Communication method and related device

Abstract

The invention provides a communication method and a related device, which are beneficial to reducing the time delay of acquiring registration information, and the method can be applied to a satellite communication system, such as an NTN (Network Temporary Network). The method comprises the steps that a first network device sends first registration information to terminal equipment, the terminal equipment sends the first registration information to a second network device, and the second network device completes registration of the terminal equipment in a second core network based on the first registration information. Wherein the first network device is a network device in a first core network, and the second network device is a network device in a second core network.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly to a communication method and related apparatus. Background Technology

[0002] Non-terrestrial networks (NTNs) are characterized by long communication distances, large coverage areas, and flexible networking. They can provide services to both fixed terminals and various mobile terminals. Due to the dynamic nature of NTN network topology, whether the core network is deployed on the ground or on a satellite, the movement of NTN equipment (e.g., satellites, drones) will cause changes in the core network parameters (e.g., registration information) of the users. The former is due to the movement of NTN equipment causing access network nodes to connect to different core networks, while the latter is due to the movement of the core network itself. When the core network parameters of the users change, the terminal devices need to perform operations such as registration updates and inter-network roaming.

[0003] When a terminal device roams across different networks, the target core network needs to obtain the registration information from the source core network. The target core network can then complete the cross-network registration based on the terminal device's registration information from the source core network.

[0004] Currently, the core network experiences significant latency in obtaining registration information. Summary of the Invention

[0005] This application provides a communication method and related apparatus, which helps to reduce the latency of obtaining registration information.

[0006] Firstly, a communication method is provided that can be applied to the terminal side, such as a terminal device or a communication module within a terminal device, or a circuit or chip (such as a modem chip, also known as a baseband chip, or a system-on-chip (SoC) chip or system-in-package (SIP) chip containing a modem core) within the terminal device. The following description uses a terminal device as an example.

[0007] The method includes: receiving first registration information from a first network device, wherein the first registration information is the registration information of a terminal device in a first core network, and the first network device is a network device in the first core network; and sending the first registration information to a second network device, wherein the second network device is a network device in a second core network. Specifically, the terminal device sending the first registration information to the second network device is used by the second network device to complete the registration of the terminal device in the second core network.

[0008] In this application, the first core network and the second core network are different core networks, and the terminal device roams from the first core network to the second core network. A first network device in the first core network can send the terminal device's registration information from the first core network to the terminal device. Then, when the terminal device roams to the second core network, it can send its registration information from the first core network to a second network device in the second core network. Compared to existing solutions where the second core network needs to obtain the terminal device's registration information from the first core network, the technical solution of this application helps reduce the latency for the second core network to obtain the terminal device's registration information from the first core network.

[0009] Furthermore, in scenarios where the core network is deployed on NTN devices, the interface between the first and second core networks may not be stable due to the high-speed movement of the NTN devices. Therefore, the second core network may not be able to directly obtain the registration information of the terminal device in the first core network. However, in the technical solution of this application, the terminal device interacts with the second core network to obtain the registration information of the terminal device in the first core network. Since the terminal device usually moves at a slower speed and the interface between it and the core network is more stable, the acquisition of registration information is more stable and timely.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, sending the first registration information to the second network device includes: sending a first request message to the second network device, the first request message being used to request registration of the second core network, the first request message including the first registration information.

[0011] In this application, when requesting registration with the second core network, the terminal device can send the first registration information along with the registration request to the second network device in the second core network, which helps to save signaling overhead.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, before sending the first registration information to the second network device, the method further includes: receiving a second request message from the second network device, the second request message being used to request the first registration information. Sending the first registration information to the second network device includes: sending the first registration information to the second network device based on the second request message.

[0013] In this application, the terminal device can send the first registration information to the second network device based on the request of the second network device, thus making the method of obtaining the first registration information more flexible.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, after sending the first registration information to the second network device, the method further includes: receiving second registration information from the second network device, wherein the second registration information is the registration information of the terminal device in the second core network, and the second registration information is generated based on the first registration information.

[0015] In this application, the terminal device receives the registration information of the terminal device in the second core network, so that the terminal device can provide the registration information of the terminal device in the second core network to other core networks in roaming scenarios.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, the first registration information includes the signature information of the first core network.

[0017] In this application, the first registration information includes the signature information of the first core network, which means that the first registration information is legally generated by the first core network, thus helping to ensure the legality of the first registration information.

[0018] In conjunction with the first aspect, in some implementations of the first aspect, before receiving the first registration information from the first network device, the method further includes: sending a third request message to the first network device, the third request message being used to request registration of the first core network, the third request message also indicating a pair of public and private keys, the private key being used to generate signature information, and the public key being used to verify the signature information.

[0019] In this application, the terminal device can indicate a pair of public and private keys in the registration request sent to the first network device, which helps to save signaling overhead.

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: sending a first signal to a third network device when a triggering condition is met, the first signal including the result of the first registration information after mapping transformation, the first signal being used to determine whether the first registration information is the latest version of the registration information of the terminal device in the first core network, and the third network device being a network device in the first core network.

[0021] In this application, the terminal device sending a first signal to the third network device can be regarded as requesting the third network device to verify whether the registration information maintained by the terminal device is the latest version of the registration information of the terminal device in the first core network. This is beneficial for the terminal side and the network side to keep the registration information synchronized and improve the reliability and availability of the registration information.

[0022] In conjunction with the first aspect, in some implementations of the first aspect, the triggering conditions include one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: receiving first indication information from a third network device, the first indication information being used to indicate a triggering condition.

[0024] In this application, the triggering condition for sending the first signal is indicated by the first core network. Alternatively, the triggering condition for sending the first signal can also be predefined by the protocol.

[0025] In conjunction with the first aspect, in some implementations of the first aspect, the method further includes: receiving second indication information from a fourth network device, the second indication information being used to indicate the latest version of the registration information of the terminal device in the first core network, wherein the fourth network device is a third network device, or the fourth network device is a network device in the second core network; and updating the first registration information to the latest version of the registration information.

[0026] In this application, the terminal device updates and maintains the registration information based on the instructions of the fourth network device. This helps to keep the registration information synchronized between the terminal side and the network side, and improves the reliability and availability of the registration information.

[0027] Secondly, a communication method is provided, which can be applied to a first network device, such as an access and mobility management function (AMF) network element, or a communication module in an AMF network element, or a circuit or chip (such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core) in an AMF network element responsible for communication functions.

[0028] The method includes: sending first registration information to a terminal device, wherein the first registration information is the registration information of the terminal device in a first core network, and the first network device is a network device in the first core network.

[0029] In this application, after the terminal device registers with the first core network, the first network device can send the first registration information of the terminal device to the terminal device in the first core network. This allows the terminal device to send the first registration information to the second network device in the second core network when it roams to other core networks (e.g., the second core network). This helps to reduce the interaction latency of the first registration information and improve the stability and timeliness of obtaining the registration information.

[0030] In conjunction with the second aspect, in some implementations of the second aspect, the first registration information includes the signature information of the first core network.

[0031] In this application, the first registration information includes the signature information of the first core network, which means that the first registration information is legally generated by the first core network, thus helping to ensure the legality of the first registration information.

[0032] In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: obtaining a pair of private keys and public keys, wherein the private key is used to generate the signature information and the public key is used to verify the signature information; and signing the first registration information based on the private key to generate signature information.

[0033] In this application, the first network device can sign the first registration information, which helps to ensure the legality of the first registration information.

[0034] In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: sending a public key to a second network device, wherein the second network device is a network device in a second core network.

[0035] In this application, the first network device can interact with the second network device using the public key corresponding to the signature information, which facilitates the verification of the signature information's legitimacy. In other words, the public key can be exchanged between different networks.

[0036] Thirdly, a communication method is provided, which can be applied to a second network device, such as an AMF network element, or a communication module in an AMF network element, or a circuit or chip in an AMF network element that is responsible for communication functions (such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core).

[0037] The method includes: receiving first registration information from a terminal device, wherein the first registration information is the registration information of the terminal device in a first core network, and the second network device is a network device in a second core network; and completing the registration of the terminal device in the second core network based on the first registration information.

[0038] In this application, the terminal device roams from the first core network to the second core network. The second network device in the second core network can receive the first registration information of the terminal device in the first core network sent by the terminal device. This helps to reduce the latency of obtaining the first registration information and improve the stability and timeliness of obtaining the registration information.

[0039] In conjunction with the third aspect, in some implementations of the third aspect, the method further includes: sending second registration information to the terminal device, the second registration information being the registration information of the terminal device in the second core network, and the second registration information being generated based on the first registration information.

[0040] In this application, the second network device sends the registration information of the terminal device in the second core network to the terminal device, so that the terminal device can provide the registration information of the terminal device in the second core network to other core networks in roaming scenarios.

[0041] In conjunction with the third aspect, in some implementations of the third aspect, receiving first registration information from a terminal device includes: receiving a first request message from the terminal device, the first request message being used to request registration of a second core network, the first request message including first registration information.

[0042] In this application, when requesting registration with the second core network, the terminal device can send the first registration information along with the registration request to the second network device in the second core network, which helps to save signaling overhead.

[0043] In conjunction with the third aspect, in some implementations of the third aspect, before receiving the first registration information from the terminal device, the method further includes: sending a second request message to the terminal device, the second request message being used to request the first registration information.

[0044] In this application, the second network device can request the terminal device's registration information in the first core network from the terminal device, thus making the method of obtaining the first registration information more flexible.

[0045] In conjunction with the third aspect, in some implementations of the third aspect, the first registration information includes the signature information of the first core network.

[0046] In this application, the first registration information includes the signature information of the first core network, which means that the first registration information is legally generated by the first core network, thus helping to ensure the legality of the first registration information.

[0047] In conjunction with the third aspect, in some implementations of the third aspect, the method further includes: receiving a public key from a first network device, wherein the first network device is a network device in a first core network, and the public key is used to verify signature information.

[0048] In this application, the first network device can interact with the second network device using a public key to generate signature information, which is beneficial for verifying the legitimacy of the signature information.

[0049] Fourthly, a communication method is provided that can be applied to the terminal side, such as a terminal device or a communication module in a terminal device, or a circuit or chip in a terminal device responsible for communication functions (such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core). The following description uses a terminal device as an example.

[0050] The method includes: receiving a first session context from a fifth network device, wherein the first session context is a session context of a terminal device in the fifth network device, and the fifth network device is a network device in a third core network; and sending the first session context to a sixth network device, wherein the sixth network device is a network device in a fourth core network.

[0051] In this application, the fifth network device and the sixth network device are different network devices. The third core network and the fourth core network can be the same core network. That is, the fifth network device and the sixth network device are two network devices in a scenario of switching between old and new network devices in the same core network. The fifth network device is the old network device, or the network device before the switch, and the sixth network device is the new network device, or the network device after the switch. The third core network and the fourth core network can also be different core networks. That is, two core networks in a scenario of inter-network roaming of terminal devices. The third core network is the core network registered by the terminal device before roaming, and the fourth core network is the core network registered by the terminal device after roaming.

[0052] In this application, the fifth network device in the third core network can send the first session context of the terminal device in the fifth communication device to the terminal device for storage. Subsequently, in inter-network roaming scenarios or during the switching between old and new network devices, the terminal device can send the first session context to the sixth network device in the fourth core network. Thus, the sixth network device can establish a session for the terminal device in the sixth network device based on the first session context, or update the session context of the terminal device in the sixth network device. Compared to existing solutions where the fourth core network needs to obtain the session context from the third core network, the technical solution of this application helps reduce the latency of obtaining the terminal device's session context in the third core network, making the acquisition more timely and effective.

[0053] In conjunction with the fourth aspect, in some implementations of the fourth aspect, sending the first session context to the sixth network device includes: sending a fourth request message to the sixth network device, the fourth request message being used to request the establishment of the first session, the fourth request message including the first session context.

[0054] In this application, when a terminal device requests to establish a session in a sixth network device, it can send the first session context along with the session establishment request to the sixth network device in the fourth core network, which helps to save signaling overhead.

[0055] In conjunction with the fourth aspect, in some implementations of the fourth aspect, before sending the first session context to the sixth network device, the method further includes: receiving a fifth request message from the sixth network device, the fifth request message being used to request the first session context. Sending the first session context to the sixth network device includes: sending the first session context to the sixth network device based on the fifth request message.

[0056] In this application, the terminal device can send the first session context to the sixth network device based on a request from the sixth network device, thus making the method of obtaining the first session context more flexible.

[0057] In conjunction with the fourth aspect, in some implementations of the fourth aspect, after sending the first session context to the sixth network device, the method further includes: receiving a second session context from the sixth network device, the second session context being the session context of the first session of the terminal device in the sixth network device, the second session context being generated based on the first session context.

[0058] In this application, the terminal device receives the session context of the terminal device in the sixth network device, so that the terminal device can provide the session context of the terminal device in the sixth network device to other core networks in roaming scenarios or when switching between old and new network devices.

[0059] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the first session context includes the signature information of the third core network.

[0060] In this application, the first session context includes the signature information of the third core network, which means that the first session context is legally generated by the third core network, thus helping to ensure the legitimacy of the first session context.

[0061] In conjunction with the fourth aspect, in some implementations of the fourth aspect, before receiving the first session context from the fifth network device, the method further includes: sending a sixth request message to the fifth network device, the sixth request message being used to request the establishment of a second session, the sixth request message also indicating a pair of public and private keys, the private key being used to generate the signature information, and the public key being used to verify the signature information.

[0062] In this application, the terminal device can indicate a pair of public and private keys in the session establishment request sent to the fifth network device, which helps to save signaling overhead.

[0063] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the method further includes: sending a second signal to the seventh network device when the triggering condition is met, the second signal including the result of the first session context after mapping transformation, the second signal being used to determine whether the first session context is the latest version in the first core network, and the seventh network device being a network device in the third core network.

[0064] In this application, the terminal device sending a second signal to the seventh network device can be regarded as requesting the seventh network device to verify whether the session context maintained by the terminal device is the latest version of the session context of the terminal device in the fifth network device. This is beneficial for the terminal side and the network side to maintain the synchronization of the session context and improve the reliability and availability of the session context.

[0065] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the triggering condition includes one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0066] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the method further includes: receiving third indication information from a seventh network device, the third indication information being used to indicate the triggering condition for sending a second signal, the second signal being used to determine whether the first session context is the latest version in the third core network, and the seventh network device being a network device in the third core network.

[0067] In this application, the triggering condition for sending the second signal is indicated by the third core network. Alternatively, the triggering condition for sending the second signal can also be predefined by the protocol.

[0068] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the method further includes: receiving fourth indication information from an eighth network device, the fourth indication information being used to indicate the latest version of the session context of the terminal device in a fifth network device, the eighth network device being a seventh network device, or the eighth network device being a network device in a fourth core network; and updating the first session context to the latest version of the session context.

[0069] In this application, the terminal device updates and maintains the session context based on the instructions of the eighth network device, which helps the terminal side and the network side maintain the synchronization of the session context and improves the reliability and availability of the session context.

[0070] Fifthly, a communication method is provided, applied to a fifth network device, such as a session management function (SMF) network element, or a communication module in an SMF network element, or a circuit or chip (such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core) in an SMF network element responsible for communication functions.

[0071] The method includes: receiving a sixth request message from a terminal device, the sixth request message being used to request the establishment of a second session; and sending a first session context to the terminal device, the first session context being the session context of the second session of the terminal device in a fifth network device, the fifth network device being a network device in a third core network.

[0072] In this application, after establishing a session between the terminal device and the terminal device, the fifth network device can send the first session context of the terminal device in the fifth network device to the terminal device. This is so that when the terminal device roams to other core networks (e.g., the fourth core network) or switches to the sixth network device, the first session context can be sent to the sixth network device in the fourth core network. This helps to reduce the interaction latency of the first registration information and improve the stability and timeliness of obtaining registration information.

[0073] In conjunction with the fifth aspect, in some implementations of the fifth aspect, the first session context includes the signature information of the third core network.

[0074] In this application, the first session context includes the signature information of the third core network, which means that the first session context is legally generated by the third core network, thus helping to ensure the legitimacy of the first session context.

[0075] In conjunction with the fifth aspect, in some implementations of the fifth aspect, the method further includes: obtaining a pair of private and public keys, wherein the private key is used to generate the signature information and the public key is used to verify the signature information; and, signing the first session context based on the private key to generate the signature information.

[0076] In this application, the fifth network device can sign the first session context, which helps to ensure the legitimacy of the first session context.

[0077] In conjunction with the fifth aspect, in some implementations of the fifth aspect, the method further includes: sending the public key to a sixth network device, which is a network device in the fourth core network.

[0078] In this application, the fifth network device can interact with the sixth network device using the public key corresponding to the signature information, which facilitates the verification of the session context's legitimacy. In other words, the public key can be exchanged between different networks.

[0079] In a sixth aspect, a communication method is provided, applied to a sixth network device, such as an SMF network element, or a communication module in an SMF network element, or a circuit or chip in an SMF network element responsible for communication functions (such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core).

[0080] The method includes: receiving a first session context from a terminal device, wherein the first session context is a session context of the terminal device in a fifth network device, and the fifth network device is a network device in a third core network; and, based on the first session context, establishing a session of the terminal device in a sixth network device, or updating the session context of the terminal device in the sixth network device, wherein the sixth network device is a network device in the third core network, or the sixth network device is a network device in a fourth core network.

[0081] In this application, the third core network is different from the fourth core network, and the terminal device roams from the third core network to the fourth core network. Alternatively, the third core network and the fourth core network are the same core network, and the terminal device switches from the fifth network device to the sixth network device, i.e., a scenario of switching between old and new network devices. The sixth network device can receive the first session context of the terminal device in the fifth network device sent by the terminal device. This helps to reduce the latency of obtaining the first session context and improve the stability and timeliness of obtaining registration information.

[0082] In conjunction with the sixth aspect, in some implementations of the sixth aspect, after establishing a session of the terminal device in the sixth network device based on the first session context, or updating the session context of the terminal device in the sixth network device, the method further includes: sending a second session context to the terminal device, the second session context being the session context of the terminal device in the sixth network device, the second session context being generated based on the first session context.

[0083] In this application, the sixth network device sends the session context of the terminal device in the sixth network device to the terminal device, so that the terminal device can provide the session context of the terminal device in the sixth network device to other network devices in subsequent roaming scenarios or when switching between old and new network devices.

[0084] In conjunction with the sixth aspect, in some implementations of the sixth aspect, receiving a first session context from a terminal device includes: receiving a fourth request message from the terminal device, the fourth request message being used to request the establishment of a first session, the fourth request message including the first session context.

[0085] In this application, when a terminal device requests to establish a session in a sixth network device, it can send the first session context along with the session establishment request to the sixth network device, which helps to save signaling overhead.

[0086] In conjunction with the sixth aspect, in some implementations of the sixth aspect, before receiving the first session context from the terminal device, the method further includes: sending a fifth request message to the terminal device, the fifth request message being used to request the first session context.

[0087] In this application, the sixth network device can request the terminal device's session context in the fifth network device, thus making the method of obtaining the first session context more flexible.

[0088] In conjunction with the sixth aspect, in some implementations of the sixth aspect, the first session context includes the signature information of the third core network.

[0089] In this application, the first session context includes the signature information of the third core network, which means that the first session context is legally generated by the third core network, thus helping to ensure the legitimacy of the first session context.

[0090] In conjunction with the sixth aspect, in some implementations of the sixth aspect, the method further includes: receiving a public key from a fifth network device, the public key being used to verify the signature information.

[0091] In this application, the fifth network device can interact with the sixth network device using the public key corresponding to the signature information, which facilitates the verification of the session context's legitimacy. In other words, the public key can be exchanged between different networks.

[0092] In a seventh aspect, a communication apparatus is provided for executing the method in any possible implementation of any of the above aspects. Specifically, the apparatus includes a module for executing the method in any possible implementation of any of the above aspects.

[0093] In one design, the device may include modules that perform the methods / operations / steps / actions described in any of the above aspects. These modules may be hardware circuits, software, or a combination of hardware circuits and software.

[0094] In another design, the device is a communication chip, which may include input circuitry or interface for transmitting information or data, and output circuitry or interface for receiving information or data.

[0095] In another design, the device is a terminal device or a network device, which may include a transmitter for sending information or data and a receiver for receiving information or data.

[0096] In another design, the device is used to perform any possible implementation of the methods described above, and the device can be configured in a terminal device or a network device.

[0097] Eighthly, a communication device is provided, comprising at least one processor for calling and running a computer program from a memory, such that the device performs the method in any possible implementation of any of the preceding aspects.

[0098] Optionally, the device further includes a memory for storing instructions and data. The memory is coupled to the processor, which, when executing the instructions stored in the memory, can implement the methods described in the foregoing aspects.

[0099] Optionally, the device may also include a transmitter and a receiver, which may be separate or integrated together and referred to as a transceiver.

[0100] Ninthly, a computer program product is provided, the computer program product comprising: a computer program (also referred to as code or instructions), which, when the computer program is run, causes a computer to perform a method in any possible implementation of any of the above aspects.

[0101] In a tenth aspect, a computer-readable storage medium is provided that stores a computer program (also referred to as code or instructions) that, when run on a computer, causes the computer to perform the method in any possible implementation of any of the above aspects.

[0102] Eleventhly, a communication system is provided, comprising the terminal device of the first aspect, the first network device of the second aspect, and the second network device of the third aspect.

[0103] In a twelfth aspect, a communication system is provided, comprising the terminal device of the fourth aspect, the fifth network device of the fifth aspect, and the sixth network device of the sixth aspect.

[0104] In a thirteenth aspect, this application provides a chip system including at least one processor for supporting the implementation of the functions involved in any possible implementation of any of the above aspects, such as receiving or processing data involved in the above methods.

[0105] In one possible design, the chip system also includes a memory for storing program instructions and data, which may be located within or outside the processor.

[0106] Optionally, the chip system may consist of chips or may include chips and other discrete components. Attached Figure Description

[0107] Figure 1 This is a schematic diagram of a network architecture for cross-network roaming;

[0108] Figure 2 This is a schematic diagram of the satellite communication architecture applicable to the embodiments of this application;

[0109] Figures 3 to 6 This is a schematic flowchart of the communication method provided in the embodiments of this application;

[0110] Figure 7 This is a schematic flowchart illustrating a method for synchronizing network parameters provided in an embodiment of this application;

[0111] Figure 8 and Figure 9 This is a schematic block diagram of a communication device provided in an embodiment of this application. Detailed Implementation

[0112] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0113] Before introducing the communication method and related apparatus provided in the embodiments of this application, the following points should be made first.

[0114] First, in the embodiments shown below, the terms and English abbreviations, such as AMF, SMF, session context, registration information, etc., are merely exemplary examples given for ease of description and should not constitute any limitation on this application. This application does not preclude the possibility of defining other terms that can achieve the same or similar functions in existing or future agreements.

[0115] Second, in the embodiments shown below, the terms "first," "second," and various numerical designations are merely for descriptive convenience to distinguish identical or similar items with substantially the same function and purpose. For example, "first network device" and "second network device" are only used to distinguish different network devices and do not limit their order of execution, nor are they used to limit the scope of the embodiments of this application. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., are not necessarily different. For example, the third core network and the fourth core network can be the same core network or different core networks.

[0116] Third, "at least one" means one or more, while "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0117] Fourth, in this application, "instruction" can include direct and indirect instructions, explicit and implicit instructions, and instructions used for determination. The information indicated by a certain message (such as the first instruction message) is called the information to be instructed. For example, the first instruction message in the embodiments of this application indicates one or more contents. In specific implementation, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index. It can also indirectly indicate the information to be instructed by indicating other information, where there is a correlation between the other information and the information to be instructed; or it can only indicate a part of the information to be instructed, while the other parts are known or pre-agreed upon. For example, the instruction can be implemented by using a pre-agreed (e.g., protocol predefined) arrangement of various information, thereby reducing the instruction overhead to a certain extent. This application does not limit the specific method of instruction. It is understood that for the sender of the instruction information, the instruction information can be used to indicate the information to be instructed, and for the receiver of the instruction information, the instruction information can be used to determine the information to be instructed.

[0118] Fifth, in this application, "send" and "receive" indicate the direction of signal transmission. For example, "send first registration information to a terminal device" can be understood as the destination of the first registration information being the terminal device, which may include direct transmission via the air interface or indirect transmission via the air interface by other units or modules. "Receive first registration information from a first network device" can be understood as the source of the first registration information being the first network device, which may include direct reception from the first network device via the air interface or indirect reception from the network device via the air interface by other units or modules. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface.

[0119] In other words, sending and receiving can occur between devices, such as between terminal devices and network devices; or they can occur within a device, such as between components, modules, chips, software modules, or hardware modules within a device via a bus, wiring, or interface.

[0120] Sixth, in this application, "when," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, not to a time limit, nor to requiring the device to perform a judgment action, nor implying any other limitations. Unless otherwise specified, "if" and "if" are interchangeable, and "when" and "under the circumstances" are interchangeable. "When" and "if" / "if" are interchangeable.

[0121] Seventh, in this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0122] Eighth, in this application, the solutions in each embodiment can be used in a reasonable combination, and the explanations or descriptions of various terms, similar operations, or steps appearing in the embodiments can be referenced or explained to each other in the various embodiments, without limitation.

[0123] The relevant technologies and concepts involved in this application are introduced below.

[0124] 1. NTN communication

[0125] Compared to terrestrial networks (TN), NTN communication offers advantages such as wider coverage and more flexible networking, enabling seamless global network coverage. The NTN network serves both as a supplement to current terrestrial networks and as an independent communication system providing users with high-speed global network access. Currently, research institutes, communication organizations, and communication companies worldwide are involved in researching NTN communication technologies and developing standards, striving to build a unified communication network encompassing air, space, and terrestrial communication.

[0126] NTN communication involves networking using equipment such as drones, high-altitude platforms, and satellites to provide data transmission and voice communication services to terminals. High-altitude platform equipment is typically located at an altitude of 8–50 km above the ground. Based on the satellite's orbital altitude, satellite communication systems can be categorized into three types: geostationary earth orbit (GEO) satellite communication systems (also known as synchronous orbit satellite systems), medium earth orbit (MEO) satellite communication systems, and low earth orbit (LEO) satellite communication systems.

[0127] GEO satellites orbit at an altitude of 35,786 km. Their main advantages are that they can remain relatively stationary relative to the ground and provide a large coverage area. However, GEO satellite communication also has significant disadvantages: 1) The long distance between GEO satellites and Earth results in high free-space propagation loss, leading to tight communication link budgets. To increase transmit / receive gain, larger aperture antennas are required for the satellites; 2) Communication transmission latency is high, reaching approximately 500 ms round-trip time, which cannot meet the needs of low-latency services; 3) GEO orbital resources are relatively scarce, launch costs are high, and coverage cannot be provided to the polar regions of Earth.

[0128] MEO satellites orbit at altitudes between 2000 and 35786 km. Their advantage is that they can achieve global coverage with a relatively small number of satellites. However, their orbital altitude is higher than LEO, resulting in significantly longer communication transmission delays. Considering both the advantages and disadvantages of MEO satellite communication, MEO satellites are primarily used for positioning and navigation.

[0129] LEO satellites orbit at altitudes ranging from 300 to 2000 km. Compared to MEO and GEO orbits, LEO satellites operate at lower altitudes, offering advantages such as shorter data propagation delays, lower transmission losses, and lower launch costs. Therefore, LEO satellite communication has gained increasing attention in recent years.

[0130] In recent years, several companies have planned to build mega-LEO constellations, including thousands or even tens of thousands of LEO satellites. As the size of satellite constellations increases, more than one satellite will be present within the line of sight of a terminal. Since the improvement in system capacity from single-satellite transmission is limited, satellite systems are gradually evolving from single-satellite transmission to multi-satellite collaborative transmission in order to effectively increase the capacity of overlapping satellite coverage areas. Utilizing multi-satellite collaborative transmission can reduce the requirements for single-satellite transmission capabilities, thereby reducing the manufacturing cost of a single satellite. Multi-satellite collaborative transmission is a key technology for future satellite communication systems.

[0131] 2. Cross-network roaming

[0132] Inter-network roaming is a feature of 5G standalone (SA) networks. In 5G SA mode, 5G users with contracts with specific operators can access the visited operator's 5G network and use 5G services through roaming. Specifically, it supports user registration and access on the visited operator's 5G network, with the home operator's 5G network providing session anchors, policy information, and contract information.

[0133] For example, when a user who has a contract with operator A moves to an area where operator A's 5G network is not covered, the user will be unable to continue using 5G services. If operator B has 5G network coverage in that area, the user can access operator B's 5G network and continue using 5G services.

[0134] In other scenarios, users may roam to different network coverage areas or service areas of the same operator. For example, a user with a contract with operator A may move from operator A's service area 1 to operator A's service area 2. Since operator A deploys different networks in service area 1 and service area 2, it can be understood that the user has crossed the coverage areas of different base stations of operator A. Different base stations are connected to different network functions (NFs) in the core network. NFs can also be called network elements.

[0135] Figure 1 This is a schematic diagram of a network architecture for inter-network roaming, taking the 5G network architecture based on service-based architecture (SBA) in the roaming scenario defined during the 3GPP standardization process as an example. Figure 1As shown, this network architecture includes both the home public land mobile network (HPLMN) and the visited public land mobile network (VPLMN). In cross-network roaming scenarios, the NF of the visited operator and the NF of the home operator belong to different operators, and NFs from different operators need to interact through a security edge protection proxy (SEPP). For example... Figure 1 As shown,

[0136] SEPP is an interoperability and transfer point between different operator's 5G stand-alone (SA) networks. As a boundary gateway between the control planes of the operator's core network (CN), it is used to transfer Hypertext Transfer Protocol (HTTP) signaling in cross-network roaming scenarios. All cross-operator information transmissions need to be processed and forwarded through SEPP. Introducing SEPP into a 5G system enables signaling aggregation, topology hiding, and security protection for cross-PLMN (Plane Network Name) inter-NF (Network Function) interaction processes.

[0137] An operator's network architecture can include three parts, namely the terminal part (e.g. Figure 1 The network consists of user equipment (UE), data network (DN), and carrier network (PLMN). The carrier network portion may include, but is not limited to, the radio access network ((RAN)) and the network center (CN). The functions of the equipment or network elements in each portion are briefly described below.

[0138] The CN component may include, but is not limited to, the following network elements: User Plane Function (UPF) elements, AMF elements, SMF elements, Unified Data Management (UDM) elements, Network Exposure Function (NEF) elements, Policy Control Function (PCF) elements, Network Repository Function (NRF) elements, Network Slice Selection Function (NSSF) elements, and Authentication Server Function (AUSF) elements. Optionally, this network architecture may also include Network Data Analytics Function (NWDAF) elements.

[0139] An AMF (Access Management Module) network element is a network element, module, or component that provides access management functions. It is mainly responsible for signaling processing, such as access control, mobility management, attach and detach, and gateway selection. When an AMF network element provides services to a session in a terminal, it provides control plane storage resources for that session to store the session identifier and the SMF identifier associated with the session identifier.

[0140] SMF network elements are network elements, modules, or components responsible for handling user services, such as user plane function selection, user plane function redirection, Internet Protocol (IP) address allocation, bearer establishment, modification and release, and QoS control.

[0141] The UPF network element is responsible for forwarding and receiving user data in the terminal. The UPF can receive user data from the DN and transmit it to the UE through the RAN node; the UPF network element can also receive user data from the UE through the RAN node and forward it to the DN. The transmission resources and scheduling functions that provide services to the UE in the UPF network element are managed and controlled by the SMF network element.

[0142] The NEF (Network Element Framework) element resides between the carrier network and third-party application function network elements (and possibly some internal application function network elements). It manages publicly accessible network data. Third-party application function network elements need to access the carrier network's internal data through the NEF element. The NEF provides corresponding security guarantees to ensure the security of third-party application function network elements accessing the carrier network. The NRF (Network Request Framework) element supports network function registration and discovery, including network function registration, management, and status detection, achieving automated management of all network functions. Each network function needs to register with the NRF before it can provide services. Registration information includes the network function type, address, and service list.

[0143] The NWDAF network element supports collecting data from other network functions, collecting data from operation administration and maintenance (OAM) functional entities, and providing analytical information to other network functions.

[0144] A terminal is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from RAN nodes within the RAN. Terminals can also be referred to as terminal devices, terminal equipment, user equipment (UE), mobile stations, mobile terminals, etc. Terminals can be widely used in various scenarios, such as satellite communication (e.g., NTN), device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), the Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, intelligent transportation, and smart cities. Specifically, a terminal can be a mobile phone, tablet computer, computer with wireless transceiver capabilities, wearable device, vehicle, aircraft, ship, robot, robotic arm, smart home device, etc. The embodiments of this application do not limit the specific technology or device form used in the terminal.

[0145] RAN nodes are used to help terminals achieve wireless access. RAN nodes can be satellite base stations in NTN communication systems or base stations in future mobile communication systems. Alternatively, RAN nodes can be modules or units that perform some of the functions of a base station; for example, they can be centralized units (CUs) or distributed units (DUs). The functions of a CU can be implemented by a single entity or by different entities. For example, the functions of a CU can be further divided, such as separating the control plane (CP) and the user plane (UP), i.e., the CU's control plane (CU-CP) and user plane (CU-UP). RAN nodes can be macro base stations, micro base stations, indoor stations, relay nodes, or host nodes, etc. This application does not limit the specific technology or equipment form used in the RAN node. RAN nodes can also be called RAN equipment, access network equipment, etc.

[0146] Communication between RAN nodes and terminals, between RAN nodes, and between terminals can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can also be conducted using spectrum below 6 gigahertz (GHz), spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0147] In the embodiments of this application, the functions of the RAN node can be executed by modules (such as chips) within the RAN node, or by a control subsystem that includes RAN node functions. This control subsystem, including RAN node functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal can be executed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions.

[0148] 3. Registration function of 5G system

[0149] Typically, terminal devices need to register with the network to perform the following functions and services: obtaining authorized network services, mobility tracking, and reachability detection. During the terminal device registration process, the core network assigns identification information to the terminal device and obtains its location information, routing information, subscription information, etc.

[0150] The registration function can be divided into the following scenarios: (1) Initial registration: The registration process is used for terminal devices to perform initial registration to the core network; (2) Mobility registration: When a terminal device discovers that it has entered the tracking area (TA) during its movement, and the connection management (CM) status is CM-CONNECTED or CM-IDLE, it needs to perform mobility registration; (3) Periodic registration update, or when a terminal device needs to update its capabilities and functions such as registration process and network protocol parameters, it can be achieved through the registration process.

[0151] In future NTN communication systems, the core network may be deployed on the ground or on NTN equipment. Regardless of whether the core network is deployed on the ground or on a satellite, the movement of the NTN equipment will cause changes to the core network parameters (e.g., registration information) serving users. The former is due to the NTN equipment moving, causing access network nodes to connect to different core networks; the latter is due to the core network itself moving. When the core network parameters serving users change, terminal devices need to perform operations such as registration updates and inter-network roaming.

[0152] When a terminal device roams across different networks, the target core network needs to obtain registration information from the source core network. The target core network can then complete the inter-network registration based on the terminal device's registration information from the source core network. However, in inter-network roaming scenarios, the target core network needs to first determine the terminal device's source core network before obtaining the registration information from that source core network, which can lead to significant latency in the registration process.

[0153] Among them, the source core network is the core network that the terminal device accesses before roaming to another network, and the target core network is the core network that the terminal device accesses after roaming to another network.

[0154] Figure 2 This is a schematic diagram of the satellite communication architecture applicable to embodiments of this application. Figure 2 Taking the next-generation radio access network (NG-RAN) as an example, this paper introduces the communication architecture between the terminal (UE) in the figure, NG-RAN, CN and DN in satellite communication.

[0155] Satellites can be categorized into two operating modes: transparent mode and regenerative mode. In transparent mode, the satellite functions as a relay, and the ground station functions as a base station or partially as one; in this case, the ground station can be considered a base station. In regenerative mode, the satellite possesses data processing capabilities and functions as a base station or partially as one; in this case, the satellite can also be considered a base station.

[0156] Satellites can provide wireless access services to terminals and schedule wireless resources for terminals accessing the network through the satellite. Satellites and terminals communicate via an air interface (which can be of various types, such as a 5G air interface). Specifically, satellites and ground stations can communicate via a next-generation (NG) interface, and satellites can interact with the core network through the ground station to exchange non-access stratum (NAS) signaling and user service data. Satellites can also communicate with each other via inter-satellite links (ISL).

[0157] Figure 3 This is a schematic flowchart illustrating a communication method 300 provided in an embodiment of this application. The steps of method 300 can be interactively executed by network devices on the terminal side and the network side. The terminal side includes, for example, a terminal device or a communication module within a terminal device, or a circuit or chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core) responsible for communication functions within the terminal device. The following description uses a terminal device as an example. The network device on the network side includes, for example, a network element or a communication module within a network element, or a circuit or chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core) responsible for communication functions within a network element.

[0158] It should be noted that the core network in this embodiment can also be replaced by a PLMN.

[0159] Method 300 includes steps S301 to S303. Optionally, method 300 also includes steps S304 to S311. The steps are described in detail below.

[0160] S301, the first network device sends first registration information to the terminal device, and the terminal device receives the first registration information accordingly.

[0161] The first registration information refers to the registration information of the terminal device in the first core network, which is the core network in which the terminal device registered before roaming to another core network. During the movement of the terminal device, it can roam from the service area of ​​the first core network to the service area of ​​another core network.

[0162] The first core network can be the home core network of the terminal device or a visited core network; this application does not limit this.

[0163] The first network device is a network device in the first core network. For example, the first network device is an AMF network element, or it can be a component (such as a processor, chip, or chip system) configured in the AMF network element, or it can be a logic module or software that can implement all or part of the AMF functions.

[0164] Optionally, the first registration information may include location information and network information.

[0165] Optionally, the initial registration information may further include the user's contract information and policy information.

[0166] The location information refers to the location information of the terminal device, or the location information of the RAN node to which the terminal device is connected. The location information can be at the cell level.

[0167] Network information may include information about the operator network to which the terminal device is contracted, such as information about the AMF network elements registered by the terminal device.

[0168] The contract information may include, but is not limited to: one or more single-network slice selection assistance information (S-NSSAI), the named data network (DNN) associated with each S-NSSAI, and key parameters of the protocol data unit (PDU) session associated with each DNN, such as the default and allowed PDU session types, the session and service continuity (SSC) mode of the PDU session, the 5G quality of service (QoS) parameters associated with the PDU session, and whether 4G / 5G handover is allowed.

[0169] Policy information may include, but is not limited to: UE route selection policy (URSP), access network discovery and selection policy (ANDSP), session-aggregate maximum bit rate (session-AMBR), and allocation and retention priority (ARP).

[0170] After receiving the first registration information, the terminal device can store the first registration information in the terminal device's storage unit so that it can be provided to the core network to which it is roaming in subsequent cross-network roaming scenarios.

[0171] In one possible design, the terminal device may include a separate storage unit, such as Figure 3 The terminal device shown includes a storage unit for storing the terminal device's registration information. This storage unit can be implemented in hardware, software, or a combination of both; this application does not limit this implementation.

[0172] It should be noted that this storage unit is deployed independently from the terminal device's internal / local storage unit. The communication module or circuits / chips responsible for communication functions in the terminal device cannot access this storage unit, but network elements in the core network can access it. For example... Figure 3 The first network device can directly write the first registration information into the storage unit. Direct writing means that after receiving the first registration information, the terminal device stores it directly into the independent storage unit without parsing it.

[0173] Alternatively, in this design, the first network device can indicate the type of the first registration information through an identifier, that is, indicate that the information received this time is the registration information of the terminal device. In this way, after the terminal device receives the first registration information, it can determine that the first registration information needs to be stored in the independent storage unit based on the identifier.

[0174] In another possible design, the initial registration information can be stored in the terminal device's internal storage unit, for example... Figure 4 In method 400, the terminal device does not involve a dedicated storage unit for storing registration information. After receiving the registration information, the terminal device can store the registration information in its internal storage unit. In this design, the baseband unit of the terminal device can parse the content of the first registration information.

[0175] It should be understood that the difference between method 300 and method 400 is that in method 300, S301 involves the first network device directly writing the first registration information into the storage unit of the terminal device. This storage unit can be an independent storage unit deployed at the factory to store registration information, different from the terminal device's own internal storage unit or local storage unit. In contrast, in method 400, S401 involves the first network device sending the first registration information to the terminal device. The baseband unit of the terminal device can parse the first registration information, determine its type, and store it in its internal storage unit. For a description of S402 to S411, please refer to the description of S302 to S311; further details will not be provided here.

[0176] S302, the terminal device sends the first registration information to the second network device, and the second network device receives the first registration information accordingly.

[0177] The second core network is the core network that the terminal device registers after roaming to another network. During the movement of the terminal device, the terminal device moves from the service area of ​​the first core network to the service area of ​​the second core network.

[0178] The second core network can be the home core network of the terminal device or a visited core network; this application does not limit this.

[0179] It should be noted that the first core network and the second core network are different. In one possible scenario, the first core network and the second core network are two different core networks deployed by the same operator in different regions; in another possible scenario, the first core network and the second core network are the core networks of two different operators.

[0180] For example, the first core network is the home core network (i.e., HPLMN) of the terminal device, which is the core network to which the terminal device is contracted, and the second core network is a visited core network (i.e., VPLMN) of the terminal device.

[0181] For example, the first core network is a core network visited by the terminal device, and the second core network is another core network visited by the terminal device.

[0182] The second network device is a different network device from the first network device. The second network device is a network device in the second core network. The second network device is, for example, an AMF network element, or a component (such as a processor, chip, or chip system) configured in the AMF network element, or a logic module or software that can realize all or part of the AMF functions.

[0183] It should be understood that the purpose of the terminal device sending the first registration information to the second network device is to enable the second network device to complete the registration of the terminal device in the second core network.

[0184] In the scenario of roaming across different networks, the terminal device obtains the first registration information from the aforementioned storage unit and sends the first registration information to the second network device.

[0185] S303, the second network device completes the registration of the terminal device in the second core network based on the first registration information.

[0186] The second network device can register the terminal device location information and network information from the first registration information with the UDM network element. At the same time, the second network device obtains the terminal device's subscription information, policy information, status subscription, etc. from the UDM network element. Then, the second communication device sends a registration success feedback to the terminal device, thus completing the registration of the terminal device in the second core network.

[0187] In this embodiment, during inter-network roaming, the first communication device can send the terminal device's first registration information in the first core network to the terminal device. Then, when the terminal device moves to the service area of ​​the second core network and needs to register with the second core network to obtain network services, the terminal device can send the first registration information to the second communication device in the second core network. In this way, the second communication device can complete the terminal device's registration in the second core network based on the first registration information. Compared to existing solutions where the second core network needs to obtain the terminal device's registration information from the first core network, the technical solution of this application helps reduce the latency for the second core network to obtain the terminal device's registration information from the first core network.

[0188] Furthermore, in scenarios where the core network is deployed on NTN devices, the interface between the first and second core networks may not be stable due to the high-speed movement of the NTN devices. Therefore, the second core network may not be able to directly obtain the registration information of the terminal device in the first core network. However, in the technical solution of this application, the terminal device interacts with the second core network to obtain the registration information of the terminal device in the first core network. Since the terminal device usually moves at a slower speed and the interface between it and the core network is more stable, the acquisition of registration information is more stable and timely.

[0189] In one possible implementation, S302 includes: the terminal device sending a first request message to the second network device, the first request message being used to request registration with the second core network, and the first request message including first registration information. Correspondingly, the second network device receives the first request message. Thus, when the terminal device moves to the service area of ​​the second core network and needs to register with the second core network, it sends the first registration information in the registration request message to the second network device, which helps reduce the signaling overhead of the terminal device. Furthermore, the second network device can obtain the first registration information from the first request message.

[0190] In another possible implementation, method 300 further includes S304: After receiving the registration request from the terminal device, the second network device sends a second request message to the terminal device. The second request message requests the terminal device's registration information in the first core network, i.e., the first registration information. Optionally, S302 includes: the terminal device sending the first registration information to the second network device based on the second request message. In this approach, the second network device can proactively request the terminal device's registration information in the first core network when it determines that the terminal device needs to register in the second core network, making this method more flexible. S304 can be executed before S302.

[0191] Optionally, method 300 further includes step S305: the second network device sends second registration information to the terminal device. The second registration information is the registration information of the terminal device in the second core network, and the second registration information is generated based on the first registration information. The second network device can adjust the first registration information based on the network resources of the second core network, for example, adjusting the supported S-NSSAI and the allowed PDU session types, thereby generating the second registration information. After receiving the second registration information, the terminal device can store the second registration information in a storage unit. Step S305 can be executed after step S303.

[0192] Optionally, the first network device may sign the first registration information using asymmetric cryptography, meaning the first registration information may include signature information from the first core network. For example, the first network device may use the private key of the first core network to sign the first registration information. After receiving the first registration information, the second network device needs to verify its legitimacy, that is, verify whether the first registration information was legitimately generated by the first core network. For example, the second network device may use the public key corresponding to the private key that generated the signature information to verify the signature information. If the verification passes, it indicates that the first registration information was legitimately generated by the first network device.

[0193] Optionally, the first network device may use the private key of the first core network to encrypt the first registration information in order to protect the integrity of the first registration information. In this way, after the terminal device receives the first registration information, it cannot parse the first registration information or tamper with the first registration information, which helps to ensure the security of the first registration information.

[0194] Optionally, method 300 further includes S306: the first network device obtains a pair of public and private keys, wherein the private key is used to generate the signature information and the public key is used to verify the signature information. S306 can be executed before S301.

[0195] In one possible implementation, the first network device obtains a pair of public and private keys, including: the first network device generates a pair of public and private keys itself.

[0196] In another possible implementation, the first network device obtains a pair of public and private keys, including: the first network device selecting a pair of public and private keys from a key store according to agreed rules. For example, the first network device selects a pair of private and public keys from the key store based on the identification information of the terminal device. The identification information of the terminal device may be, for example, a globally unique temporary UE identity (GUTI) or a subscription permanent identifier (SUPI), or identification information of the terminal device defined by other communication systems or future communication systems; this application embodiment does not limit this.

[0197] In another possible implementation, the first network device obtains a pair of public and private keys, including: the first network device receiving a pair of public and private keys indicated by the terminal device. In this approach, the terminal device can select a pair of private and public keys from a keystore and inform the first network device which pair was selected. Alternatively, the terminal device can inform the first network device of the selected pair of private and public keys during the registration process with the first core network.

[0198] For example, method 300 further includes S307: the terminal device sends a third request message to the first network device, the third request message being used to request registration with the first core network, the third request message also indicating a public key and a private key pair, the private key being used to generate the signature information, and the public key being used to verify the signature information. Accordingly, the first network device receives the third request message. Based on the private key indicated in the third request message, the first network device signs the terminal device's registration information (i.e., the first registration information) in the first core network, and then sends the first registration information to the terminal device, the first registration information including the signature information of the first core network. S307 can be executed before S301.

[0199] Optionally, after the terminal device sends a third request message to the first network device to initiate a registration request, the terminal device completes two-way authentication with the first core network, involving interaction between multiple network devices in the first core network, such as AMF, AUSF, and UDM. After authentication is completed, the first network device registers the terminal device's registration information with the UDM, such as location information and network information. Simultaneously, the first network device obtains the user's subscription information, policy information, and status subscription from the UDM. Afterward, the first network device sends a registration success feedback to the terminal device.

[0200] Optionally, successful registration feedback may include the GUTI assigned to the terminal device, a list of tracking areas, slice parameters, functions supported by the first core network, and parameters for the periodic registration timer.

[0201] The functions supported by the first core network can be understood as the types of services that the first core network can provide to terminal devices after they register with the first core network, such as ultra-reliable and low-latency communications (URLLC) and enhanced mobile broadband (eMBB).

[0202] It should be noted that in the embodiments of this application, "send" and "receive" refer to the direction of signal transmission, and are not limited to direct "send" and "receive" or indirect "send" and "receive" through other devices or nodes.

[0203] For example, the first network device sends first registration information to the terminal device, indicating that the receiving end of the first registration information is the terminal device. The first network device can send the first registration information directly to the terminal device via the air interface, or it can send the first registration information indirectly to the terminal device through other devices or nodes. Figure 3 or Figure 4 As shown, the first network device indirectly sends the first registration information to the terminal device through the RAN node. Correspondingly, the terminal device receives the first registration information from the first network device, indicating that the source of the first registration information is the first network device. The terminal device can receive the first registration information directly from the first network device via the air interface, or it can receive the first registration information indirectly from other devices or nodes, for example... Figure 3 or Figure 4 As shown, the terminal device indirectly receives the first registration information from the RAN node.

[0204] For example, when a terminal device sends first registration information to a second network device, it indicates that the receiving end of the first registration information is the second network device. The terminal device can send the first registration information directly to the second network device via the air interface, or it can send the first registration information indirectly to the second network device through other devices or nodes. Figure 3 or Figure 4 As shown, the terminal device indirectly sends the first registration information to the second network device through the RAN node. Correspondingly, the second network device receives the first registration information from the terminal device, indicating that the source of the first registration information is the terminal device. The second network device can receive the first registration information directly from the terminal device via the air interface, or it can indirectly receive the first registration information from other devices or nodes, for example... Figure 3 or Figure 4 As shown, the second network device indirectly receives the first registration information from the RAN node.

[0205] The method described above, where the terminal device carries registration information during registration on a different network, can also be applied to other core network processes such as session establishment and session modification. The session establishment process will be described below as an example.

[0206] Figure 5 This is a schematic flowchart of a method 500 provided in an embodiment of this application. The steps of method 500 can be interactively executed by network devices on the terminal side and the network side. The terminal side is, for example, a terminal device or a communication module in a terminal device, or a circuit or chip in a terminal device responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core). The following description uses a terminal device as an example. The network device on the network side is, for example, a network element or a communication module in a network element, or a circuit or chip in a network element responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core).

[0207] It should be noted that the core network in this embodiment can also be replaced by a PLMN.

[0208] Method 500 includes steps S501 to S503. Optionally, method 500 also includes steps S504 to S511. Each step is described in detail below.

[0209] S501, the fifth network device sends the first session context to the terminal device, and the terminal device receives the first session context accordingly.

[0210] The first session context is the session context of the terminal device in the fifth network device, and the fifth network device is the network device in the third core network.

[0211] It should be understood that during the movement of a terminal device, the terminal device can move from one service area to another. The two service areas before and after the movement can be two different service areas of the same core network, or service areas of two different core networks.

[0212] The third core network can be the core network to which the terminal device belongs, or it can be a visited core network; this application does not limit this in its embodiments.

[0213] The fifth network device is a network device in the third core network, such as an SMF network element, or a component configured in the AMF network (such as a processor, chip, or chip system), or a logic module or software that can implement all or part of the SMF functions.

[0214] Optionally, the first session context may include subscription information and policy information. For a description of subscription information and policy information, please refer to the above description; it will not be repeated here.

[0215] After receiving the first session context, the terminal device can store the first session context in the terminal device's storage unit so that it can be provided to the core network to which it is roaming in subsequent cross-network roaming scenarios.

[0216] Similar to the storage unit described above for storing registration information, in one possible design, the terminal device may include a separate storage unit, such as... Figure 4 The terminal device shown includes a storage unit for storing the session context of the terminal device. This storage unit can be implemented in hardware, software, or a combination of both; this application does not limit this implementation.

[0217] It should be noted that this storage unit is deployed independently from the terminal device's internal / local storage unit. The communication module or circuits / chips responsible for communication functions in the terminal device cannot access this storage unit, but network elements in the core network can access it. For example... Figure 5 The fifth network device can directly write the first session context into the storage unit. Direct writing means that after receiving the first session context, the terminal device stores it directly into the independent storage unit without parsing it.

[0218] Alternatively, in this design, the fifth network device can indicate the type of the first session context by an identifier, that is, indicate that the information received this time is the session context of the terminal device. In this way, after the terminal device receives the first session context, it can determine that the first session context needs to be stored in the independent storage unit based on the identifier.

[0219] In another possible design, the first session context can be stored in the terminal device's internal storage unit, for example... Figure 6 In the method 600 shown, the terminal device does not involve a dedicated storage unit for storing registration information. After receiving the session context, the terminal device can store the session context in its internal storage unit. In this design, the baseband unit of the terminal device can parse the contents of the first session context.

[0220] It should be understood that the difference between method 500 and method 600 is that in method 500, S501 involves the fifth network device directly writing the first session context into the storage unit of the terminal device. This storage unit can be an independent storage unit deployed at the factory for storing session context, different from the terminal device's own internal storage unit or local storage unit. In contrast, in method 600, S601 involves the fifth network device sending the first session context to the terminal device. The terminal device then processes the first session context normally; for example, the baseband unit of the terminal device can parse the first session context, determine its type, and store it in its internal storage unit. A description of S602 to S611 can be found in the description of S502 to S511, and will not be repeated here.

[0221] S502, the terminal device sends the first session context to the sixth network device, and the sixth network device receives the first session context accordingly.

[0222] The sixth network device is a network device in the fourth core network. The sixth network device differs from the fifth network device; however, the sixth network device and the fifth network device are of the same type of network element.

[0223] For example, the fifth network device is the SMF in the third core network, and the sixth network device is the SMF network element in the fourth core network.

[0224] In one possible scenario, the third core network differs from the fourth core network, meaning the terminal device roams between two different core networks. For example, roaming from the service area of ​​operator A's core network to the service area of ​​operator B's core network. Another example is roaming from operator A's core network deployed in service area 1 to operator A's core network deployed in service area 2.

[0225] In another possible scenario, the third and fourth core networks can be the same core network, while the fifth and sixth network devices are different network devices within the same core network. That is, the terminal device moves from one service area of ​​a core network to another service area of ​​that core network. This scenario involves a handover between the old and new network devices, and correspondingly, the terminal device's session context also needs to be switched. In this case, the fifth network device is the old network device, and the sixth network device is the new network device.

[0226] For example, when a handover occurs based on the N2 interface (the interface between the RAN and AMF), and there is a need to exchange session context between the new SMF and the old SMF, the solution provided in the embodiments of this application can be used to write the session context of the terminal device in the old SMF or AMF into the storage unit of the terminal device. During the handover process, the terminal device sends the session context of the terminal device in the old SMF or AMF to the new SMF or AMF.

[0227] It should be understood that the purpose of the terminal device sending the first session context to the sixth network device is to enable the sixth network device to establish a session of the terminal device in the sixth network device, or to update the session context of the terminal device in the sixth network device.

[0228] In scenarios involving roaming across different networks or switching between old and new network devices within the same core network, the terminal device retrieves the first session context from the aforementioned storage unit and sends the first session context to the sixth network device.

[0229] S503, the sixth network device establishes a session of the terminal device in the sixth network device based on the first session context, or updates the session context of the terminal device in the sixth network device.

[0230] In this embodiment, the fifth network device in the third core network can send the first session context of the terminal device in the fifth communication device to the terminal device for storage. Subsequently, in inter-network roaming scenarios or during switching between old and new network devices, the terminal device can send the first session context to the sixth network device in the fourth core network. Thus, the sixth network device can establish a session for the terminal device in the sixth network device based on the first session context, or update the session context of the terminal device in the sixth network device. Compared to existing solutions where the fourth core network needs to obtain the session context from the third core network, the technical solution of this application helps reduce the latency of obtaining the session context of the terminal device in the third core network, making the acquisition more timely and effective.

[0231] In one possible implementation, S502 includes: the terminal device sending a fourth request message to the sixth network device, the fourth request message being used to request the establishment of a first session, and the fourth request message including the first session context. Correspondingly, the second network device receives the fourth request message. Thus, when the terminal device moves to the service area of ​​the fourth core network and needs to establish a session in the fourth core network, it carries the first session context of the terminal device in the fifth network device in the session establishment request and sends it to the sixth network device, which helps to reduce the signaling overhead of the terminal device.

[0232] In another possible implementation, method 500 further includes S504: After receiving a session establishment request from the terminal device, the sixth network device sends a fifth request message to the terminal device, the fifth request message being used to request a first session context. Optionally, S502 includes: the terminal device sending the first session context to the second network device based on the fifth request message. In this approach, if the sixth network device determines that the terminal device needs to establish a session in the fourth core network, it can proactively request the session context of the terminal device in the fifth network device, which is more flexible. S504 can be executed before S502.

[0233] Optionally, method 500 further includes S505: the sixth network device sends a second session context to the terminal device. The second session context is the session context of the terminal device in the sixth network device, and the second session context is generated based on the first session context. The sixth network device can adjust or update the first session context based on the network parameters of the fourth core network, for example, adjusting the supported S-NSSAI, adjusting the DNN configuration, etc., to generate the second session context. After receiving the second session context, the terminal device can store the second session context in a storage unit. S505 can be executed after S503.

[0234] Optionally, the fifth network device can sign the first session context using asymmetric cryptography, meaning the first session context can include signature information from the third core network. For example, the fifth network device can sign the first session context using the private key of the third core network. After receiving the first session context, the sixth network device needs to verify its legitimacy, that is, verify whether the first session context was legitimately generated by the third core network. For example, the sixth network device can verify the signature information using the public key corresponding to the private key that generated the signature. If the verification passes, it indicates that the first session context was legitimately generated by the fifth network device.

[0235] Optionally, the fifth network device may use the private key of the third core network to encrypt the first session context in order to protect the integrity of the first session context. In this way, after the terminal device receives the first session context, it cannot parse the first session context or tamper with the first session context, which helps to ensure the security of the first session context.

[0236] Optionally, method 500 further includes S506: the fifth network device obtains a pair of public and private keys, wherein the private key is used to generate signature information for the first session context, and the public key is used to verify the signature information for the first session context. S506 can be executed before S501.

[0237] In one possible implementation, the fifth network device obtains a pair of public and private keys, including: the fifth network device generates a pair of public and private keys on its own.

[0238] In another possible implementation, the fifth network device obtains a pair of public and private keys, including: the fifth network device selecting a pair of public and private keys from a key store according to agreed rules. For example, the fifth network device selects a pair of private and public keys from the key store based on the identification information of the terminal device. The identification information of the terminal device may be, for example, GUTI or SUPI, or identification information of the terminal device defined by other communication systems or future communication systems; this application embodiment does not limit this.

[0239] In another possible implementation, the fifth network device acquires a pair of public and private keys, including receiving a pair of public and private keys indicated by the terminal device. In this approach, the terminal device can select a pair of private and public keys from a keystore and inform the fifth network device which pair of private and public keys it has selected.

[0240] Optionally, the terminal device may inform the fifth network device which pair of private and public keys it has selected during the process of requesting to establish a session in the fourth core network. For example, method 500 further includes S507: the terminal device sends a sixth request message to the fifth network device, the sixth request message being used to request the establishment of a second session, the sixth request message also indicating a pair of public and private keys, the private key being used to generate signature information for the first session context, and the public key being used to verify the signature information for the first session context. Accordingly, the fifth network device receives the sixth request message. S507 can be executed before S501.

[0241] Optionally, after the terminal device sends a sixth request message to the fifth network device to request the establishment of a second session, the SMF network element in the third core network can create the UE initial context locally, including the session identifier, the context identifier, the DNN, etc.

[0242] It should be noted that in the embodiments of this application, "send" and "receive" refer to the direction of signal transmission, and are not limited to direct "send" and "receive" or indirect "send" and "receive" through other devices or nodes.

[0243] For example, the fifth network device sends a first session context to the terminal device, indicating that the terminal device is the recipient of the first session context. The fifth network device can send the first session context directly to the terminal device via the air interface, or it can send the first session context indirectly to the terminal device through other nodes. Figure 5 or Figure 6 As shown, the fifth network device indirectly sends the first session context to the terminal device through the RAN node. Correspondingly, the terminal device receives the first session context from the fifth network device, indicating that the source of the first session context is the fifth network device. The terminal device can receive the first session context directly from the fifth network device via the air interface, or indirectly from other units, modules, or nodes, for example... Figure 5 or Figure 6 As shown, the terminal device indirectly receives the first session context from the RAN node.

[0244] For example, a terminal device sends a first session context to a sixth network device, indicating that the sixth network device is the recipient of the first session context. The terminal device can send the first session context directly to the sixth network device via the air interface, or it can send the first session context indirectly to the sixth network device through other devices or nodes, for example... Figure 5 or Figure 6 As shown, the terminal device indirectly sends the first session context to the sixth network device through the RAN node. Correspondingly, the sixth network device receives the first session context from the terminal device, indicating that the source of the first session context is the terminal device. The sixth network device can receive the first session context directly from the terminal device via the air interface, or it can receive the first session context indirectly from other devices or nodes, for example... Figure 5 or Figure 6 As shown, the sixth network device indirectly receives the first session context from the RAN node.

[0245] As described above, the terminal device can store network parameters (such as registration information and / or session context) from the core network for use by the target core network (e.g., the second or fourth core network mentioned above) in scenarios such as inter-network roaming or switching between old and new network devices. To maintain synchronization between the network parameters maintained by the terminal device and those maintained by the source core network, and to avoid situations where changes in the network parameters of the source core network prevent the terminal device from obtaining them correctly, this application provides a method for synchronizing network parameters, such as... Figure 7As shown, in method 700, the source core network can detect the network parameters stored by the terminal device to determine whether the network parameters currently stored by the terminal device are the latest version.

[0246] The steps of method 700 are described in detail below.

[0247] S701, the source core network configures the transmission method of the detection signal for the terminal device. This detection signal is used to determine whether the network parameters stored by the terminal device are the latest version of the network parameters of the terminal device in the source core network.

[0248] The source core network is the core network that the terminal device registers before roaming to another network, such as the first core network or the third core network mentioned above. Correspondingly, in this application, the core network that the terminal device registers after roaming to another network is referred to as the target core network, such as the second core network or the fourth core network mentioned above.

[0249] Network parameters can include core network parameters such as registration information and session context.

[0250] Optionally, the transmission method of the detection signal may include: periodic transmission or condition-triggered transmission. Condition-triggered transmission could be, for example, when the terminal device undergoes cell handover or when the terminal device's movement range exceeds a threshold. If periodic transmission is used, the source core network can configure the transmission period, or interval, of the detection signal for the terminal device.

[0251] The detection signal can also be called a heartbeat signal, a synchronization signal, or an update signal.

[0252] S702, when the conditions for transmitting the detection signal are met, the terminal device sends a detection signal to the source core network. This detection signal carries the result of the network parameters maintained by the terminal device after mapping transformation; that is, the result of the network parameters after mapping transformation is the payload of the detection signal. Correspondingly, the source core network receives the detection signal.

[0253] For ease of description, the result of the network parameters sent by the terminal device after mapping transformation is referred to as the network parameter verification value in the following text.

[0254] For example, the mapping transformation is a hash transformation.

[0255] S703, the source core network performs the same mapping transformation on the locally maintained network parameters to generate the detection values ​​of the network parameters.

[0256] S704, the source core network compares the network parameter to be verified value with the network parameter detection value to determine whether the network parameters maintained by the terminal equipment are the latest version of the network parameters.

[0257] Optionally, if the value to be verified for the network parameter is the same as, or consistent with, the source core network determines that the network parameter stored by the terminal device is the latest version of the network parameter. If the value to be verified for the network parameter is different from, or inconsistent with, the source core network determines that the network parameter stored by the terminal device is not the latest version of the network parameter, and the registration information stored by the terminal device needs to be updated. See S705-A and S706-A below, or S705-B below.

[0258] In S705-A, the source core network sends the latest version of network parameters to the target core network. Correspondingly, the target core network receives the latest version of network parameters. Further, the target core network can execute S706-A.

[0259] In S706-A, the target core network sends the latest version of network parameters to the terminal equipment. Correspondingly, the terminal equipment receives the latest version of the network parameters.

[0260] In S705-B, the source core network sends the latest version of network parameters to the terminal device. Correspondingly, the terminal device receives the latest version of network parameters. Further, the terminal device can execute S706-B.

[0261] In S706-B, the terminal device sends the latest version of network parameters to the target core network. Correspondingly, the target core network receives the latest version of the network parameters.

[0262] In this embodiment, the source core network can verify whether the network parameters maintained by the source core network in the terminal device are the latest version of the network parameters. If not, the source core network can synchronize the latest version of the network parameters to the terminal device. This is beneficial for the terminal device and the core network to maintain synchronization of network information and improve the availability of the network parameters maintained by the terminal device.

[0263] It should be understood that the network parameter synchronization method provided in this application can be applied to method 300 or method 400 described above. When applied to method 300 or method 400, the network parameters include registration information. The following description uses the application of the network parameter synchronization method to method 300 as an example.

[0264] Optionally, method 300 further includes S308: when the triggering condition is met, the terminal device sends a first signal to the third network transposed. The first signal includes the result of the first registration information after mapping transformation. The first signal is used to determine whether the first registration information is the latest version of the terminal device's registration information in the first core network. The first signal is the detection signal described above.

[0265] The third network device is a network device in the first core network. For example, the first network device is a UDM network element, or it can be a component configured in the UDM network element (such as a processor, chip, or chip system), or it can be a logic module or software that can implement all or part of the UDM functions.

[0266] Optionally, the triggering conditions may include one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0267] Optionally, the triggering condition can be predefined by the protocol or indicated by a third network device. This application embodiment does not limit this. For example, method 300 further includes S309: the third network device sends first indication information to the terminal device, the first indication information indicating the triggering condition. Accordingly, the terminal device receives the first indication information.

[0268] Optionally, method 300 further includes S310: the fourth network device sends second indication information to the terminal device, the second indication information indicating the latest version of the terminal device's registration information in the first core network. Accordingly, the terminal device receives the second indication information. Further, method 300 further includes S311: the terminal device updates the first registration information to the latest version of the registration information.

[0269] In this configuration, the fourth network device is either the third network device or, in other words, the fourth network device in the first core network indicates the latest version of the registration information to the terminal device. Alternatively, the fourth network device can be a network device in the second core network, meaning that the third network device in the first core network first sends the latest version of the registration information to the fourth network device in the second core network, and then the fourth network device in the second core network indicates the latest version of the registration information to the terminal device.

[0270] It should be understood that the network parameter synchronization method provided in this application can be applied to method 500 or 600 described above. When applied to method 500 or method 600, the network parameters include the session context. The following description uses the application of the network parameter synchronization method to method 500 as an example.

[0271] Optionally, method 500 further includes S508: when the triggering condition is met, the terminal device sends a second signal to the seventh network device. The second signal includes the result of the mapping transformation of the first session context. The second signal is used to determine whether the first session context is the latest version of the terminal device's session context in the third core network. The second signal is the detection signal described above.

[0272] The seventh network device is a network device in the third core network. For example, the first network device is a UDM network element, or it can be a component configured in the UDM network element (such as a processor, chip, or chip system), or it can be a logic module or software that can implement all or part of the UDM functions.

[0273] Optionally, the triggering conditions may include one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0274] Optionally, the triggering condition can be predefined by the protocol or indicated by the seventh network device. This application embodiment does not limit this. For example, optionally, method 500 further includes S509: the seventh network device sends third indication information to the terminal device, the third indication information being used to indicate the triggering condition.

[0275] Optionally, method 500 further includes S510: the eighth network device sends fourth indication information to the terminal device, the fourth indication information being used to indicate the latest version of the session context of the terminal device in the third core network. Accordingly, the terminal device receives the fourth indication information. Further, method 500 further includes S511: the terminal device updates the first session context to the latest version of the session context.

[0276] In this context, the eighth network device is the seventh network device, meaning that the eighth network device in the third core network indicates the latest version of the session context to the terminal device. Alternatively, the eighth network device is a network device in the fourth core network, meaning that the seventh network device in the third core network first sends the latest version of the session context to the eighth network device in the fourth core network, and then the eighth network device in the fourth core network indicates the latest version of the session context to the terminal device.

[0277] It should be understood that the above embodiments are described using network parameters stored in the terminal device, including registration information and / or session context, as an example. Other network parameters may also be stored in the terminal device, or only some parameters in the registration information may be stored, such as location information, network information, subscription information, or policy information. This application does not limit the network parameters stored in the terminal device.

[0278] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0279] The methods provided in the embodiments of this application above are described using terminal devices and network devices as examples. In this application, each embodiment can be implemented independently or in combination based on certain inherent connections; in each embodiment, different implementation methods can be implemented in combination or independently. To achieve the functions of the methods provided in the embodiments of this application above, the steps executed by the terminal device can be implemented by the terminal device itself or by different functional entities constituting the terminal device. The steps executed by the network device can be implemented by the network device itself or by different functional entities constituting the network device. To achieve the functions of the methods provided in the embodiments of this application above, the terminal device and network device may include hardware structures and / or software modules, implementing the above functions in the form of hardware structures, software modules, or hardware structures plus software modules. Whether a particular function is executed in the form of hardware structures, software modules, or hardware structures plus software modules depends on the specific application and design constraints of the technical solution.

[0280] It should be understood that network devices include, for example, the first network device, the second network device, the third network device, the fourth network device, the fifth network device, the sixth network device, the seventh network device, or the eighth network device described above.

[0281] The above text combines Figures 3 to 6 The communication method according to the embodiments of this application is described in detail below, in conjunction with Figure 8 and Figure 9 The present application provides a detailed description of a communication apparatus according to embodiments thereof.

[0282] Figure 8 and Figure 9 This is a schematic block diagram of a communication device provided in an embodiment of this application. These communication devices can be used to implement the functions of the terminal device or network device in the above method embodiments, and therefore can also achieve the beneficial effects of the above method embodiments.

[0283] like Figure 8 As shown, the communication device 800 includes a transceiver module 810 and a processing module 820. The transceiver module 810 can also be referred to as a communication interface or a communication module.

[0284] The device 800 can be used to perform the actions performed by the terminal device or network device in the above method embodiments. Alternatively, the device 800 can be a component (e.g., a chip) configured in the terminal device or network device. The processing module 820 is used to perform processing-related operations of the terminal device or network device in the above method embodiments. The transceiver module 810 is used to perform receiving and transmitting-related operations of the terminal device or network device in the above method embodiments.

[0285] Optionally, the transceiver module 810 may include a sending module and a receiving module. The sending module is used to perform the sending operation in the above method embodiments. The receiving module is used to perform the receiving operation in the above method embodiments.

[0286] It should be noted that device 800 may include a transmitting module but not a receiving module. Alternatively, device 800 may include a receiving module but not a transmitting module. Specifically, it depends on whether the above-described scheme executed by device 800 includes both transmitting and receiving actions.

[0287] Optionally, the device 800 is used to perform the above. Figure 2 The actions performed by the terminal device or network device in the illustrated embodiments. For details, please refer to the above. Figure 2 The relevant descriptions in the illustrated embodiments will not be repeated here.

[0288] Optionally, the device 800 may further include a storage module, which can be used to store data and / or to store computer programs or instructions. The processing module 820 can read the computer programs / instructions and / or data in the storage module so that the device 800 can implement the above-described method embodiments.

[0289] When device 800 is used to achieve, such as Figure 3 or Figure 4 When the terminal device functions as shown in the method embodiment, the transceiver module 810 is used to: receive first registration information from a first network device, wherein the first registration information is the registration information of the terminal device in a first core network, and the first network device is a network device in the first core network; and send the first registration information to a second network device, wherein the second network device is a network device in a second core network.

[0290] Optionally, the transceiver module 810 is configured to: send a first request message to the second network device, the first request message being used to request registration of the second core network, the first request message including first registration information.

[0291] Optionally, the transceiver module 810 is configured to: receive a second request message from the second network device, the second request message being used to request first registration information; and, based on the second request message, send the first registration information to the second network device.

[0292] Optionally, the transceiver module 810 is configured to: receive second registration information from the second network device, wherein the second registration information is the registration information of the terminal device in the second core network, and the second registration information is generated based on the first registration information.

[0293] Optionally, the first registration information includes the signature information of the first core network.

[0294] Optionally, the transceiver module 810 is used to: send a third request message to the first network device, the third request message being used to request registration of the first core network, the third request message also indicating a pair of public and private keys, the private key being used to generate signature information, and the public key being used to verify the signature information.

[0295] Optionally, the transceiver module 810 is used to: send a first signal to a third network device when a trigger condition is met. The first signal includes the result of the mapping transformation of the first registration information. The first signal is used to determine whether the first registration information is the latest version of the registration information of the terminal device in the first core network. The third network device is a network device in the first core network.

[0296] Optionally, the triggering conditions include one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0297] Optionally, the transceiver module 810 is configured to: receive first indication information from a third network device, the first indication information being used to indicate triggering conditions.

[0298] Optionally, the transceiver module 810 is configured to: receive second indication information from a fourth network device, the second indication information indicating that the terminal device has the latest version of registration information in the first core network, the fourth network device being a third network device, or the fourth network device being a network device in the second core network; and update the first registration information to the latest version of registration information.

[0299] When device 800 is used to achieve, such as Figure 3 or Figure 4 In the method embodiment shown, when the first network device functions, the transceiver module 810 is used to: send first registration information to the terminal device, the first registration information being the registration information of the terminal device in the first core network, and the first network device being a network device in the first core network.

[0300] Optionally, the first registration information includes the signature information of the first core network.

[0301] Optionally, the processing module 820 is configured to: obtain a pair of private keys and public keys, wherein the private key is used to generate the signature information and the public key is used to verify the signature information; and, sign the first registration information based on the private key to generate signature information.

[0302] Optionally, the transceiver module 810 is used to: send a public key to a second network device, wherein the second network device is a network device in a second core network.

[0303] When device 800 is used to achieve, such as Figure 3 or Figure 4In the method embodiment shown, when the second network device functions, the transceiver module 810 is used to: receive first registration information from the terminal device, the first registration information being the registration information of the terminal device in the first core network, and the second network device being a network device in the second core network; the processing module 820 is used to: complete the registration of the terminal device in the second core network based on the first registration information.

[0304] Optionally, the transceiver module 810 is used to: send second registration information to the terminal device, the second registration information being the registration information of the terminal device in the second core network, and the second registration information being generated based on the first registration information.

[0305] Optionally, the transceiver module 810 is configured to: receive a first request message from a terminal device, the first request message being used to request registration of a second core network, the first request message including first registration information.

[0306] Optionally, the transceiver module 810 is used to: send a second request message to the terminal device, the second request message being used to request the first registration information.

[0307] Optionally, the first registration information includes the signature information of the first core network.

[0308] Optionally, the transceiver module 810 is used to: receive a public key from a first network device, wherein the first network device is a network device in a first core network, and the public key is used to verify signature information.

[0309] When device 800 is used to achieve, such as Figure 5 or Figure 6 When the terminal device functions as shown in the method embodiment, the transceiver module 810 is used to: receive a first session context from a fifth network device, wherein the first session context is the session context of the terminal device in the fifth network device, and the fifth network device is a network device in the third core network; and send the first session context to a sixth network device, wherein the sixth network device is a network device in the fourth core network.

[0310] Optionally, the transceiver module 810 is configured to: send a fourth request message to the sixth network device, the fourth request message being used to request the establishment of a first session, the fourth request message including the first session context.

[0311] Optionally, the transceiver module 810 is configured to: receive a fifth request message from the sixth network device, the fifth request message being used to request a first session context; and, based on the fifth request message, send the first session context to the sixth network device.

[0312] Optionally, the transceiver module 810 is configured to: receive a second session context from the sixth network device, the second session context being the session context of the first session of the terminal device in the sixth network device, and the second session context being generated based on the first session context.

[0313] Optionally, the first session context includes signature information from the third core network.

[0314] Optionally, the transceiver module 810 is configured to: send a sixth request message to the fifth network device, the sixth request message being used to request the establishment of a second session, the sixth request message also indicating a pair of public and private keys, the private key being used to generate the signature information, and the public key being used to verify the signature information.

[0315] Optionally, the transceiver module 810 is configured to: send a second signal to the seventh network device when the triggering condition is met, the second signal including the result of the first session context after mapping transformation, the second signal being used to determine whether the first session context is the latest version in the first core network, and the seventh network device being a network device in the third core network.

[0316] Optionally, the triggering condition includes one or more of the following: periodic triggering; cell handover of the terminal device; or, the moving distance of the terminal device exceeds a threshold.

[0317] Optionally, the transceiver module 810 is configured to: receive third indication information from the seventh network device, the third indication information being used to indicate the triggering condition for sending the second signal, the second signal being used to determine whether the first session context is the latest version in the third core network, and the seventh network device being a network device in the third core network.

[0318] Optionally, the transceiver module 810 is configured to: receive fourth indication information from an eighth network device, the fourth indication information indicating the latest version of the session context of the terminal device in a fifth network device, wherein the eighth network device is a seventh network device, or the eighth network device is a network device in a fourth core network; and update the first session context to the latest version of the session context.

[0319] When device 800 is used to achieve, such as Figure 5 or Figure 6 In the method embodiment shown, when the fifth network device functions, the transceiver module 810 is used to: receive a sixth request message from the terminal device, the sixth request message being used to request the establishment of a second session; and send a first session context to the terminal device, the first session context being the session context of the second session of the terminal device in the fifth network device, the fifth network device being a network device in the third core network.

[0320] Optionally, the first session context includes signature information from the third core network.

[0321] Optionally, the processing module 820 is configured to: obtain a pair of private keys and public keys, wherein the private key is used to generate the signature information and the public key is used to verify the signature information; and, based on the private key, sign the first session context to generate the signature information.

[0322] Optionally, the transceiver module 810 is used to send the public key to a sixth network device, which is a network device in the fourth core network.

[0323] When device 800 is used to achieve, such as Figure 5 or Figure 6 In the method embodiment shown, when the sixth network device functions, the transceiver module 810 is used to: receive a first session context from the terminal device, wherein the first session context is the session context of the terminal device in the fifth network device, and the fifth network device is a network device in the third core network; the processing module 820 is used to: establish a session of the terminal device in the sixth network device based on the first session context, or update the session context of the terminal device in the sixth network device, wherein the sixth network device is a network device in the third core network, or the sixth network device is a network device in the fourth core network.

[0324] Optionally, the transceiver module 810 is used to: send a second session context to the terminal device, the second session context being the session context of the terminal device in the sixth network device, and the second session context being generated based on the first session context.

[0325] Optionally, the transceiver module 810 is configured to: receive a fourth request message from the terminal device, the fourth request message being used to request the establishment of a first session, the fourth request message including the first session context.

[0326] Optionally, the transceiver module 810 is used to: send a fifth request message to the terminal device, the fifth request message being used to request the first session context.

[0327] Optionally, the first session context includes signature information from the third core network.

[0328] Optionally, the transceiver module 810 is configured to: receive a public key from a fifth network device, which is used to verify the signature information.

[0329] For a more detailed description of each step, please refer to the relevant descriptions in the method embodiments above, which will not be repeated here.

[0330] Figure 9 This is a schematic block diagram of another communication device 900 provided in an embodiment of this application, such as... Figure 9As shown, device 900 includes one or more processors 910 and interface circuitry 920. The one or more processors 910 and interface circuitry 920 are coupled to each other. It is understood that interface circuitry 920 can be a transceiver or an input / output interface. Optionally, device 900 may also include memory 930 for storing instructions executed by processor 910, or for storing input data required by processor 910 to execute instructions, or for storing data generated after processor 910 executes instructions. Sometimes, interface circuitry 920 can also be understood as part of the one or more processors 910, in which case device 900 includes the one or more processors 910.

[0331] The one or more processors 910 and memory 930 can be configured separately or integrated, and this application does not limit this.

[0332] When device 900 is used to achieve Figures 3 to 7 In the method shown, the one or more processors 910 are used to implement the functions of the processing module 820, and the interface circuit 920 is used to implement the functions of the transceiver module 810.

[0333] When the aforementioned device 900 is a chip applied to a terminal device, the chip of the terminal device implements the functions of the terminal device in the above method embodiments. The chip of the terminal device receives information from the network device, which can be understood as the information being first received by other modules (such as an RF module or antenna) in the terminal device, and then sent to the chip of the terminal device by these modules. The chip of the terminal device sends information to the network device, which can be understood as the information being first sent to other modules (such as an RF module or antenna) in the terminal device, and then sent to the network device by these modules.

[0334] When the aforementioned device 900 is a chip applied to a network device, the chip of the network device implements the functions of the network device in the above method embodiments. The chip of the network device receives information from the terminal device, which can be understood as the information being first received by other modules (such as radio frequency modules or antennas) in the network device, and then sent to the chip of the network device by these modules. The chip of the network device sends information to the terminal device, which can be understood as the information being first sent to other modules (such as radio frequency modules or antennas) in the network device, and then sent to the terminal device by these modules.

[0335] This application also provides a computer-readable storage medium for storing a computer program that, when run on a computer, causes the computer to perform the methods described in the above embodiments. Alternatively, the computer program includes instructions for implementing the methods described in the above embodiments.

[0336] This application also provides a computer program product, including: a computer program or instructions that, when run on a computer, cause the computer to perform the methods described above.

[0337] This application also provides an apparatus, which can be a chip, including at least one processor for supporting the implementation of the methods in the above embodiments, such as receiving or processing data involved in the methods in the above embodiments.

[0338] It should be understood that, in the embodiments of this application, the processor can be a central processing unit, or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0339] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly manifested as execution by a hardware processor, or as a combination of hardware and software modules within the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor executes the instructions in the memory, combining them with its hardware to complete the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0340] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0341] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0342] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0343] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0344] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0345] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, external hard drives, ROM, RAM, magnetic disks, or optical disks.

[0346] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method characterized by comprising: The method applied to a terminal side comprises: receiving first registration information from a first network device, the first registration information being registration information of a terminal device in a first core network, the first network device being a network device in the first core network; sending the first registration information to a second network device, the second network device being a network device in a second core network.

2. The method of claim 1, wherein, The sending of the first registration information to the second network device comprises: sending a first request message to the second network device, the first request message being used to request registration of the second core network, the first request message comprising the first registration information.

3. The method of claim 1, wherein, Before the sending of the first registration information to the second network device, the method further comprises: receiving a second request message from the second network device, the second request message being used to request the first registration information; The sending of the first registration information to the second network device comprises: sending the first registration information to the second network device based on the second request message.

4. The method according to any one of claims 1 to 3, characterized in that, After the sending of the first registration information to the second network device, the method further comprises: receiving second registration information from the second network device, the second registration information being registration information of the terminal device in the second core network, the second registration information being generated based on the first registration information.

5. The method according to any one of claims 1 to 4, characterized in that, The first registration information comprises signature information of the first core network.

6. The method of claim 5, wherein, Before the receiving of the first registration information from the first network device, the method further comprises: sending a third request message to the first network device, the third request message being used to request registration of the first core network, the third request message further indicating a pair of a public key and a private key, the private key being used to generate the signature information, and the public key being used to verify the signature information.

7. The method according to any one of claims 1 to 6, characterized in that, The method further comprises: in a case where a triggering condition is met, sending a first signal to a third network device, the first signal comprising a result of a mapping transformation of the first registration information, the first signal being used to determine whether the first registration information is the latest version of registration information of the terminal device in the first core network, the third network device being a network device in the first core network.

8. The method of claim 7, wherein, The triggering condition comprises one or more of the following: periodic triggering; cell switching of the terminal device; or a moving distance of the terminal device exceeding a threshold value.

9. The method according to claim 7 or 8, characterized in that, The method further comprises: receiving first indication information from the third network device, the first indication information being used to indicate the triggering condition.

10. The method according to any one of claims 7 to 9, characterized in that, The method further comprises: receiving second indication information from a fourth network device, the second indication information being used to indicate the latest version of registration information of the terminal device in the first core network, the fourth network device being the third network device, or the fourth network device being a network device in the second core network; updating the first registration information to the latest version of registration information.

11. A communication method characterized by comprising: The method applied to a first network device comprises: The first registration information is signature information of the first core network.

12. The method of claim 11, wherein, The method further includes:

13. The method of claim 12, wherein, obtaining a pair of a private key and a public key, the private key being used to generate the signature information, and the public key being used to verify the signature information; signing the first registration information based on the private key to generate the signature information. The method further includes:

14. The method of claim 13, wherein, sending the public key to a second network device, the second network device being a network device in a second core network. The method applied to a second network device includes:

15. A method of communication, comprising: receiving first registration information from a terminal device, the first registration information being registration information of the terminal device in a first core network, and the second network device being a network device in a second core network; completing registration of the terminal device in the second core network based on the first registration information. After the completion of the registration of the terminal device in the second core network based on the first registration information, the method further includes:

16. The method of claim 15, wherein, sending second registration information to the terminal device, the second registration information being registration information of the terminal device in the second core network, and the second registration information being generated based on the first registration information. The receiving first registration information from a terminal device includes:

17. The method according to claim 15 or 16, characterized in that, receiving a first request message from the terminal device, the first request message being used to request registration of the second core network, and the first request message including the first registration information. Before the receiving first registration information from a terminal device, the method further includes:

18. The method of claim 15 or 16, wherein, sending a second request message to the terminal device, the second request message being used to request the first registration information. The first registration information includes signature information of the first core network.

19. The method according to any one of claims 15 to 18, characterized in that, The method further includes:

20. The method of claim 19, wherein, receiving a public key from a first network device, the first network device being a network device in the first core network, and the public key being used to verify the signature information. The module for implementing the method as claimed in any one of claims 1 to 10, or the module for implementing the method as claimed in any one of claims 11 to 14, or the module for implementing the method as claimed in any one of claims 15 to 20.

21. A communications device, characterized by The at least one processor is coupled with a memory, and the memory is used to store a program or instruction, when the program or instruction is executed by the at least one processor, the method as claimed in any one of claims 1 to 10 is executed, or the method as claimed in any one of claims 11 to 14 is executed, or the method as claimed in any one of claims 15 to 20 is executed.

22. A communications device, characterized by The computer program is used to store a computer program, when the computer program is run on a computer, the method as claimed in any one of claims 1 to 10 is executed, or the method as claimed in any one of claims 11 to 14 is executed, or the method as claimed in any one of claims 15 to 20 is executed.

23. A computer-readable storage medium, characterized in that, The module for implementing the method as claimed in any one of claims 1 to 10, or the module for implementing the method as claimed in any one of claims 11 to 14, or the module for implementing the method as claimed in any one of claims 15 to 20.

24. A computer program product, characterised in that, ​ A computer program or instructions, which, when executed, cause a method as claimed in any one of claims 1 to 10 to be performed, or cause a method as claimed in any one of claims 11 to 14 to be performed, or cause a method as claimed in any one of claims 15 to 20 to be performed.

Images