Communication method and device

Abstract

The invention provides a communication method and device, belongs to the technical field of communication, can be applied to a non-terrestrial network NTN, and improves the communication stability. In the method, a first access network device determines a system message and sends the system message, and a terminal device determines whether to access the first access network device according to the system message after receiving the system message from the first access network device; the first access network device is a non-ground device, the system message comprises first information, the first information is used for indicating at least one core network element, and the at least one core network element is used for providing a core network service for a terminal served by the first access network device. Thus, when the network topology of the core network associated with the first access network device changes, the terminal device can make an access decision according to the network element information in the core network currently associated with the first access network device, thereby improving the stability of communication.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to communication methods and apparatus. Background Technology

[0002] Traditional terrestrial networks (TN), such as New Radio (NR) systems or the Internet of Things (IoT), cannot provide seamless coverage for terminals. Therefore, NR systems, IoT systems, and future communication systems can incorporate non-terrestrial networks (NTN) to provide seamless coverage services for terminals. NTN can deploy some or all of the base station functions on satellites to provide communication coverage for terminals, thereby improving the reliability of the communication system.

[0003] However, the high speed of satellite movement may lead to poor communication stability. Summary of the Invention

[0004] This application provides a communication method and apparatus that can improve communication stability in NTN scenarios.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] Firstly, a communication method is provided, comprising: a first access network device determining a system message and sending the system message; wherein the first access network device is a non-terrestrial device, the system message includes first information, the first information being used to indicate at least one core network element, the at least one core network element being used to provide core network services to a terminal served by the first access network device, and the system message being used to determine whether to access the first access network device. Based on the first aspect, it is understood that by carrying the first information in the system message, the first access network device enables the terminal receiving the system message to obtain network element information in the core network associated with the first access network device. Based on the network element information, the terminal can determine whether to access the first access network device. If at least one core network element meets the terminal's needs, it will determine to access the first access network device. If at least one core network element does not meet the terminal's needs, it will determine not to access the first access network device, but to access other access network devices besides the first access network device. In this way, even if the movement of the first access network device causes a change in the core network topology associated with the first access network device, the terminal can make access decisions based on the network element information in the core network currently associated with the first access network device, thereby improving communication stability and enabling users corresponding to the terminal to obtain stable communication services.

[0007] The first access network device in this application can be a first access network device or a component of the first access network device, such as a communication module, processor, chip, chip system, or circuit that can be applied in the first access network device. It can also be a logic module or software that can realize all or part of the functions of the first access network device.

[0008] It can be understood that the aforementioned at least one core network element can also be referred to as at least one core network element associated with the first access network device, or at least one core network element included in the core network associated with the first access network device.

[0009] In one possible design, the system message further includes second information indicating the service time of at least one core network element. This service time indicates the duration during which the at least one core network element provides network services to the terminal. Thus, based on the second information, the terminal can determine whether at least one core network element can provide services to it during the time period it needs network services. This facilitates the terminal's access decision based on the system message; for example, if at least one core network element associated with the first access network device cannot provide network services, the terminal can determine not to access the first access network device.

[0010] Optionally, the method in the first aspect further includes: the first access network device determining the service time based on the topology information of the core network where at least one core network element is located and / or the topology information of the access network where the first access network device is located. That is, the first access network device can determine the time during which at least one core network element provides network service to the area (denoted as the first area) served by the first access network device based on the topology information of the core network where at least one network element is located. Alternatively, the first access network device can determine the topology information of the core network where at least one associated network element is located based on the topology information of its own access network, and thus determine the time during which at least one core network element provides network service to the first area based on the topology information of that core network. This enables the first access network device to obtain accurate service time, thereby preventing the terminal from making access decisions based on incorrect information.

[0011] Optionally, the service time can be at least one of the following: duration, start time, end time, or time information. The duration indicates the time period during which at least one core network element provides services; the start time indicates the start time of services provided by at least one core network element; the end time indicates the end time of services provided by at least one core network element; and the time information indicates time-related information of the core network topology where at least one core network element resides. The specific service time can be set according to actual conditions and is not limited.

[0012] Optionally, the second information is also used to indicate a first area, whereby the first access network device can provide services to terminals within that first area. It can be understood that the first area is the area where the first access network device can provide network services; or, in other words, the first area is the area where at least one core network element can provide network services. This enables the terminal to determine subsequent operations, such as access decisions, pre-registration processes, etc., based on the first area.

[0013] In a second aspect, a communication method is provided, the method comprising: a terminal device receiving a system message from a first access network device, and determining whether to access the first access network device based on the system message, wherein the first access network device is a non-terrestrial device, the system message including first information, the first information being used to indicate at least one core network element, the at least one core network element being used to provide core network services to the terminal served by the first access network device.

[0014] The terminal device in this application can be a terminal device or a component of a terminal device, such as a communication module, processor, chip, chip system, or circuit that can be applied in a terminal device, or a logic module or software that can realize all or part of the functions of a terminal device.

[0015] In one possible design, the system message further includes second information, which indicates the service time of at least one core network element, and the service time indicates the time during which at least one core network element provides network services to the terminal.

[0016] Optionally, the service time is at least one of the following: duration, start time, end time, or time information, wherein the duration is used to indicate the time period during which at least one core network element provides services, the start time is used to indicate the start time of the service provided by at least one core network element, the end time is used to indicate the end time of the service provided by at least one core network element, and the time information is used to indicate time-related information of the core network topology where at least one core network element is located.

[0017] Optionally, the second information is also used to indicate a first area, wherein the first access network device is capable of providing services to terminals in the first area.

[0018] Furthermore, the method described in the second aspect also includes: the terminal device executing a registration process or a pre-registration process based on the second information. This enables the terminal device to perform the registration process or pre-registration process in a timely manner based on the service time and the first region.

[0019] In conjunction with the first or second aspect, one possible design scheme includes a third piece of information in the system message. This third information indicates the type of network service provided by at least one core network element. Based on this third information, the terminal device can determine whether the network service provided by the core network associated with the first access network device can meet its needs. If the network service provided by the core network meets the terminal device's needs, the terminal device will access the first access network device. This enables the user corresponding to the terminal device to obtain stable communication services.

[0020] Optionally, the network service type includes at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter. The specific type can be flexibly set according to the actual situation without any restrictions.

[0021] In conjunction with the first or second aspect, one possible design scheme includes a fourth piece of information in the system message, which indicates the load capacity of at least one core network element. Based on this load capacity, the terminal device can determine whether to connect to the first access network device. If the load capacity is high, it will connect to the first access network device; if the load capacity is low, it will not connect. This ensures that the terminal device can smoothly perform various services after connecting to the first access network device, thereby providing better communication services to the users corresponding to the terminal device.

[0022] In conjunction with the first or second aspect, one possible design scheme includes a fifth piece of information in the system message, which indicates the quality of service (QoS) of at least one core network element. Thus, the terminal device can determine whether to connect to the first access network device based on this QoS; for example, it will connect to the first access network device if the QoS is good, and it will not connect if the QoS is poor. This ensures the network QoS of the terminal device, thereby providing better communication services to the users corresponding to the terminal device.

[0023] Optionally, the Quality of Service (QoS) includes at least one of the following: a QoS parameter or a latency parameter. The QoS parameter can be the latency of user data, the maximum guaranteed rate, the peak rate, etc., and the latency parameter can be the estimated latency (or the latency of the control plane process) for executing control plane procedures, etc. The QoS can be set according to actual conditions without restriction.

[0024] In conjunction with the first or second aspect, one possible design scheme includes a sixth piece of information in the system message. This sixth piece of information indicates which core network elements, other than at least one core network element, are accessible to terminals in the first area, and the first access network device can provide services to terminals in the first area. It can be understood that these other core network elements are network elements in a core network other than the core network containing the aforementioned at least one core network element, such as one or more specific network elements. Thus, when a network switching requirement arises, the terminal device can determine the core network for network switching and the corresponding access network device based on the sixth piece of information, thereby ensuring successful network switching for the terminal device.

[0025] In conjunction with the first or second aspect, in one possible design scheme, the system message further includes a seventh piece of information. This seventh piece of information is used to indicate at least one core network element associated with the second access network device. This core network element provides core network services to the terminals served by the second access network device, and the second access network device is adjacent to the first access network device. Thus, the terminal device can determine whether to access the first access network device based on the first and seventh pieces of information. In other words, the terminal device can determine which access network device's associated at least one network element better meets its needs based on the at least one network element associated with the first and second access network devices, thereby making an access decision.

[0026] Optionally, at least one core network element associated with the first access network device is different from at least one core network element associated with the second access network device; or, the service capabilities of at least one core network element associated with the first access network device are different from the service capabilities of at least one core network element associated with the second access network device, and the service capabilities include at least one of the following: network service type, service quality, or load capacity.

[0027] Optionally, the system message also includes eighth information, which indicates the type of network service provided by at least one core network element associated with the second access network device. Thus, when the terminal device determines not to access the first access network device, it can determine whether the network service provided by the core network associated with the second access network device can meet its needs, and if the network service provided by that core network meets the terminal device's needs, it can determine to access the second access network device.

[0028] Furthermore, the network service type is at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter.

[0029] Optionally, the system message also includes a ninth piece of information, which indicates the load capacity of at least one core network element associated with the second access network device. Thus, when the terminal device determines not to connect to the first access network device, it can determine whether the load capacity meets its requirements, and if the load capacity meets its requirements, it can determine whether to connect to the second access network device. Alternatively, the terminal device can determine whether to connect to the first access network device based on the load capacity, provided that both the core network associated with the first access network device and the core network associated with the second access network device meet its requirements.

[0030] Optionally, the system message also includes tenth information, which indicates the quality of service (QoS) of at least one core network element associated with the second access network device. Thus, when the terminal device determines not to access the first access network device, it can determine whether the QoS meets its requirements, and if the QoS meets its requirements, it can determine to access the second access network device. Alternatively, the terminal device can determine whether to access the first access network device based on the QoS, provided that both the core network associated with the first access network device and the core network associated with the second access network device meet its requirements.

[0031] Furthermore, the quality of service includes at least one of the following: Quality of Service (QoS) parameters or latency parameters.

[0032] Furthermore, the technical effects of the second method can be referenced from those of the first method, and will not be elaborated further here.

[0033] Thirdly, a communication method is provided, comprising: a first access network device receiving first information from a terminal device, the first access network device being a non-terrestrial device, the first information indicating the core network service requirements of the terminal device; if the core network corresponding to the first access network device does not meet the core network service requirements of the terminal device, the first access network device sending second information to the terminal device, the second information instructing the terminal device to initiate random access to other access network devices besides the first access network device. Based on this third aspect, it is understood that during the random access process, the terminal device sends its core network service requirements to the first access network device; if the core network corresponding to the first access network device does not meet the core network service requirements of the terminal device, the first access network device instructs the terminal device to access other access network devices besides the first access network device. Thus, the core network topology associated with the first access network device can dynamically change, and if the core network associated with the first access network device does not meet the core network service requirements of the terminal device, the terminal device can avoid accessing the first access network device, thereby improving service stability and enabling users corresponding to the terminal device to obtain stable communication services.

[0034] The first access network device in this application can be a first access network device or a component of the first access network device, such as a communication module, processor, chip, chip system, or circuit that can be applied in the first access network device, or a logic module or software that can realize all or part of the functions of the first access network device.

[0035] In one possible design, the method described in the third aspect further includes: when the core network associated with the first access network device meets the core network service requirements of the terminal device, the first access network device sends third information to the terminal device, the third information being used to instruct the first access network device to accept random access from the terminal device. That is, at this time, the terminal device can continue to access the first access network device and complete random access.

[0036] Fourthly, a communication method is provided, the method comprising: a terminal device sending first information to a first access network device, the first access network device being a non-terrestrial device, the first information being used to indicate the terminal device's core network service requirements for a core network; and, if the core network associated with the first access network device does not meet the terminal device's core network service requirements, the terminal device receiving second information from the first access network device, the second information being used to instruct the terminal device to initiate random access to other access network devices besides the first access network device.

[0037] The terminal device in this application can be a terminal device or a component of a terminal device, such as a communication module, processor, chip, chip system, or circuit that can be applied in a terminal device, or a logic module or software that can realize all or part of the functions of a terminal device.

[0038] In one possible design, the method described in the fourth aspect further includes: when the core network associated with the first access network device meets the core network service requirements of the terminal device, the terminal device receives third information from the first access network device, the third information being used to instruct the first access network device to accept random access from the terminal device.

[0039] In conjunction with the third or fourth aspect, in one possible design, the second information is further used to indicate one or more candidate access network devices, whose associated core network meets the core network service requirements of the terminal device. That is, the first access network device can indicate to the terminal device one or more access network devices for subsequent access. This avoids the terminal device failing to access the access network device again, thus affecting the user's communication service.

[0040] Optionally, the second information is also used to indicate the network services that the core network associated with the aforementioned candidate access network devices can provide. Thus, when the second information indicates multiple candidate access network devices, the terminal device can select a superior candidate access network device for random access based on the network services corresponding to each candidate access network device, thereby enabling the user corresponding to the terminal device to receive better communication services.

[0041] In conjunction with the third or fourth aspect, one possible design scheme involves carrying the second information within a redirection message. Of course, the second information can also be carried within other existing messages or newly defined messages; the specific configuration can be flexibly set according to the actual situation without limitation.

[0042] In conjunction with the third or fourth aspect, one possible design scheme includes core network service requirements comprising a first capability level, which belongs to multiple capability levels, each associated with a different set of network services. Thus, the terminal device can indicate its core network service requirements to the first access network device through the first capability level. It is understood that these multiple capability levels can be preset in the terminal device, configured by the network side, or predefined by the protocol. The terminal device can determine the first capability level that meets its requirements from the multiple capability levels based on its service needs provided by the core network.

[0043] Optionally, the set of network services may include at least one of the following: user registration, user authentication, user roaming, or user location. The specific services can be flexibly configured according to the actual situation without any restrictions.

[0044] In conjunction with the third or fourth aspect, in one possible design scheme, the core network service requirement includes service time, which indicates the time during which the terminal device needs network service. It can be understood that the service time can be the period or duration during which the terminal device needs network service, for example: a service time of 13:00-15:00, meaning the terminal device needs core network service from 13:00 to 15:00; or a service time of 30 minutes, meaning the terminal device needs core network service for 30 minutes after the first access network device receives the first information.

[0045] In conjunction with the third or fourth aspect, in one possible design scheme, the first information is carried in either of the following messages: Msg3 or MsgA. It is understood that Msg3 and MsgA can be used to request random access; for details, please refer to the relevant descriptions in existing technologies, which will not be elaborated here. Furthermore, the first information can also be carried in other messages, such as newly defined messages, which can be flexibly set according to the actual situation without restriction.

[0046] Furthermore, the technical effects of the fourth method can be referenced from those of the third method, and will not be elaborated further here.

[0047] Fifthly, a communication method is provided, comprising: a first access network device receiving first information from a terminal device, the first information indicating core network service requirements of the terminal device; the first access network device sending second information to M second access network devices according to the first information, the second information indicating core network service requirements of the terminal device, where M is an integer greater than 0; the first access network device receiving third information from each of the M second access network devices, the third information indicating whether the core network associated with the second access network device meets the core network service requirements; the first access network device sending fourth information to the terminal device according to the third information, the fourth information instructing the terminal device to switch the network to a third access network device, the third access network device being one of N second access network devices out of the M second access network devices, where N is an integer greater than 0 and less than or equal to M; or, the first access network device sending fifth information to the terminal device according to the third information, the fifth information instructing the terminal device to switch the network to any access network device in a set of access network devices, the set of access network devices including N second access network devices out of the M second access network devices, where N is an integer greater than 0 and less than or equal to M. As described in the fifth aspect, after receiving a core network service request from a terminal device, the first access network device can interact with M second access network devices based on this request to determine N second access network devices that meet the terminal device's core network service request. In this way, the first access network device can, based on these N second access network devices, instruct the terminal device to perform network switching on an access network device, such as a third access network device or a set of access network devices, thereby ensuring stable communication services for the user corresponding to the terminal device after network switching.

[0048] The first access network device in this application can be a first access network device or a component of the first access network device, such as a communication module, processor, chip, chip system, or circuit that can be applied in the first access network device, or a logic module or software that can realize all or part of the functions of the first access network device.

[0049] In one possible design, the second information is carried within the switch request message. Of course, the second information can also be carried within other existing messages, or even newly defined messages; the specific configuration can be flexibly set according to the actual situation without any limitations.

[0050] A sixth aspect provides a communication method, the method comprising: a second access network device receiving second information from a first access network device, the second information being used to indicate core network service requirements of a terminal device, the first access network device providing network services to the terminal device; and in response to the first information, the second access network device sending third information to the first access network device, the third information being used to indicate whether the core network associated with the second access network device meets the core network service requirements.

[0051] The second access network device in this application can be a second access network device or a component of a second access network device, such as a communication module, processor, chip, chip system, or circuit that can be applied in the second access network device, or a logic module or software that can realize all or part of the functions of the second access network device.

[0052] In one possible design, the second information is carried in the handover request message.

[0053] A seventh aspect provides a communication method, the method comprising: a terminal device sending first information to a first access network device, the first information indicating a core network service requirement of the terminal device; the terminal device receiving fourth information from the first access network device, the fourth information indicating that the terminal device switches the network to a third access network device, the third access network device being one of N second access network devices out of M second access network devices, where N is an integer greater than 0 and less than or equal to M; or, the terminal device receiving fifth information from the first access network device, the fifth information indicating that the terminal device switches the network to any access network device in a set of access network devices, the set of access network devices including N second access network devices out of M second access network devices, where N is an integer greater than 0 and less than or equal to M.

[0054] The terminal device in this application can be a terminal device or a component of a terminal device, such as a communication module, processor, chip, chip system, or circuit that can be applied in a terminal device, or a logic module or software that can realize all or part of the functions of a terminal device.

[0055] In conjunction with the fifth, sixth, or seventh aspects, one possible design scheme includes core network service requirements comprising a first capability level, which belongs to multiple capability levels, each of which is associated with a different set of network services.

[0056] Optionally, the set of network services includes at least one of the following: user registration, user authentication, user roaming, or user location.

[0057] In conjunction with the fifth, sixth, or seventh aspects, in one possible design scheme, the core network service requirements include service time, which is used to indicate the time when the terminal device needs network services.

[0058] Furthermore, the technical effects of the methods in the sixth or seventh aspect can also be referenced from the technical effects of the methods in the fifth aspect, which will not be elaborated here.

[0059] Eighthly, a communication method is provided, the method comprising: a first access network device performing the method described in the fifth aspect, and a second access network device performing the method described in the sixth aspect.

[0060] A ninth aspect provides a communication device. The communication device includes: modules or units (e.g., chips, chip systems, or circuits) for performing each of the methods / operations / steps / actions described in any one of the first to seventh aspects, such as a transceiver module and a processing module. For example, the transceiver module is used to indicate the transceiver function of the communication device, and the processing module is used to perform functions of the communication device other than the transceiver function.

[0061] Optionally, the transceiver module may include a transmitting module and a receiving module. The transmitting module implements the transmitting function of the communication device described in the ninth aspect, and the receiving module implements the receiving function of the communication device described in the ninth aspect.

[0062] Optionally, the communication device according to the ninth aspect may further include a storage module storing a program or instructions. When the processing module executes the program or instructions, the communication device can perform the method described in any one of the first to seventh aspects.

[0063] It is understood that the communication device described in the ninth aspect may be a terminal device or a network device, or a chip (system) or other component or assembly that can be disposed in the terminal device or the network device, or a device that includes the terminal device or the network device. This application does not limit it in this regard.

[0064] Furthermore, the technical effects of the communication device described in the ninth aspect can be referred to the technical effects of the method described in any of the implementations of the first to seventh aspects, and will not be repeated here.

[0065] A tenth aspect provides a communication device. The communication device includes a processor, which, when executing computer instructions, causes the communication device to perform the method described in any one of the possible implementations of the first to seventh aspects.

[0066] In one possible design, the communication device described in the tenth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the tenth aspect and other communication devices.

[0067] In one possible design, the communication device described in the tenth aspect may further include a memory. This memory may be integrated with the processor or disposed separately. The memory may be used to store computer programs and / or data relating to the methods described in any of the first to seventh aspects.

[0068] In the embodiments of this application, the communication device described in the tenth aspect may be a terminal device or network device described in any one of the first to seventh aspects, or may be a chip (system) or other component or assembly disposed in the terminal device or the network device, or may include the terminal device or the network device.

[0069] Furthermore, the technical effects of the communication device described in the tenth aspect can be referred to the technical effects of the method described in any of the implementations of the first to seventh aspects, and will not be repeated here.

[0070] Eleventhly, a communication device is provided. The communication device includes a processor coupled to a memory, the processor being configured to execute a computer program stored in the memory, such that the communication device performs the method described in any one of the possible implementations of the first to seventh aspects.

[0071] In one possible design, the communication device described in the eleventh aspect may further include a transceiver. This transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the eleventh aspect and other communication devices.

[0072] In the embodiments of this application, the communication device described in the eleventh aspect may be a terminal device or network device described in any one of the first to seventh aspects, or may be a chip (system) or other component or assembly disposed in the terminal device or network device, or may include the terminal device or network device.

[0073] Furthermore, the technical effects of the communication device described in the eleventh aspect can be referred to the technical effects of the method described in any of the implementations of the first to seventh aspects, and will not be repeated here.

[0074] In a twelfth aspect, a communication device is provided, comprising: a processor and a memory; the memory being used to store a computer program, which, when executed by the processor, causes the communication device to perform the method described in any one of the first to seventh aspects.

[0075] In one possible design, the communication device described in the twelfth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the communication device described in the twelfth aspect and other communication devices.

[0076] In the embodiments of this application, the communication device described in the twelfth aspect may be a terminal device or network device described in any one of the first to seventh aspects, or may be a chip (system) or other component or assembly disposed in the terminal device or network device, or may include the terminal device or network device.

[0077] Furthermore, the technical effects of the communication device described in the twelfth aspect can be referred to the technical effects of the method described in any of the implementations of the first to seventh aspects, and will not be repeated here.

[0078] In a thirteenth aspect, a communication apparatus is provided for implementing the method described in any of the possible implementations of the first to seventh aspects.

[0079] In a fourteenth aspect, a communication chip is provided, comprising: a logic circuit and a communication interface, the logic circuit being used to execute computer instructions, and the communication interface being used for the communication chip to communicate with other devices or chips, wherein when the logic circuit executes the computer instructions, the method described in any one of the first to seventh aspects is implemented.

[0080] In a fifteenth aspect, a communication system is provided, comprising at least one of the following: a first access network device for performing the method of the first aspect, or a terminal device for performing the method of the second aspect.

[0081] In a sixteenth aspect, a communication system is provided, comprising at least one of the following: a first access network device for performing the method of the third aspect, or a terminal device for performing the method of the fourth aspect.

[0082] In a seventeenth aspect, a communication system is provided, comprising at least one of the following: a first access network device for performing the method of the fifth aspect, a second access network device for performing the method of the sixth aspect, or a terminal device for performing the method of the seventh aspect.

[0083] Eighteenth aspect: A computer-readable storage medium is provided, comprising: a computer program or instructions; when the computer program or instructions are executed on a computer, causing the computer to perform the method described in any one of the possible implementations of the first to seventh aspects.

[0084] In a nineteenth aspect, a computer program product is provided, comprising a computer program or instructions that, when executed on a computer, cause the computer to perform the method described in any one of the possible implementations of the first to seventh aspects. Attached Figure Description

[0085] Figure 1 A schematic diagram of the architecture of the 5GS fifth-generation mobile communication system provided in this application embodiment;

[0086] Figure 2 A schematic diagram illustrating the core network deployment method provided in the embodiments of this application;

[0087] Figure 3 Schematic diagram of NTN RAN architecture provided in the embodiments of this application Figure 1 ;

[0088] Figure 4 Schematic diagram of NTN RAN architecture provided in the embodiments of this application Figure 2 ;

[0089] Figure 5 Schematic diagram of NTN RAN architecture provided in the embodiments of this application Figure 3 ;

[0090] Figure 6 Flowchart of the communication method provided in the embodiments of this application Figure 1 ;

[0091] Figure 7 A schematic diagram of the first access network device and the second access network device provided in the embodiments of this application;

[0092] Figure 8 Flowchart of the communication method provided in the embodiments of this application Figure 2 ;

[0093] Figure 9 Flowchart of the communication method provided in the embodiments of this application Figure 3 ;

[0094] Figure 10 Schematic diagram of the communication device provided in the embodiments of this application Figure 1 ;

[0095] Figure 11 Schematic diagram of the communication device provided in the embodiments of this application Figure 2 . Detailed Implementation

[0096] For ease of understanding, the technical terms involved in the embodiments of this application will be introduced below.

[0097] 1. Fifth generation (5G) mobile communication system (5G system, 5GS)

[0098] Figure 1 This is a schematic diagram of the 5GS architecture, as shown below. Figure 1 As shown, 5GS includes: access network (AN) and core network (CN), and may also include: terminal equipment.

[0099] 1.1 Terminal Equipment

[0100] The terminal equipment can be a terminal device with transceiver functions, or a chip or chip system that can be installed in the terminal device. The terminal equipment can also be referred to as user equipment (UE), access terminal, subscriber unit, user station, mobile station (MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user device. The terminals in the embodiments of this application may be mobile phones, cellular phones, smartphones, tablets, wireless data cards, personal digital assistants (PDAs), wireless modems, handsets, laptop computers, machine-type communication (MTC) terminals, computers with wireless transceiver capabilities, virtual reality (VR) terminals, augmented reality (AR) terminals, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, vehicle-mounted terminals, roadside units (RSUs) with terminal functions, and terminals in satellite communication, etc. The terminal device of this application can also be an on-board module, on-board component, on-board chip, or on-board unit built into a vehicle as one or more components or units. The embodiments of this application do not limit the type or category of the terminal device. Furthermore, the terminal device of this application can be mobile or fixed.

[0101] 1.2AN

[0102] An AN exists between a terminal and a CN, providing a communication connection between the two. An AN, also known as a radio access network (RAN), is an entity used to transmit signals, or receive signals, or both transmit and receive signals.

[0103] In one possible implementation, RAN equipment can also be referred to as an access node, RAN entity, RAN node, or equipment with base station processing capabilities. For example, RAN equipment can include non-terrestrial network equipment (or NTN-RAN equipment) and terrestrial RAN equipment. NTN-RAN equipment can provide coverage for terminals by deploying base stations or part of the base station functions on non-terrestrial equipment (such as satellites, high-altitude platforms, or drones). For example, in NTN, RAN equipment can be a satellite or network equipment deployed on a satellite. Terrestrial RAN equipment can include base stations in NR systems (such as next-generation node B (gNodeB, gNB)), or one or a group of antenna panels (including multiple antenna panels) of a base station in 5G, or it can be a network node constituting a gNB, transmission and reception point (TRP or transmission point, TP), or transmission measurement function (TMF), such as a building base band unit (BBU), or a centralized unit (CU) or distributed unit (DU), an RSU with base station functions, or a wired access gateway, or a 5G CN network element. Alternatively, TN-RAN equipment may also include access points (APs) in Wi-Fi systems, wireless relay nodes, wireless backhaul nodes, various forms of macro base stations, micro base stations (also known as small stations), relay stations, access points, wearable devices, vehicle-mounted equipment, etc. Alternatively, RAN equipment may also include: access network equipment or base stations in future mobile communication systems.

[0104] It is understood that in future mobile communication systems, the aforementioned RAN equipment may also have other naming methods, all of which are covered within the protection scope of the embodiments of this application, and this application does not impose any limitations on them.

[0105] In one possible implementation, the RAN device may include a CU, DU, CU (control plane, CP), CU (user plane, UP), or radio unit (RU). The RAN device may also include an active antenna unit (AAU). The CU implements some of the network device's functions, and the DU implements some of the network device's functions. For example, the CU is responsible for handling non-real-time protocols and services, implementing the functions of the radio resource control (RRC) and / or packet data convergence protocol (PDCP) layers. The DU is responsible for handling physical layer protocols and real-time services, 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, radio frequency processing, and related functions of the active antenna. Since RRC layer information ultimately becomes PHY layer information, or is derived from PHY layer information, in this architecture, higher-layer signaling, such as RRC signaling, can also be considered as being sent by the DU, or by the DU and AAU. It is understood that RAN devices can be one or more of the following: CU nodes, DU nodes, and AAU nodes. Furthermore, a CU can be classified as a network device within the RAN, or it can be classified as a network device within the CN; this application does not limit this classification.

[0106] 1.3CN

[0107] The Network Center (CN) is primarily responsible for maintaining the subscription data of the mobile network and providing terminals with functions such as session management, mobility management, policy management, and security authentication. The CN mainly includes the following: User Plane Function (UPF), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), Network Slice Selection Function (NSSF), Network Exposure Function (NEF), Network Repository Function (NRF), Policy Control Function (PCF), Unified Data Management (UDM), Unified Data Repository (UDR), and Application Function (AF).

[0108] like Figure 1 As shown, the UE accesses the 5G network through the RAN device. The UE communicates with the AMF through the N1 interface (N1 for short); the RAN communicates with the AMF through the N2 interface (N2 for short); the RAN communicates with the UPF through the N3 interface (N3 for short); the SMF communicates with the UPF through the N4 interface (N4 for short); and the UPF accesses the data network (DN) through the N6 interface (N6 for short). Furthermore, Figure 1 The control plane functions shown, such as AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR, and AF, interact using service-oriented interfaces. For example, the service-oriented interface provided by AUSF includes Nausf; AMF includes Namf; SMF includes Nsmf; NSSF includes Nnssf; NEF includes Nnef; NRF includes Nnrf; PCF includes Npcf; UDM includes Nudm; UDR includes Nudr; and AF includes Naf.

[0109] UPF is primarily responsible for user data processing (forwarding, receiving, billing, etc.).

[0110] AUSF is primarily used to perform security authentication for terminal devices.

[0111] AMF is primarily used for mobility management in mobile networks. Examples include user location updates, user network registration, and user handover.

[0112] SMF is primarily used for session management in mobile networks. This includes session establishment, modification, and release. Specific functions include assigning Internet Protocol (IP) addresses to users and selecting a UPF (User-Defined Provider) to handle packet forwarding.

[0113] The PCF primarily supports providing a unified policy framework to control network behavior, delivering policy rules to control-layer network functions, and acquiring user subscription information related to policy decisions. The PCF can provide policies to the AMF and SMF, such as Quality of Service (QoS) policies and slice selection policies.

[0114] NSSF is primarily used to select network slices for end devices.

[0115] The Network Front-End (NEF) is a control plane function provided by operators, primarily enabling third parties to use services offered by the network. It supports the network in opening its capabilities, analyzing events and data, providing security configuration information to the Public Land Mobile Network (PLMN) from external applications, and converting information exchanged between the PLMN and external systems. For example, the NEF can expose some capabilities of the 5G network to third-party applications through an application programming interface (API). These applications can then access these 5G network capabilities by calling the APIs provided by the NEF, allowing them to control certain behaviors of the 5G network and terminal devices.

[0116] NRF is a control plane function provided by the operator, which can be used to maintain real-time information about network functions and services in the network.

[0117] UDM is primarily used to store user data, such as contract data and authentication / authorization data.

[0118] UDR is primarily used to store structured data, including contract data, policy data, externally exposed structured data, and application-related data.

[0119] The AF primarily provides services by interacting with the CN, such as providing roaming UE network selection information, guiding data flow routing, and accessing the NEF.

[0120] It should be understood that Figure 1 The network functions described below are only schematic representations and are not limited to the NFs described later. Figure 1 The network functions shown are as described above. The naming conventions are defined solely for the purpose of distinguishing different functions and should not be construed as limiting the scope of this application. This application does not preclude the possibility of using other naming conventions in 5G networks and other future networks. For example, in future communication networks, some or all of the aforementioned network elements may use the terminology from 5G, or they may use other names, etc.

[0121] 2.NTN

[0122] Because traditional TN systems, such as NR systems (also known as 5th generation, 5G) or IoT systems, cannot provide seamless coverage for terminals (e.g., in scenarios where communication is impossible in physical areas such as the ocean, desert, or air where base stations cannot be deployed), NR systems, IoT systems, and future communication systems can incorporate NTN to provide seamless coverage services for terminals. NTN can deploy some or all of the base station's functions on non-terrestrial network equipment (e.g., ships, high-altitude platforms, drones, or satellites) to provide communication coverage for terminals, thereby improving the reliability of the communication system. It should be noted that, for ease of understanding, the following explanation uses satellite as an example of NTN-RAN equipment; it should not be construed as limiting the NTN-RAN equipment in this application to satellites. This will be clarified uniformly here and will not be repeated below.

[0123] In NTN scenarios, there are three main deployment methods for the CN: 1. Deploying the CN in space, such as deploying core network elements on a satellite platform, with the space-based core network providing core network services to users, for example: Figure 2 The core network is divided into a master core layer and a slave core layer. The slave core layer includes a small number of essential network elements, which provide services to satellite base stations independently. Other network elements are deployed in the master core layer. Secondly, the core network (CN) can be deployed in space and on the ground, such as deploying a simplified core network in satellites and a full-function core network on the ground, to provide core network services to users in a coordinated manner. Thirdly, the core network can be deployed on the ground, relying on the ground core network to return the user's core network services to the ground for processing.

[0124] NTN can be classified according to the satellite's operating mode, such as transparent mode architecture and regenerative mode architecture. In transparent mode architecture, the satellite's role is to perform radiofrequency filtering, frequency conversion, and amplification; that is, in transparent satellite architecture, the satellite mainly acts as a layer 1 (L1) relay device, used to regenerate physical layer signals (i.e., radiofrequency filtering, frequency conversion, and amplification), without involving other higher protocol layers. Regenerative mode can refer to a satellite acting as a base station, possessing some or all of the data processing capabilities of a base station.

[0125] The following examples, with reference to the accompanying diagrams, illustrate several NTN-based RAN architectures.

[0126] like Figure 3 As shown, Figure 3 The RAN architecture (or next-generation RAN, NG-RAN) described here is a transparent satellite architecture, comprising a remote radio unit (RRU) and a base station. The RRU may include a satellite and an NTN gateway. The satellite can operate in transparent mode, acting as a layer 1 relay between the terminal and the base station. For example, the satellite may be used to regenerate PHY layer signals, meaning it may not have higher-layer protocol layer (e.g., RRC layer) functionality. The transmission link between the satellite and the terminal can be called a service link (SL). The transmission link between the satellite and the NTN gateway can be called a feeder link (FL). The NTN gateway can be deployed together with the base station or separately; this application does not specifically limit this. Furthermore, different satellites can connect to the same ground base station.

[0127] It should be understood that the power supply link is the transmission link between the satellite and the base station. In the case where the NTN gateway and the base station are deployed separately, the power supply link (FL) can include the transmission link between the satellite and the NTN gateway, as well as the transmission link between the NTN network element and the base station.

[0128] like Figure 3As shown, a terminal can access a base station via satellite, and then access the core network (CN) through the base station, such as the 5th generation core network (5G CN). It can be understood that in... Figure 3 In this configuration, the satellite merely acts as a frequency converter, essentially functioning as an analog radio frequency repeater. This means the satellite replicates the NR-Uu radio interface signal from the feed link to the service link, and vice versa. The satellite radio interface on the feed link transmits the NR-Uu interface signal; the satellite does not terminate the NR-Uu interface signal but rather replicates it. Furthermore, the NTN gateway supports all necessary functions for forwarding NR-Uu interface signals.

[0129] like Figure 4 As shown, Figure 4 The RAN architecture in this context is a regenerative satellite architecture without inter-satellite links (ISL), and... Figure 3 The differences between the transparent satellite architectures shown are: Figure 4 The satellites in this context possess base station capabilities, serving as RAN (Radio Access Network) equipment to provide services to terminals. ISL (Integrated Switched Link) refers to the transmission link between satellites. ISL can be a radio interface or an optical interface; the specific ISL is defined by 3GPP, for example, using the Xn interface, without specific limitations. Furthermore, the interface between the satellite and the NTN gateway can be a satellite radio interface (SRI).

[0130] like Figure 5 As shown in (a) in the figure, Figure 5 The RAN architecture in (a) is a regenerative satellite architecture with ISL, and... Figure 4 The differences between the architectures shown are: Figure 5 The architecture shown in (a) contains ISL, meaning that satellite #1 and satellite #2 can transmit data via ISL.

[0131] like Figure 5 As shown in (b) in the figure, Figure 5 The RAN architecture in (b) and Figure 3 The differences between the transparent satellite architectures shown are: Figure 5 The satellite shown in (b) has some of the processing functions of the base station, such as the DU function of the RAN equipment. The satellite can act as the DU of the RAN equipment, and the base station can act as the CU of the RAN equipment.

[0132] Understandable. Figures 4-5In the architecture shown, base station functionality or digital unit (DU) is deployed on the satellite. In this architecture, the satellite acts as a base station to regenerate signals received from the ground, that is, to transmit NR-Uu interface signals on the service link between the terminal and the satellite, and to transmit SRI signals on the feed link between the NTN gateway and the satellite.

[0133] Furthermore, the above description uses a satellite as an example. The satellite can also be replaced by other non-terrestrial network devices, such as ships, high-altitude platforms, or drones. This application does not specifically limit this.

[0134] It is understandable that in NTN communication, the core network topology associated with the satellite base station will change due to the movement of the satellite base station, and the core network service of the core network associated with the satellite base station may also change accordingly. This may lead to poor communication stability, thereby affecting the user's communication service.

[0135] To address the aforementioned technical problems, this application proposes the following technical solutions to improve communication stability in NTN scenarios.

[0136] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0137] The technical solutions of this application can be applied to various communication systems, such as 4th generation (4G) mobile communication systems, such as long term evolution (LTE) systems, 5th generation (5G) mobile communication systems, such as new radio (NR) systems, and communication systems that evolve after 5G, such as future communication network systems. They can also be applied to wireless fidelity (WiFi) systems, vehicle to everything (V2X) communication systems, device-to-device (D2D) communication systems, vehicle networking communication systems, etc.

[0138] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches are also possible.

[0139] Furthermore, in the embodiments of this application, the words "exemplary," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0140] In the embodiments of this application, the terms "information," "signal," "message," "channel," and "signaling" may sometimes be used interchangeably. It should be noted that, without emphasizing their distinction, their intended meanings are consistent. Similarly, "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing their distinction, their intended meanings are consistent. Furthermore, the " / " mentioned in this application can be used to indicate an "or" relationship.

[0141] The network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0142] To facilitate understanding of the embodiments of this application, the communication system applicable to the embodiments of this application will be described first.

[0143] This communication system is applicable to 5GS, including: terminal devices and access network devices.

[0144] The aforementioned terminal device can be a terminal equipment or a component of a terminal equipment, such as a communication module, processor, chip, chip system, or circuit that can be applied in a terminal equipment, or a logic module or software that can realize all or part of the functions of a terminal equipment. The aforementioned access network device can be an access network device or a component of an access network device, such as a communication module, processor, chip, chip system, or circuit that can be applied in an access network device, or a logic module or software that can realize all or part of the functions of an access network device. For details on terminal equipment and access network equipment, please refer to the foregoing descriptions; further elaboration is not provided here.

[0145] It is understood that the aforementioned access network equipment can be either terrestrial or non-terrestrial. Terrestrial access network equipment is a network node located on the ground, typically positioned near the ground. For example, it can be installed on or within a building or tower. Non-terrestrial access network equipment is not a network node located on the ground; it can be deployed on an airborne platform or satellite, or other forms of network equipment deployed at high altitudes, structurally and functionally similar to terrestrial network equipment. An airborne platform can include at least one of the following: satellite, drone, hot air balloon, airplane, or other aircraft. Examples of terrestrial access network equipment include network equipment carried by or otherwise implemented in a drone, such as a high altitude platform (HAP), and satellites. It should be understood that in this embodiment, non-terrestrial access network equipment is primarily exemplified by network equipment deployed on a satellite. Furthermore, the aforementioned access network device can be one or more, such as a first access network device and at least one second access network device, which can be flexibly configured according to actual circumstances without limitation.

[0146] In one possible implementation, the first access network device sends a system message carrying information indicating at least one network element associated with the first access network device. Upon receiving this system message, the terminal device can obtain the information about the at least one network element associated with the first access network device based on the system message, and make an access decision based on this information. For example, if the at least one network element associated with the first access network meets the terminal device's requirements, it determines to access the first access network device; conversely, if the at least one network element associated with the first access network does not meet the terminal device's requirements, it determines not to access the first access network device. In this way, even when the core network topology associated with the first access network device changes dynamically, the terminal can make access decisions based on the network element information in the core network currently associated with the first access network device, thereby improving communication stability and enabling users corresponding to the terminal device to obtain stable communication services.

[0147] In another possible implementation, during random access, the terminal device sends information indicating its core network service requirements to a first access network device. Upon receiving this information, the first access network device determines whether its associated core network meets the service requirements. If the associated core network does not meet the service requirements, the first access network device instructs the terminal device to access another access network device besides the first access network device. This avoids the terminal device accessing the first access network device when the core network topology associated with it changes dynamically and the associated core network does not meet the terminal device's core network service requirements, thereby improving communication stability and ensuring stable communication services for the user corresponding to the terminal device.

[0148] In another possible implementation, during cell handover, the first access network device sends a core network service request from the terminal device to at least one second access network device. Upon receiving the core network service request, each of the at least one second access network device can determine whether its associated core network meets the core network service requirement and feeds back the result to the first access network device. Thus, the first access network device can make handover decisions based on the feedback from these at least one second access network device, such as indicating to the terminal device which access network device meets the core network service requirement. This ensures communication stability after cell handover, allowing the user corresponding to the terminal device to receive stable communication services.

[0149] It should be understood that the above description is an exemplary description of the embodiments of this application and is not intended to limit the embodiments of this application. For specific embodiments of this application, please refer to the following: Figures 6-9 Description of the illustrated embodiments.

[0150] It is understood that the above communication system may also include other network devices and / or terminal devices, which can be flexibly configured according to the actual situation without any restrictions.

[0151] For ease of understanding, the following will combine... Figures 6-9 The communication method provided in the embodiments of this application will be described in detail.

[0152] For example, Figure 6 Flowchart of the communication method provided in the embodiments of this application Figure 1 This method can be applied to communication between a terminal device and an access network device in the aforementioned communication system. The access network device can be a non-terrestrial access network device. The following explanation uses an example where the access network device includes a first access network device and at least one second access network device.

[0153] like Figure 6 As shown, the flow of this communication method is as follows:

[0154] S601, the first access network device determines the system message.

[0155] S602, the first access network device sends a system message. Correspondingly, the terminal device receives the system message from the first access network device.

[0156] S603, the terminal device determines whether to connect to the first access network device based on the system message.

[0157] The steps described above will be explained in detail below.

[0158] For S601:

[0159] The first access network device is a non-terrestrial device. For example, it can be a base station mounted on a satellite, such as a satellite base station, or it can be a base station mounted on a high-altitude platform; there are no restrictions. The first access network device can provide services to terminals in a first area, which is the area where the first access network device can provide network services, or in other words, the first area is the beam coverage area of ​​the first access network device. Providing services to terminals can be understood as the first access network device supporting cells serving terminals; that is, the cell is the serving cell for the terminal. In other words, the first access network device in this embodiment can also be understood as the cell served by the first access network device.

[0160] System messages are used by the terminal device to determine whether to access the first access network device. That is, after receiving a system message sent by the first access network device, the terminal device can determine whether to access the first access network device based on the system message (details are described in section S603 below). The system message can reuse existing messages, such as system information block 1 (SIB1), etc. The system message can also be a newly defined message without restriction.

[0161] The system message includes first information, which indicates at least one core network element, or in other words, indicates the core network topology associated with the first access network device. The at least one core network element is a network element included in the core network associated with the first access network device, meaning that at least one network element has an association or correspondence with the first access network device. The aforementioned at least one network element can also be referred to as at least one network element associated with or corresponding to the first access network device. The aforementioned at least one core network element is used to provide core network services to the terminals served by the first access network device. The terminals served by the first access network device can be understood as terminals in a first area, or terminals served by a cell supported by the first access network device. Core network services are related to at least one core network element. For example, if at least one core network element includes SMF (Session Establishment Function), then the core network service may include session establishment service; or, if at least one core network element includes AUSF (Authorization Authentication Function), then the core network service may include authentication service. The at least one core network element can be configured according to actual conditions without limitation.

[0162] The first access network device can indicate at least one core network element using a fixed-length bitmap. For example, bit 1 indicates the presence of the corresponding core network element, bit 0 indicates the absence of the corresponding core network element, and the order of the core network elements is AMF, SMF, UPF, UDM, ..., AUSF; as shown in Table 1 below, bits 1, 1, 1, 0, ..., 0 indicate that the core network associated with the first access network device includes AMF, SMF, and UPF, that is, at least one element is AMF, SMF, or UPF. For another example, bit 0 indicates the presence of the corresponding core network element, bit 1 indicates the absence of the corresponding core network element, and the order of the core network elements is AMF, SMF, UPF, UDM, ..., AUSF; as shown in Table 1 below, bits 1, 1, 1, 0, ..., 0 indicate that the core network associated with the first access network device includes UDM, ..., AUSF, that is, at least one element is UDM, ..., AUSF. Of course, the first access network device can also instruct at least one core network element in other ways, and the specific settings can be flexibly configured according to the actual situation without any restrictions.

[0163] Table 1

[0164] Core network elements AMF SMF UPF UDM …… AUSF Bit 1 1 1 0 …… 0

[0165] Optionally, the aforementioned system message further includes second information, which indicates the service time of at least one core network element. This service time indicates the time during which the at least one core network element provides network services to the terminal, or in other words, the time during which the at least one core network element can provide network services to the terminal. Thus, based on the second information, the terminal can determine whether at least one core network element can provide services to it during the time period it needs network services, thereby facilitating the terminal's access decision based on the system message.

[0166] The service time can be at least one of the following: duration, start time, end time, or time information, which are described below.

[0167] The duration is used to indicate the time period during which at least one network element provides services. This duration can be the time period during which the entire network provides services for at least one network element, or the time period during which each individual network element within the at least one network element provides services. For example, if the duration is 14:00-16:00, and the at least one network element is AMF, SMF, and UPF, then the time period during which AMF, SMF, and UPF provide network services is 14:00-16:00. For example, the duration includes duration 1 to duration 4, where duration 1 is 14:00-15:00, duration 2 is 14:00-15:30, duration 3 is 14:00-16:00, and duration 4 is 14:00-16:00; at least one network element is AMF, SMF, UPF, and PCF, and AMF, SMF, UPF, and PCF correspond to duration 1 to duration 4 respectively. Then, the time period for AMF to provide network services is 14:00-15:00, the time period for SMF to provide network services is 14:00-15:30, and the time period for UPF and PCF to provide network services is 14:00-16:00.

[0168] The startup time is used to indicate the start time of service provision by at least one network element. This startup time can be the overall service startup time for the at least one network element, or the service startup time for each individual network element within the at least one network element. For example, if the startup time is 10:00, and the at least one network element is AMF, SMF, UPF, and PCF, then the startup time for AMF, SMF, UPF, and PCF is 10:00. As another example, if the startup time includes startup times 1 to 3, where startup times 1 and 2 are both 10:00, and startup time 3 is 10:10; and the at least one network element includes AMF, SMF, and UPF, with AMF, SMF, and UPF corresponding to startup times 1 to 3 respectively, then the startup time for AMF and SMF to provide network services is 10:00, and the startup time for UPF to provide network services is 10:10.

[0169] The termination time indicates the end time of service provided by at least one network element. This termination time can be the overall service termination time for the at least one network element, or the service termination time for each individual network element within the at least one network element. It can be understood that this termination time is similar to the startup time mentioned above; please refer to the example of the startup time for understanding, and it will not be repeated here. Furthermore, the startup time and termination time can together indicate the time period or duration of service provided by at least one network element.

[0170] Time information is used to indicate time-related information of the core network topology where at least one network element resides. Specifically, time-related information is used to indicate the service time of at least one network element as a whole, meaning it indicates the time during which at least one network element can provide service to the first area. The time-related information can be at least one of the following: core network topology duration, core network topology start time, or core network topology end time. The core network topology duration indicates the time period or duration during which the core network topology where at least one network element resides provides service; the core network topology start time indicates the start time of service provided by the core network topology where at least one network element resides; and the core network topology end time indicates the end time of service provided by the core network topology where at least one network element resides. The core network topology duration, core network topology start time, and core network topology end time are similar to the duration, start time, and end time mentioned above when they indicate at least one network element as a whole, and can be understood by referring to the aforementioned related content; they will not be repeated here.

[0171] There are multiple ways for the first access network device to obtain the aforementioned service time. For example, the communication method may further include: the first access network device determining the service time based on the topology information of the core network where at least one network element is located and / or the topology information of the access network where the first access network device is located. That is, the first access network device can determine the time for at least one core network element to provide network services to the first area based on the topology information of the core network where at least one network element is located. Alternatively, the first access network device can determine the topology information of the core network where at least one associated network element is located based on the topology information of its own access network, and thus determine the time for at least one core network element to provide network services to the first area based on the topology information of that core network. Alternatively, the first access network device can determine the time for at least one core network element to provide network services to the first area based on the topology information of the core network where at least one network element is located and the topology information of the access network where the first access network device is located. It is understood that a core network element can provide core network services to the user corresponding to the terminal through the access network device to which it is connected. Therefore, the time when the core network element can provide services can be predicted based on the current and future connection relationship between the core network element and the access network device. This enables the first access network device to obtain accurate service time, thereby preventing the terminal from making access decisions based on incorrect information. The specific implementation principles of the access network device determining service time based on the core network topology information, and the specific implementation principles of the access network device determining service time based on the core network topology information and the access network topology information, can be found in existing technologies and will not be elaborated here.

[0172] The first access network device can interact with any one of the at least one network elements through the NG interface to obtain the core network topology information of the at least one network element. This any one network element can also be a network element that provides the first access network device with an interface to access the core network, such as an AMF (Advanced Feature Function). Furthermore, the first access network device can also obtain the operating status information of at least one network element through this method, such as the remaining resources or load of at least one network element during the service period. After obtaining the operating status information of at least one network element, the first access network device can send this information to the terminal, such as through a system message or a second message, so that the terminal can perform subsequent operations based on this operating status information, such as determining whether to connect to the first access network device.

[0173] It is understandable that the first access network device can also determine the service time through other means. For example, the first access network device can determine the service time itself based on ephemeris information. The specific implementation principle of calculating the service time based on ephemeris information can be found in existing technologies and will not be elaborated here. Alternatively, the ground telemetry and control station or ground operation and maintenance unit can send the aforementioned service time to the first access network device. Of course, the first access network device can also obtain the service time through other means, and the specific methods can be flexibly set according to the actual situation without restriction.

[0174] The second information can also be used to indicate the first area, and the first access network device can provide services to terminals in the first area. Furthermore, at least one of the aforementioned network elements can provide services to the first area. In other words, the first area can indicate the service range of the first access network device and at least one network element associated with the first access network device. The first area can be referred to the aforementioned related descriptions, which will not be repeated here. Thus, the terminal can perform subsequent operations based on this first area, such as access decisions, pre-registration processes, etc.

[0175] There are several ways to indicate the first area. For example, the first access network device can indicate the first area by using a reference point and radius, the first access network device can also indicate the first area by using multiple coordinates, or the first access network device can indicate the first area by using the coverage range of the beam. For the specific implementation principle, please refer to the existing technology, which will not be elaborated here.

[0176] In addition, the first area can be sent to the first access network device by the ground telemetry and control station or the ground operation and maintenance unit, or the first access network device can obtain the first area through other possible means without restriction.

[0177] Furthermore, the aforementioned communication method may also include: the terminal device executing (or triggering, or initiating) a registration process or a pre-registration process based on the second information. That is, the second information can trigger the terminal device to execute the registration process or the pre-registration process. The specific implementation principle of the registration process or the pre-registration process can be found in existing technologies and will not be elaborated here. In this way, the terminal device can promptly perform the registration process or the pre-registration process based on the service time and the first region.

[0178] It is understandable that carrying the second information in the system message can also be implemented independently, that is, without combining it with the aforementioned carrying the first information in the system message. In this case, after receiving the second information, the terminal device can determine whether to access the first access network device based on the second information, that is, the terminal device can select a suitable access network device to initiate random access; or, after receiving the second information, the terminal device can perform cell reselection based on the second information. For example, if the cell reselection condition is that the service time of network element #1 meets time #1, then the terminal device can determine whether to perform cell reselection when network element #1 does not meet time #1 based on the service time indicated by the second information.

[0179] Optionally, the system message also includes third information, which indicates the type of network service provided by the at least one core network element. This network service type can indicate the network services that the at least one core network element can provide to the terminal. For example, the network service type may include at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameters, where the slice parameters indicate the capabilities that a network slice can provide. It is understood that the above network services can refer to existing technologies, and will not be elaborated further here. After receiving the third information, the terminal device can determine, based on the third information, whether the network service provided by the core network associated with the first access network device can meet its needs. If the network service provided by the core network meets the terminal device's needs, the terminal device will access the first access network device. This enables the user corresponding to the terminal device to obtain stable communication services.

[0180] For example, if the network service type indicated by the third information is user registration, user authentication, and user roaming, and the user needs roaming service, then the network service provided by at least one core network element can meet the user's needs, and the user's corresponding terminal device can determine that it is connected to the first access network device.

[0181] For example, if the network service type indicated by the third information is user registration, user authentication, and user roaming, and the user needs location services, then the network services provided by at least one core network element cannot meet the user's needs, and the user's corresponding terminal device can determine not to connect to the first access network device.

[0182] Optionally, the system message also includes fourth information, which indicates the load capacity of the at least one core network element. Upon receiving the fourth information, the terminal device can determine whether to connect to the first access network device based on the load capacity of the at least one core network element associated with the first access network device. If the load capacity is high, it will connect to the first access network device; if the load capacity is low, it will not connect. This ensures that the terminal device can smoothly perform various services after connecting to the first access network device, thereby providing stable communication services to the users corresponding to the terminal device.

[0183] It is understandable that the fourth information can indicate the overall load capacity of at least one core network element. For example, the first access network device can use the lowest load capacity corresponding to at least one core network element (i.e., the lowest load capacity of each core network element among at least one core network element) as the overall load capacity of at least one core network element, which can reduce the communication overhead of the first access network device. The fourth information can also indicate the load capacity of each core network element among at least one core network element, that is, each core network element among at least one core network element corresponds to a load capacity, which is beneficial for the terminal device to make access decisions based on the third information.

[0184] Optionally, the system message also includes fifth information, which indicates the quality of service (QoS) of at least one core network element. This QoS may include at least one of the following: a QoS parameter or a latency parameter. The QoS parameter can be the latency of user data, the maximum guaranteed rate, the peak rate, etc., and the latency parameter can be the estimated latency (or delay of) the execution of control plane procedures, etc. The specific settings can be configured according to actual conditions and are not limited. After receiving the fifth information, the terminal device can determine whether to connect to the first access network device based on the QoS of the at least one core network element. If the QoS is good, it will connect to the first access network device; if the QoS is poor, it will not connect. This ensures the network service quality of the terminal device, thereby providing better communication services to the users corresponding to the terminal device.

[0185] Optionally, the system message also includes sixth information, which indicates other core network elements accessible to the terminal in the first area besides the aforementioned at least one core network element, and that the first access network device can provide services to the terminal in the first area. Other core network elements can be understood as network elements in a core network other than the core network containing the aforementioned at least one core network element, such as one or more specific network elements. The sixth information can also indicate core networks accessible to the terminal other than the core network containing the aforementioned at least one core network element, such as the core networks of one or more operators. The first area can be referred to the aforementioned related descriptions, which will not be repeated here. After receiving the sixth information, the terminal device can, when there is a need to switch networks, determine the core network for network switching and the corresponding access network device based on the sixth information. This ensures that the terminal device can successfully switch networks.

[0186] It is understandable that the first access network device can obtain information about other core networks or core network elements that the terminal can access through the operation and maintenance system during network construction.

[0187] Optionally, the system message also includes a seventh piece of information, which is used to indicate at least one core network element associated with the second access network device. The at least one core network element associated with the second access network device is used to provide core network services to the terminals served by the second access network device. The second access network device is adjacent to the first access network device.

[0188] The second access network device is a non-terrestrial device. For example, it can be a base station mounted on a satellite, or a base station mounted on a high-altitude platform; there are no restrictions. The second access network device can provide services to terminals in a second area, which is the area where the second access network device can provide network services, or in other words, the beam coverage area of ​​the second access network device. Providing services to terminals can be understood as the cells supported by the second access network device serving the terminals; that is, the cell is the serving cell for the terminals. In other words, the second access network device in this embodiment can also be understood as the cell served by the second access network device. The terminals served by the second access network device can be understood as terminals in the second area, or terminals served by cells supported by the first access network device.

[0189] The adjacency of a second access network device to a first access network device can be understood as the service range of the second access network device being adjacent to that of the first access network device, i.e., the second region being adjacent to or partially overlapping with the first region. The adjacency of a second access network device to a first access network device can also be understood as the cells supported by the second access network device being adjacent to those supported by the first access network device.

[0190] Furthermore, the second access network device and the first access network device can be associated with the same core network or different core networks. For example, the second access network device and the first access network device can be associated with different core network elements within the same core network. Another example is... Figure 7 As shown, the second access network device is associated with core network 2, and the first access network device is associated with core network 1. In this case, the core network elements associated with the second access network device and the first access network device are different.

[0191] After receiving the seventh piece of information, the terminal device can determine whether to access the first access network device based on the first and seventh pieces of information. In other words, the terminal device can determine which access network device's associated at least one network element better meets its needs based on at least one network element associated with the first access network device and at least one network element associated with the second access network device, thereby making an access decision.

[0192] Furthermore, the system message may also carry information related to at least one core network element associated with the second access network device. For example, the system message may further include at least one of the following: eighth information, ninth information, or tenth information, wherein the eighth information is used to indicate the type of network service provided by the at least one core network element associated with the second access network device; the ninth information is used to indicate the load capacity of the at least one core network element associated with the second access network device; and the tenth information is used to indicate the quality of service of the at least one core network element associated with the second access network device. It is understood that the information related to the at least one core network element associated with the second access network device is similar to the information related to the at least one core network element associated with the first access network device, and can be understood with reference to the foregoing content; it will not be repeated here.

[0193] Furthermore, the network functions provided by at least one core network element associated with the first access network device are different from those provided by at least one core network element associated with the second access network device; and / or, the service capabilities of at least one core network element associated with the first access network device are different from those of at least one core network element associated with the second access network device.

[0194] The aforementioned differences in network functions can be understood as at least one core network element associated with the first access network device being different from at least one core network element associated with the second access network device. This difference can be understood as being completely different or partially different. For example, if at least one core network element associated with the first access network device is AMF and UPF, and at least one core network element associated with the second access network device is PCF and SMF, then at least one core network element associated with the first access network device is completely different from at least one core network element associated with the second access network device. As another example, if at least one core network element associated with the first access network device is AMF, SMF, UPF, and PCF, and at least one core network element associated with the second access network device is AMF, SMF, and PCF, then at least one core network element associated with the first access network device is partially different from at least one core network element associated with the second access network device.

[0195] Alternatively, the aforementioned differences in network functions can be understood as the fact that at least one core network element associated with the first access network device has a different network slice than the network slice associated with the second access network device.

[0196] The aforementioned service capabilities may include at least one of the following: network service type, service quality, or load capacity, as detailed in the foregoing introduction, and will not be repeated here. For example, the network services provided by at least one core network element associated with the first access network device are session establishment, session update, user registration, and user roaming, while the network services provided by at least one core network element associated with the second access network device are session establishment, session update, user registration, and user location.

[0197] It can also be understood that the first access network device can send system messages when there are multiple accessible access network devices at the terminal. Furthermore, carrying information about at least one core network element associated with the second access network device (such as the aforementioned seventh, eighth, ninth, and tenth information) in the system message can be implemented independently, without combining it with the aforementioned carrying of the first information in the system message. In this case, after receiving the seventh information, the terminal device can determine whether to access the second access network device based on the seventh information.

[0198] It can also be understood that the above content introduces the various information that can be carried in system messages. Below are some examples of possible system messages. For example, a system message may include a first message and a third message. Alternatively, a system message may include a first message, a third message, and a fourth message. Or, a system message may include a first message, a third message, and a fifth message. The information included in a system message can be flexibly set according to the actual situation and is not limited.

[0199] For S602:

[0200] After receiving the system message, the first access network device can broadcast the system message. The terminal device can receive the system message during cell search.

[0201] Alternatively, in the scenario of sending system messages on demand (SIB), the terminal device can first request the first access network device to send a system message. After receiving the request from the terminal device, the first access network device sends the system message to the terminal device, and the terminal device receives the system message accordingly.

[0202] For S603:

[0203] After receiving a system message, the terminal device can determine the core network capabilities of the first access network device based on the system message, and then determine whether to access the first access network device based on those core network capabilities. Alternatively, if the system message carries seventh information, the terminal device can determine the core network capabilities of the first access network device and the second access network device based on the system message, and then determine whether to access the first access network device based on those core network capabilities.

[0204] For example, the system message carries first information and second information. The first information indicates that at least one core network element associated with the first access network device is AMF, SMF, UPF, or AUSF. The second information indicates that the service time of at least one core network element is 10:00-19:00, and the terminal device needs to perform authentication service from 15:00-15:30. After receiving the system message, the terminal device can determine that the core network associated with the first access network device can meet its needs. At this time, the terminal device determines the first access network device.

[0205] For example, the system message carries first information, fifth information, seventh information, and ninth information. The first information indicates that at least one core network element associated with the first access network device is AMF, SMF, UPF, or PCF. The fifth information indicates that the control plane delay is 5 seconds (s). The seventh information indicates that at least one core network element associated with the second access network device is AMF, SMF, UPF, or PCF. The ninth information indicates that the control plane delay is 6 seconds. After receiving the system information, the terminal device can determine the core network capabilities of the first access network device and the second access network device, and determine that the core network capabilities of the first access network device are superior to those of the second access network device. At this time, the terminal device determines the first access network device.

[0206] In summary, in this embodiment, the first access network device carries information about at least one network element associated with it in the system message. After receiving the system message, the terminal device can make an access decision based on it. Thus, even when the core network topology associated with the first access network device changes dynamically, the terminal can make an access decision based on the network element information in the core network currently associated with the first access network device, thereby ensuring stable communication services for the user corresponding to the terminal device.

[0207] For example, Figure 8 Flowchart of the communication method provided in the embodiments of this application Figure 2 This method can be applied to communication between a terminal device and an access network device in the aforementioned communication system. The access network device can be a non-terrestrial access network device. The following explanation uses this access network device as the first access network device as an example.

[0208] like Figure 8 As shown, the flow of this communication method is as follows:

[0209] S801, the terminal device sends first information to the first access network device. Correspondingly, the first access network device receives the first information from the terminal device.

[0210] The first access network device is a non-terrestrial device. For details, please refer to the relevant introduction in the aforementioned "S601". It will not be repeated here.

[0211] The first information is used to indicate the core network service requirements of the terminal device. The first information can be carried in any of the following messages: message (Msg)3 or MsgA. Msg3 and MsgA can be used to request random access; for details, please refer to the relevant descriptions in the existing technology, which will not be elaborated here. It is understood that the first information can also be carried in other messages, such as newly defined messages, and can be flexibly set according to the actual situation without restriction.

[0212] Core network service requirements can be understood as the needs of terminal devices for services provided by the core network; or, they can be understood as the capabilities that the core network must possess to provide services to terminal devices. Core network service requirements can be the types of network services needed by the terminal device, such as user registration and authentication; they can also be the performance requirements of the terminal device for one or more core network elements, such as load requirements for one or more core network elements; or they can be the terminal device's requirements for the quality of service of the core network, such as QoS parameter requirements and latency requirements. Specific requirements can be flexibly set according to actual conditions without restriction.

[0213] Optionally, the core network service requirements include a first capability level. In other words, the first information is used to indicate the first capability level. The first capability level belongs to multiple capability levels; that is, the first capability level can be one of these multiple capability levels. Each of these multiple capability levels is associated with a different set of network services, network service performance, or network service quality. The set of network services may include at least one of the following: user registration, user authentication, user roaming, or user location. Each network service can refer to existing technologies, which will not be elaborated here. Network service performance may include load performance, etc. Network service quality may include QoS parameters, latency, etc. It is understood that these multiple capability levels may be preset in the terminal device, configured by the network side for the terminal device, or predefined by the protocol. The terminal device can determine the first capability level that meets the requirements from the multiple capability levels based on its service needs provided by the core network.

[0214] For example, the protocol defines the classification of core network service capabilities. Specifically, the first capability level is able to support user initial registration and mobility registration; the second capability level is able to support user initial registration, mobility registration, session establishment and session update; and the third capability level is able to support user initial registration, mobility registration, session establishment, session update, roaming and access traffic steering / switching / splitting (ATSSS). If a terminal device needs the core network to provide user initial registration and mobility registration services, the terminal device can determine from the first capability level to the third capability level that its needs correspond to the first capability level, and then send the first capability level to the first access network device.

[0215] For example, the protocol defines the classification of core network service capabilities. Specifically, the first capability level has a control plane process processing latency of 5s, the second capability level has a control plane process processing latency of 8s, and the third capability level has a control plane process processing latency of 10s. If the terminal device requires a core network control plane process processing latency of 9s, then the terminal device can determine the second capability level from the first to the third capability levels and send the second capability level to the first access network device.

[0216] It is understood that the above content is only an example, and the ability level can be set according to the actual situation without any restrictions.

[0217] Optionally, the core network service requirement includes service time. In other words, the first information is used to indicate the service time. The service time indicates the time during which the terminal device requires network service. The service time can be the time period or duration during which the terminal device requires network service, for example: a service time of 13:00-15:00, meaning the terminal device requires core network service from 13:00 to 15:00; or a service time of 30 minutes, meaning the terminal device requires core network service for 30 minutes after the first access network device receives the first information.

[0218] In this embodiment of the application, after receiving the first information from the terminal device, the first access network device can determine whether to accept the random access of the terminal device based on the core network service requirements of the terminal device. For example, if the core network corresponding to the first access network device does not meet the core network service requirements, the random access of the terminal device will not be accepted (referred to as case 8.1, described in S802 below). Or, if the core network corresponding to the first access network device meets the core network service requirements, the random access of the terminal device will be accepted (referred to as case 8.2, described in S803 below).

[0219] S802, if the core network corresponding to the first access network device does not meet the core network service requirements, the first access network device sends second information to the terminal device. Correspondingly, the terminal device receives the second information from the first access network device.

[0220] The core network corresponding to the first access network device can provide core network services to the terminals served by the first access network device. The fact that the core network corresponding to the first access network device does not meet the core network service requirements can be understood as the core network corresponding to the first access network device not meeting the requirements of the terminal device for the core network providing services to it.

[0221] In one possible implementation, the second information is used to indicate that the core network corresponding to the first access network device does not meet the core network service requirements of the terminal device, or the second information is used to indicate that the first access network device will not accept the random access request from the terminal device. In this case, after receiving the second information, the terminal device can determine not to access the first access network device based on the second information. Furthermore, the terminal device can initiate random access to other access network devices besides the first access network device.

[0222] In another possible implementation, the second information is used to instruct the terminal device to initiate random access to other access network devices besides the first access network device. In this case, after receiving the second information, the terminal device can initiate random access to other access network devices besides the first access network device based on the second information.

[0223] Furthermore, the second information is also used to indicate one or more candidate access network devices, whose associated core network meets the core network service requirements. That is, the first access network device can indicate to the terminal device the access network device it should subsequently access. This avoids the terminal device failing to access the access network device again, thus affecting the user's communication service. It can be understood that after receiving the second information, if the second information indicates a candidate access network device, the terminal device can initiate random access to that candidate access network device; if the second information indicates multiple candidate access network devices, the terminal device can randomly select one of these candidate access network devices for random access. In addition, the first access network device can indicate the corresponding access network device to the terminal device by indicating the frequency point, identifier, and other information of the candidate access network devices.

[0224] Furthermore, the second information is also used to indicate the network services that the core network associated with one or more candidate access network devices can provide. These network services may include network service type, service quality, service performance, etc., as detailed in the foregoing descriptions, and will not be repeated here. Thus, when the second information indicates multiple candidate access network devices, the terminal device can select the better candidate access network device for random access based on the network services corresponding to each candidate access network device, thereby enabling the user corresponding to the terminal device to receive better communication services.

[0225] Furthermore, the second information can be carried in redirection information. Of course, the second information can also be carried in other existing messages, as well as newly defined messages. The specific settings can be flexibly configured according to the actual situation without any restrictions.

[0226] In summary, in this embodiment, during random access, the terminal device can send a core network service request to the first access network device. Upon receiving the core network service request, the first access network device can, based on the request, instruct the terminal device to access another access network device besides the first access network device if it determines that the core network corresponding to the first access network device does not meet the core network service requirement. This ensures stable communication for the terminal device, enabling the user corresponding to the terminal device to obtain stable communication. Furthermore, it avoids the terminal device failing to access the network again.

[0227] Optionally, in conjunction with the above embodiments, the communication method may further include: when the core network associated with the first access network device meets the core network service requirements, the first access network device sends third information to the terminal device, and correspondingly, the terminal device receives the third information from the first access network device, the third information being used to instruct the first access network device to accept random access from the terminal device. Figure 8 (S803). That is, at this time, the terminal device can continue to access the first access network device and complete random access.

[0228] It is understood that the terminal device can also send core network service requests to a core network element during the interaction process with the core network element (such as the registration process, session establishment process, etc.), and when the core network element determines that its core network does not meet the core network service request, it instructs the terminal device to access another core network besides that core network. For example, the terminal device can carry the core network service request in the registration request message sent to the AMF. When the AMF receives the registration request and determines that its core network #1 does not meet the core network service request, it instructs the terminal device to access another core network besides that core network #1. In addition, the specific implementation principles of the various operations performed by the core network element based on the core network service request and the specific implementation principles of the various operations performed by the first access network device based on the core network service request can be understood with reference to the foregoing content, and will not be repeated here.

[0229] For example, Figure 9 Flowchart of the communication method provided in the embodiments of this application Figure 3 This method can be applied to communication between a terminal device and an access network device in the aforementioned communication system. The following explanation uses an example where the access network device includes a first access network device and at least one second access network device.

[0230] like Figure 9 As shown, the flow of this communication method is as follows:

[0231] S901, the terminal device sends first information to the first access network device. Correspondingly, the first access network device receives the first information from the terminal device.

[0232] The first access network device provides network services to the terminal device, meaning that a connection has been established between the terminal device and the first access network device.

[0233] The first piece of information is used to indicate the core network service requirements of the terminal device.

[0234] In one possible implementation, core network service requirements may include a first capability level, which belongs to multiple capability levels, each of which is associated with a different set of network services. This set of network services may include at least one of the following: user registration, user authentication, user roaming, or user location.

[0235] In another possible implementation, core network service requirements may include service time, which indicates when a terminal device needs network services.

[0236] It is understandable that the core network service requirements can be referred to in the relevant introduction in the aforementioned "S801", and will not be repeated here.

[0237] In the embodiments of this application, the terminal device may send first information to the first access network device during the random access procedure, handover procedure, or other processes. For example, the terminal device may send the first information to the first access network device via Msg3 or MsgA during the random access procedure. As another example, the terminal device may send the first information to the first access network device via a measurement report or a newly defined message during cell handover. It is understood that the above are examples, and the specific method by which the terminal device sends the first information to the first access network device can be flexibly set according to actual circumstances and is not limited.

[0238] S902, the first access network device sends second information to M second access network devices based on the first information. Correspondingly, the M second access network devices receive the second information from the first access network device.

[0239] The second piece of information is used to indicate the core network service requirements of the terminal device. This second piece of information can be carried within a handover request message. Of course, it can also be carried within other existing messages, as well as newly defined messages; the specific settings can be flexibly configured according to the actual situation without restriction.

[0240] M second access network devices can be one or more second access network devices, where M is an integer greater than 0.

[0241] After receiving the second information, each of the M second access network devices can determine whether the core network associated with the second access network device meets the core network service requirements of the terminal device, and send the determined result (the third information below) to the first access network device.

[0242] S903, each of the M second access network devices sends third information to the first access network device. Correspondingly, the first access network device receives the third information from each of the M second access network devices.

[0243] The third information is used to indicate whether the core network associated with the second access network device meets the core network service requirements. It can be understood that the content indicated by the third information sent by each of the M second access network devices can be the same or different; that is, all M core networks associated with the M second access network devices can meet the core network service requirements, or none of the M core networks associated with the M second access network devices can meet the core network service requirements, or the M core networks associated with the M second access network devices can partially meet the core network service requirements.

[0244] For example, M is 3, and the M second access network devices are second access network device #1, second access network device #2, and second access network device #3. Second access network device #1 determines that its associated core network meets the core network service requirements, second access network device #2 determines that its associated core network does not meet the core network service requirements, and second access network device #3 determines that its associated core network meets the core network service requirements. Then, second access network device #1 sends a third message to the first access network device indicating that the core network associated with second access network device #1 meets the core network service requirements, second access network device #2 sends a third message to the first access network device indicating that the core network associated with second access network device #2 does not meet the core network service requirements, and second access network device #3 sends a third message to the first access network device indicating that the core network associated with second access network device #3 meets the core network service requirements.

[0245] In addition, the third information may include network services that the core network associated with the second access network device can provide, and these network services may refer to the aforementioned Figure 8 The relevant descriptions in the illustrated embodiments are provided. Furthermore, the network services can be in the form of a list.

[0246] After receiving third information from each of the M second access network devices, if N of the M second access network devices have core networks associated with them that meet the core network service requirements, the first access network device can make a handover decision based on these N second access network devices, where N is an integer greater than 0 and less than or equal to M. This means that the core networks associated with each of the N second access network devices all meet the core network service requirements of the terminal device.

[0247] For example, the first access network device may select one of the N second access network devices (denoted as the third access network device) and instruct the terminal device to switch to the third access network device (denoted as case 9.1, described in S904 below); or, the first access network device may send the N second access network devices to the terminal device, and the terminal device may decide which of the N second access network devices to access (denoted as case 9.2, described in S905 below).

[0248] S904, the first access network device sends fourth information to the terminal device based on the third information. Correspondingly, the terminal device receives the fourth information from the first access network device.

[0249] The fourth piece of information is used to instruct the terminal device to switch the network to a third access network device, which belongs to N second access network devices out of M second access network devices. The core network associated with each of these N second access network devices meets the core network service requirements. In other words, the first access network device instructs the terminal device on the access network device to perform cell handover.

[0250] After receiving the fourth information, the terminal device can switch networks to the third access network device based on the fourth information.

[0251] S905, the first access network device sends fifth information to the terminal device based on the third information. Correspondingly, the terminal device receives the fifth information from the first access network device.

[0252] The fifth piece of information instructs the terminal device to switch the network to any access network device in the access network device set. This access network device set includes N second access network devices out of M second access network devices. The core network associated with each of these N second access network devices meets the core network service requirements; that is, at least one second access network device in the access network device set can be used by the terminal device for network switching. In other words, the first access network device sends the access network devices that meet the core network service requirements to the terminal device, and the terminal device determines which second access network device to connect to.

[0253] After receiving the fifth piece of information, the terminal device can select a second access network device from the set of access network devices for network switching based on the fifth piece of information.

[0254] In summary, in this embodiment, the first access network device can interact with M second access network devices based on the core network service requirements sent by the terminal device to determine N second access network devices that meet the core network service requirements of the terminal device. Based on these N second access network devices, the terminal device can switch to the second access network device that meets the core network requirements during network switching. In this way, after network switching, the user corresponding to the terminal device can receive stable communication services.

[0255] It is understood that in this embodiment of the application, if there is no second access network device among the M second access network devices that meets the core network service requirements, the first access network device may not send information to the terminal device, that is, the cell handover is stopped at this time.

[0256] It's understandable. Figure 9The illustrated embodiment can also be applied to scenarios involving conditional handover. Specifically, during the handover preparation phase, such as upon receiving a measurement report from a terminal device, the first access network device can send second information to M second access network devices and, based on the third information fed back by the M second access network devices, determine a third access network device or a set of access network devices. The specific implementation principle of this conditional handover can be found in existing technologies and will not be elaborated here.

[0257] In addition, the terminal device can also send core network service requests to the core network element during the interaction with the core network element, as detailed above. Figure 8 The relevant descriptions in the illustrated embodiments will not be repeated here. During the cell handover process of the terminal device, the handover decision can be made by the core network element (such as AMF). The specific implementation principle of the handover decision made by the core network element is similar to that of the handover decision made by the first access network device described above, and can be understood by reference, so it will not be repeated here.

[0258] Understandable. Figure 6 The illustrated embodiments Figure 8 The illustrated embodiments, and Figure 9 The identical parts shown can be understood by mutual reference and will not be repeated here. Furthermore, in the various embodiments of this application, unless otherwise specified or logically conflicting, the terminology and / or descriptions between different embodiments are consistent and can be mutually referenced. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships. In addition, in the various embodiments of this application, the names of each message, each piece of information, and each parameter are merely illustrative representations, and each message, each piece of information, and each parameter can be replaced with any possible representation without limitation.

[0259] The above combination Figures 6-9 The communication method provided in the embodiments of this application is described in detail below. Figures 10-11 This document describes in detail the communication apparatus used to perform the communication method provided in the embodiments of this application.

[0260] Figure 10 This is a schematic diagram of the structure of the communication device provided in the embodiments of this application. Figure 1 For example, such as Figure 10 As shown, the communication device 1000 includes a processing module 1001 and a transceiver module 1002. For ease of explanation, Figure 10 Only the main components of the communication device are shown.

[0261] In some embodiments, the communication device 1000 may be adapted to the above-described communication system to perform the above-described... Figure 6 The function of the first access network device in the method shown.

[0262] Processing module 1001 is used to determine a system message, which includes first information used to indicate at least one core network element, which is used to provide core network services to the terminal served by the first access network device, and the first access network device is a non-terrestrial device; transceiver module 1002 is used to send a system message, which is used to determine whether to access the first access network device.

[0263] In one possible design, the system message further includes second information, which indicates the service time of at least one core network element, and the service time indicates the time during which at least one core network element provides network services to the terminal.

[0264] Optionally, the processing module 1001 is further configured to determine the service time based on the topology information of the core network where at least one core network element is located and / or the topology information of the access network where the first access network device is located.

[0265] Optionally, the service time is at least one of the following: duration, start time, end time, or time information, wherein the duration is used to indicate the time period during which at least one core network element provides services, the start time is used to indicate the start time of the service provided by at least one core network element, the end time is used to indicate the end time of the service provided by at least one core network element, and the time information is used to indicate time-related information of the core network topology where at least one core network element is located.

[0266] Optionally, the second information is also used to indicate a first area, wherein the first access network device is capable of providing services to terminals in the first area.

[0267] In one possible design, the system message also includes third information, which is used to indicate the type of network service provided by at least one core network element.

[0268] Optionally, the network service type includes at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter.

[0269] In one possible design, the system message also includes a fourth message, which indicates the load capacity of at least one core network element.

[0270] In one possible design, the system message also includes a fifth message, which is used to indicate the quality of service of at least one core network element.

[0271] Optionally, the quality of service includes at least one of the following: QoS parameters or latency parameters.

[0272] In one possible design, the system message also includes a sixth message, which indicates the core network elements that the terminal in the first area can access, in addition to at least one core network element, and the first access network device can provide services to the terminal in the first area.

[0273] In one possible design, the system message also includes a seventh message, which is used to indicate at least one core network element associated with the second access network device. The at least one core network element associated with the second access network device is used to provide core network services to the terminals served by the second access network device. The second access network device is adjacent to the first access network device.

[0274] Optionally, at least one core network element associated with the first access network device is different from at least one core network element associated with the second access network device; or, the service capabilities of at least one core network element associated with the first access network device are different from the service capabilities of at least one core network element associated with the second access network device, and the service capabilities include at least one of the following: network service type, service quality, or load capacity.

[0275] Optionally, the system message may also include an eighth message, which indicates the type of network service provided by at least one core network element associated with the second access network device.

[0276] Furthermore, the network service type is at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter.

[0277] Optionally, the system message may also include a ninth message, which indicates the load capacity of at least one core network element associated with the second access network device.

[0278] Optionally, the system message may also include tenth information, which is used to indicate the quality of service of at least one core network element associated with the second access network device.

[0279] Furthermore, the quality of service includes at least one of the following: Quality of Service (QoS) parameters or latency parameters.

[0280] Optionally, the transceiver module 1002 may include a transmitting module ( Figure 10 (not shown in the image) and receiving module ( Figure 10 (Not shown in the diagram). The transmitting module implements the transmitting function of the communication device 1000, and the receiving module implements the receiving function of the communication device 1000.

[0281] Optionally, the communication device 1000 may also include a storage module. Figure 10(Not shown in the image), the storage module stores programs or instructions. When the processing module 1001 executes the program or instructions, the communication device 1000 can perform the above-described method. Figure 5 The function of the first access network device in the method shown.

[0282] It is understood that the communication device 1000 may be a network device, or a chip (system) or other component or assembly that can be set in the network device, or a device that includes the network device. This application does not limit this.

[0283] In addition, the technical effects of the communication device 1000 can be referenced. Figure 6 The technical effects of the communication method shown will not be elaborated here.

[0284] In other embodiments, the communication device 1000 may be adapted to the above-described communication system to perform the above-described... Figure 6 The method shown describes the function of the terminal device.

[0285] The transceiver module 1002 is used to receive system messages from a first access network device, which is a non-terrestrial device. The system messages include first information, which is used to indicate at least one core network element. The at least one core network element is used to provide core network services to the terminals served by the first access network device. The processing module 1001 is used to determine whether to access the first access network device based on the system messages.

[0286] In one possible design, the system message further includes second information, which indicates the service time of at least one core network element, and the service time indicates the time during which at least one core network element provides network services to the terminal.

[0287] Optionally, the service time is at least one of the following: duration, start time, end time, or time information, wherein the duration is used to indicate the time period during which at least one core network element provides services, the start time is used to indicate the start time of the service provided by at least one core network element, the end time is used to indicate the end time of the service provided by at least one core network element, and the time information is used to indicate time-related information of the core network topology where at least one core network element is located.

[0288] Optionally, the second information is also used to indicate a first area, wherein the first access network device is capable of providing services to terminals in the first area.

[0289] Furthermore, the processing module 1001 is also used to execute a registration process or a pre-registration process based on the second information.

[0290] In one possible design, the system message also includes third information, which is used to indicate the type of network service provided by at least one core network element.

[0291] Optionally, the network service type includes at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter.

[0292] In one possible design, the system message also includes a fourth message, which indicates the load capacity of at least one core network element.

[0293] In one possible design, the system message also includes a fifth message, which is used to indicate the quality of service of at least one core network element.

[0294] Optionally, the quality of service includes at least one of the following: QoS parameters or latency parameters.

[0295] In one possible design, the system message also includes a sixth message, which indicates the core network elements that the terminal in the first area can access, in addition to at least one core network element, and the first access network device can provide services to the terminal in the first area.

[0296] In one possible design, the system message also includes a seventh message, which is used to indicate at least one core network element associated with the second access network device. The at least one core network element associated with the second access network device is used to provide core network services to the terminals served by the second access network device. The second access network device is adjacent to the first access network device.

[0297] Optionally, at least one core network element associated with the first access network device is different from at least one core network element associated with the second access network device; or, the service capabilities of at least one core network element associated with the first access network device are different from the service capabilities of at least one core network element associated with the second access network device, and the service capabilities include at least one of the following: network service type, service quality, or load capacity.

[0298] Optionally, the system message may also include an eighth message, which indicates the type of network service provided by at least one core network element associated with the second access network device.

[0299] Furthermore, the network service type is at least one of the following: user registration, user authentication, user roaming, user location, slice identifier, or slice parameter.

[0300] Optionally, the system message may also include a ninth message, which indicates the load capacity of at least one core network element associated with the second access network device.

[0301] Optionally, the system message may also include tenth information, which is used to indicate the quality of service of at least one core network element associated with the second access network device.

[0302] Furthermore, the quality of service includes at least one of the following: Quality of Service (QoS) parameters or latency parameters.

[0303] Optionally, the transceiver module 1002 may include a transmitting module ( Figure 10 (not shown in the image) and receiving module ( Figure 10 (Not shown in the diagram). The transmitting module implements the transmitting function of the communication device 1000, and the receiving module implements the receiving function of the communication device 1000.

[0304] Optionally, the communication device 1000 may also include a storage module. Figure 10 (Not shown in the image), the storage module stores programs or instructions. When the processing module 1001 executes the program or instructions, the communication device 1000 can perform the above-described method. Figure 6 The method shown describes the function of the terminal device.

[0305] It is understood that the communication device 1000 may be a terminal device, a chip (system) or other component or assembly that can be set in the terminal device, or a device that includes the terminal device. This application does not limit this.

[0306] In addition, the technical effects of the communication device 1000 can be referenced. Figure 6 The technical effects of the communication method shown will not be elaborated here.

[0307] In other embodiments, the transceiver module 1002 is used to perform the above-described... Figures 8-9 The sending and receiving functions of the method shown are executed by the processing module 1001. Figures 8-9 The method shown includes functions other than sending and receiving.

[0308] Optionally, the transceiver module 1002 may include a transmitting module ( Figure 10 (not shown in the image) and receiving module ( Figure 10 (Not shown in the diagram). The transmitting module implements the transmitting function of the communication device 1000, and the receiving module implements the receiving function of the communication device 1000.

[0309] Optionally, the communication device 1000 may also include a storage module. Figure 10 (Not shown in the image), the storage module stores programs or instructions. When the processing module 1002 executes the program or instructions, the communication device 1000 can perform the above-described method. Figures 8-9 The method shown describes the functions of the access network device (first access network device, second access network device) and the terminal device.

[0310] It is understood that the communication device 1000 may be a network device or a terminal device, or a chip (system) or other component or assembly that can be disposed in a network device or a terminal device, or a device that includes a network device or a terminal device. This application does not limit this.

[0311] Figure 11 Schematic diagram of the communication device provided in the embodiments of this application Figure 2 For example, the communication device may be a terminal device or a network device, or it may be a chip (system) or other component or assembly that can be disposed in the terminal device or the network device. Figure 11 As shown, the communication device 1100 may include a processor 1101. Optionally, the communication device 1100 may also include a memory 1102 and / or a transceiver 1103. The processor 1101 is coupled to the memory 1102 and the transceiver 1103, for example, they can be connected via a communication bus.

[0312] The following is combined Figure 11 A detailed description of each component of the communication device 1100 is provided below:

[0313] The processor 1101 is the control center of the communication device 1100. It can be a single processor or a collective term for multiple processing elements. For example, the processor 1101 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement the embodiments of this application, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0314] Optionally, the processor 1101 can perform various functions of the communication device 1100, such as performing the communication method described above, by running or executing software programs stored in the memory 1102 and calling data stored in the memory 1102.

[0315] In a specific implementation, as one example, the processor 1101 may include one or more CPUs, for example... Figure 11 CPU0 and CPU1 are shown in the diagram.

[0316] In a specific implementation, as one example, the communication device 1100 may also include multiple processors, for example... Figure 11The processors 1101 and 1104 shown are illustrated. Each of these processors can be a single-core processor or a multi-core processor. Here, "processor" can refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0317] The memory 1102 is used to store the software program that executes the solution of this application, and is controlled by the processor 1101 to execute it. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0318] Optionally, the memory 1102 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 1102 may be integrated with the processor 1101 or may exist independently, and may be connected via the interface circuit of the communication device 1100. Figure 11 (Not shown in the image) is coupled to processor 1101, and this embodiment of the application does not specifically limit this.

[0319] Transceiver 1103 is used for communication with other communication devices. For example, if communication device 1100 is a terminal, transceiver 1103 can be used to communicate with a network device or with another terminal device. As another example, if communication device 1100 is a network device, transceiver 1103 can be used to communicate with a terminal or with another network device.

[0320] Optionally, transceiver 1103 may include a receiver and a transmitter. Figure 11 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the transmitting function.

[0321] Optionally, the transceiver 1103 can be integrated with the processor 1101, or it can exist independently and be connected via the interface circuit of the communication device 1100. Figure 11 (Not shown in the image) is coupled to processor 1101, and this embodiment of the application does not specifically limit this.

[0322] Understandable Figure 11 The structure of the communication device 1100 shown does not constitute a limitation on the communication device. Actual communication devices may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0323] Furthermore, the technical effects of the communication device 1100 can be referred to the technical effects of the method described in the above method embodiments, and will not be repeated here.

[0324] It should be understood that the processor in the embodiments of this application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0325] It should also be understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0326] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0327] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0328] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0329] It should be understood that, in the various embodiments of this application, the order of the above-mentioned processes does not imply 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 this application.

[0330] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0331] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0332] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0333] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0334] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0335] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0336] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, The method includes: A first access network device determines a system message. The first access network device is a non-terrestrial device. The system message includes first information, which is used to indicate at least one core network element. The at least one core network element is used to provide core network services to the terminals served by the first access network device. The first access network device sends the system message, which is used to determine whether to access the first access network device.

2. A communication method, characterized in that, The method includes: The terminal device receives a system message from a first access network device, which is a non-terrestrial device. The system message includes first information, which is used to indicate at least one core network element. The at least one core network element is used to provide core network services to the terminal served by the first access network device. The terminal device determines whether to connect to the first access network device based on the system message.

3. The method according to claim 1 or 2, characterized in that, The system message also includes second information, which is used to indicate the service time of the at least one core network element, and the service time is used to indicate the time during which the at least one core network element provides network services to the terminal.

4. The method according to claim 3, characterized in that, The service time is at least one of the following: duration, start time, end time, or time information, wherein the duration is used to indicate the time period during which the at least one core network element provides services, the start time is used to indicate the start time of the service provided by the at least one core network element, the end time is used to indicate the end time of the service provided by the at least one core network element, and the time information is used to indicate time-related information of the core network topology where the at least one core network element is located.

5. The method according to claim 3 or 4, characterized in that, The second information is also used to indicate a first area, wherein the first access network device is capable of providing services to terminals in the first area.

6. The method according to any one of claims 1-5, characterized in that, The system message also includes third information, which is used to indicate the type of network service provided by the at least one core network element.

7. The method according to any one of claims 1-6, characterized in that, The system message also includes a fourth piece of information, which is used to indicate the load capacity of the at least one core network element.

8. The method according to any one of claims 1-7, characterized in that, The system message also includes a fifth piece of information, which is used to indicate the quality of service of the at least one core network element.

9. The method according to any one of claims 1-8, characterized in that, The system message also includes a sixth message, which indicates which core network elements, other than the at least one core network element, can be accessed by terminals in the first area, and the first access network device can provide services to terminals in the first area.

10. The method according to any one of claims 1-9, characterized in that, The system message also includes a seventh piece of information, which is used to indicate at least one core network element associated with the second access network device. The at least one core network element associated with the second access network device is used to provide core network services to the terminals served by the second access network device. The second access network device is adjacent to the first access network device.

11. The method according to claim 10, characterized in that, At least one core network element associated with the first access network device is different from at least one core network element associated with the second access network device; or, The service capabilities of at least one core network element associated with the first access network device are different from the service capabilities of at least one core network element associated with the second access network device. The service capabilities include at least one of the following: network service type, service quality, or load capacity.

12. A communication device, characterized in that, The device includes: The processing module is used to determine a system message, the system message including first information, the first information being used to indicate at least one core network element, the at least one core network element being used to provide core network services to the terminal served by the first access network device, the first access network device being a non-terrestrial device; The transceiver module is used to send the system message, which is used to determine whether to access the first access network device.

13. A communication device, characterized in that, The device includes: The transceiver module is used to receive system messages from a first access network device, which is a non-terrestrial device. The system messages include first information, which is used to indicate at least one core network element. The at least one core network element is used to provide core network services to the terminals served by the first access network device. The processing module is used to determine whether to access the first access network device based on the system message.

14. The apparatus according to claim 12 or 13, characterized in that, The system message also includes second information, which is used to indicate the service time of the at least one core network element, and the service time is used to indicate the time during which the at least one core network element provides network services to the terminal.

15. The apparatus according to claim 14, characterized in that, The service time is at least one of the following: duration, start time, end time, or time information, wherein the duration is used to indicate the time period during which the at least one core network element provides services, the start time is used to indicate the start time of the service provided by the at least one core network element, the end time is used to indicate the end time of the service provided by the at least one core network element, and the time information is used to indicate time-related information of the core network topology where the at least one core network element is located.

16. The apparatus according to claim 14 or 15, characterized in that, The second information is also used to indicate a first area, wherein the first access network device is capable of providing services to terminals in the first area.

17. The apparatus according to any one of claims 12-16, characterized in that, The system message also includes third information, which is used to indicate the type of network service provided by the at least one core network element.

18. The apparatus according to any one of claims 12-17, characterized in that, The system message also includes a fourth piece of information, which is used to indicate the load capacity of the at least one core network element.

19. The apparatus according to any one of claims 12-18, characterized in that, The system message also includes a fifth piece of information, which is used to indicate the quality of service of the at least one core network element.

20. The apparatus according to any one of claims 12-19, characterized in that, The system message also includes a sixth piece of information, which indicates which network elements, other than the at least one core network element, can be accessed by terminals in the first area, and the first access network device can provide services to terminals in the first area.

21. The apparatus according to any one of claims 12-20, characterized in that, The system message includes a seventh piece of information, which is also used to indicate at least one core network element associated with the second access network device. The at least one core network element associated with the second access network device is used to provide network services to terminals accessing the second access network device. The second access network device is adjacent to the first access network device.

22. The apparatus according to claim 21, characterized in that, At least one core network element associated with the first access network device is different from at least one core network element associated with the second access network device; or, The service capabilities of at least one core network element associated with the first access network device are different from the service capabilities of at least one core network element associated with the second access network device. The service capabilities include at least one of the following: network service type, service quality, or load capacity.

23. A communication device, characterized in that, include: A processor and a memory; the memory is used to store computer instructions that, when executed by the processor, cause the communication device to perform the communication method as described in any one of claims 1-11.

24. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a computer program or instructions that, when executed on a communication device, cause the communication device to perform the method as described in any one of claims 1-11.

25. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when executed by a communication device, cause the method of any one of claims 1-11 to be performed.

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