN PDU session. The information about the newly re-accessed cell may be any of the following: the network identifier, cell identifier, access network device identifier, and tracing area code (TAC) of the network where the terminal device is located after the terminal device has moved, e.g., PLMN ID + cell ID + RAN Node ID + TAC. The location information of the terminal device in the first network before the terminal device moves may be any of the following: the first network identifier, cell identifier, tracing area code, access network device identifier, closed access group ID (CAG ID), e.g., PLMN ID+NID + cell ID + TAC + RAN code ID or PLMN ID+CAG ID + cell ID + TAC + RAN code ID.The identifier of the terminal device may be, for example, an international mobile subscriber identification number (IMSI), such as 5G-S-IMSI.

[0154]

[0173] It should be understood that the specific information listed above carried in the PDU session establishment request message sent from the terminal device to the first AMF is merely an example. The PDU session establishment request message may further include a plurality of other types of information. This is not limited in this embodiment of the present application.

[0155]

[0174] S502. The first AMF sends the first request message to the first access network device.

[0156]

[0175] The first AMF acquires the location information of the first access network device based on the location information of the first network carried in the PDU session establishment request message sent from the terminal device, and based on the location information, sends the first request message to the first access network device.

[0157]

[0176] In an implementation, the first request message is used to inquire of the first access network device whether the data of the corresponding terminal device needs to be transferred (i.e., to transfer data) in the first access network device.

[0158]

[0177] It should be understood that the transfer data in this embodiment of the present application may be data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device, received by the first access network device, and further transmitted to the core network.

[0159]

[0178] In an implementation, the first request message may be, for example, a data transfer request or a handover request.

[0160]

[0179] In an implementation, in step S501, the first request message may be the location information of the terminal device after the terminal device has moved, including the location information transmitted from the terminal device to the first AMF. Further, the first request message may further include information such as the reason for sending the first request message, the location information of the terminal device before the terminal device moves, the identifier of the PDU session requested to be established by the terminal device, the PDU session type, the QoS flow identifier, and the identifier of the terminal device.

[0161]

[0180] S503. The first access network device transmits the first indication information and the first cause information to the second access network device.

[0162]

[0181] The second access network device is an access network device in the second network. The second network is a network corresponding to the cell where the terminal device is located after the terminal device has moved, and the second network and the first network may be different types of networks; for example, when the first network is a non-public network SNPN, the second network may be a public land mobile network PLMN; when the first network is a PLMN, the second network may be an SNPN; when the first network is a PNI-NPN, the second network may be an SNPN; or when the first network is an SNPN, the second network may be a PNI-NPN.

[0163]

[0182] The core networks of the first network and the second network are independently deployed, and one of the first access network device of the first network and the second access network device of the second network is a shared access network device, that is, there is a first interface between the first access network device and the second access network device. The first interface may be configured to perform user plane data communication and control plane data communication, and the first interface may be, for example, an Xn interface.

[0164]

[0183] In implementation, the first access network device may send first indication information and first cause information to the second access network device based on the location information of the newly accessed cell of the terminal device, which is the location information received in step S502. The first indication information is used to indicate that the first access network device has transfer data to be transferred to the second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data.

[0165]

[0184] Since the first interface between the first access network device and the second access network device can be used for user plane data communication and control plane data communication, it should be understood that the first access network device may directly send the first indication information and the first cause information to the second access network device via the first interface.

[0166]

[0185] In an implementation, the first indication information may be used to indicate whether the first access network device needs to transfer data (where the indication information may be, for example, a string such as required, not required, possible, or impossible). When the first access network device indicates that data transfer is not required, the reason for not performing the data transfer may also be described. For example, the reason may be as follows: completed. This means that the data scheduled for transfer has been transferred; released. This means that the data scheduled for transfer has been released and thus cannot be transferred.

[0167]

[0186] In an implementation, the first indication information may include at least one of the following information: protocol data unit PDU session identifier, quality of service QoS flow identifier, data radio bearer DRB identifier, mapping list between DRB and QoS flow, transmission status information of data within DRB, and data transfer cause.

[0168]

[0187] In an implementation, the first indication information may further carry indication information (for example, 0, 1, a direct transfer path is available, or a direct transfer path is not available) to indicate whether the data to be transferred by the first access network device can be directly transferred to the second access network device via the first interface.

[0169]

[0188] S504. The second access network device transmits the first information to the first access network device.

[0170]

[0189] The first information includes transport network layer information set by the second access network device for the data transfer path, and the data transfer path is configured to transmit transfer data.

[0171]

[0190] After receiving the first instruction information transmitted by the first access network device, the second access network device should be understood to determine, based on the first instruction information, that the first access network device has transfer data to be transferred to the second access network device. The second access network device sets the transport network layer information of the data transfer path configured to transfer the transfer data.

[0172]

[0191] In an implementation, the transport network layer information of the uplink or downlink data transfer path, which is set by the second access network device, may include, for example, a transport layer address (e.g., an IP address) and a General Packet Radio Service Tunneling Protocol (GTP) tunnel endpoint identifier (GTP-TEID).

[0173]

[0192] S505. Establish an IPsec tunnel for the PDU session of the terminal device in the first network.

[0174]

[0193] Since the terminal device requests the first AMF to establish a PDU session in S501, it should be understood that each network element sets corresponding resources for the PDU session of the terminal device in the first network, and the terminal device should be able to access the data of the first network by using the second network. The resource may be, for example, an IPsec tunnel.

[0175]

[0194] In an implementation, the first AMF may send a PDU session establishment request message to the N3IWF. The PDU session establishment request message may be, for example, a PDU resource setting message or an initial UE context setting message. The PDU session establishment request message may carry information such as an identifier of the PDU session requested to be established, a DRB ID, a QFI, a reason for establishing the PDU session, a type of the PDU session, and an identifier of the terminal device. For example, the reason for establishing the PDU session may include, for example, cross-network handover of the terminal device, cross-network cell reselection of the terminal device, and cross-network cell selection of the terminal device (for example, reselection from a cell of an SNPN to a PLMN or a PNI-NPN, that is, SNPNtoPLMN or SNPN). The type of the PDU session may be, for example, NPN, PLMN, SNPN, PNI-NPN, or NPNto5GS. The identifier of the terminal device may be, for example, an IP address of the terminal device.

[0176]

[0195] In an implementation, the N3IWF determines to establish a corresponding IPsec tunnel for the PDU session based on the PDU session establishment request message sent by the first AMF.

[0177]

[0196] In implementation, the terminal device, the second access network device, the second AMF, the second UPF, and the N3IWF may set corresponding resources of the PDU session, QoS flows, or DRBs of the terminal device in the first network for the terminal device. For the specific setting process, please refer to the existing process. Details are not described in this case.

[0178]

[0197] S506. The first access network device transmits transfer data to the second access network device based on the first information.

[0179]

[0198] In implementation, the first access network device may transmit user plane data that needs to be transferred to the second access network device via the first interface based on the transport network layer information (e.g., UL / DL transfer UPTNL information) transmitted by the second access network device.

[0180]

[0199] In implementation, the second access network device can transmit the transfer data in the PDU session established by the terminal device in the first network and the uplink data in the new arrival data to the core network, and transmit the transfer data in the PDU session and the downlink data in the new arrival data to the terminal device.

[0181]

[0200] In an implementation, when the data transfer path is based on DRB granularity, the first access network device can further send the data transmission status in the DRB to the second access network device. For example, the first access network device can send an uplink RAN status transfer message to the second access network device to indicate the data transmission status. The uplink RAN status transfer message can carry the packet data convergence protocol sequence number (PDCP-SN), and the hyper frame number (HFN) receiver status (i.e., the uplink PDCP-SN and HFN receiver status) information, as well as the downlink PDCP-SN and HFN transmitter status (i.e., the downlink PDCP-SN and HFN transmitter status) information.

[0182]

[0201] For example, the data transmission state may be described by using information such as UL / DL count values (including UL / DL PDCP SN, HFN for PDCP SN, etc.), the transmission status of UL PDCP SDU (reflecting whether the UL PDCP is successfully transmitted. For example, 0 indicates that the corresponding PDCP is not successfully transmitted, and 1 indicates that the corresponding PDCP is successfully transmitted), or the reception status of DL PDCP SDU (indicating whether the DL PDCP is successfully received. For example, 0 indicates that the corresponding PDCP is not successfully received, and 1 indicates that the corresponding PDCP is successfully received).

[0183]

[0202] S507. The second access network device performs PDCP numbering for the transferred data and the new data.

[0184]

[0203] In an implementation, when the data transfer path is based on DRB granularity, the second access network device performs PDCP numbering and reordering on new data and transfer data in a PDU session established by a terminal device in the first network based on the data transmission status information received by the first access network device; then, the uplink data may be sent to the core network, and the downlink data may be sent to the terminal device.

[0185]

[0204] To enable sequential data transmission and avoid repeated data transmission, it should be understood that the second access network device should not send any uplink data whose PDCP SN value is smaller than the provided UL PDCP SN value, and the provided DL PDCP SN value should be used as the PDCP SN value of the first downlink packet scheduled for transmission for which the PDCP-SN has not been assigned. In other words, after performing PDCP numbering and reordering on new data and transfer data, the second access network device sequentially sends the received transfer data to the core network or the terminal device, and transfers the related data of the terminal device in the second network or the first network that will be received by the second access network device later. In this way, the transfer data of the terminal device can be transferred in the correct order, and repeated data transmission is avoided.

[0186]

[0205] In one example, for downlink user plane data, the second access network device may perform PDCP numbering and reordering on the received new data and transfer data by using DRB, and then send the data to the terminal device. The terminal device sends the received data to a higher layer based on the PDCP SN number, and the higher layer analyzes the user plane data.

[0187]

[0206] In another example, for uplink user plane data, the second access network device can send the uplink user plane data to the first UPF or the second UPF by using the NG interface resource. When the transfer data belongs to the first network, the second access network device can send the transfer data to the first UPF, and the first UPF is the core network device of the first network. When the transfer data belongs to the second network, the second access network device can send the transfer data to the second UPF, and the second UPF is the core network device of the second network.

[0188]

[0207] According to the data transmission method provided in this embodiment of the present application, after the terminal device moves from the cell of the first access network device in the first network to the cell of the second access network device in the second network, the first access network device can send, to the second access network device, indication information indicating that data transfer needs to be performed via the first interface between the first access network device and the second access network device. The second access network device can, based on the indication information, set corresponding transport network layer information for the data transfer path required in the data transfer process, send the transport network layer information to the first access network device, set user plane data for transferring bearer resources between the first access network device and the second access network device, ensure service continuity of the terminal device in the first network, and achieve cross-network movement with relatively few packet losses or no packet losses at all.

[0189]

[0208] FIG. 12 is a schematic flowchart of another data transmission method according to an embodiment of the present application.

[0190]

[0209] Specific application scenarios of the data transmission method provided in this embodiment may be, for example, as follows: A terminal device sets PDU session resources in a network cell of a first access network device (shared-RAN), and then moves to a second network and accesses a second access network device. The first access network device may be a shared access network device, and there is a first interface between the first access network device and the second access network device. The first interface can be used for user plane transmission or control plane signaling transmission. In this scenario, a method for realizing transfer data transmission between the first access network device and the second access network device may be, for example, as follows: The terminal device may notify the second access network device of the location information of the first access network device that was accessed by the terminal device before the terminal device moves. The second access network device requests the context of the terminal device from the first access network device based on the location information. The first access network device transmits the context of the terminal device to the second access network device. The second terminal device transmits the location information of the data transfer path to the first access network device based on the information in the context, and sets up a data transfer bearer resource between the first access network device and the second access network device.

[0191]

[0210] The first network in this embodiment of the present application may be an NPN, and the second network may be a PLMN; the first network may be a PLMN and the second network may be an NPN; the first network may be a PNI-NPN and the second network may be an SNPN; or the first network may be an SNPN and the second network may be a PNI-NPN; and it should be understood that the first interface may be an Xn interface. The data transmission method may specifically include the following steps.

[0192]

[0211] S601. Establish a PDU session of the terminal device in the first network.

[0193]

[0212] Before the terminal device moves, it is understood that the terminal device may be located within the first network, access a cell of the first network, and set the PDU session resources of the first network. When the terminal device autonomously decides to move to a cell of the second network, the terminal device needs to re-establish a PDU session with the first network in order to execute the subsequent data transfer process. Specifically, the terminal device first establishes an IPsec path to the N3IWF to transmit NAS signaling, and then requests the first AMF to establish a PDU session.

[0194]

[0213] In implementation, after an IPsec path is established between the terminal device and the N3IWF, the terminal device can send NAS signaling (e.g., PDU session establishment request message / initial UE message) to the first AMF to request to establish a PDU session in the first network. When requesting the first AMF to establish a PDU session in the first network, the terminal device can further add to the PDU session establishment request message sent by the first AMF the reason (cause) for establishing the PDU session, the type of the PDU session, the location information of the newly accessed cell, the location information of the cell in the first network where the terminal device was located before the terminal device moved to the second network, etc. For example, the reason for establishing the PDU session may be any of the following: cross-network handover of the terminal device, cross-network cell reselection of the terminal device, or cross-network cell selection of the terminal device (e.g., reselection from a cell of an SNPN to a cell of a PLMN or PNI-NPN, i.e., SNPNtoPLMN or SNPN-NPN). The type of the PDU session may be an NPN PDU session or an NPNto5GS PDU session. The information about the newly re-accessed cell may be any of the following: network identifier after cell reselection, cell identifier, access network device identifier, and TAC, e.g., PLMN ID + cell ID + RAN Node ID + TAC. The location information of the terminal device in the first network before the terminal device moves may be any of the following: first network identifier, cell identifier, tracking area code, access network device identifier, e.g., PLMN ID+NID + cell ID + TAC + RAN code ID or PLMN ID+CAG ID + cell ID + TAC + RAN code ID. The identifier of the terminal device may be, for example, an international mobile subscriber identity number IMSI, e.g., 5G-S-IMSI.

[0195]

[0214] It should be understood that the specific information listed above, which is carried in the PDU session establishment request message transmitted from the terminal device to the first AMF, is merely an example. The PDU session establishment request message may further include a plurality of other types of information. This is not limited in this embodiment of the present application.

[0196]

[0215] In order to enable transfer data transmission between the first access network device and the second access network device, each network element (e.g., the first AMF, the second AMF, the second UPF, or the second access network device, where the first AMF is the AMF in the first network; the second AMF, the second UPF, and the second access network device are network elements in the second network) should be understood to need to set corresponding resources for the PDU session of the terminal device in the first network. The resource may be, for example, an IPsec tunnel.

[0197]

[0216] In an implementation, the first AMF may send a PDU session establishment request message to the N3IWF. The PDU session establishment request message may be, for example, a PDU resource setup message or an initial UE context setup message. The PDU session establishment request message may carry information such as an identifier of the PDU session requested to be established, a DRB ID, a QFI, a reason for establishing the PDU session, a type of the PDU session, and an identifier of the terminal device. For example, the reason for establishing the PDU session may include, for example, cross-network handover of the terminal device, cross-network cell reselection of the terminal device, and cross-network cell selection of the terminal device (for example, reselection from a cell of an SNPN to a cell of a PLMN or a PNI-NPN, that is, SNPNtoPLMN or SNPNtoPNI-NPN). The type of the PDU session may be, for example, an NPN, a PLMN, an SNPN, a PNI-NPN, or an NPNto5GS. The identifier of the terminal device may be, for example, an IP address of the terminal device.

[0198]

[0217] In an implementation, the N3IWF determines to establish a corresponding IPsec tunnel for the PDU session based on the PDU session establishment request message sent by the first AMF.

[0199]

[0218] In an implementation, the terminal device, the second access network device, the second AMF, the second UPF, and the N3IWF may set corresponding resources, QoS flows, or DRBs of the terminal device in the first network for the terminal device. For the specific setting process, refer to the existing process. Details are not described in this case.

[0200]

[0219] S602. The terminal device sends a first message to the second access network device.

[0201]

[0220] In an implementation, the first message may include location information of the first network where the terminal device was located before the terminal device moved to the second network. The location information may be, for example, an identifier of the second network, an identifier of the re-accessed cell, a network identifier, a TAC, or an access network device identifier. When the second network is a PLMN, the location information may be PLMN ID + cell ID + TAC + RAN node ID. Additionally, the first message may further carry an identifier of the terminal device such as a 5G-S-IMSI, an IMSI, or a C-RNTI.

[0202]

[0221] In an implementation, the first message may be a radio resource control (RRC) message.

[0203]

[0222] S603. The second access network device sends a second request message to the first access network device.

[0204]

[0223] The first access network device is an access network device in the first network, and the second access network device is an access network device in the second network. The core networks of the first network and the second network are deployed independently, and one of the first access network device of the first network and the second access network device of the second network is a shared access network device, that is, there is a first interface between the first access network device and the second access network device. The first interface may be configured to perform user plane data communication and control plane data communication, and the first interface may be, for example, an Xn interface.

[0205]

[0224] In an implementation, the second request message is used to query the context of the terminal device regarding the first access network device. Specifically, when the first network is an NPN and the second network is a PLMN, the PLMN-RAN may send data transfer request / handover request / acquire UE context request information to the NPN shared RAN via the Xn-C interface to request to obtain the context of the terminal device within the NPN.

[0206]

[0225] In an implementation, the second request message may include the reason why the second access network device sends the second request message to the first access network device, the type of movement, the original identifier of the terminal device before the terminal device moves (such as 5G-S-IMSI, IMSI, or C-RNTI), and the new identifier of the terminal device after the terminal device moves (for example, XnAP UE ID). The reason why the second access network device sends the second request message to the first access network device may be cross-network handover of the terminal device, cross-network cell reselection of the terminal device, cross-network cell selection of the terminal device (for example, reselection from a cell of an SNPN to a cell of a PLMN or a PNI-NPN, that is, SNPNtoPLMN or SNPNtoPNI-NPN), etc. The type of movement may be, for example, NPNto5GS or 5GStoNPN.

[0207]

[0226] S604. The first access network device sends the first indication information and the first cause information to the second access network device.

[0208]

[0227] In implementation, the first access network device transmits a response message to the second access network device based on the second request message received in step S603. The response message may be, for example, a handover request / acquire UE context response, and the response message may include the context of the terminal device. Further, the response message may further carry the original identifier of the terminal device (e.g., 5G-S-IMSI, IMSI, or C-RNTI) before the terminal device moves.

[0209]

[0228] In implementation, the first access network device may transmit first indication information and first cause information to the second access network device based on the second request message received in step S603. The first indication information is used to indicate that the first access network device has transfer data to be transferred to the second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data.

[0210]

[0229] It should be understood that the transfer data in this embodiment of the present application may be data transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored transmitted by the terminal device and received by the first access network device.

[0211]

[0230] Since the first interface between the first access network device and the second access network device may be used for user plane data communication and control plane data communication, it should be understood that the first access network device may directly transmit the first indication information and the first cause information to the second access network device via the first interface.

[0212]

[0231] In an implementation, the first indication information may be used to indicate whether the first access network device needs to transfer data (where the indication information may be, for example, a character string such as required, not required, possible, or impossible). If the first access network device indicates that data transfer is not required, the reason for not performing the data transfer may also be described. For example, the reason may be as follows: completed. This means that the data scheduled for transfer has been transferred; released. This means that the data scheduled for transfer has been released and thus cannot be transferred.

[0213]

[0232] In an implementation, the first indication information may include at least one of the following information: a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, transmission status information of data within the DRB, and a data transfer cause.

[0214]

[0233] In an implementation, the first indication information may further carry indication information (for example, 0, 1, a direct transfer path is available, or a direct transfer path is not available) to indicate whether the data to be transferred by the first access network device can be directly transferred to the second access network device via the first interface.

[0215]

[0234] S605. The second access network device sends the first information to the first access network device.

[0216]

[0235] The first information includes transport network layer information set by the second access network device for the data transfer path, and the data transfer path is configured to transmit the transferred data.

[0217]

[0236] After receiving the first instruction information sent by the first access network device, it should be understood that the second access network device determines, based on the first instruction information, that the first access network device has transfer data to be transferred to the second access network device. The second access network device sets the transport network layer information of the data transfer path configured to transfer the transfer data.

[0218]

[0237] In an implementation, the transport network layer information of the uplink or downlink data transfer path, which is set by the second access network device, may include, for example, a transport layer address (e.g., an IP address) and a GTP tunnel endpoint identifier (GTP-Tunnel Endpoint Identifier, GTP-TEID).

[0219]

[0238] S606. The first access network device sends the transfer data to the second access network device based on the first information.

[0220]

[0239] In an implementation, the first access network device may send user plane data that needs to be transferred to the second access network device via the first interface based on the transport network layer information (e.g., UL / DL transfer UP TNL information) sent by the second access network device.

[0221]

[0240] In an implementation, the second access network device can transmit transfer data and uplink data in new arrival data in a PDU session established by a terminal device in the first network to the core network, and can transmit transfer data and downlink data in new arrival data in the PDU session to the terminal device.

[0222]

[0241] In an implementation, when the data transfer path is based on DRB granularity, the first access network device can further transmit the data transmission state in the DRB to the second access network device. For example, the first access network device transmits an uplink RAN status transfer message to the second access network device to indicate the data transmission state, and the uplink RAN status transfer message can carry a packet data convergence protocol sequence number (PDCP-SN), and hyper frame number (HFN) receiver status (i.e., uplink PDCP-SN and HFN receiver status) information, as well as downlink PDCP-SN and HFN transmitter status (i.e., downlink PDCP-SN and HFN transmitter status) information.

[0223]

[0242] For example, the data transmission state is a UL / DL count value (including UL / DL PDCP SN, HFN for PDCP SN, etc.), the transmission status of the UL PDCP SDU (reflecting whether the UL PDCP was successfully transmitted. For example, 0 indicates that the corresponding PDCP was not successfully transmitted, and 1 indicates that the corresponding PDCP was successfully transmitted), or It may be described by using information such as the reception status of the DL PDCP SDU (indicating whether the DL PDCP is received normally. For example, 0 indicates that the corresponding PDCP is not received normally, and 1 indicates that the corresponding PDCP is received normally).

[0224]

[0243] S607. The second access network device performs PDCP numbering on the transferred data and the new data.

[0225]

[0244] In an implementation, when the data transfer path is based on DRB granularity, the second access network device performs PDCP numbering and rearrangement on the new data and the transferred data in the PDU session established by the terminal device in the first network based on the data transmission status information received by the first access network device; then, the uplink data may be sent to the core network, and the downlink data may be sent to the terminal device.

[0226]

[0245] To enable sequential data transmission and avoid repeated data transmission, it should be understood that the second access network device should not send any uplink data whose PDCP SN value is smaller than the provided UL PDCP SN value, and the provided DL PDCP SN value should be used as the PDCP SN value of the first downlink packet to be transmitted for which the PDCP-SN is not assigned. In other words, after performing PDCP numbering and rearrangement on the new data and the transferred data, the second access network device sequentially sends the received transferred data to the core network or the terminal device, and transmits the related data of the terminal device in the second network or the first network, which will be subsequently received by the second access network device. In this way, the transferred data of the terminal device can be transmitted in the correct order, and repeated data transmission is avoided.

[0227]

[0246] In one example, for downlink user plane data, the second access network device may perform PDCP numbering and rearrangement on the received new data and transfer data by using the DRB, and then send the data to the terminal device. The terminal device may send the received data to a higher layer based on the PDCP SN number, and the higher layer analyzes the user plane data.

[0228]

[0247] In another example, for uplink user plane data, the second access network device may send the uplink user plane data to the first UPF or the second UPF by using the NG interface resource. When the transfer data belongs to the first network, the second access network device may send the transfer data to the first UPF, and the first UPF is the core network device of the first network. When the transfer data belongs to the second network, the second access network device may send the transfer data to the second UPF, and the second UPF is the core network device of the second network.

[0229]

[0248] According to the data transmission method provided in this embodiment of the present application, after the terminal device moves from the cell of the first access network device in the first network to the cell of the second access network device in the second network, the first access network device can send, via the first interface between the first access network device and the second access network device, instruction information indicating that data transfer needs to be performed to the second access network device. The second access network device sets corresponding transport network layer information for the data transfer path required in the data transfer process based on the instruction information, sends the transport network layer information to the first access network device, sets user plane data for transferring bearer resources between the first access network device and the second access network device, guarantees the service continuity of the terminal device in the first network, and realizes cross-network movement with relatively few packet losses or no packet losses at all.

[0230]

[0249] Figure 13 is a schematic flowchart of another data transmission method according to an embodiment of the present application.

[0231]

[0250] In one example, when the first network is NPN, the second network is PLMN, and the first access network device is a shared access network, a specific application scenario of the data transmission method provided in this embodiment may be, for example, as shown in FIGS. 14 and 15: The terminal device configures PDU session resources in the network cell of the NPN access network device (NPN-RAN). Then, the terminal device moves to the PLMN and accesses the PLMN access network device (PLMN-RAN). The first access network device is a shared access network device (shared-RAN), and there is a first interface between the first access network device and the second access network device. The first interface may be used for user plane transmission, but cannot be used for control plane data transmission. In this scenario, the method for realizing transfer data transmission between the first access network device and the second access network device may be as follows: The terminal device or the first AMF triggers data transfer. Network elements such as the first AMF, N3IWF, the terminal device, and the second AMF send indication information indicating that the first access network device needs to transfer data to the second access network device. After setting the transmission network layer information used for data transfer, network elements such as the terminal device, N3IWF, and the first AMF send the transmission network layer information to the first access network device to set up a data transfer bearer resource between the first access network device and the second access network device.

[0232]

[0251] In another example, when the first network is a PLMN, the second network is an NPN, and the second access network device (NPN-RAN) is a shared access network (shared-RAN), a specific application scenario of the data transmission method provided in this embodiment may be, for example, as shown in FIGS. 16 and 17: The terminal device configures PDU session resources in the network cell of the PLMN access network device (PLMN-RAN). Then, the terminal device moves to the NPN and accesses the NPN-RAN. There is a first interface between the first access network device and the second access network device. The first interface may be used for user plane transmission, but cannot be used for control plane signaling transmission. In this scenario, the method for realizing transfer data transmission between the first access network device and the second access network device may be as follows: The terminal device or the first AMF triggers data transfer. Network elements such as the first AMF, N3IWF, the terminal device, and the second AMF send indication information indicating that the first access network device needs to transfer data to the second access network device. After setting the transmission network layer information used for data transfer, network elements such as the terminal device, N3IWF, and the first AMF send the transmission network layer information to the first access network device to set up a data transfer bearer resource between the first access network device and the second access network device.

[0233]

[0252] It should be understood that the first interface in this embodiment of the present application may be an Xn interface. The data transmission method may specifically include the following steps.

[0234]

[0253] S701. Establish a PDU session of the terminal device in the first network.

[0235]

[0254] Before the terminal device moves, it should be understood that the terminal device may be located within the first network, access the cell of the first network, and configure the PDU session resources of the first network. When the terminal device autonomously determines to move to the cell of the second network, the terminal device needs to re - establish the PDU session with the first network in order to execute the subsequent data transfer process. Specifically, the terminal device first establishes an IPsec path to the N3IWF to transmit NAS signaling, and then requests the first AMF to establish a PDU session.

[0236]

[0255] In implementation, after an IPsec path is established between the terminal device and the N3IWF, the terminal device can send NAS signaling (e.g., PDU session establishment request message / initial UE message) to the first AMF to request the establishment of a PDU session in the first network. When requesting the first AMF to establish a PDU session in the first network, the terminal device can further add to the PDU session establishment request message sent by the first AMF the reason for establishing the PDU session, the type of the PDU session, the location information of the newly accessed cell, the location information of the cell in the first network where the terminal device was located before the terminal device moved to the second network, etc. For example, the reason for establishing the PDU session may be cross-network handover of the terminal device or cross-network cell reselection of the terminal device (e.g., reselection from an NPN cell to a PLMN cell, i.e., SNPNtoPLMN). The type of the PDU session may be an NPN PDU session or an NPNto5GS PDU session. The information about the newly re-accessed cell may be as follows: the network identifier of the network where the terminal device is located after the terminal device moves, the cell identifier, the access network device identifier, and the TAC, e.g., PLMN ID + cell ID + RAN Node ID + TAC. The location information of the terminal device in the first network before the terminal device moves may be as follows: the first network identifier, the cell identifier, the tracing area code, the access network device identifier, the closed access group identifier, e.g., NID + cell ID + TAC + RAN code ID or PLMN ID+CAG ID + cell ID + TAC + RAN code ID. The identifier of the terminal device may be, for example, the international mobile subscriber identity IMSI, e.g., 5G-S-IMSI.

[0237]

[0256] It should be understood that the specific information listed above, which is carried in the PDU session establishment request message sent from the terminal device to the first AMF, is merely an example. The PDU session establishment request message may further include a plurality of other types of information. This is not limited to this embodiment of the present application.

[0238]

[0257] In order to enable transfer data transmission between the first access network device and the second access network device, each network element (for example, the first AMF, the second AMF, the second UPF, or the second access network device, where the first AMF is the AMF in the first network; the second AMF, the second UPF, and the second access network device are network elements in the second network) should be understood to need to set corresponding resources for the PDU session of the terminal device in the first network. The resource may be, for example, an IPsec tunnel.

[0239]

[0258] In an implementation, the first AMF may send a PDU session establishment request message to the N3IWF. The PDU session establishment request message may be, for example, a PDU resource setup message or an initial UE context setup message. The PDU session establishment request message may carry information such as an identifier of the PDU session requested to be established, a DRB ID, a QFI, a reason for establishing the PDU session, a type of the PDU session, and an identifier of the terminal device. For example, the reason for establishing the PDU session may include, for example, cross-network handover of the terminal device, cross-network cell reselection of the terminal device, and cross-network cell selection of the terminal device (e.g., reselection from a cell of an SNPN to a cell of a PLMN or a PNI-NPN, i.e., SNPNtoPLMN or SNPNtoPNI-NPN). The type of the PDU session may be, for example, NPN, PLMN, SNPN, PNI-NPN, or NPNto5GS. The identifier of the terminal device may be, for example, an IP address of the terminal device.

[0240]

[0259] In an implementation, the N3IWF determines to establish a corresponding IPsec tunnel for the PDU session based on the PDU session establishment request message sent by the first AMF.

[0241]

[0260] In an implementation, the terminal device, the second access network device, the second AMF, the second UPF, and the N3IWF may set corresponding resources, QoS flows, or DRBs of the terminal device in the first network for the PDU session. For the specific setting process, refer to the existing process. Details are not described in this case.

[0242]

[0261] S702. The first AMF sends a first message to the second access network device.

[0243]

[0262] In implementation, the first AMF can determine the location information of the first access network device based on the location information of the terminal device received in step S701 before the terminal device moves, and can send a first request message to the first access network device based on the location information. The first request message is used to inquire whether the first access network device has transfer data.

[0244]

[0263] It should be understood that the transfer data in this embodiment of the present application may be data that has been sent by the first access network device but not successfully received by the terminal device, out-of-order data sent by the terminal device and received by the first access network device, or data to be restored that has been sent by the terminal device and received by the first access network device.

[0245]

[0264] In implementation, the first request message may be, for example, a data transfer request or a handover request.

[0246]

[0265] In an implementation, the first request message may include location information of the terminal device after the terminal device has moved, which is the location information sent from the terminal device to the first AMF. Further, the first request message may further include a reason for establishing a PDU session, location information of the terminal device before the terminal device has moved, an identifier of the PDU session requested to be established by the terminal device, a PDU session type, a QoS flow identifier, and information such as an identifier of the terminal device. The reason for establishing a PDU session may be, for example, cross-network handover of the terminal device, cross-network cell reselection of the terminal device, or cross-network cell selection of the terminal device (for example, reselection from a cell of an SNPN to a PLMN or a PNI-NPN, that is, SNPNtoPLMN or SNPNtoPNI-NPN). When the second network is a PLMN, the location information of the terminal device after the terminal device has moved may be, for example, PLMN ID + cell ID + RAN ID + TAC. The identifier of the terminal device may be, for example, terminal device identification information such as a C-RNTI or an NG-RAN node UE NGAP ID.

[0247]

[0266] S703. The first access network device sends the first indication information and the first cause information to the first AMF.

[0248]

[0267] The first indication information is used to indicate that the first access network device has transfer data to be transferred to the second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data.

[0249]

[0268] In an implementation, the first indication information may be used to indicate whether the first access network device needs to transfer data (where the indication information may be, for example, a string such as required, not required, possible, or impossible). When the first access network device indicates that data transfer is not required, the reason for not performing the data transfer may also be described. For example, the reason may be as follows: completed. This means that the data scheduled for transfer has been transferred; released. This means that the data scheduled for transfer has been released and thus cannot be transferred.

[0250]

[0269] In an implementation, the first indication information may include at least one of the following information: a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, transmission status information of data within the DRB, and a data transfer cause.

[0251]

[0270] In an implementation, the first indication information may further carry indication information (for example, 0, 1, a direct transfer path is available, or a direct transfer path is not available) to indicate whether the data to be transferred by the first access network device can be directly transferred to the second access network device via the first interface.

[0252]

[0271] In an implementation, the first indication information may be included in a data transfer response or a request confirmation message, and the message may further carry information such as a first network PDU session identifier / DRB identifier / quality of service flow identifier (QFI).

[0253]

[0272] In an implementation, when the data transfer path is at the DRB session granularity, the first access network device can further send the data transmission state in the DRB to the second access network device. For example, the first access network device can send an uplink RAN status transfer message to the second access network device to indicate the data transmission state. The uplink RAN status transfer message can carry packet data convergence protocol sequence number (PDCP-SN) and hyper frame number (HFN) receiver status (i.e., uplink PDCP-SN and HFN receiver status) information, as well as downlink PDCP-SN and HFN transmitter status (i.e., downlink PDCP-SN and HFN transmitter status) information.

[0254]

[0273] For example, the data transmission state may be described by using information such as UL / DL count values (including UL / DL PDCP SN, HFN for PDCP SN, etc.), the transmission status of UL PDCP SDU (reflecting whether the UL PDCP was successfully transmitted. For example, 0 indicates that the corresponding PDCP was not successfully transmitted, and 1 indicates that the corresponding PDCP was successfully transmitted), or the reception status of DL PDCP SDU (indicating whether the DL PDCP was successfully received. For example, 0 indicates that the corresponding PDCP was not successfully received, and 1 indicates that the corresponding PDCP was successfully received).

[0274] S704. The first AMF sends the first indication information to the N3IWF.

[0255]

[0275] In an implementation, the first indication information sent from the first AMF to the N3IWF may be included in a PDU resource setting request or an initial UE context setting message.

[0256]

[0276] In an implementation, the first AMF may also send to the N3IWF those such as a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, data transmission status information in the DRB, a data transfer cause, and data transfer information related to the DRB granularity, which are included in the first indication information received in step S702.

[0257]

[0277] S705. The N3IWF sends the first indication information to the terminal device.

[0258]

[0278] In an implementation, based on the information received in step S703, the N3IWF determines to establish an IPsec tunnel for the PDU session in the terminal device of the first network.

[0259]

[0279] In an implementation, the first indication information sent from the first N3IWF to the terminal device may be included in an IKE_creat_SA request message. Optionally, the IKE_creat_SA request message may be used to instruct the terminal device to establish an IPsec tunnel. Further, the IKE_creat_SA request message may further include a reason for setting the PDU session / QoS flow / DRB resource and a type of the PDU session / QoS flow / DRB resource. When the data transfer path performs transfer at the DRB granularity, the N3IWF further needs to notify the terminal device of the data transfer information related to the DRB granularity.

[0260]

[0280] S706. The terminal device sends the first indication information to the second access network device.

[0261]

[0281] In implementation, the terminal device transmits the first instruction information to the second access network device based on the information received in step S705. The first instruction information transmitted from the terminal device to the second access network device may be included in the UL information transfer message.

[0262]

[0282] In implementation, the first instruction information may include at least one of the following information: protocol data unit PDU session identifier, quality of service QoS flow identifier, data radio bearer DRB identifier, mapping list between DRB and QoS flow, transmission status information of data within DRB, and data transfer cause.

[0263]

[0283] S707. The second access network device transmits the first information to the terminal device.

[0264]

[0284] The first information includes the transport network layer information set by the second access network device for the data transfer path, and the data transfer path is configured to transmit transfer data information.

[0265]

[0285] After receiving the first instruction information transmitted by the terminal device, it should be understood that the second access network device determines, based on the first instruction information, that the first access network device has transfer data to be transferred to the second access network device. The second access network device sets the transport network layer information of the data transfer path configured to transfer the transfer data.

[0266]

[0286] In an implementation, the transport network layer information of an uplink or downlink data transfer path, which is set by a second access network device, may include, for example, a transport layer address (e.g., an IP address) and a GTP tunnel endpoint identifier (GTP-TEID).

[0267]

[0287] In an implementation, the second access network device may first send the first information to the second AMF. After the second AMF performs a process such as analyzing the first information, the second access network device sends the first information to the terminal device. For example, the second access network device sends handover request confirmation / initial UE context setup response / PDU session resource setup response information to the second AMF, and the information carries the transport network layer information (e.g., UL / DL transfer UP TNL information) of the uplink / downlink data transfer path set by the second access network device for the PDU session / QoS flow / DRB. The second AMF sends downlink NAS transport information to the second access network device, and the downlink NAS transport information can carry the PDU session identifier / DRB ID / QFI of the first network and the corresponding UL / DL transfer UP TNL information. Then, the second access network device transfers the downlink NAS transport information to the terminal device.

[0268]

[0288] S708. The terminal device sends the first information to the N3IWF.

[0269]

[0289] The first information sent from the terminal device to the N3IWF may be included in the IKE_creat_child_SA response message. The IKE_creat_child_SA response message may be used to indicate that the terminal device has successfully established a PDU session / QoS flow / DRB bearer.

[0270]

[0290] In an implementation, the IKE_creat_child_SA response message carries the UL / DL transfer UP TNL information set for the corresponding PDU session / QoS flow / DRB bearer that requires data transfer to be performed.

[0271]

[0291] S709. The N3IWF sends the first information to the first AMF.

[0272]

[0292] The first information sent from the N3IWF to the first AMF may be included in the PDU resource setup response / initial UE context setup response message. The PDU resource setup response / initial UE context setup response message can indicate that the N3IWF has successfully established a PDU session / QoS flow / DRB bearer.

[0273]

[0293] In an implementation, the PDU resource setup response / initial UE context setup response message carries the UL / DL transfer UP TNL information set for the corresponding PDU session / QoS flow / DRB bearer that requires data transfer to be performed.

[0274]

[0294] S710. The first AMF sends the first information to the first access network device.

[0275]

[0295] The first information sent from the first AMF to the first access network device may be included in a data transfer command / handover command message. The data transfer command / handover command message is used to indicate data transfer path information (i.e., UL / DL transfer UP TNL information) set by the second access network device for the corresponding PDU session / QoS flow / DRB that requires data transfer to be executed.

[0276]

[0296] S711. The first access network device transmits transfer data to the second access network device based on the first information.

[0277]

[0297] In an implementation, the first access network device may transmit user plane data to be transferred to the second access network device via the first interface based on transport network layer information (e.g., UL / DL transfer UP TNL information) sent from the second access network device.

[0278]

[0298] In an implementation, the second access network device can transmit transfer data in a PDU session established by a terminal device in the first network and uplink data in new arrival data to the core network, and transmit downlink data in new arrival data and transfer data in the session to the terminal device.

[0279]

[0299] In an implementation, if the data transfer path is based on DRB granularity, the first access network device can further send the data transmission state in the DRB to the second access network device. For example, the first access network device can send an uplink RAN status transfer message to the second access network device to indicate the data transmission status, and the uplink RAN status transfer message can carry the packet data convergence protocol sequence number (PDCP-SN), and hyper frame number (HFN) receiver status (i.e., uplink PDCP-SN and HFN receiver status) information, as well as downlink PDCP-SN and HFN transmitter status (i.e., downlink PDCP-SN and HFN transmitter status) information.

[0280]

[0300] For example, the data transmission state can be described by using information such as UL / DL count values (including UL / DL PDCP SN, HFN for PDCP SN, etc.), the transmission status of UL PDCP SDU (reflecting whether the UL PDCP was successfully transmitted. For example, 0 indicates that the corresponding PDCP was not successfully transmitted, and 1 indicates that the corresponding PDCP was successfully transmitted), or the reception status of DL PDCP SDU (indicating whether the DL PDCP was successfully received. For example, 0 indicates that the corresponding PDCP was not successfully received, and 1 indicates that the corresponding PDCP was successfully received).

[0281]

[0301] S712. The second access network device performs PDCP numbering on the transferred data and the new data.

[0282]

[0302] In an implementation, when the data transfer path is based on DRB granularity, the second access network device performs PDCP numbering and rearrangement for new data and transfer data in a PDU session established by a terminal device in the first network based on the data transmission status information received by the first access network device; then, the uplink data may be sent to the core network, and the downlink data may be sent to the terminal device.

[0283]

[0303] To enable sequential data transmission and avoid repeated data transmission, it should be understood that the second access network device should not send any uplink data whose PDCP SN value is smaller than the provided UL PDCP SN value, and the provided DL PDCP SN value should be used as the PDCP SN value of the first downlink packet scheduled for transmission for which the PDCP-SN has not been assigned. In other words, after performing PDCP numbering and rearrangement for new data and transfer data, the second access network device sequentially sends the received transfer data to the core network or the terminal device, and transfers the related data of the terminal device in the second network or the first network, which will be received by the second access network device later. In this way, the transfer data of the terminal device can be transferred in the correct order, and repeated data transmission is avoided.

[0284]

[0304] In one example, for downlink user plane data, the second access network device may perform PDCP numbering and rearrangement for the received new data and transfer data by using DRB, and then send the data to the terminal device. The terminal device sends the received data to a higher layer based on the PDCP SN number, and the higher layer analyzes the user plane data.

[0285]

[0305] In another example, for uplink user plane data, the second access network device can send the uplink user plane data to the first UPF or the second UPF by using the NG interface resource. If the transfer data belongs to the first network, the second access network device can send the transfer data to the first UPF, and the first UPF is the core network device of the first network. If the transfer data belongs to the second network, the second access network device can send the transfer data to the second UPF, and the second UPF is the core network device of the second network.

[0286]

[0306] According to the data transmission method provided in this embodiment of the present application, after the terminal device autonomously moves from the cell of the first access network device in the first network to the cell of the second access network device in the second network, the first access network device sends indication information indicating that data transfer needs to be executed to the second access network device. The second access network device sets corresponding transport network layer information for the data transfer path required in the data transfer process based on the indication information, sends the transport network layer information to the first access network device, sets the user plane data for transferring bearer resources between the first access network device and the second access network device, guarantees the service continuity of the terminal device in the first network, and realizes cross-network movement with relatively few packet losses or no packet losses at all.

[0287]

[0307] Embodiments of the present application further provide a communication system for data transmission. The communication system includes at least one first access network device, a second access network device, and a first AMF. The first access network device, the second access network device, and the first AMF are configured to execute the method provided in the foregoing embodiments of the present application.

[0288]

[0308] FIG. 18 is a schematic structural diagram of an access network device according to an embodiment of the present application. The access network device 1800 includes a transmission module 1801 and a reception module 1802.

[0289]

[0309] In an implementation, the transmission module 1801 can be configured to transmit first indication information and first cause information to a second access network device. The first indication information is used to indicate that the first access network device has transfer data to be transmitted to the second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data. The transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device and received by the first access network device. One of the first access network device and the second access network device is an access network device shared by the first network and the second network. The first access network device and the second access network device belong to the first network and the second network respectively. The core network elements of the first network and the second network are independently deployed. A first interface exists between the first access network device and the second access network device. The first interface is configured to perform user plane data communication and control plane data communication.

[0290]

[0310] In an implementation, the reception module 1802 is configured to receive first information transmitted from the second access network device. The first information includes transport network layer information set by the second access network device for a data transfer path. The data transfer path is configured to transmit transfer data.

[0291]

[0311] In an implementation, the transmission module 1801 is further configured to transmit the transfer data to a second access network device.

[0292]

[0312] In an implementation, the reception module 1802 is further configured to receive a first request message transmitted from a first access mobility management function network element AMF, where the first request message is used to query whether the first access network device has transfer data, and the first AMF is the AMF in the first network.

[0293]

[0313] In an implementation, the transmission module 1801 may be further configured to transmit first indication information to the second access network device based on the first request message.

[0294]

[0314] In an implementation, the reception module 1802 may be configured to receive a second request message transmitted from the second access network device, where the second request message is used to query the context of the terminal device regarding the first access network device.

[0295]

[0315] In an implementation, the transmission module 1801 may be further configured to transmit first indication information to the second access network device based on the second request message.

[0296]

[0316] For example, the first network is a stand-alone non-public network SNPN, and the second network is a public land mobile network PLMN; the first network is a PLMN and the second network is an SNPN; the first network is a public network integrated non-public network PNI-NPN and the second network is an SNPN; or the first network is an SNPN and the second network is a PNI-NPN.

[0297]

[0317] In an implementation, the transmission module 1801 may transmit transfer data information to a second access network device via an interface.

[0298]

[0318] In an implementation, the first request message and the second request message may include at least one of the following information: the reason for transmitting the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0299]

[0319] In an implementation, the first indication information may include at least one of the following information: a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, transmission status information of data in the DRB, and a data transfer reason.

[0300]

[0320] In an implementation, the first indication information is further used to indicate that the transfer data can be transferred by the first access network device to the second access network device via the first interface.

[0301]

[0321] FIG. 19 is a schematic structural diagram of another access network device according to an embodiment of the present application. The access network device 1900 includes a reception module 1901 and a transmission module 1902.

[0302]

[0322] In an implementation, the receiving module 1901 can be configured to receive first indication information and first cause information transmitted from a first access network device. The first indication information is used to indicate that the first access network device has transfer data to be transmitted to a second access network device. The first cause information is used to indicate the reason why the first access network device needs to transfer data. The transfer data is data that has been transmitted by the first access network device but not successfully received by the terminal device, out-of-order data transmitted by the terminal device and received by the first access network device, or data to be restored that has been transmitted by the terminal device and received by the first access network device. One of the first access network device and the second access network device is an access network device shared by a first network and a second network. The first access network device and the second access network device belong to the first network and the second network respectively. The core network elements of the first network and the second network are independently deployed. A first interface exists between the first access network device and the second access network device. The first interface is configured to perform user plane data communication and control plane data communication.

[0303]

[0323] In an implementation, the transmitting module 1902 may be configured to transmit first information to the first access network device based on the first indication information. The first information is transport network layer information set by the second access network device for a data transfer path. The data transfer path is used to transmit transfer data information.

[0304]

[0324] In an implementation, the receiving module 1901 may be further configured to receive transfer data transmitted from a first access network device.

[0305]

[0325] In an implementation, the receiving module 1901 may be further configured to receive a first message transmitted by a terminal device, where the first message is used to indicate location information of a first network where the terminal device was located before the terminal device moved to a second network.

[0306]

[0326] In an implementation, the transmitting module 1902 may be configured to transmit a second request message to the first access network device based on the first message, where the second request message is used to query context of the terminal device regarding the first access network device.

[0307]

[0327] In an implementation, the transmitting module 1902 may be further configured to directly transmit first information to the first access network device via an interface.

[0308]

[0328] In an implementation, the second request message may further include at least one of the following information: a reason for transmitting the first request message, location information of the terminal device after the terminal device moved, location information of the terminal device before the terminal device moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0309]

[0329] In an implementation, the first network is an SNPN, and the second network is a PLMN; the first network is a PLMN and the second network is an SNPN; the first network is a PNI-NPN and the second network is an SNPN; or the first network is an SNPN and the second network is a PNI-NPN.

[0310]

[0330] In an implementation, the first indication information includes at least one of the following information: a protocol data unit (PDU) session identifier, a quality of service (QoS) flow identifier, a data radio bearer (DRB) identifier, a mapping list between the DRB and the QoS flow, data transfer status information in the DRB, and a data transfer cause.

[0311]

[0331] FIG. 20 is a schematic structural diagram of an AMF according to an embodiment of the present application. The AMF 2000 includes a receiving module 2001 and a transmitting module 2002.

[0312]

[0332] In an implementation, the receiving module 2001 can be configured to receive a second message transmitted from a terminal device. The second message includes location information of a first network where the terminal device was located before the terminal device moved, and location information of a second network where the terminal device is located after the terminal device moved. The core network elements of the first network and the second network are independently deployed.

[0313]

[0333] In an implementation, the transmitting module 2002 can be configured to transmit a first request message to a first access network device based on the second message. The first request message is used to query whether the first access network device has transfer data. The transfer data is data that was transmitted by the first access network device but not successfully received by the terminal device, out-of-order data that was transmitted by the terminal device and received by the first access network device, or data that was transmitted by the terminal device and should be restored by the first access network device. The first access network device is an access network device in the first network.

[0314]

[0334] In an implementation, the first network is an SNPN, and the second network is a PLMN; or the first network is a PLMN and the second network is an SNPN; or the first network is a PNI-NPN and the second network is an SNPN; or the first network is an SNPN and the second network is a PNI-NPN.

[0315]

[0335] In an implementation, the first request message includes at least one of the following information: the reason for sending the first request message, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, a PDU session type, a QoS flow identifier, and an identifier of the terminal device.

[0316]

[0336] In an implementation, the second message further includes at least one of the following information: the reason for the terminal device to send the second message to the first AMF, the location information of the terminal device after the terminal device has moved, the location information of the terminal device before the terminal device has moved, a PDU session identifier, the reason for setting a PDU session in the first network, the type of the PDU session in the first network, and an identifier of the terminal device.

[0317]

[0337] FIG. 21 is a schematic structural diagram of a communication device for data transmission according to an embodiment of the present application.

[0318]

[0338] The communication device 2100 includes at least one processor 2101 and a communication interface 2102. The communication interface 2102 is configured to exchange information between the communication device and other communication devices. When program instructions are executed by at least one processor, the communication device can implement the method provided in the foregoing embodiments of the present application. The communication device may be a first access network device, a second access network device, or a network element such as the first AMF in the embodiment of the present application.

[0319]

[0339] Those skilled in the art will recognize that in combination with the examples described in the embodiments disclosed in this specification, the units and algorithm steps may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether a function is executed by hardware or software depends on the design constraints of a particular application or technical solution. Those skilled in the art may use various methods to implement the described functions for each particular application, but such implementation should not be construed as going beyond the scope of this application.

[0320]

[0340] For the sake of convenience and simplicity of explanation, it should be clearly understood by those skilled in the art that for the detailed operation processes of the aforementioned systems, devices, and units, reference may be made to the corresponding processes in the embodiments of the aforementioned methods, and the details will not be described again in this case.

[0321]

[0341] In some embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the above-described device embodiments are merely examples. For example, the way of dividing into units is merely a logical function division, and in actual implementation, other division methods may be used. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the illustrated or described mutual coupling, direct coupling, or communication connection may be implemented via some interface. The indirect coupling or communication connection between devices or units may be implemented in an electrical, mechanical, or other form.

[0322]

[0342] Units described as separate parts may or may not be physically separated. Parts shown as units may or may not be physical units, and may be located in one place, or may be distributed over multiple network units. Some or all of the units can be selected based on actual requirements to achieve the objectives of the solutions in the embodiments.

[0323]

[0343] Furthermore, the functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

[0324]

[0344] When the function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application, in essence, or the parts contributing to the prior art, or some of the technical solutions, may be implemented in the form of software products. The software product is stored in a storage medium and contains several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to execute all or some of the steps of the methods described in the embodiments of the present application. The aforementioned storage medium includes any medium capable of storing program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0325]

[0345] The above merely describes specific implementations of the present application and is not intended to limit the protection scope of the present application. Any changes or substitutions that can be easily grasped by those skilled in the art within the technical scope disclosed in the present application shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall follow the protection scope of the claims.

Claims

1. A method for validating system information, comprising: a step in which a terminal device receives first system information broadcast by a wireless access network device, wherein the first system information includes a non-public network (NPN) identification information list and first associated information, and the NPN identification information list includes at least one NPN identification information; and a step in which, when a first NPN identification information in the NPN identification information list is the same as second NPN identification information stored in the terminal device, and the first associated information is the same as second associated information stored in the terminal device, the terminal device determines that second system information is valid, wherein the second system information includes the second NPN identification information and the second associated information; wherein a primary public land mobile network (PLMN) is identified based on a PLMN identifier (ID) included in the NPN identification information list, and instruction information added to at least any one of the PLMN IDs included in the first associated information and the second associated information.

2. The method according to claim 1, wherein the NPN identification information includes a public land mobile network (PLMN) identifier (ID) and a network ID (NID).

3. The method according to claim 1, wherein the NPN identification information includes a PLMN ID and a closed access group (CAG).

4. The method according to any one of claims 1 to 3, wherein the first associated information and the second associated information include at least one of the following items: area scope, system information area ID, value tag, and cell identifier.

5. A terminal device, comprising: a communication unit configured to receive first system information broadcast by a wireless access network device, wherein the first system information includes a non-public network (NPN) identification information list and first associated information, and the NPN identification information list includes at least one NPN identification information; and A processing unit configured to determine that second system information is valid when first NPN identification information in the NPN identification information list is the same as second NPN identification information stored in the terminal device and the first associated information is the same as second associated information stored in the terminal device, the second system information including the second NPN identification information and the second associated information; A terminal device including the public land mobile network (PLMN) identifier (ID) included in the NPN identification information list, and a primary PLMN is identified based on at least one of the PLMN IDs included in the first associated information and the second associated information and instruction information added thereto. **Claim 6** The terminal device according to claim 5, wherein the NPN identification information includes a public land mobile network (PLMN) identifier (ID) and a network ID (NID). **Claim 7** The terminal device according to claim 5, wherein the NPN identification information includes a PLMN ID and a closed access group (CAG). **Claim 8** The terminal device according to any one of claims 5 to 7, wherein the first associated information and the second associated information include at least one of the following items: area scope, system information area ID, value tag, and cell identifier. **Claim 9** A communication device including a memory and a processor, the memory being configured to store computer program executable instructions, and the processor being configured to activate the computer program executable instructions to execute the method according to any one of claims 1 to 4. **Claim 10** A communication device including a processor, the processor being coupled to a memory, the memory being configured to store computer program executable instructions, and the processor being configured to activate the computer program executable instructions to execute the method according to any one of claims 1 to 4. **Claim 11** A computer-readable storage medium including a computer program, wherein when the computer program is executed on a computer, the computer is capable of executing the method according to any one of claims 1 to 4.

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