Communication method, apparatus, system, storage medium, and program product

Abstract

Embodiments of the present disclosure provide a communication method, an apparatus, a system, and a storage medium. In the method, a first core network device receives a registration request for requesting to make a terminal device access a second network; and when allowing the terminal device to access the second network, the first core network device sends first information to a first access network device serving the terminal device, wherein the first information is used for indicating that when selecting a target access network device or a target cell for the terminal device to access the second network, priority is given to an access network device or a cell of which service coverage comprises the coverage range of the second network. Therefore, the embodiments of the present disclosure can improve the continuity of service when a terminal device moves between networks (e.g., between a subnet and a carrier network).

Description

A method, device, system, storage medium and program product for communication

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 29, 2023, with application number 202311872166.8 and application name “A method, device, system, storage medium and program product for communication”, the entire contents of which are incorporated into this application by reference. Technical Field

[0002] The present disclosure relates generally to the field of communications, and more particularly to a method, apparatus, system, computer-readable storage medium, and computer program product for communications. Background Art

[0003] 5G introduces technologies such as multi-access edge computing (MEC) and slicing, enabling network deployment in campuses, factories, museums, and other locations. This shifts mobile networks from a 2C (for customers) to a 2B (for businesses) and expands the market for 3GPP (3rd Generation Partnership Project) mobile networks. When a terminal device moves between networks, it can cause service interruptions. Summary of the Invention

[0004] Embodiments of the present disclosure provide a method, apparatus, system, computer-readable storage medium, and computer program product for communication, which can improve service continuity.

[0005] In the first aspect, a communication method is provided, and the execution subject of the method can be a core network device for communication, or a chip in a core network device for communication. The following description is made by taking the execution subject being a core network device for communication as an example. In the method, a first core network device receives a registration request for requesting that a terminal device access a second network; when allowing the terminal device to access the second network, the first core network device sends a first information to a first access network device serving the terminal device, and the first information is used to indicate: when selecting a target access network device or a target cell for the terminal device to access the second network, an access network device or a cell whose service range includes the coverage range of the second network is preferred. In this way, when the terminal device requests to access the second network, it can preferably use an access network device or a cell whose service range includes the coverage range of the second network, thereby reducing the access delay, improving the access success rate, reducing the access cost, and improving the continuity of the second network service.

[0006] In some implementations, the first information includes at least one of the following: identification information of the second network; a cell list including information about one or more cells whose service range includes coverage of the second network; or an access network device list including information about one or more access network devices whose service range includes coverage of the second network. In this way, the first access network device can perceive, based on the indication, the one or more cells whose service range includes coverage of the second network.

[0007] In some implementations, the first core network device is a core network device serving a first network. The method of the first aspect further includes: the first core network device receiving a context request (which may be referred to as a second context request) from a second core network device, the second core network device serving a second network, the second context request being used to obtain a context for a terminal device, the second context request including first indication information indicating that the second core network device serves the second network; and the first core network device sending the context of the terminal device to the second core network device based on the first indication information, the context not including sensitive information of the terminal device. In this manner, leakage of sensitive user information can be prevented.

[0008] In some implementations, the method further includes: the first core network device receiving second instruction information from the second core network device instructing the deletion of the context of the terminal device; and the first core network device deleting the context of the terminal device and the session resources corresponding to the terminal device from the first core network device based on the second instruction information. In this way, when the terminal device moves from the first network to the coverage area of ​​the second network, the corresponding resources in the first network can be deleted, thereby saving network resources.

[0009] In some implementations, the first core network device is a core network device serving the first network, and the method of the first aspect further includes: the first core network device receiving a handover request message (which may be referred to as a first handover request message) from the first access network device, the first handover request message including identification information of a target access network device or identification information of a target cell to be accessed by the terminal device; the first core network device selecting a second core network device serving the second network based on the target access network device or target cell to be accessed by the terminal device being an access network device or cell whose service range includes coverage of the second network; and the first core network device sending a context of the terminal device to the second core network device, the context not including sensitive information of the terminal device. This prevents leakage of user sensitive information.

[0010] In some implementations, the first core network device further includes determining, based on at least one of the following, that the target access network device or target cell to be accessed by the terminal device is an access network device or cell whose service range includes the coverage range of the second network: the first handover request message indicates that the target access network device or target cell to be accessed by the terminal device serves the second network; or the coverage range of the second network includes the service area of ​​the target access network device or target cell to be accessed by the terminal device, and the subscription information of the second network includes the coverage range of the second network. In this manner, the first core network device determines whether to allow the terminal device to access.

[0011] In some implementations, the first core network device further transmits second information to the first access network device, the second information being used to instruct the terminal device to select a target access network device or target cell for accessing the second network, to select an access network device or cell whose service range includes an area within the coverage area of ​​the second network that the terminal device is permitted to access. In this manner, when selecting a target access network or cell for the terminal device, the terminal device can select an access network device or cell within the area permitted to access the second network, thereby avoiding power consumption caused by the terminal device repeatedly attempting to access the second network due to unsuccessful access attempts.

[0012] In some implementations, the first core network device further transmits third information to the terminal device, the third information being used to instruct the terminal device, when selecting a target access network device or target cell for accessing the second network, to select an access network device or cell whose service range includes an area within the coverage area of ​​the second network that the terminal device is permitted to access. In this manner, when selecting a target access network or cell, the terminal device can select an access network device or cell within the area permitted to access the second network, avoiding repeated attempts due to unsuccessful access attempts and thus saving power consumption of the terminal device.

[0013] In some implementations, the first core network device is a core network device serving the first network, and the registration request includes identification information of the terminal device, where the identification information is an identifier assigned by the second core network device serving the second network. The method of the first aspect further includes: determining the second core network device based on the identification information; sending a context request (which may be referred to as a first context request) to the second core network device, the first context request being used to obtain a context for the terminal device, the first context request including the identification information of the terminal device; and receiving the context for the terminal device from the second core network device. In this manner, the context for the terminal device can be obtained from the core network device serving the second network based on the identification information of the terminal device, so as to access the second network.

[0014] In some implementations, the first core network device is a core network device serving the first network, and the method of the first aspect further includes: storing address information of the second core network device in the context of the terminal device, so that the second core network device can be determined from the context of the terminal device.

[0015] In some implementations, sending the terminal device context of the first network includes: determining that the second core network device has permission to obtain the terminal device context; and sending the terminal device context based on the second core network device having the permission. In this way, the terminal device context is only sent to core network devices with corresponding permission, thereby improving security.

[0016] In some implementations, the first core network device is a core network device serving the first network, and the first access network device is an access network device serving the first network. The method of the first aspect further includes: receiving a handover request message (which may be referred to as a third handover request message) sent by the first access network device, the third handover request message indicating the target access network device or target cell to be accessed by the terminal device; based on determining that the target access network device or target cell to be accessed by the terminal device is an access network device or cell whose service range includes the coverage of the first network, selecting the third core network device serving the first network to serve the terminal device; and sending the context of the terminal device to the third core network device, the context including information of the second core network device serving the second network and identification information of the second network, the identification information of the second network being used to indicate that the network accessed by the terminal device is the second network. In this way, when the terminal device is located within the coverage of the first network, it can select an access network device or cell whose service range includes the coverage of the first network to access the second network, so as to improve the service continuity of the second network.

[0017] In some implementations, the first core network device is a core network device serving the second network, and the first access network device is an access network device serving the second network. The method of the first aspect further includes: receiving a handover request message (which may be referred to as a fourth handover request message) sent by the first access network device, the fourth handover request message indicating the target access network device or target cell to be accessed by the terminal device; based on determining that the target access network device or target cell is an access network device or cell whose service range includes the coverage of the first network, selecting the fourth core network device serving the first network to serve the terminal device; and sending the context of the terminal device to the fourth core network device, the context including information of the first core network device and identification information of the second network, the identification information of the second network being used to indicate that the network accessed by the terminal device is the second network. In this way, when the terminal device moves from the coverage of the second network to the coverage of the first network, it can select an access network device or cell whose service range includes the coverage of the first network to access the second network, so as to improve service continuity.

[0018] In some implementations, the method further includes: determining, based on the service area information of the second network, whether to allow the terminal device to access the second network, so that terminal devices in the service area of ​​the second network are allowed to access the second network, while access by terminal devices outside the service area is restricted.

[0019] In some implementations, the first core network device is a core network device serving the first network, further comprising: obtaining subscription information of the second network in the first network (or second network subscription information), the subscription information including information about the service area of ​​the second network; and determining, based on the subscription information, whether to allow the terminal device to access the second network. In this way, determining whether to allow the terminal device to access the second network based on the subscription information at the granularity of the second network improves access efficiency and security.

[0020] In some implementations, the first core network device is a core network device serving the first network, and the method of the first aspect further includes: sending an access request to a second core network device serving the second network, the access request being used to request the second core network device to authorize the terminal device to access the second network; and receiving an authorization acceptance indication sent by the second core network device, and determining, based on the authorization acceptance indication, that the terminal device is permitted to access the second network. In this manner, authorization of access to the terminal device is achieved through the core network device of the second network.

[0021] In some implementations, the access request includes first identification information of the terminal device, and the first identification information includes at least one of the following: a Mobile Station International Subscriber Directory Number (MSISDN), a Subscription Hidden Identifier (SUCI), or a temporary identity.

[0022] In a second aspect, a communication method is provided. The method may be performed by a second core network device used for communication, or a chip within the second core network device used for communication. The following description uses the second core network device used for communication as an example. In this method, the second core network device serving the second network receives a registration request message from a terminal device. The registration request message is used to request access to the second network by the terminal device, and the registration request message includes identification information of the terminal device. Based on the identification information of the terminal, the second core network device sends a context request to the core network device serving the first network. The context request is used to obtain a context for the terminal device, and the context request includes first indication information indicating that the second core network device serves the second network. The second core network device receives the context of the terminal device from the core network device serving the first network. The context of the terminal device does not include sensitive information of the terminal device. In this way, sensitive information of the terminal device is hidden from the subnet control plane, preventing leakage of user sensitive information.

[0023] In some implementations, the method further includes sending an instruction to a core network device serving the first network to delete the context of the terminal device, thereby saving resources and improving security.

[0024] On the third aspect, a communication method is provided, wherein the execution subject of the method may be a second core network device used for communication, or a chip in the second core network device used for communication. The following description is made by taking the execution subject being the second core network device used for communication as an example. In the method, the core network device serving the second network receives a switching request message sent by the first access network device serving the terminal device, and the switching request message indicates the target access network device or target cell to be accessed by the terminal device; and based on determining that the target access network device or target cell is the access network device or cell serving the first network, the core network device serving the first network is selected to serve the terminal device. In this way, when the terminal device is within the coverage of the first network, services can be provided through the core network device of the first network to access the second network.

[0025] In some implementations, determining that the target access network device or target cell is an access network device or cell serving the first network is based on at least one of the following: a handover request message sent by the first access network device serving the terminal device indicates that the target access network device or target cell is an access network device or cell whose service range includes the coverage of the first network; a service area of ​​the target access network device or target cell is not within the coverage of a second network, where the service area of ​​the second network is indicated by the first subscription information of the second network in the first network; or a core network device serving the second network has not established a connection and exchanged information with the target access network device. In this manner, the terminal device is detected to have moved to an area within the coverage of the first network, thereby triggering handover or RRC redirection and improving service continuity. In some implementations, the method further includes sending a handover request message to the core network device serving the first network, the handover request message including at least one of the following: identification information of the second network, a context of the terminal device, or callback address information of the core network device serving the second network. The callback address information is used for message exchange between the core network device serving the first network and the core network device serving the second network, and the identification information of the second network is used to instruct the terminal device to access the second network. In this way, the service terminal device is switched to access the second network through the first network, thereby avoiding service interruption.

[0026] In a fourth aspect, a communication method is provided, wherein the execution subject of the method may be a first access network device serving a terminal device, or a chip used in the first access network device. The following description is made using the first access network device as an example. In the method, the first access network device serving the terminal device receives first information, and the first information is used to indicate that when selecting a target access network device or target cell for the terminal device to access the second network, an access network device or cell whose service range includes the coverage range of the second network is preferred; the first access network device determines the first target access network device or first target cell to be accessed by the terminal device based on the first information; and the first access network device sends a handover request message to the core network device serving the terminal device, the handover request message including the identification information of the first target access network device or the identification information of the first target cell; or the first access network device sends a radio resource control (RRC) redirection message to the terminal device, the RRC redirection message instructing the terminal device to reselect the first target access network device or the first target cell to access the second network. In this way, the first access network device serving the terminal device can, according to the indication, prefer an access network device or cell in the coverage range of the second network and trigger a handover or RRC redirection to improve the continuity of the second network service.

[0027] In some implementations, the first information includes at least one of the following: identification information of the second network; a cell list, the cell list including information about one or more cells whose service range includes the coverage of the second network; or access network devices, the access network devices including information about one or more access network devices whose service range includes the coverage of the second network. This allows the first access network device serving the terminal device to select an access network device list based on the identification information of the second network or the cell list within the coverage of the second network, thereby optimizing the access network device or cell, improving access network device or cell selection efficiency, increasing connection success rate, and avoiding service interruption.

[0028] In some implementations, the method further includes: the first access network device receiving measurement report information of the first target cell from the terminal device, the measurement report information including identification information of the second network; or the first access network device receiving indication information, the indication information being used to indicate that the service range of the first target access network device or the first target cell includes the coverage range of the second network; or the first access network device determining, based on local configuration information, that the service range of the first target access network device or the first target cell includes the coverage range of the second network. This allows the first access network device to perceive cells or access network devices in the second network, thereby accessing the second network with minimal latency and improved service continuity on the second network.

[0029] In some implementations, the method further includes: the first access network device sending indication information to the terminal device, the indication information being used to indicate that, when the service range of the first target cell includes the coverage range of the second network, identification information of the second network should be included in the measurement report information of the first target cell. This allows the access network device serving the terminal device to perceive the cell or access network device of the second network based on the measurement report information of the terminal device.

[0030] In some implementations, the first access network device further receives second information, where the second information is used to instruct the first access network device to select a cell in the access-allowed area of ​​the second network when determining a target cell. In this way, the terminal selects a cell in the access-allowed area to access the second network, thereby avoiding service interruption and improving access success rate.

[0031] In some implementations, the first access network device further includes selecting a first target access network device or first target cell if, among adjacent access network devices or adjacent cells of the access network device or cell currently accessed by the terminal device, there is an access network device or cell whose service range includes the coverage range of the second network. Accessing the access network device or cell within the coverage range of the second network may be preferred, thereby reducing access delay, improving access success rate, reducing access costs, and improving service continuity of the second network.

[0032] In some implementations, the handover request message indicates that the first target access network device or the first target cell serves the second network, so that the first access network device serving the terminal device determines the access network device or cell in the second network according to the instruction, so that the terminal device can access the second network and avoid service termination.

[0033] In a fifth aspect, a communication method is provided, and the execution subject of the method can be a terminal device, or a chip in the terminal device. The following description is made using the example of the execution subject being a terminal device. In this method, the terminal device receives indication information from the first access network device, and the indication information is used to indicate: the terminal device measures the first target cell; the terminal device sends measurement reporting information of the first target cell according to the indication information, and the measurement reporting information of the first target cell includes identification information of the target network, and the service range of the first target cell includes the coverage range of the target network. In this way, the first access network device can perceive whether the network served by the first target cell is the network that the terminal device preferably accesses based on the measurement reporting information.

[0034] In some implementations, the indication information is further used to indicate that, when the service range of the first target cell includes the coverage range of the target network, identification information of the target network is included in the measurement reporting information of the first target cell.

[0035] In some implementations, the indication information further indicates that when the target network is a second network, the measurement report information includes an identifier of the target network. The second network is a specific type of network, such as a non-public land mobile network. Thus, the terminal device does not need to include the identifier of the target network in every measurement report information. Instead, the terminal device only includes the identifier of the target network in the measurement report information when the first target cell is a cell serving the second network, thereby saving signaling overhead.

[0036] In some implementations, the terminal reads a first system information broadcast (SIB) field of the first target cell to obtain an identifier of a network served by the first target cell.

[0037] In some implementations, a terminal device receives third information from a first core network device, the third information being used to instruct: when the terminal device selects a target access network device or target cell for accessing the second network, it is to select an access network device or cell whose service range includes an area within the coverage of the second network that the terminal device is permitted to access. This allows the terminal device to preferentially access the second network within the coverage of the second network, based on the configuration, thereby reducing access latency, improving access success rates, reducing access costs, and improving service continuity on the second network.

[0038] In a sixth aspect, a communication device is provided, and the beneficial effects can be found in the description of the first aspect and will not be repeated here. The communication device has the function of implementing the behavior in the method instance of the first aspect above. The function can be implemented by hardware, or it can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In one possible design, the communication device includes: a first receiving unit for receiving a registration request for requesting that a terminal device access the second network; a first sending unit for sending first information to the first access network device serving the terminal device when allowing the terminal device to access the second network, the first information is used to indicate: when selecting a target access network device or target cell for the terminal device to access the second network, the preferred service range includes an access network device or cell with a coverage range of the second network.

[0039] In a seventh aspect, a communication device is provided, and the beneficial effects can be found in the description of the second aspect and will not be repeated here. The communication device has the function of implementing the behavior in the method instance of the second aspect above. The function can be implemented by hardware, or it can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In one possible design, the communication device includes: a second receiving unit for receiving a registration request message from a terminal device, the registration request message is used to request that the terminal device be connected to the second network, and the registration request message includes identification information of the terminal device; and a second sending unit for sending a context request to the core network device serving the first network based on the identification information of the terminal, the context request is used to obtain the context of the terminal device, and the context request includes first indication information for indicating that the second core network device serves the second network; the second receiving unit is also used to receive the context of the terminal device from the core network device serving the first network, and the context of the terminal device does not include sensitive information of the terminal device.

[0040] In an eighth aspect, a communication device is provided. The beneficial effects can be found in the description of the third aspect and will not be repeated here. The communication device has the function of implementing the behavior in the method instance of the third aspect. The function can be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In one possible design, the communication device includes: a receiving unit for receiving a switching request message sent by a first access network device serving a terminal device, the switching request message indicating a target access network device or target cell to be accessed by the terminal device; and a selection unit for selecting a core network device serving the first network to serve the terminal device based on determining that the target access network device or target cell is an access network device or cell serving the first network.

[0041] In a ninth aspect, a communication device is provided, and the beneficial effects can be found in the description of the fourth aspect and will not be repeated here. The communication device has the function of implementing the behavior in the method example of the fourth aspect. The function can be implemented by hardware, or it can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In one possible design, the communication device includes: a third receiving unit for receiving first information, the first information is used to indicate: when selecting a target access network device or target cell for a terminal device to access the second network, the access network device or cell whose service range includes the coverage range of the second network is preferred; a determination unit for determining, based on the first information, the first target access network device or the first target cell to be accessed by the terminal device; and a third sending unit for sending a handover request message to the core network device serving the terminal device, the handover request message including the identification information of the first target access network device or the identification information of the first target cell; or the third sending unit is used to send a radio resource control (RRC) redirection message to the terminal device, the RRC redirection message instructing the terminal device to reselect the first target access network device or the first target cell to access the second network.

[0042] In the tenth aspect, a communication device is provided. The beneficial effects can be found in the description of the fifth aspect and will not be repeated here. The communication device has the function of implementing the behavior in the method instance of the fifth aspect. The function can be implemented by hardware, or by hardware executing the corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions. In one possible design, the communication device includes: a fourth sending unit for sending a registration request, the registration request is used by the first core network device to determine that the terminal device is allowed to access the second network; and a fourth receiving unit for receiving third information from the first core network device, the third information is used to indicate: when the terminal device selects a target access network device or target cell to access the second network, the access network device or cell whose service range includes an area in the coverage range of the second network that the terminal device is allowed to access is selected.

[0043] In an eleventh aspect, a device is provided, comprising: a processor, and a memory storing instructions, wherein when the instructions are executed by the processor, the electronic device executes any one of the methods according to the first to fifth aspects and their implementations.

[0044] In a twelfth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores instructions, and when the instructions are executed by an electronic device, the electronic device executes the method executed by the device in the above aspects.

[0045] In a thirteenth aspect, a computer program product includes instructions, and when the instructions are executed by an electronic device, the electronic device executes the method executed by the device in the above aspects.

[0046] In a fourteenth aspect, embodiments of the present disclosure provide a chip system comprising a processor configured to implement the functions of the apparatus described in the aforementioned methods. In one possible design, the chip system further comprises a memory configured to store program instructions and / or data. The chip system may be comprised solely of a chip or may include a chip and other discrete components.

[0047] In a fifteenth aspect, an embodiment of the present disclosure further provides a system for communication, comprising: an apparatus for executing any one of the methods in the first to fifth aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1A shows a schematic diagram of a communication system architecture of some solutions.

[0049] FIG1B shows a schematic diagram of a communication system according to some embodiments of the present disclosure.

[0050] FIG1C shows a schematic diagram of a communication system architecture according to some embodiments of the present disclosure.

[0051] FIG2A shows a schematic diagram of a communication process according to some embodiments of the present disclosure.

[0052] FIG2B shows a schematic diagram of a communication process according to some other embodiments of the present disclosure.

[0053] FIG3 shows a schematic diagram of a communication process in an example scenario of some embodiments of the present disclosure.

[0054] FIG4 shows a schematic diagram of a communication process of example scenarios of other embodiments of the present disclosure.

[0055] FIG5 shows a schematic diagram of a communication process of example scenarios of still other embodiments of the present disclosure.

[0056] FIG6 shows a schematic diagram of a communication process of example scenarios of still other embodiments of the present disclosure.

[0057] FIG7 shows a schematic diagram of a communication process of example scenarios of still other embodiments of the present disclosure.

[0058] FIG8 shows a schematic diagram of a communication flow of example scenarios of still other embodiments of the present disclosure.

[0059] FIG9 shows a schematic flowchart of some embodiments of the present disclosure implemented at a communication device.

[0060] FIG10 shows a schematic flowchart of other embodiments of the present disclosure implemented in a communication device.

[0061] FIG11 shows a schematic flowchart of still further embodiments of the present disclosure implemented at a communication device.

[0062] FIG12 is a schematic diagram showing the main components of an example device of a possible implementation method of an embodiment of the present disclosure.

[0063] FIG13 shows a simplified block diagram of an example device for one possible implementation of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0064] The following describes embodiments of the present disclosure in more detail with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the embodiments of the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0065] In the description of the embodiments of the present disclosure, the term "including" and similar terms should be understood as open inclusion, that is, "including but not limited to." The term "based on" should be understood as "based at least in part on." The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0066] Embodiments of the present disclosure may be implemented in accordance with any suitable communication protocol, including but not limited to cellular communication protocols such as third generation (3G), fourth generation (4G), fifth generation (5G), and future communication protocols (e.g., sixth generation (6G)), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol currently known or developed in the future.

[0067] 5G's public network integrated non-public networks (PNI-NPN) technology supports access in campus scenarios using methods such as slicing, multi-protocol data unit (PDU) sessions, or traffic splitting. In this model, user equipment (UE) from only one operator can access the campus. That is, if a campus partnered with operator A and operator A deployed its network for the campus, users from operator B would be unable to access the campus network. Campuses, such as enterprises, campuses, and stadiums, are called subnet locations. The owners of subnet locations are called subnet tenants, while visitors to subnet locations or members / employees of subnet locations are called subnet users. The services provided by subnet tenants to subnet users, such as XR gaming, in-venue AR navigation, and immersive conferencing, are called subnet services. In this document, the network deployed for a subnet location is called a subnet, and a subnet is used by subnet users to access the services provided by the subnet location. The party that deploys a subnet for a subnet tenant to provide access to subnet users visiting the subnet location is called a subnet operator. In some proposed architectures, as shown in Figure 1A, cross-operator subnet sharing is supported. In this architecture, a subnet domain collaborates with only one operator to deploy a subnet, allowing UEs from other operators to access it. Network elements deployed by the collaborating operator include the radio access network (RAN), the user plane (UP), and the control plane (CP). To support access from terminals of other operators, the base station (SN-RAN) broadcasts a subnet identifier, and the terminal selects the base station based on the subnet identifier. An interface exists between the control plane and the authentication server function (AUSF) / unified data management (UDM) of the terminal's home operator, enabling terminal identity authentication based on the subscriber identity module (SIM) card. The subnet user subscription is stored in the subnetwork subscriber and policy management (SSPM) element within the subnet domain, which is used to authorize UE access to the subnet. To support rapid deployment, subnet operators can be introduced into the business model. Subnet tenants sign contracts with subnet operators, who then work with large network operators to deploy subnets. The subnet control plane (CP) in the subnet domain forwards control signaling between the operator and the subnet domain, while the gateway (GW) forwards user plane data between the subnet domain and the operator domain.The introduction of subnet CPs and gateways eliminates the need for operators to connect to every campus. Instead, they connect to pre-deployed GWs and subnet CPs. Interconnection with the subnet domain falls to the subnet operator, simplifying their work and enabling rapid network deployment. When a UE accesses a subnet, the larger network CP provides mobility and session management. The larger network CP performs SIM card-based authentication for the UE, while the subnet CP authorizes user access based on the subnet domain's user subscription data (stored in the SSPM).

[0068] The above architecture supports UEs accessing campus services through a shared subnet. However, when the UE leaves the subnet's coverage area, it cannot maintain the continuity of ongoing subnet services. For certain scenarios, such as scenario 1, a user is connected to a subnet service through a subnet and is currently holding a conference call. If the user urgently needs to leave the company but still wants to continue the conference call, the above architecture cannot solve the problem of how to maintain the conference call in this scenario. For another example, in scenario 2, an automatic guided vehicle (AGV) may move outside the subnet's coverage area while moving within the campus. That is, the AGV may move back and forth between the main network and the subnet's coverage area. During this process, the AGV needs to maintain service continuity. The above architecture also cannot solve the problem of how to improve the AGV's service continuity in this scenario. In some existing solutions, when a UE accesses the extranet, it is usually necessary to establish a VPN to access campus services. This requires establishing a VPN connection, which results in high latency, causing service interruptions and requiring manual reconnection. Frequent UE movement across boundaries results in a poor user experience. Furthermore, the campus needs to maintain two systems: the VPN system and the subnet system, increasing maintenance complexity. If some terminal devices leave the campus and lose internet access, they will be unable to connect back to the campus. The solutions in some embodiments of the present disclosure can ensure service continuity when UEs move between subnets and the operator's main network.

[0069] FIG1B shows a schematic diagram of a communication system according to some embodiments of the present disclosure. As shown in FIG1B , the communication method provided by the embodiments of the present disclosure can be applied to a communication system 100, such as a wireless communication system such as 5G and satellite communication. In the communication system 100, a terminal device 110, access network devices 120 and 130, and core network devices 140 and 150 are shown. The network 160 and the network 170 can be different networks. For example, the network 160 can be a first network (such as an operator's large network, specifically a public land mobile network (PLMN)), and the network 170 can be a second network (such as a subnet such as a campus network, specifically a non-PLMN). The network 160 can include a core network device 140 serving the network 160 and an access network device 120 whose service range includes the coverage range of the network 160. The network 170 can include a core network device 150 serving the network 170 and an access network device 130 whose service range includes the coverage range of the network 170. The terminal device 110 can access the corresponding network 160 or 170 through the access network device 120 or 130. Taking the terminal device 110 accessing the network 160 through the access network device 120 as an example, when the location of the terminal device 110 changes from being located within the coverage range of the network 160 to being located within the coverage range of the network 170, the access network device 120 can trigger RRC redirection or switching, so that the terminal device 110 is provided with services by the access network device 130 and the core network device 150 in the network 170 under the coverage range of the network 170.

[0070] The communication system 100 in the embodiment of the present disclosure includes but is not limited to: narrowband Internet of Things (NB-IoT) system, global system for mobile communications (GSM), enhanced data rate for GSM evolution (EDGE), wideband code division multiple access (WCDMA), code division multiple access 2000 (CDMA2000), time division-synchronization code division multiple access (TD-SCDMA), long term evolution (LTE), and the three major application scenarios of 5G mobile communication systems, namely eMBB, URLLC, and eMTC.

[0071] It should be understood that the above wireless communication system is applicable to both high-frequency scenarios (above 6G) such as millimeter waves and low-frequency scenarios (sub6G). Application scenarios of wireless communication systems include, but are not limited to, fifth-generation systems (5G), new radio (NR) communication systems, and future communication systems such as evolved public land mobile networks (PLMN) systems.

[0072] The term "terminal" or "terminal device" used in the embodiments of the present disclosure refers to any terminal device that can perform wired or wireless communication with network devices or with each other. Terminal devices may sometimes be referred to as user equipment (UE). Terminal devices may be any type of mobile terminal, fixed terminal, or portable terminal. Terminal devices may be various wireless communication devices with wireless communication capabilities. For example, a terminal device (terminal device 110 as shown in FIG1B ) may be user equipment (UE), terminal, access terminal, terminal unit, terminal station, mobile station (MS), remote station, remote terminal, mobile terminal, wireless communication device, terminal agent, or terminal device, etc. The terminal device may also be a communication chip with a communication module, or a vehicle with communication capabilities, or an on-board device (such as an on-board communication device, an on-board communication chip), etc. The terminal device may have wireless transceiver capabilities, which can communicate (such as wireless communication) with one or more network devices of one or more communication systems and receive network services provided by the network devices. The network devices here include but are not limited to the access network devices 120 and 130 shown in FIG1B .

[0073] For example, the terminal device can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA) device, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle device, a wearable device, a terminal device in a future 5G network, or a terminal device in a future evolved PLMN network, etc.

[0074] For another example, the terminal device may specifically be a mobile phone, a tablet computer, a computer with wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, etc.

[0075] In addition, the terminal device can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; the terminal device can also be deployed on the water surface (such as ships, etc.); the terminal device can also be deployed in the air (such as airplanes, balloons and satellites, etc.). The network device can be an access network device (or access network point). Among them, the access network device refers to a device that provides network access functions, such as a radio access network (RAN) base station, etc. The network device may specifically include a base station (BS), or include a base station and a wireless resource management device for controlling the base station, etc. The network device may also include a relay station (relay device), an access point, a base station in a 5G network or an NR base station, a base station in a future evolved PLMN network, etc. The network device may be a wearable device or a vehicle-mounted device. The network device may also be a communication chip with a communication module.

[0076] The terms "network node" or "network device" used in the embodiments of this disclosure refer to entities or nodes that can be used to communicate with terminal devices, such as access network devices. Access network devices can be devices deployed in a radio access network to provide wireless communication capabilities for mobile terminals, such as radio access network (RAN) network devices. Access network devices can include various types of base stations. Base stations are used to provide wireless access services to terminal devices. For example, network equipment (such as access network equipment 120 and 130) include but are not limited to: base stations (g nodeB, gNB) in 5G, evolved node B (evolved node B, eNB) in long term evolution (LTE) system, radio network controller (RNC), wireless controller under cloud radio access network (CRAN) system, base station controller (BSC), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (baseBand unit, BBU), transmission point (transmitting and receiving point, TRP), transmission point (transmitting point, TP), mobile switching center, and can also be evolutionary NB (eNB or eNodeB) in LTE, base station equipment in future 5G network or access network equipment in future evolved PLMN network, and can also be wearable device or vehicle-mounted device.

[0077] In some deployments, network devices may include a centralized unit (CU) and a distributed unit (DU). The network device may also include an active antenna unit (AAU). The CU implements some of the network device's functions, while the DU implements some of the network device's functions. For example, the CU is responsible for processing non-real-time protocols and services, and implementing the functions of the radio resource control (RRC) and packet data convergence protocol (PDCP) layers. The DU is responsible for processing physical layer protocols and real-time services, and implementing the functions of the radio link control (RLC), media access control (MAC), and physical (PHY) layers. The AAU implements some physical layer processing functions, RF processing, and active antenna-related functions. Because RRC layer information ultimately becomes PHY layer information, or is converted from PHY layer information, in this architecture, higher-layer signaling, such as RRC layer signaling, can also be considered to be sent by the DU, or by the DU+AAU. It is understandable that the network device may be a device including one or more of a CU node, a DU node, and an AAU node. In addition, the CU may be divided into a network device in an access network (radio access network, RAN), or the CU may be divided into a network device in a core network (core network, CN), and this application does not limit this. Examples of network devices include, but are not limited to, Node B (NodeB or NB), evolved NodeB (eNodeB or eNB), next generation NodeB (gNB), transmit receive point (TRP), remote radio unit (RRU), radio head (RH), remote radio head (RRH), IAB node, low power node, such as a femto node, a micro node, a reconfigurable smart surface (RIS), a network controlled repeater, and the like.

[0078] In addition, network devices such as access network devices 120 and 130 can be connected to core network (CN) devices (such as core network devices 140 and 150). Core network devices 140 and 150 can be used to provide core network services for access network devices 120 and 130 and terminal device 110. Core network devices 140 and 150 can correspond to different devices in different systems. For example, in 3G, core network devices can correspond to the serving GPRS support node (SGSN) of the general packet radio service (GPRS) and / or the gateway GPRS support node (GGSN) of GPRS. In 4G, core network devices can correspond to the mobility management entity (MME) and / or the serving gateway (S-GW). In 5G, core network devices can correspond to the access and mobility management function (AMF), the session management function (SMF), or the user plane function (UPF).

[0079] Figure 1C shows a schematic diagram of the communication system architecture of some embodiments of the present disclosure. In the architecture shown in Figure 1C, the subnet UE subscription is used to manage the subscription data and policies of subnet users. This function can be deployed on-premises within the subnet tenant campus. The subnet CP is used to determine whether the UE is allowed to access the subnet based on the subnet user subscription when the UE accesses the subnet. The subnet UP (i.e., the subnet UPF in Figure 1C, such as the SN-UPF) is responsible for forwarding user-plane data between the UE and the subnet service. The subnet base station is used to access the subnet through the subnet base station when the UE is within the coverage area of ​​the subnet. The large network CP is responsible for UE mobility management and session management when the UE accesses the subnet through the large network base station. The large network UP (i.e., the UPF in Figure 1C) is used to forward user-plane data between the large network base station and the subnet when the UE accesses the subnet through the large network base station. The large network base station is used to access the subnet through the large network base station when the UE moves out of the subnet coverage area. In some examples, the subnet CP can be the subnet AMF and / or the subnet SMF, and the large network CP can be the large network AMF and / or the large network SMF. This architecture can support UE access to the campus network (i.e., subnet) through the serving PLMN (Public Land Mobile Network). In some examples, when the UE is within the coverage of the serving PLMN, it requests the subnet AMF to authorize the UE's access through the serving PLMN's AMF. The UE's authentication can be performed by the subnet AMF. In this case, the subnet AMF can interface with the AUSF / UDM of the HPLMN (Home PLMN) to authenticate the UE. The UE's authentication can also be performed by the large network AMF. In this case, the large network AMF can directly interface with the AUSF / UDM of the HPLMN to authenticate the UE.

[0080] Figure 2A shows a schematic diagram of the communication process of some embodiments of the present disclosure. As shown in Figure 2A, in process 200, the terminal device 210 can be an example of the above-mentioned terminal device 110, the first access network device 220 can be an example of the above-mentioned access network device 120, and the first core network device 230 can be an example of the above-mentioned core network device 140. The first access network device 220 and the first core network device 230 are network elements in the first network (such as the network 160 above). The example of the first network can be an operator network, or a large network. In other examples, the first access network device 220 can be an example of the above-mentioned access network device 130, and the first core network device 230 can be an example of the above-mentioned core network device 150. The first access network device 220 and the first core network device 230 are network elements in the second network (such as the network 170 above). The example of the second network can be a campus network, or a subnet. In some embodiments, the example of the terminal device 110 can be a UE. The example of the first access network device 220 can be a base station, for example, a base station whose service range includes the coverage range of the first network or the second network. An example of the first core network device 230 may specifically be a network element of a control plane function (CP) in the core network, such as an AMF (Access and Mobility Management Function) and / or an SMF (Session Management Function) in the first network or the second network. In some examples below, the large network AM / SM refers to the AMF / SMF in the large network, and the subnet AM / SM refers to the AMF / SMF in the subnet. The above-mentioned devices, functions, or network elements are not limited to the specific examples listed above.

[0081] At 204, the first core network device 230 receives a registration request for requesting access to the second network for the terminal device 210. Specifically, when the terminal device 210 accesses the second network through a first access network device whose service range includes the coverage of the first network or the second network, as shown in 202, the terminal device 210 may send the registration request to the first access network device 220. The first access network device 220 receives the registration request and sends the registration request to the corresponding first core network device 230, thereby receiving the registration request. After receiving the registration request, the first core network device 230 determines whether to allow the terminal device 210 to access the second network. In some examples, the first core network device 230 may determine whether to allow the terminal device 210 to access the second network based on the service area information of the second network. For example, if the service area of ​​the second network does not include the current location of the terminal device 210, the terminal device 210 is denied access; otherwise, access is allowed. In other examples, the first core network device 230 is a core network device serving the first network. The first core network device 230 can obtain the subscription information of the second network on the first network (or the subscription information of the second network, which is subscription information at the network granularity). If the subscription information includes the service area of ​​the second network, and the service area of ​​the second network includes the current location of the terminal device 210, the terminal device 210 is allowed to access. Otherwise, the terminal device 210 is not allowed to access. In still other examples, the first core network device 230 is a core network device serving the first network. The first core network device 230 can send an access request to the core network device serving the second network (referred to as the second core network device). The access request is used to request the second core network device to authorize the terminal device 210 to access the second network. When the first core network device 230 receives the authorization acceptance indication sent by the second core network device, the first core network device 230 determines to allow the terminal device 210 to access the second network based on the authorization acceptance indication. If the second core network device does not authorize the terminal device 210 to access, the first core network device 230 denies the terminal device 210 access to the second network. In some examples, the access request includes identification information of the terminal device, where the identification information of the terminal device includes at least one of the following: a Mobile Station International Subscriber Directory Number (MSISDN), a Subscription Hidden Identifier (SUCI), or a temporary identifier. In some embodiments, the specific implementation of determining whether to allow access to the terminal device 210 can be a combination of one or more of the examples listed above.

[0082] In 206, when allowing the terminal device 210 to access the second network, the first core network device 230 sends first information to the first access network device 220 serving the terminal device 210. The first information is used to indicate that when selecting a target access network device or target cell for the terminal device 210 to access the second network, an access network device or cell whose service range includes the coverage of the second network is preferred. Here and throughout the specification, "an access network device or cell whose service range includes the coverage of the second network" can be replaced with "an access network device or cell providing services for the second network" or "an access network device or cell broadcasting identification information (i.e., a subnet identifier) ​​of the second network." Similarly, those skilled in the art will understand that the service range of an access network device or cell including the coverage of the second network has the same meaning as the following expressions: the access network device or cell provides services for the second network; or the access network device or cell broadcasts identification information of the second network. In some examples, the first information includes: identification information of the second network, or a cell list (which includes: information on one or more cells whose service range includes the coverage range of the second network), or an access network device list (which includes: information on one or more access network devices whose service range includes the coverage range of the second network), or a combination of one or more of the above. In this way, when the first core network device 230 selects a target access network device or target cell, if there is an available access network device or cell serving the second network, the access network device or cell serving the second network is preferentially selected so that the terminal device 210 can directly access the subnet through the access network device or cell (rather than remotely accessing the subnet through a large network base station).

[0083] In some embodiments, on the first access network device 220 side, after the first access network device 220 receives the first information, when the terminal device 210 moves from the network corresponding to the service range of the first access network device (i.e., the source network) to the coverage range of another network (i.e., the target network), the first access network device 220 acts as the source access network device. Then, at 208, the first access network device 220 can determine the first target access network device or the first target cell to be accessed by the terminal device 210 based on the first information. At 212, the first access network device 220 sends a handover request message to the core network device serving the terminal device 210, the handover request message including the identification information of the first target access network device or the identification information of the first target cell; or at 214, the first access network device 220 sends a radio resource control (RRC) redirection message to the terminal device 210, the RRC redirection message instructing the terminal device 210 to reselect the first target access network device or the first target cell to access the target network. In some examples, when the target network is a second network, the handover request message can indicate that the first target access network device or the first target cell serves the second network. In some examples, the first access network device 220 may receive measurement report information of a first target cell from the terminal device 210, the measurement report information including identification information of the target network. The first access network device 220 may determine, based on the identification information of the target network, that the service range of the first target access network device or the first target cell to be accessed by the terminal device 210 includes the coverage range of the target network. In some instances, the measurement report information only includes the identification information of the second network when the target network is a second network. That is, when the target network is a first network, the measurement report information may not include the identification information of the first network. Optionally or alternatively, the first access network device 220 may receive indication information indicating that the service range of the first target access network device or the first target cell to be accessed by the terminal device 210 includes the coverage range of the second network. In some examples, the indication information may be obtained through information exchange between the first access network device 220 and the first target access network device through information exchange. For example, the first target access network device sends the indication information to the first access network device 220 through information exchange. Optionally or alternatively, the first access network device 220 may determine, based on local configuration information, that the service range of the first target access network device or the first target cell includes the coverage range of the second network. In some embodiments, the first access network device 220 may further send indication information to the terminal device 210, the indication information being used to instruct: the terminal device 210 to measure the first target cell, the measurement reporting information including identification information of the target network, and the target network being the network served by the first target cell.In some examples, the terminal device 210 measures the first target cell, reads the first system broadcast message (SIB) field of the first target cell, obtains the identifier of the network served by the first target cell, and sends measurement reporting information, which includes the identifier of the network served by the first target cell. In some implementations, the indication information further indicates that when the target network is the second network, the measurement reporting information includes the identifier of the target network. That is, the terminal device does not need to include the identifier information of the target network in each measurement reporting information, but only includes the identifier information of the target network in the measurement reporting information when the first target cell is a cell serving the second network. In the case where the service range of the first target cell includes the coverage range of the second network (that is, when the first target cell serves the second network), the measurement reporting information includes the identifier information of the second network. In some examples, when there is an access network device or cell whose service range includes the coverage of the second network among the adjacent access network devices or adjacent cells of the access network device or cell currently accessed by the terminal device 210, the first access network device 220 selects the first target access network device or first target cell to be accessed by the terminal device 210 from the access network devices or cells within the coverage of the second network.

[0084] In some embodiments, the first core network device 230 is a core network device serving the first network. For example, in an example scenario where the terminal device 210 moves from the first network to the second network in an idle state (see the example of FIG. 4 below for details), the first core network device 230 may receive a context request from a second core network device serving the second network. The context request is used to obtain the context of the terminal device 210, and the context request may include first indication information indicating that the second core network device serves the second network. Based on the first indication information, the first core network device 230 may send the context of the terminal device 210 to the second core network device, where the context may not include sensitive information of the terminal device 210. This example can be further described in detail in conjunction with the embodiments shown in FIG. 2B and FIG. 4 below, for example, referring to the operation of the core network device 260 serving the first network receiving the context request from the second core network device 250 and the operation of the core network device 260 serving the first network sending the context of the terminal device to the second core network device 250 in FIG. 2B , or the operation of the subnet AM / SM 440 (an example of the second core network device) obtaining (409) the context of the UE (an example of the terminal device 210) from the large network AM / SM 460 (an example of the core network device serving the first network) in FIG. 4 . In some examples, the first core network device 230 can first determine that the second core network device has the authority to obtain the context of the terminal device 210, and then send the context of the terminal device 210 based on the second core network device having the authority. In some examples, the first core network device 220 can receive second indication information from the second core network device for instructing the deletion of the context of the terminal device 210, and the first core network device 210 can delete the context of the terminal device 210 and the session resources corresponding to the terminal device 210 in the first core network device based on the second indication information. For details, please refer to operations 413 and 415 in the embodiment shown in Figure 4.

[0085] In other embodiments, the first core network device 230 is a core network device serving the first network. For example, in an example scenario where the terminal device 210 moves from the second network to the first network in an idle state, the registration request includes identification information of the terminal device 210, which is an identifier assigned by a second core network device serving the second network. The first core network device 230 determines the second core network device based on the identification information and sends a context request to the second core network device. The context request is used to obtain the context of the terminal device 210, and the context request includes the identification information of the terminal device 210. The first core network device 230 receives the context of the terminal device 210 from the second core network device. For details, see operation 609 of the embodiment shown in Figure 6.

[0086] When the first core network device 230 is a core network device serving the first network, the first core network device 230 may store the address information of the second core network device in the context of the terminal device 210 .

[0087] In some embodiments, the first core network device is a core network device serving the first network. For example, in an example scenario where the terminal device 210 moves from the coverage of the first network to the coverage of the second network in a connected state (for a specific example, refer to the example shown in FIG5 below), the first access network device 220 is an access network device whose service range includes the coverage of the first network. The first core network device 230 can receive a handover request message from the first access network device 220, where the handover request message includes identification information of a target access network device or target cell to be accessed by the terminal device 210. The first core network device 230 selects a second core network device serving the second network based on the target access network device or target cell serving the second network. The first core network device 230 sends a context of the terminal device 210 to the second core network device, where the context does not include sensitive information of the terminal device 210. The target access network device or target cell serves the second network. In other words, the target access network device or target cell to be accessed by the terminal device 210 is an access network device or cell whose service range includes the coverage of the second network. In some examples, the first core network device 230 determines, based on the network currently accessed by the terminal device 210, to select a second core network device serving the second network. Specifically, when the target access device or target cell to be accessed serves the second network and the terminal device 210 accessed the second network through the first network before the handover, the first core network device 230 selects the second core network device serving the second network. In some examples, the first core network device 230 may also send a handover request message to the second core network device serving the second network. The handover request message sent to the second core network device includes identification information of the target access network device and the terminal device's context. In some examples, the terminal device's context does not include sensitive information. In some examples, the first core network device 230 determines that the target access network device or target cell to be accessed by the terminal device 210 is an access network device or cell whose service range includes the coverage area of ​​the second network, based on the fact that the target access network device or target cell to be accessed by the terminal device, as indicated in the handover request message, serves the second network and / or based on the fact that the service area of ​​the second network includes the service area of ​​the target access network device or target cell to be accessed by the terminal device. The subscription information of the second network includes the service area of ​​the second network, and the first core network device 230 can determine the service area of ​​the second network according to the subscription information of the second network.

[0088] In some examples, the first core network device 230 sends second information to the first access network device 220, and accordingly, the first access network device 220 receives the second information from the first core network device 230. The second information is used to indicate that when selecting a target access network device or target cell for the terminal device 210 to access the second network, the access network device or cell whose service range includes an area within the coverage of the second network that the terminal device 210 is allowed to access is selected. A specific example of the second information can refer to the mobility restriction information sent to the base station below. The first core network device 230 sends third information to the terminal device 210, and the third information is used to indicate that when the terminal device 210 selects a target access network device or target cell to access the second network, the access network device or cell whose service range includes an area within the coverage of the second network that the terminal device 210 is allowed to access is selected. A specific example of the third information can refer to the mobility restriction information sent to the terminal device (e.g., UE) below. In some examples, the first core network device 210 is a core network device serving the first network, and the first core network device 210 obtains the above-mentioned mobility restriction information (i.e., the area information within the coverage range of the second network that the terminal device 210 is allowed to access) from the second core network device, wherein the second core network device is a core network device serving the second network.

[0089] In some examples, the first core network device 210 is a core network device serving the first network, and the first access network device 220 is an access network device serving the first network, such as an example scenario in which a cross-access network device handover occurs during the movement of the terminal device 210 within the first network. The first core network device 230 can receive a handover request message sent by the first access network device 220, which indicates the target access network device or target cell to be accessed by the terminal device 210. Based on determining that the target access network device or target cell to be accessed by the terminal device 210 is an access network device or cell whose service range includes the coverage range of the first network, the core network device serving the first network (which may be referred to as a third core network device) is selected to serve the terminal device. The first core network device 210 sends the context of the terminal device to the third core network device, the context including information about the second core network device serving the second network and identification information of the second network. The identification information of the second network is used to indicate that the network accessed by the terminal device 210 is the second network.

[0090] In some embodiments, for example, in a handover scenario in which a terminal device 210 switches in a connected state from an access network device whose service scope includes the coverage of a second network to an access network device whose service scope includes the coverage of a first network (see the example shown in FIG. 7 below for details), at a second core network device, the second core network device receives a handover request message sent by the first access network device 220 serving the terminal device 210, where the handover request message indicates a target access network device or target cell to be accessed by the terminal device 210. Based on determining that the target access network device or target cell is an access network device or cell serving the first network, the second core network device selects a core network device serving the first network to serve the terminal device 210. The second core network device may determine that the target access network device or target cell to be accessed by the terminal device 210 is an access network device or cell serving the first network based on one or more of the following factors. For example, the first factor may be an indication from the handover request message sent by the first access network device 220 serving the terminal device 210 that the target access network device or target cell is an access network device or cell serving the first network. The second factor may be that the service area of ​​the target access network device or the target cell is not within the coverage area of ​​the second network, wherein the service area of ​​the second network is indicated by the first subscription information of the second network in the first network. In other examples, the first and second factors mentioned above may be combined. In some examples, the second core network device may also send a switching request message to the core network device serving the first network, and the switching request message includes: identification information of the second network, or the context of the terminal device, or callback address information of the core network device serving the second network, or a combination thereof. The callback address information is used for message interaction between the core network device serving the first network and the core network device serving the second network, and the identification information of the second network is used to instruct the terminal device 210 to access the second network.

[0091] Figure 2B shows a schematic diagram of the communication process of other embodiments of the present disclosure. This process 200-1 can refer to the relevant description of the case in which the first core network device 230 in process 200 is a core network device serving the second network (i.e., the second core network device). At 201, the second core network device 250 serving the second network receives a registration request message from a terminal device (not shown in Figure 2B). The registration request message is used to request that the terminal device access the second network, and the registration request message includes identification information of the terminal device. The registration request message may be received from the terminal device by the second access network device 240 and sent to the second core network device 250. At 203, the second core network device 250 sends a context request to the core network device serving the first network based on the identification information of the terminal device. The context request is used to obtain the context of the terminal device 210, and the context request includes first indication information indicating that the second core network device 250 serves the second network. At 205, the second core network device 250 receives the context of the terminal device from the core network device serving the first network. The context of the terminal device does not include sensitive information of the terminal device.

[0092] Figure 3 illustrates a communication flow diagram for example scenarios according to some embodiments of the present disclosure. Specifically, Figure 3 illustrates a process 300 for registering a terminal device with a subnet through a large network base station when the terminal device is not within the subnet's coverage area. A subnet is a network deployed in a location such as an enterprise, campus, or stadium, allowing subnet users to access and access subnet services provided by the subnet location. The owner of the subnet location can be referred to as a subnet tenant, while visitors to the subnet location or members / employees of the subnet location can be referred to as subnet users. Subnet tenants can provide subnet services, such as services provided to subnet users, such as XR gaming, in-venue AR navigation, and immersive conferencing. The party that deploys a subnet for a subnet tenant and provides access to subnet users visiting the subnet location can be referred to as a subnet operator. When a terminal device registers with the subnet through a large network CP (such as an AMF), the large network CP still requests the subnet CP (such as the subnet AMF) to authorize access for the terminal device. In this process 300, the large network is an example of a first network, and the subnet is an example of a second network. The UE 310 shown in Figure 3 is an example of a terminal device, the large network base station 320 is an example of an access network device serving the first network, the large network AM / SM 330 is an example of a control plane (CP) function serving the first network, the large network UPF 340 is an example of a user plane (UP) function serving the first network, the subnet AM / SM 350 is an example of a control plane function serving the second network, the subnet UPF 360 is an example of a user plane function serving the second network, and the SSPF 370 corresponds to the subscription of the subnet terminal device (e.g., UE) and is specifically used to store the subscription information of the subnet user. The HPLMN AUSF / UDM 380 is the AUSF (authentication service network element) of the HPLMN (the home operator of the terminal device's SIM card) that provides SIM card-based authentication, or the UDM (the operator's subscription server) of the HPLMN that stores the UE's subscription information in the large network of its home operator. It should be noted that the network elements or functions in each step of the following process are described with their corresponding examples, but are not limited to these examples and can also be other examples of the corresponding network elements or functions.

[0093] In 301, if UE 310 wishes to access a subnet, it may send a registration request to the large network base station 320. The registration request message may carry a subnet identifier. UE 310 may also send the subnet identifier to the large network base station 320 via an access layer message (such as an RRC message) so that the large network base station 320 can select a suitable large network CP (e.g., large network AM / SM 330) based on the subnet identifier. If the terminal device sends a subnet identifier, in 303, the large network base station 320 may select the large network AM / SM 330 based on the subnet identifier. The functions of the large network AM / SM 330 support UE 310 accessing the subnet. In 305, the large network base station 320 may send a registration request to the large network AM / SM 330. The base station may also send the subnet identifier received from the terminal device to the large network AM / SM 330. In 307, the large network AM / SM 330 triggers authentication of UE 310. The home operator of UE 310's SIM card may not be the operator corresponding to the current large network. Large network AM / SM 330 requests the home operator of UE 310's SIM card to authenticate the SIM card. For example, it selects the HPLMN AUSF / UDM 380 corresponding to UE 310 based on the SUCI to authenticate UE 310. At 309, large network AM / SM 330 sends a subnet access request message to the subnet CP (e.g., subnet AM / SM 350) requesting UE 310 to access the subnet. This message requests subnet AM / SM 350 to authorize access to UE 310. In some examples, large network AM / SM 330 may send an MSISDN to subnet AM / SM 350 as an identifier for UE 310. In other examples, large network AM / SM 330 may also send a temporary identifier allocated by the SUCI or AUSF / UDM to subnet AM / SM 350 as an identifier for UE 310. In some examples, the MSISDN may also serve as an identifier of the UE 310 in the subnet, and the subscription of the UE 310 in the subnet may be indexed using the identifier (eg, the SUCI and temporary identifier may not be used as the identifier of the UE 310 in the subnet).

[0094] At 311, subnet AM / SM 350 obtains the subscription of UE 310 in the subnet. In some examples, if the request message sent by large network AM / SM 330 to subnet AM / SM 350 at 309 includes the identity of the trusted UE 310 in the subnet, subnet AM / SM 350 obtains the subscription of UE 310 in the subnet based on the identity of UE 310 in the subnet. The MSISDN obtained by large network AM / SM 330 from the AUSF / UDM and sent to subnet AM / SM 350 can serve as the identity of the trusted UE 310 in the subnet. In other examples, if the request message sent by the large network AM / SM 330 to the subnet AM / SM 350 in 309 does not include the identifier of the trusted UE 310 in the subnet, the subnet AM / SM 350 can obtain the identifier of the UE 310 in the subnet through 313 and obtain the UE's subscription in the subnet based on the identifier of the UE 310 in the subnet.

[0095] Subnet AM / SM 350 may authenticate UE 310 as needed, as shown in 313. At 313, subnet AM / SM 350 determines to initiate authentication of UE 310 as needed. In some examples, subnet AM / SM 350 may be configured to always authenticate UE 310, or in other examples, subnet AM / SM 350 may trust the authentication of UE 310 by macro-network AM / SM 330 and therefore not authenticate UE 310, or, when the identity of UE 310 in the subnet is assigned by the subnet and macro-network AM / SM 330 cannot verify the identity, subnet AM / SM 350 authenticates UE 310. In some examples, subnet AM / SM 350 authenticates UE 310. Specifically, subnet AM / SM 350 can authenticate UE 310 based on a SIM card. If based on a SIM card, subnet AM / SM 350 needs to request the home operator of the SIM card to perform authentication (same as or similar to operation 307). In other examples, subnet AM / SM 350 can also use other authentication methods, for example, an authentication method based on OAUTH: UE 310 obtains a token from AUSF / UDM 380 and sends it to the subnet, and the subnet authenticates UE 310 based on the token. Of course, other methods can also be used to authenticate UE 310. The embodiments of the present disclosure do not limit the specific method of how the subnet CP authenticates the UE.

[0096] At 315, subnet AM / SM 350 authorizes UE 310 to access the subnet. Specifically, subnet AM / SM 350 may authorize UE 310's access based on UE 310's subscription in the subnet obtained from SSPF 370, such as determining whether to allow UE 310 to access the subnet. At 317, subnet AM / SM 350 sends a response to large network AM / SM 330, indicating that UE 310 is allowed to access the subnet. For example, if subnet AM / SM 350 permits UE access to the subnet, it sends an indication to large network AM / SM 330 indicating that UE 310 is allowed to access the subnet. Large network AM / SM 330 determines that UE 310 is allowed to access the subnet based on the response sent by subnet AM / SM 350, indicating that UE 310 is allowed to access the subnet. In some examples, if UE 310 includes information about areas within the subnet coverage that UE 310 is allowed to access in the subnet subscription information, the subnet AM / SM 350 also sends this information to the large network SM / SM 330, so that the large network SM / SM 330 determines the mobility restriction information to be sent to the large network base station 320 and determines the mobility restriction information to be sent to UE 310.

[0097] At 319, the large network AM / SM 330 obtains the subscription information at the subnet granularity. The subscription information at the subnet granularity is the subscription of the subnet in the operator network (large network). In some examples, the subnet granularity subscription information may include: information on the area where the subnet UE is allowed to access the subnet (i.e., the access allowed area) and the subnet service area information. Subnet granularity subscription is a subscription with the subnet as the granularity, i.e., the subscription of the subnet in the large network. The large network AM / SM 330 can determine whether to allow UE 310 to access the subnet based on the area information where the subnet UE is allowed to access the subnet. If the current location of UE 310 is not within the area where the subnet UE is allowed to access the subnet, the UE's access is denied; otherwise, the UE is allowed to access. The large network AM / SM 330 also determines the mobility restriction information to be sent to the large network base station 320 and the mobility restriction information to be sent to the UE 310 based on the area information where the subnet UE is allowed to access the subnet. The mobility restriction information sent to the large network base station 320 is used by the large network base station 320 to select a target CELL for the UE 310, so that when the UE 310 needs to switch, only cells that are allowed to be accessed are selected for switching. The mobility restriction information sent to the UE 310 is used for the UE 310 to select a target cell when it moves in an idle state, so that only cells within the allowed access area are selected for access. The process shown in Figure 3 is explained by taking the large network AM / SM 330 obtaining subnet granularity subscription information at 319 as an example. Alternatively, the large network AM / SM 330 can obtain the subnet granularity subscription information after 305, that is, after receiving the registration request from the UE 310. If the subnet granularity subscription information is obtained after operation 305, and the subnet area information included in the subnet granularity subscription information does not include the current location of the UE 310, operation 307 and its subsequent processes may not be performed, and the registration of the UE 310 may be directly rejected.

[0098] At 321, if the UE is allowed to access, the large network AM / SM 330 sends a message including the context of UE 310 to the large network base station 320. The message may include mobility restriction information. The message may also instruct the large network base station 320 to prefer the subnet base station when selecting the target base station. Specifically, the large network AM / SM 330 may include a subnet identifier in the message sent to the large network base station 320, and the large network base station 320 may prefer a base station that supports the subnet based on the subnet identifier. In some embodiments, the large network base station 320 may sense nearby cells / base stations that support the subnet based on the configuration. Additionally or alternatively, when configuring the measurement reporting information of the UE 310, the large network base station 320 may instruct the UE 310 to include the subnet identifier supported by the cell in the measurement reporting information, and the large network base station 320 may sense nearby cells / base stations that support the subnet based on the measurement reporting information of the UE 310. Additionally or alternatively, large-network base station 320 may perceive nearby cells / base stations that support subnets based on information exchanged on the inter-base station interface. For example, a neighboring base station of large-network base station 320 may send the subnet identifier of the subnet served by its cell to large-network base station 320. In other embodiments, large-network AM / SM 330 may determine a list of subnet cells adjacent to large-network base station 320 based on the subnet coverage area and send the list to large-network base station 320. Large-network base station 320 may prioritize cells in the list for handover / redirection based on this list. The message sent by large-network AM / SM 330 to large-network base station 320 may include a registration acceptance message sent to UE 310. The registration acceptance message includes mobility restriction information. At 323, large-network base station 320 may send the registration acceptance message to UE 310.

[0099] Figure 4 shows a schematic diagram of the communication process of example scenarios of other embodiments of the present disclosure. Specifically, Figure 4 shows a process 400 of a terminal device moving from a large network coverage area to a subnet coverage area in an idle state. In the process 400, the large network is an example of a first network, and the subnet is an example of a second network. The UE 410 shown in Figure 4 is an example of a terminal device, the large network base station 420 is an example of an access network device serving the first network, the subnet base station 430 is an example of an access network device serving the second network, the subnet AM / SM 440 is an example of a control plane function serving the second network, the subnet UPF 450 is an example of a user plane function serving the second network, the large network AM / SM 460 is an example of a control plane (CP) function serving the first network, and the large network UPF 470 is an example of a user plane (UP) function serving the first network. It should be noted that the network elements or functions in each step of the following process are described with their corresponding examples, but are not limited to this example, and can also be other examples of corresponding network elements or functions. In this embodiment, the large network base station 420 triggers RRC redirection and switches the UE 410 from the large network base station 420 to the sub-network base station 430 through the process 400 .

[0100] In 401, the large network base station 420 sends an RRC redirection message to the UE 410. The message may carry information about the target cell so that the UE 410 selects the designated cell. Referring to 321 in the process 300 shown in Figure 3, during the UE registration phase, the large network CP (e.g., large network AM / SM) may configure the large network base station so that the large network base station may give priority to supporting subnet base stations / cells when selecting target base stations / target cells, or the large network CP may determine a list of subnet cells adjacent to the large network base station and send the subnet cell list to the large network base station so that the large network base station may give priority to selecting cells in the subnet cell list for switching or redirection based on the subnet cell list. The large network base station 420 selects a target cell for the UE 410 based on the above-mentioned preferred subnet base station / cell information. In this example, there is a target cell of the serving subnet, so the target cell selected by the large network base station is the cell of the serving subnet.

[0101] In 403, UE 410 selects a subnet base station 430 and sends a registration request message to the subnet base station 430. If UE 410 receives an RRC redirection message from the large network base station 420, it can select a cell based on the target cell information in the redirection message. If UE 410 does not receive the target cell information or the RRC redirection message, or if UE 410 is in an idle state, UE 410 can select a serving cell of the subnet based on the subnet identifier broadcast by the subnet base station 430. In some examples, the registration request message can carry a subnet identifier. In some examples, the registration request message can carry a temporary identifier of the UE, which is allocated by the large network CP. The temporary identifier includes information about the large network CP and can be used to address the large network CP, where the large network CP is, for example, the large network AM / SM 460. UE 410 can also carry a subnet identifier in the access stratum (AS) message when sending the registration request message.

[0102] At 405, subnet base station 430 selects a subnet CP (e.g., subnet AM / SM 440). When subnet base station 430 is connected to multiple control plane network elements, subnet base station 430 may select subnet AM / SM 440 based on the subnet identifier in the access stratum message. When subnet base station 430 is connected to only one subnet AM / SM 440, subnet base station 430 selects the subnet AM / SM 440 with which it has an interface. At 407, subnet base station 430 sends a registration request to subnet AM / SM 440. Subnet base station 430 may also send the subnet identifier received from UE 410 to subnet AM / SM 440.

[0103] In some embodiments, subnet AM / SM 440 can obtain the context of UE 410 from large network AM / SM 460, as shown in 409. Subnet AM / SM 440 identifies large network AM / SM 460 based on the temporary identifier of UE 410 in the registration request message and sends a context request message to large network AM / SM 460. Large network AM / SM 460 sends the context of UE 410 to subnet AM / SM 440. In some examples, large network AM / SM 460 needs to verify the authority of subnet AM / SM 440 to confirm that subnet AM / SM 440 is authorized to obtain the UE context. If subnet AM / SM 440 is not authorized to obtain the UE context, large network AM / SM 460 may refuse to send the UE context. If large network AM / SM 460 cannot determine the identity and authority of subnet AM / SM 440, large network AM / SM 460 may refuse to send the UE context. The method by which the large network AM / SM 460 determines the identity and authority of the subnet AM / SM 440 may be based on the access token mechanism of the 5G NRF (Network Repository Function): before sending a context request message, the subnet AM / SM 440 first obtains a token from the NRF to authorize the operation. The subnet AM / SM 440 then sends the token to the large network AM / SM 460, which then determines whether the operation is permitted based on the token. If the token indicates that the subnet AM / SM 440 has the authority, the large network AM / SM 460 sends the UE context to the subnet AM / SM 440. In some examples, the UE context sent by the large network AM / SM 460 to the subnet AM / SM 440 may not include sensitive UE information, such as the IMSI. In some embodiments, the UE context of the large network AM / SM 460 does not include the IMSI, for example, if the AUSF / UDM does not send the IMSI to the large network AM / SM 460. As an example, the large network AM / SM 460 stores the SUCI of the UE 410 as the UE's identifier. Alternatively, the AUSF / UDM may allocate a temporary identifier and send the temporary identifier to the large network AM / SM 460. The temporary identifier can uniquely identify the UE 410 within the AUSF / UDM, and the large network AM / SM 460 uses the temporary identifier as the UE 410's identifier. In this case, because the context of the UE 410 in the large network AM / SM 460 does not include the IMSI, the context sent to the subnet AM / SM 440 also does not include the IMSI. In other embodiments, the context of the UE 410 in the large network AM / SM 460 includes the IMSI, but when the subnet AM / SM 440 requests the context, the large network AM / SM 460 determines not to send the IMSI.For example, the large network AM / SM 460 may determine, based on the access token, that the context does not include the IMSI. Alternatively, as another example, the context request sent by the subnet AM / SM 440 may include indication information indicating that the subnet AM / SM 440 serves the subnet, and the large network AM / SM 460 may determine not to send the IMSI based on the indication information.

[0104] At 411, if subnet AM / SM 440 needs to authenticate UE 410, subnet AM / SM 440 triggers the authentication process. If subnet AM / SM 440 does not obtain the context of UE 410 from mainnet AM / SM 460 (e.g., there is no interface for obtaining the context, or mainnet AM / SM 460 refuses to provide the context), subnet AM / SM 440 triggers the authentication process. In other examples, subnet AM / SM 440 may also trigger authentication based on other conditions, such as always performing authentication or determining whether to trigger authentication based on the time of the last authentication. The present disclosure does not limit the conditions for triggering authentication.

[0105] At 413, after subnet AM / SM 440 accepts UE 410's registration, subnet AM / SM 440 can instruct large network AM / SM 460 to delete resources related to UE 410. For example, it can instruct large network AM / SM 460 to delete UE 410's context and the corresponding session resources for UE 410 (e.g., deleting the tunnel in large network UPF 470). At 415, large network AM / SM 460 notifies large network UPF 470 to delete the session resources. At 417, subnet AM / SM 440 updates the session in subnet UPF 450. Subnet UPF 450 can allocate uplink tunnel information for subnet base station 430 to send uplink data to subnet UPF 450. At 419, subnet AM / SM 440 notifies subnet base station 430 to establish session resources. Subnet AM / SM 440 may send context information of UE 410 to subnet base station 430. This context information may include session information for the session to be established (e.g., uplink tunnel information of subnet UPF 450). In this step, subnet AM / SM 440 may also instruct subnet base station 420 to prioritize the subnet base station when selecting a target base station. For details, refer to the corresponding description in 321. Subnet base station 430 allocates a downlink tunnel and configures a wireless air interface for the session. Subnet base station 430 sends the downlink tunnel information to subnet AM / SM 440, which then sends the downlink tunnel information to subnet UPF 450. In 421, subnet AM / SM 440 sends a registration accept message to UE 410. Alternatively, the registration accept message may be sent to large-network base station 420 in 419, which in turn sends it to UE 410.

[0106] Figure 5 shows a schematic diagram of the communication process of example scenarios of some other embodiments of the present disclosure. Specifically, Figure 5 shows a process 500 of a terminal device moving from a large network coverage to a subnet coverage in a connected state. In this process 500, the large network is an example of a first network, and the subnet is an example of a second network. The UE 510 shown in Figure 5 is an example of a terminal device, the subnet base station 520 is an example of an access network device serving the second network, the large network base station 530 is an example of an access network device serving the first network, the large network AM / SM 540 is an example of a control plane (CP) function serving the first network, the large network UPF 550 is an example of a user plane (UP) function serving the first network, the subnet AM / SM 560 is an example of a control plane function serving the second network, and the subnet UPF 570 is an example of a user plane function serving the second network. It should be noted that the network elements or functions in each step of the following process are described with their corresponding examples, but are not limited to this example, and can also be other examples of corresponding network elements or functions. As shown in FIG5 , in process 500 , a connected UE 510 moves from a large network coverage area to a subnet coverage area, and the process is as follows.

[0107] In 501, the large network base station 530 sends a handover request message to the large network AM / SM 540. The large network base station 530 can carry indication information in the handover request message to indicate that the target cell / target base station is a subnet cell / subnet base station, that is, the cell / base station providing services for the subnet or the service range of the target cell / target base station is within the coverage of the subnet. Before sending the handover request message, the large network base station 530 can prioritize the subnet base station 520 when selecting the target cell / target base station for the UE 510. For example, the large network AM / SM 540 can send a subnet identifier to the large network base station 530, and the large network base station 530 can prioritize the subnet base station 520 / subnet cell based on the subnet identifier. In some examples, the large network base station 530 can perceive nearby cells / base stations that support the subnet based on local configuration information. In other examples, when configuring the measurement reporting information of UE 510, the large network base station 530 may instruct UE 510 to include the subnet identifier supported by the cell in the measurement reporting information. The large network base station 530 may perceive the nearby cells / base stations that support the subnet based on the measurement reporting information of UE 510. In still other examples, the large network base station 530 perceives the nearby cells / base stations that support the subnet based on the information exchange between the base station interfaces. For example, the large network base station 530 may receive the mapping relationship between the cell identifier and the subnet identifier sent by the adjacent base station, and may perceive the cell / base station that supports the subnet based on the mapping relationship. In still other examples, the large network AM / SM 540 may determine the subnet cell list adjacent to the large network base station 530 based on the subnet coverage area, and send the subnet cell list to the large network base station 530. The large network base station 530 may perform switching / redirection based on the cell list and the cell in the preferred cell list.

[0108] At 503, large network AM / SM 540 selects subnet AM / SM 560. Before selecting subnet AM / SM 560, large network AM / SM 540 determines that the target cell / target base station is a subnet cell / subnet base station. In some examples, large network AM / SM 540 may determine that the target cell / target base station is a subnet cell / subnet base station based on indication information carried in a handover request message sent from large network base station 530. In other examples, large network AM / SM 540 may determine that the target cell / target base station is a subnet cell / subnet base station based on subnet area information in the subnet's subscription information. When the service range of the target cell / target base station is within the coverage range of the subnet, large network AM / SM 540 determines that the target cell / target base station is a subnet cell / subnet base station. If the target cell / target base station is a subnet cell / subnet base station, large network AM / SM 540 selects subnet AM / SM 560 serving UE 510. Referring to the above process 300, the large network AM / SM 540 selects the subnet AM / SM 560 at 309 and stores the information of the subnet AM / SM 560 in the context of the UE 510. The large network AM / SM 540 can determine the address information of the subnet AM / SM 560 based on the context of the UE 510. The address information of the subnet AM / SM 560 can be a URI (Uniform Resource Identifier), which includes the FQDN (Fully Qualified Domain Name) or IP address of the subnet AM / SM 560, and the context identifier of the UE 510 in the subnet AM / SM 560.

[0109] At 505, the large network AM / SM 540 sends a handover request message to the subnet AM / SM 560. The handover request message includes the context of UE 510, which includes the security context of UE 510. Referring to 409 in process 400, the UE 510 identification information in the context of UE 510 may be a SUCI or a UE temporary identity allocated by the AUSF / UDM. The UE context sent by the large network AM / SM 540 to the subnet AM / SM 560 may not include sensitive UE information such as the IMSI. The handover request message may also include information about the target cell / target base station. In some examples, the handover request message may also include a subnet identifier.

[0110] At 507, subnet AM / SM 560 updates the subnet UPF session, and subnet UPF 570 allocates uplink tunnel information. At 509, subnet AM / SM 560 sends a handover request message to the target base station. In this example, the target base station is subnet base station 520. The handover request message may include uplink tunnel information from subnet UPF 570. In some examples, the handover request message may also include session information, which the target base station uses to allocate radio resources for the session. At 511, subnet base station 520 sends a handover response message to subnet AM / SM 560. The handover response message may include a wireless transparent container for transmission to the source base station (in this example, the source base station is the large network base station 530). At 513, subnet AM / SM 560 sends a handover response message to large network AM / SM 540. The handover response message includes the aforementioned wireless transparent container. At 515, the large network AM / SM 540 sends a handover command message to the source base station (i.e., large network base station 530). The handover command message includes the wireless transparent container. At 517, the large network base station 530 sends an RRC reconfiguration to the UE 510 based on the wireless transparent container. At 519, the UE 510 accesses the subnet through the target base station (in this example, the subnet base station 520) and sends a handover confirmation to the subnet base station 520. At 521, after receiving the handover confirmation, the subnet base station 520 sends a handover notification to the subnet AM / SM 560. At 523, the subnet AM / SM 560 notifies the subnet UPF 570 to switch the downlink path. The message used to notify the path switch includes the downlink tunnel information of the subnet base station 520. The subnet UPF 570 begins sending downlink data to the subnet base station 520. At 525 , UE 510 initiates a registration process. During this process, subnet AM / SM 560 may instruct subnet base station 520 to prioritize the base station / cell of the serving subnet when selecting a target base station / cell for the UE. For details, see 321 .

[0111] Figure 6 shows a communication process diagram of example scenarios of some other embodiments of the present disclosure. Specifically, the process 600 shown in Figure 6 is a process for a terminal device to move from a subnet coverage area to a large network coverage area in an idle state, or a process for a terminal device to register through a large network after receiving an RRC redirection from a subnet base station. In this process 600, the large network is an example of a first network, and the subnet is an example of a second network. The UE 610 shown in Figure 6 is an example of a terminal device, the subnet base station 620 is an example of an access network device serving the second network, the large network base station 630 is an example of an access network device serving the first network, the large network AM / SM 640 is an example of a control plane (CP) function serving the first network, the large network UPF 650 is an example of a user plane (UP) function serving the first network, the subnet AM / SM 660 is an example of a control plane function serving the second network, and the subnet UPF 670 is an example of a user plane function serving the second network. It should be noted that the network elements or functions in each step of the following process are described with reference to their corresponding examples, but are not limited to these examples, and may also be other examples of the corresponding network elements or functions.

[0112] At 601, subnet base station 620 sends an RRC redirection message to UE 610. Specifically, when UE 610 is in a connected state and moves out of the subnet coverage area, subnet base station 620 may send an RRC redirection message so that UE 610 can access the subnet through macro-network base station 630. Subnet base station 620 can perceive information about adjacent macro-network cells / major network base stations through local configuration information and, based on measurements, learn that UE 610 has moved out of the subnet coverage area and into the coverage area of ​​macro-network base station 630. Subnet base station 620 may also configure UE 610 to measure neighboring cells and instruct UE 610 to report the subnet identifier of the neighboring cell. Based on the measurement report of UE 610, subnet base station 620 may perceive that the neighboring cell does not support the current subnet, meaning that the coverage area of ​​the current subnet does not include the service area of ​​the neighboring cell. The subnet base station 620 may preferably select the subnet base station 620 when selecting a target base station. When there is no subnet base station 620 available in the neighboring base station, the large network base station 630 is selected and the RRC redirection process is triggered.

[0113] At 603, UE 610 selects to send a registration request message to a large network base station 630. The registration request message may include a temporary identifier allocated to UE 610 by a subnet CP (e.g., subnet AM or subnet SM). At 605, large network base station 630 selects a large network CP, such as large network AM / SM 640. For details, see operation 303 in process 300. At 607, large network base station 630 sends a registration request message to large network AM / SM 640. For details, see operation 305 in process 300.

[0114] At 609, the large network AM / SM 640 obtains the context of UE 610 from the subnet AM / SM 660. To obtain the context of UE 610, the large network AM / SM 640 may address the subnet AM / SM 660 based on the temporary identifier of UE 610, or based on the temporary identifier and the subnet identifier, and obtain the context of UE 610 from the subnet AM / SM 660. The context of UE 610 does not include the SUPI. The specific content of the UE 610 identifier in the context is described in other embodiments above, and the description of the UE identifier in the context in operation 409 of process 400. If the large network AM / SM 640 requires the SUPI (or IMSI) of UE 610, the large network AM / SM 640 may initiate re-authentication for UE 610 and send the SUPI to the large network AM / SM 640 after authentication is successful or the AUSF / UDM sends the SUPI.

[0115] At 611, the large network AM / SM 640 can trigger re-authentication of UE 610 as needed, i.e., re-authorization of UE 610. At 613, the large network AM / SM 640 obtains subnet-granular subscription information. Referring to operation 319 in process 300, subnet-granular subscription information may include information about the area in which the subnet UE is allowed to access the subnet (i.e., the permitted access area) and subnet service area information. At 615, the large network AM / SM 640 requests the large network UPF 650 to establish a session. The large network UPF allocates an uplink tunnel identifier and a downlink tunnel identifier and sends the allocated tunnel identifiers to the large network CP. At 617, the large network AM / SM 640 sends the downlink tunnel information of the large network UPF 650 to the subnet AM / SM 660. At 619, the subnet AM / SM 660 notifies the subnet UPF 670 to send downlink data to the large network UPF 650 using the large network UPF 650 tunnel. At 621, subnet AM / SM 660 sends a Handover Downlink Tunnel Response message. At 623, metropolitan AM / SM 640 requests metropolitan base station 630 to establish a session. Specifically, metropolitan AM / SM 640 sends the uplink tunnel information from metropolitan UPF 650 to metropolitan base station 630, which then allocates the downlink tunnel information. In this operation, the message sent by metropolitan AM / SM 640 to metropolitan base station 630 may include QoS information corresponding to the session, which is used by metropolitan base station 630 to allocate air interface resources. In some examples, this message may also include a Registration Acceptance (NAS) message. In some examples, this message may also include mobility restriction information. The mobility restriction information sent by metropolitan AM / SM 640 to metropolitan base station 630 is described in operation 319 of process 300 above and will not be repeated here. In some examples, this message may also include a subnet identifier, which may be used by metropolitan base station 630 to initiate a handover procedure or an RRC redirection procedure.

[0116] At 625, large network base station 630 sends a registration accept message to UE 610. Large network AM / SM 640 determines mobility restriction information based on the allowed area information in the subnet subscription and sends this mobility restriction information to UE 610 in the registration accept message. The allowed area information includes the area within the subnet coverage that UE 610 is allowed to access. Large network AM / SM 640 sends a notification message to subnet AM / SM 660 to inform UE 610 that UE 610 has accessed the subnet through large network AM / SM 640.

[0117] At 627 , the large network AM / SM 640 sends a context reception indication to the subnet AM / SM 660 . After receiving the context reception indication, the subnet AM / SM 660 may delete part of the context of the UE 610 , such as the security context of the UE 610 , at 629 .

[0118] Figure 7 shows a schematic diagram of the communication process of example scenarios of some other embodiments of the present disclosure. Specifically, the process 700 is a handover process for a terminal device to switch from the coverage of a subnet base station to the coverage of a large network base station in a connected state. In the process 700, the large network is an example of a first network, and the subnet is an example of a second network. The UE 710 shown in Figure 7 is an example of a terminal device, the large network base station 720 is an example of an access network device serving the first network, the subnet base station 730 is an example of an access network device serving the second network, the large network AM / SM 740 is an example of a control plane (CP) function serving the first network, the large network UPF 750 is an example of a user plane (UP) function serving the first network, the subnet AM / SM 760 is an example of a control plane function serving the second network, and the subnet UPF 770 is an example of a user plane function serving the second network. It should be noted that the network elements or functions in each step of the following process are described with their corresponding examples, but are not limited to these examples and can also be other examples of corresponding network elements or functions.

[0119] At 701, subnet base station 730 sends a handover request message to subnet AM / SM 760. This message may include information about the cell / base station of large-network base station 720 (e.g., cell ID, base station ID, TAI, etc.). In some examples, this message may also carry indication information to indicate that the target cell / target base station to be accessed by UE 710 is a non-subnet base station. When selecting a target base station, subnet base station 730 preferably selects a subnet base station and only selects a large-network base station when a suitable subnet base station cannot be selected.

[0120] At 703, subnet AM / SM 760 selects large network AM / SM 740. Before subnet AM / SM 760 selects large network AM / SM 740, subnet AM / SM 760 determines whether the target cell / target base station to be accessed by UE 710 is a non-subnet cell / base station by using one or more of the following methods (methods a) to c). Method a): Determine whether the target cell / target base station to be accessed by UE 710 is a non-subnet cell / base station based on an indication in a handover request message sent by subnet base station 730 to subnet AM / SM 760. Method b): Determine whether the target cell / target base station to be accessed by UE 710 is a non-subnet cell / base station based on whether the area served by the target cell / target base station includes the subnet area. Method c): Determine whether the target cell / target base station to be accessed by UE 710 is a non-subnet cell / base station based on whether a connection has been established between subnet AM / SM 760 and the target base station. For example, assuming that subnet AM / SM 760 has established connections with all subnet base stations and exchanged relevant information, subnet AM / SM 760 can query the subnet base station to which it has established a connection based on the target cell / target base station identifier. If found, the target cell / target base station is a subnet cell / base station; otherwise, the target cell / target base station is a non-subnet cell / base station. When the target cell / base station is a non-subnet base station, subnet AM / SM 760 selects large network AM / SM 740 based on the cell / base station information (such as the cell identifier, base station identifier, TAI, etc.).

[0121] At 705, subnet AM / SM 760 sends a handover request message to large network AM / SM 740. This message may include the context of UE 710, including its security context. In some examples, the message may also include a subnet identifier. In some examples, the message may include information about the target base station. In some examples, the message may also include callback URI information for subnet AM / SM 760, which is used for subsequent message exchange between large network AM / SM 740 and subnet AM / SM 760. At 707, large network AM / SM 740 requests large network UPF 750 to establish a session and allocate tunnel information. At 709, large network AM / SM 740 sends a handover request message to large network base station 720. This message may include a subnet identifier, which is used to select a target base station for the next handover / redirection. At 711, large network base station 720 sends a handover response to large network AM / SM 740. In 713, large network AM / SM 740 sends a handover response to subnet AM / SM 760. In 715, subnet AM / SM 760 sends a handover command to subnet base station 730. In 717, the subnet base station notifies UE 710 to handover to the target large network base station 720. In 719, UE 710 accesses the target large network base station 720 and sends a handover confirmation to large network base station 720. In 721, large network base station 720 sends a handover notification to large network AM / SM 740. In 723, large network AM / SM 740 notifies subnet AM / SM 760 to switch the downlink path. Subnet AM / SM 760 notifies subnet UPF 770 to switch the downlink path. Subnet AM / SM 760 sends downlink tunnel information from large network UPF 750 to subnet UPF 770. Subnet UPF 770 begins sending downlink data to large network UPF 750. At 725, after the handover is complete, UE 710 initiates a registration process with the target base station (i.e., large network base station 720). During the registration process, large network AM / SM 740 obtains the large network's subscription information and configures mobility restriction information for large network base station 720 and UE 710 based on the large network's subscription information. The mobility restriction information sent to the base station and the mobility restriction information sent to the terminal device (e.g., UE) are described in the above process 300.

[0122] FIG8 shows a schematic diagram of a communication process for example scenarios of some further embodiments of the present disclosure. Specifically, process 800 is a process for a terminal device to undergo cross-base station handover while moving within a large network. In process 800, the large network is an example of a first network, and the subnet is an example of a second network. The UE 810 shown in FIG8 is an example of a terminal device, the target large network base station 820 is an example of an access network device that serves the first network and is accessed by the terminal device, the source large network base station 830 is an example of an access network device that serves the first network and was previously accessed by the terminal device, the source large network AM / SM 840 is an example of a control plane (CP) function that serves the first network and previously served the terminal device, and the source large network UPF 850 ​​is an example of a user plane (UP) function that serves the first network and previously served the terminal device. Target large network AM / SM 860 is an example of a control plane (CP) function serving the first network and the terminal device to be served. Target large network UPF 870 is an example of a user plane (UP) function serving the first network and the terminal device to be served. Subnet AM / SM 880 is an example of a control plane function serving the second network. Subnet UPF 890 is an example of a user plane function serving the second network. It should be noted that the network elements or functions in each step of the following process are described using their corresponding examples, but are not limited to these examples and may also be other examples of the corresponding network elements or functions.

[0123] As shown in Figure 8, in process 800, at 801, source large network base station 830 sends a handover request message to source large network AM / SM 840. When selecting a target cell / base station, source large network base station 830 prioritizes a subnet base station if one exists. In this example, since no subnet cell / base station is selectable, the selected target cell / base station is a large network cell / base station. In some examples, when selecting a target cell / base station, a cell / base station that allows access may be selected as the target cell / base station based on configured mobility restriction information. At 803, source large network AM / SM 840 selects a target large network AM / SM 860. When selecting a target CP (e.g., target AM / SM), source large network AM / SM 840 may select a target AM / SM based on whether the target cell / base station is a subnet cell / base station. For example, if the target cell / base station is a subnet cell / base station, the subnet AM / SM in the context of UE 810 is selected. Otherwise, the large network AM / SM is selected based on information about the target cell / base station. In this example, the target AM / SM selected is target large network AM / SM 860. At 805, source large network AM / SM 840 sends a handover request message to target large network AM / SM 860. This handover request message may include the identification information of target large network base station 820, the security context of UE 810, the subnet identifier, and the identification information of subnet AM / SM 880. The context of UE 810 may include the subnet identifier and information about subnet AM / SM 760. At 807, an N3 tunnel is established. This operation can be referred to as operation 507 in process 500, where target large network UPF 870 allocates downlink tunnel information. At 809, target large network AM / SM 860 sends a session establishment request to target large network base station 820. At 811, target large-network base station 820 sends a session establishment response to target large-network AM / SM 860. This message includes downlink tunnel information of target large-network base station 820 and optional forwarding tunnel information. The forwarding tunnel is used by target large-network base station 820 to receive data sent from source base station 830. At 813, target large-network AM / SM 860 sends the forwarding tunnel information and the downlink tunnel information of target large-network base station 820 to target large-network UPF 870. Target large-network UPF 870 allocates the forwarding tunnel information and sends it to target large-network AM / SM 860. At 815, target large-network AM / SM 860 sends a handover response to source large-network AM / SM 840, including the forwarding tunnel information allocated by target large-network UPF 870. At 817, source large-network AM / SM 840 sends the forwarding tunnel information allocated by target large-network UPF 870 to source large-network UPF 850. Source large-network UPF 850 ​​allocates the forwarding tunnel information. At 819 , the source network AM / SM 840 sends a handover command to the source network base station 830 , including the forwarding tunnel information allocated by the source network UPF 850 ​​.At this point, source large network base station 830 can forward the downlink data received from source large network UPF 850 ​​to target large network base station 820 via source large network UPF 850 ​​and target large network UPF 870. At 821, source large network base station 830 sends an RRC reconfiguration to UE 810. At 823, UE 810 sends a handover confirmation to target large network base station 820. At 825, after receiving the handover confirmation, target large network base station 820 sends a handover notification to target large network AM / SM 860. At 827, target large network AM / SM 860 notifies subnet AM / SM 880 of a path switch. This message includes the downlink tunnel information allocated by target large network UPF 870 in step 807. At 829, referring to operation 523 in process 500, the downlink tunnel information allocated by target large network UPF 870 in step 807 is sent to subnet UPF 890. At this point, subnet UPF 890 sends downlink data directly to target macro-network UPF 870, completing the path switch. At 831, UE 810 initiates a registration process. During the registration process, target macro-network AM / SM 860 obtains subnet-level subscription information and configures the mobility restriction information for target macro-network base station 820 and UE 810 based on the subnet-level subscription information.

[0124] Based on some embodiments of the present disclosure described above, the subscription information of the second network (e.g., subnet-level subscription information) stores information about the area (allowed service area) and subnet campus range that terminal devices (e.g., UEs) of the second network (e.g., subnet) are allowed to access. When a UE accesses a first network (e.g., a large network), the core network device (subnet CP) serving the second network authorizes the UE, and the core network device (large network CP) serving the first network obtains the subnet-level subscription information. The large network CP further determines, based on the subnet-level subscription information, that the UE is allowed to access the subnet. The UE can then access the subnet through the large network. This allows the UE to access a subnet through a third-party PLMN network, without requiring a subscription to the PLMN. When the UE accesses the large network, the large network CP can determine mobility restriction information based on the subnet-level access area information and send it to the UE / access network device for use when selecting a target cell / base station. This allows the base station and UE to select an accessible cell, avoiding power consumption caused by the UE's repeated attempts due to access failure. The UE context of the subnet CP does not include the UE's sensitive information (such as SUPI, IMSI), but is replaced by SUCI, a temporary identifier or an external unique identifier (such as ISDN). Among them, the temporary identifier can be allocated by AUSF / UDM and can address AUSF / UDM. If the large network CP needs to obtain SUPI, it can query AUSF / UDM based on the UE identifier in the context. Since the subnet CP may be deployed down to the campus, its security is not as good as the equipment in the current operator network. The scheme of hiding the real identifier of the UE and not sending the sensitive information of the UE in the embodiment of the present disclosure can prevent the leakage of user sensitive information. The UE context of the large network CP includes the information of the subnet CP, and selects and establishes a connection with the subnet CP during registration. During switching or redirection, the source base station senses whether the surrounding base stations support the subnet, and prefers the subnet base station when selecting the target base station. In this way, the UE is preferably located in the subnet area.

[0125] Figure 9 shows a schematic flow chart of some embodiments of the present disclosure implemented at a communication device. As shown in Figure 9, the communication device that executes process 900 can be a first core network device or a chip, module, or module in the first core network device. An example of the first core network device can be the first core network device 230 mentioned above. In box 910, the first core network device receives a registration request for requesting that the terminal device access the second network. In box 920, the first core network device sends first information to the first access network device serving the terminal device when allowing the terminal device to access the second network. The first information is used to indicate: when selecting a target access network device or target cell for the terminal device to access the second network, the preferred service range includes an access network device or cell with a coverage range of the second network. In some embodiments, process 900 may also include other operations performed at the first core network device (e.g., a large network CP or a large network AM / SM, or a subnet CP, or a subnet AM / SM) described in conjunction with Figures 2 to 8 in the embodiments of the present disclosure.

[0126] Figure 10 shows a schematic flowchart of another embodiment of the present disclosure implemented at a communication device. As shown in Figure 10, the communication device executing process 1000 may be a second core network device or a chip, module, or submodule within the second core network device. An example of a second core network device is the second core network device 250 described above. In block 1010, the second core network device serving the second network receives a registration request message from a terminal device. The registration request message is used to request access to the second network by the terminal device, and the registration request message includes identification information of the terminal device. In block 1020, the second core network device sends a context request to the core network device serving the first network based on the identification information of the terminal device. The context request is used to obtain a context for the terminal device, and the context request includes first indication information indicating that the second core network device serves the second network. In block 1030, the second core network device receives the context of the terminal device from the core network device serving the first network. The context of the terminal device does not include sensitive information of the terminal device. In some embodiments, process 1000 may also include other operations performed at the second core network device (e.g., subnet CP or subnet AM / SM) as described in conjunction with Figures 2 to 8 of the present disclosure.

[0127] Figure 11 shows a schematic flowchart of further embodiments of the present disclosure implemented at a communication device. As shown in Figure 11, the communication device executing process 1100 may be a first access network device serving a terminal device, or a chip, module, or module within the first access network device. An example of the first access network device may be the aforementioned first access network device 220. In block 1110, the first access network device serving the terminal device receives first information indicating that, when selecting a target access network device or target cell for the terminal device to access a second network, an access network device or cell whose service range includes the coverage of the second network is preferred. In block 1120, the first access network device determines, based on the first information, a first target access network device or first target cell for the terminal device to access. In block 1130, the first access network device sends a handover request message to the core network device serving the terminal device, the handover request message including identification information of the first target access network device or first target cell. Alternatively, the first access network device sends a radio resource control (RRC) redirect message to the terminal device, instructing the terminal device to reselect the first target access network device or first target cell to access the second network. In some embodiments, process 1100 may also include other operations performed at the first access network device (e.g., a large network base station when acting as a source base station or a subnet base station when acting as a source base station) described in conjunction with Figures 2 to 8 in the embodiments of the present disclosure.

[0128] FIG12 is a schematic diagram of the structure of possible communication devices provided by an embodiment of the present disclosure. These communication devices can implement the functions of the communication devices in the above-mentioned method embodiments (for example, the communication devices mentioned in the embodiments shown in FIG9 to FIG11 ), and thus can also achieve the beneficial effects possessed by the above-mentioned method embodiments. For example, in some embodiments of the present disclosure, the communication device can be an access network device 120 or 130, or a core network device 140 or 150, as shown in FIG1B , or a module (such as a chip) applied to the access network device 120 or 130, or the core network device 140 or 150.

[0129] As shown in Figure 12, a communication device 1200 includes a communication unit 1210 and, in some examples, may also include a processing unit 1220. The communication device may be used to implement the functions of the communication device in the method embodiments shown in Figures 9 to 11. In the example of a communication device implementing the functions of the communication device shown in Figure 9, the communication unit 1210 may include a first receiving unit and a first transmitting unit, which in some examples may be specifically implemented as a transmitter and a receiver. In the example of a communication device implementing the functions of the communication device shown in Figure 10, the communication unit 1210 may include a second receiving unit and a second transmitting unit, which in some examples may be specifically implemented as a transmitter and a receiver. In the example of a communication device implementing the functions of the communication device shown in Figure 11, the communication unit 1210 may include a third receiving unit and a third transmitting unit, which in some examples may be specifically implemented as a transmitter and a receiver. The processing unit 1220 may be specifically implemented as a determining unit, which in some examples may be specifically implemented as a processor.

[0130] When the communication device 1200 is used to implement the functions of the communication device in the method embodiment shown in Figure 9 above, the first receiving unit in the communication unit 1210 is used to receive a registration request for requesting the terminal device to access the second network, and the first sending unit is used to send first information to the first access network device serving the terminal device when allowing the terminal device to access the second network. The first information is used to indicate: when selecting a target access network device or target cell for the terminal device to access the second network, it is preferred that the service range includes an access network device or cell whose coverage range includes the second network.

[0131] When the communication device 1200 is used to implement the functions of the communication device in the method embodiment shown in Figure 10 above, the second receiving unit in the communication unit 1210 is used to receive a registration request message from a terminal device, where the registration request message is used to request that the terminal device be connected to the second network, and the registration request message includes identification information of the terminal device; and the second sending unit is used to send a context request to the core network device serving the first network based on the identification information of the terminal, where the context request is used to obtain the context of the terminal device, and the context request includes first indication information for indicating that the second core network device serves the second network; the second receiving unit is also used to receive the context of the terminal device from the core network device serving the first network, where the context of the terminal device does not include sensitive information of the terminal device.

[0132] When the communication device 1200 is used to implement the functions of the communication device in the method embodiment shown in Figure 11 above, the third receiving unit in the communication unit 1210 receives the first information, and the first information is used to indicate: when selecting a target access network device or target cell for the terminal device to access the second network, the access network device or cell whose service range includes the coverage range of the second network is preferred; the third sending unit in the communication unit 1210 is used to send a switching request message to the core network device serving the terminal device, and the switching request message includes the identification information of the first target access network device or the identification information of the first target cell; or the third sending unit is used to send a radio resource control (RRC) redirection message to the terminal device, and the RRC redirection message instructs the terminal device to reselect the first target access network device or the first target cell to access the second network. The determination unit as the processing unit 1220 is used to determine the first target access network device or the first target cell to be accessed by the terminal device based on the first information.

[0133] For a more detailed description of the above units, please refer to the relevant description in the above method embodiment, which will not be explained again here.

[0134] Figure 13 shows a simplified block diagram of an example device of a possible implementation method in an embodiment of the present disclosure. As shown in Figure 13, the communication device 1300 includes a processor 1310 and an interface circuit 1320. The processor 1310 and the interface circuit 1320 are coupled to each other. It will be understood that the interface circuit 1320 can be a transceiver or an input / output interface. Optionally, the communication device 1300 may also include a memory 1330 for storing instructions executed by the processor 1310 or storing input data required by the processor 1310 to execute instructions or storing data generated after the processor 1310 executes instructions. It should be noted that, in some embodiments, the processor 1310 and the memory 1330 can be integrated into the same device. When the communication device 1300 is used to implement the method in the above-mentioned method embodiment, the interface circuit 1320 is used to perform the functions of the above-mentioned communication unit 1210.

[0135] When the communication device is a chip used in a communication device, the chip of the communication device implements the functions of the communication device in the above-mentioned method embodiment. The communication device chip sends data to other modules (such as a radio frequency module or an antenna) in the communication device, and the data may be sent to other devices; or the communication device chip receives data from other modules (such as a radio frequency module or an antenna) in the communication device, and the data is received from other devices.

[0136] It is understood that the processor in the embodiments of the present disclosure may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0137] The present disclosure provides a communication system. The communication system may include the communication device involved in the embodiments shown in Figures 9 to 11 above. Optionally, the communication device in the communication system may correspondingly execute the communication method shown in Figures 9 to 11.

[0138] The present disclosure also provides a circuit that can be coupled to a memory and can be used to execute the communication device-related process in any of the above method embodiments. The chip system may include the chip and other components such as a memory or a transceiver.

[0139] It should be understood that the processor mentioned in the embodiments of the present disclosure may be a CPU, or may 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 may be a microprocessor or any conventional processor, etc.

[0140] It should also be understood that the memory mentioned in the embodiments of the present disclosure may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0141] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) is integrated into the processor.

[0142] It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0143] It should be understood that in the various embodiments of the present disclosure, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

[0144] Those skilled in the art will appreciate that the modules and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians 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 disclosure.

[0145] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0146] In the several embodiments provided in the present disclosure, it should be understood that the disclosed communication methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0147] The modules described as separate components may or may not be physically separate, and 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 elements. Some or all of these elements may be selected to achieve the purpose of this embodiment according to actual needs.

[0148] In addition, each functional module in each embodiment of the present disclosure may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0149] If this function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present disclosure, or the part that makes the contribution, or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method of each embodiment of the present disclosure. The aforementioned computer-readable storage medium can be any available medium that can be accessed by a computer. By way of example and not limitation, computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), universal serial bus flash disk, mobile hard disk, or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer.

[0150] As used herein, the term "including" and similar terms should be understood as open inclusion, i.e., "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc. can refer to different or the same objects and are only used to distinguish the objects referred to, and do not imply a specific spatial order, temporal order, order of importance, etc. of the objects referred to. In some embodiments, values, processes, selected items, determined items, devices, means, components, assemblies, etc. are referred to as "best", "lowest", "highest", "minimum", "maximum", etc. It should be understood that such descriptions are intended to indicate that a selection can be made from a number of available functional options, and that such a selection need not be better, lower, higher, smaller, larger, or otherwise preferred than other options in other aspects or all aspects. As used herein, the term "determine" can encompass a variety of actions. For example, "determine" can include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, database, or another data structure), ascertaining, etc. Furthermore, "determining" may include receiving (eg, receiving information), accessing (eg, accessing data in a memory), etc. Furthermore, "determining" may include resolving, selecting, choosing, establishing, etc.

[0151] The above is only a specific embodiment of the present disclosure, but the scope of protection of the embodiments of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the embodiments of the present disclosure should be included in the scope of protection of the embodiments of the present disclosure. Therefore, the scope of protection of the embodiments of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A communication method, comprising: A first core network device receives a registration request for requesting to access a second network by a terminal device; When the first core network device permits the terminal device to access the second network, the first core network device sends first information to a first access network device serving the terminal device, where the first information is used to indicate that when selecting a target access network device or a target cell for the terminal device to access the second network, an access network device or a cell whose preferred service range includes the coverage range of the second network is preferred.

2. The method according to claim 1, wherein the first information comprises at least one of the following: Identification information of the second network; A cell list, where the cell list comprises: information of one or more cells whose service range includes the coverage range of the second network; or An access network device list, where the access network device list comprises: information of one or more access network devices whose service range includes the coverage range of the second network.

3. The method according to claim 1 or 2, wherein the first core network device is a core network device serving a first network, and the method further comprises: The first core network device receives a context request from a second core network device, where the second core network device serves the second network, and the context request is used to obtain the context of the terminal device, and the context request comprises first indication information for indicating that the second core network device serves the second network; And The first core network device sends the context of the terminal device to the second core network device based on the first indication information, where the context does not comprise sensitive information of the terminal device.

4. The method according to claim 3, further comprising: The first core network device receives second indication information from the second core network device for indicating to delete the context of the terminal device; And The first core network device deletes the context of the terminal device and the session resources corresponding to the terminal device in the first core network device based on the second indication information.

5. The method according to claim 1, wherein the first core network device is a core network device serving the first network, and the method further comprises: The first core network device receives a handover request message from the first access network device, where the handover request message comprises identification information of a target access network device or identification information of a target cell to which the terminal device is to access; The first core network device selects a second core network device serving the second network based on that the target access network device or the target cell to which the terminal device is to access is an access network device or a cell whose service range includes the coverage range of the second network; And The first core network device sends the context of the terminal device to the second core network device, where the context does not comprise sensitive information of the terminal device.

6. The method according to claim 5 further comprises: The first core network device determines that the target access network device or the target cell to which the terminal device is to access is an access network device or a cell whose service range includes the coverage range of the second network based on at least one of the following: The handover request message indicates that the target access network device or target cell to which the terminal device is to be connected serves the second network; or The service area of the second network includes the service area of the target access network device or target cell to which the terminal device is to be connected, and the subscription information of the second network includes the service area of the second network.

7. The method according to any one of claims 1 to 6, further comprising: The first core network device sends second information to the first access network device, where the second information is used to indicate that when selecting a target access network device or target cell for the terminal device to access the second network, select an access network device or cell whose service range includes the area in the coverage range of the second network where the terminal device is allowed to access.

8. The method according to any one of claims 1 to 7, further comprising: The first core network device sends third information to the terminal device, where the third information is used to indicate that when the terminal device selects a target access network device or target cell to access the second network, select an access network device or cell whose service range includes the area in the coverage range of the second network where the terminal device is allowed to access.

9. A communication method, comprising: A second core network device serving the second network receives a registration request message from a terminal device, where the registration request message is used to request to connect the terminal device to the second network, and the registration request message includes identification information of the terminal device; Based on the identification information of the terminal device, the second core network device sends a context request to a core network device serving the first network, where the context request is used to obtain the context of the terminal device, and the context request includes a first indication information for indicating that the second core network device serves the second network; and The second core network device receives the context of the terminal device from the core network device serving the first network, and the context of the terminal device does not include sensitive information of the terminal device.

10. A communication method, comprising: A first access network device serving a terminal device receives first information, where the first information is used to indicate that when selecting a target access network device or target cell for the terminal device to access the second network, preferably select an access network device or cell whose service range includes the coverage range of the second network; Based on the first information, the first access network device determines a first target access network device or a first target cell to which the terminal device is to be connected; and The first access network device sends a handover request message to a core network device serving the terminal device, where the handover request message includes identification information of the first target access network device or identification information of the first target cell; or The first access network device sends a Radio Resource Control (RRC) redirection message to the terminal device, where the RRC redirection message instructs the terminal device to reselect the first target access network device or the first target cell to access the second network.

11. The method according to claim 10, wherein the first information includes at least one of the following: The identification information of the second network; A cell list, where the cell list includes: information about one or more cells whose service scope includes the coverage scope of the second network; or An access network device, where the access network device includes: information about one or more access network devices whose service scope includes the coverage scope of the second network.

12. The method according to claim 11, wherein the method further includes: The first access network device receives the measurement report information of the first target cell from the terminal device, and the measurement report information includes the identification information of the second network; Or The first access network device receives indication information, and the indication information is used to indicate that the service scope of the first target access network device or the first target cell includes the coverage scope of the second network; or The first access network device determines according to local configuration information that the service scope of the first target access network device or the first target cell includes the coverage scope of the second network.

13. The method according to claim 12, further includes: The first access network device sends indication information to the terminal device, and the indication information is used to indicate that: when the service scope of the first target cell includes the coverage scope of the second network, the measurement report information of the first target cell includes the identification information of the second network.

14. The method according to any one of claims 10 to 12, further includes: The first access network device receives second information, and the second information is used to indicate that when the first access network device determines the target cell, it selects a cell in the allowed access area of the second network.

15. The method according to any one of claims 10 to 14, wherein the method further includes: When there is an access network device or a cell whose service scope includes the coverage scope of the second network among the adjacent access network devices or adjacent cells of the access network device or cell to which the terminal device is currently connected, the first access network device selects the first target access network device or the first target cell.

16. The method according to any one of claims 10 to 15, wherein the handover request message indicates that the first target access network device or the first target cell serves the second network.

17. A communication method, including: A core network device serving a second network receives a handover request message sent by a first access network device serving a terminal device, and the handover request message indicates a target access network device or a target cell to which the terminal device is to be connected; And Based on determining that the target access network device or the target cell is an access network device or a cell serving a first network, select a core network device serving the first network to serve the terminal device.

18. The method according to claim 17, wherein it is determined that the target access network device or the target cell is an access network device or a cell serving the first network based on at least one of the following: The handover request message sent by the first access network device serving the terminal device indicates that the target access network device or the target cell is an access network device or cell whose service area includes the coverage area of the first network; The service area of the target access network device or the target cell is not in the area covered by the second network, and the service area of the second network is indicated by the first subscription information of the second network in the first network; Or The core network device serving the second network has not established a connection and exchanged information with the target access network device.

19. The method according to claim 17 or 18, further comprising: Sending the handover request message to the core network device serving the first network, the handover request message including at least one of the following: the identification information of the second network, the context of the terminal device, or the callback address information of the core network device serving the second network, wherein the callback address information is used for message interaction between the core network device serving the first network and the core network device serving the second network, and the identification information of the second network is used to indicate that the terminal device accesses the second network.

20. A communication method, applied to a communication device, comprising: Receiving indication information from a first access network device, the indication information being used to indicate measurement of a first target cell; Sending measurement report information of the first target cell according to the indication information, the measurement report information of the first target cell including identification information of a target network, and the service area of the first target cell includes the coverage area of the target network.

21. The method according to claim 20, wherein the indication information is further used to indicate: When the service area of the first target cell includes the coverage area of the target network, including the identification information of the target network in the measurement report information of the first target cell.

22. The method according to claim 20 or 21, wherein the indication information further indicates that when the target network is the second network, the measurement report information includes the identification of the target network.

23. The method according to any one of claims 20 to 22, the method further comprising Reading a first system broadcast message field of the first target cell to obtain the identification of the network served by the first target cell.

24. The method according to any one of claims 20 to 23, the method further comprising Receiving third information from a first core network device, the third information being used to indicate that when selecting a target access network device or a target cell for accessing the second network, selecting an access network device or a cell whose service area includes the area in the coverage area of the second network where the communication device is allowed to access.

25. The method according to any one of claims 20 to 22, the communication device being a terminal device or a chip in the terminal device.

26. A communication device, comprising a module for performing the method according to any one of claims 1 to 8.

27. A communication device, comprising a module for performing the method as claimed in claim 9.

28. A communication device, comprising a module for performing the method as claimed in any one of claims 10 to 16.

29. A communication device, comprising a module for performing the method as claimed in any one of claims 17 to 19.

30. A communication device, comprising a module for performing the method as claimed in any one of claims 20 to 25.

31. A communication device, comprising: A processor, and a memory storing instructions which, when executed by the processor, cause the method according to any one of claims 1 to 8, claim 9, claims 10 to 16, claims 17 to 19, or claims 20 to 25 to be performed.

32. A communication system, comprising at least two of the following: The communication device as claimed in claim 26, the communication device as claimed in claim 27, the communication device as claimed in claim 28, the communication device as claimed in claim 29, or the communication device as claimed in claim 30.

33. A computer-readable storage medium storing instructions which, when executed, cause the method according to any one of claims 1 to 8, claim 9, or claims 10 to 16, claims 17 to 19, or claims 20 to 25 to be performed.

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