Communication method, apparatus, and system

Abstract

The present application relates to the field of communications, and discloses a communication method, apparatus, and system, aiming to solve the problem of large latency caused by source communication apparatuses relaying context to target communication apparatuses by means of core network devices or inter-orbit satellite base stations when communication apparatuses (e.g., access network apparatuses or core network apparatuses) providing service for terminal apparatuses switch from the source communication apparatuses to the target communication apparatuses. The method comprises: a first communication apparatus acquires context from a second communication apparatus which provides service for the first communication apparatus, and then sends the context to a third communication apparatus which replaces the second communication apparatus to provide service for the first communication apparatus, wherein the context is the context of a terminal apparatus served by the second communication apparatus. The solution of the present application can be widely applied to the technical field of communications and the fields of artificial intelligence, vehicle-to-everything, smart home networking and the like.

Description

Communication method, device and system

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on January 24, 2024, with application number 202410103236.1 and application name “A communication method, device and system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a communication method, device, and system. Background Art

[0003] The integration of satellite communication networks and terrestrial fifth-generation mobile communication technology (5G) networks can provide ubiquitous coverage regardless of terrain. In this integrated satellite and 5G network, satellite base stations are deployed in non-geostationary Earth orbit (NGEO). Compared to user equipment (UE), satellite base stations are in high-speed motion. Therefore, connected UEs need to frequently switch between different satellite cells to ensure service continuity.

[0004] When the UE switches from the cell of the source satellite base station to the cell of the target satellite base station, and the source satellite base station is deployed on an ascending satellite and the target satellite base station is deployed on a descending satellite, due to the very large relative motion speed between the ascending satellite and the descending satellite, it is difficult for the source satellite base station and the target satellite base station to establish a usable inter-satellite link. At this time, the source satellite base station can relay the context of the terminal in the source satellite base station to the target satellite base station through the core network equipment or the off-orbit satellite base station, so that the target satellite base station establishes a connection with the UE based on the context of the terminal.

[0005] However, since the context of the terminal in the source satellite base station is relayed through the core network equipment or the off-orbit satellite base station, the source satellite base station needs to first transmit the context of the terminal in the source satellite base station to the core network equipment or the off-orbit satellite base station, and then the core network equipment or the off-orbit satellite base station further transmits the context of the terminal in the source satellite base station to the target satellite base station, resulting in a large delay in transmitting the terminal context between the source satellite base station and the target satellite base station. Summary of the Invention

[0006] The embodiments of the present application provide a communication method, device, and system to solve the problem of large delay when a communication device (for example, an access network device or a core network device) providing services to a terminal device switches from a source communication device to a target communication device, and the source communication device relays the context to the target communication device through a core network device or an off-orbit satellite base station.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In the first aspect, an embodiment of the present application provides a communication method, which can be executed by a first communication device and a functional module or chip within the first communication device. Taking the execution of the first communication device as an example, the method includes: obtaining a context from a second communication device; sending a context to a third communication device; wherein the context is the context of a terminal device served by the second communication device, and the second communication device is a communication device that provides services to the first communication device; and the third communication device is a communication device that replaces the second communication device to provide services to the first communication device.

[0009] Based on the method described in the first aspect, after the first communication device obtains the context of the second communication device, it sends the context to the third communication device. The context is the context of the terminal device served by the second communication device, so that the second communication device no longer needs to relay the context of the terminal device served by the second communication device to the third communication device through the core network equipment or the off-orbit satellite base station, thereby reducing the delay in relaying the context of the terminal device served by the second communication device and reducing the switching delay.

[0010] In one possible design, in the communication method described in the first aspect, the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device.

[0011] Based on this possible design, an actual communication scenario applicable to the communication method provided in an embodiment of the present application is given. For example, in a communication scenario where the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device, the terminal device can obtain the context of the terminal device served by the first access network device, and then send the context of the terminal device served by the first access network device to the second access network device, wherein the first access network device is a communication device that provides services to the terminal device; the second access network device is a communication device that replaces the first access network device to provide services to the terminal device. Thus, the first access network device can transmit the context of the terminal device served by the first access network device to the second access network device through the terminal device, which reduces the delay in relaying the context of the terminal device served by the first access network device compared to the first access network device relaying the context of the terminal device served by the first access network device to the second access network device through the core network device or the off-orbit satellite base station.

[0012] In one possible design, the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device. The first communication device sends a context to the third communication device, including: receiving first indication information from the second access network device, and sending the context to the second access network device through the first time-frequency resource indicated by the first indication information.

[0013] Based on this possible design, in a communication scenario where the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device, a first indication information indicating a first time-frequency resource is given, so that the terminal device can send a context to the second access network device on the first time-frequency resource indicated by the first indication information, avoiding the problem of the terminal blindly transmitting the context and wasting transmission resources.

[0014] In one possible design, the first indication information is carried in a random access response, or the first indication information is carried in a radio resource control (RRC) signaling. For example, the first indication information can be carried in an uplink context grant (UL grant for UE context) signaling.

[0015] Based on this possible design, messages that can carry the first indication information in different communication scenarios are provided. Specifically, during random access by a terminal device, the first indication information can be carried in a random access response; during the process of an inactive terminal device resuming a connected state, the first indication information can be carried in RRC signaling. In this way, different messages are used to carry the first indication information for different scenarios, allowing the present solution to be flexibly and diversely applied to various communication scenarios, thereby improving the solution's utilization rate.

[0016] In one possible design, the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device. The first communication device sending the context to the third communication device also includes: sending second indication information to the second access network device, wherein the second indication information is used to indicate sending the context to the second access network device.

[0017] Based on this possible design, in a communication scenario where the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device, a second indication information is provided to instruct the sending of a context to the second access network device, so that the terminal device can instruct the second access network device to send the context through the second indication information, and further enable the second access network device to receive the context according to the instruction of the second indication information, thereby achieving the purpose of the terminal sending the context to the second access network device.

[0018] In one possible design, the second indication information is carried in a random access request, or the second indication information is carried in an RRC resume request message. For example, the second indication information can be carried in a radio resource control resume request (RRC resume request) signaling specified in an existing wireless communication protocol.

[0019] Based on this possible design, messages that can carry the second indication information in different communication scenarios are provided. Specifically, during random access by a terminal device, the second indication information can be carried in a random access request; during the process of an inactive terminal resuming a connected state, the second indication information can be carried in an RRC recovery request message. In this way, different messages are used to carry the second indication information in different scenarios, allowing for flexible and diverse application of this solution in various communication scenarios, thereby improving its utilization.

[0020] In one possible design, in the communication method described in the first aspect, the first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device.

[0021] Based on this possible design, a practical communication scenario applicable to the communication method provided in an embodiment of the present application is provided. For example, in a communication scenario where the first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device, the access network device can obtain a context from the first core network device and then send the context to the second core network device. The context is the context of the terminal device served by the first core network device. The first core network device is a communication device that provides services to the access network device; the second core network device is a communication device that takes over the service provided by the first core network device to the access network device. Thus, the first core network device can transmit the context to the second core network device through the access network device, achieving the purpose of the second core network device receiving the context. Furthermore, the terminal device served by the access network device does not need to re-initiate the process of requesting the second core network device to allocate resources, thereby saving resource overhead for the terminal device.

[0022] In one possible design, the first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device. A next generation (NG) interface is established between the access network device and the second core network device; the first communication device sends a context to the third communication device, including: sending a next generation application protocol (NGAP) signaling to the second core network device through the aforementioned NG interface, and the NGAP signaling carries the context.

[0023] Based on this possible design, in a scenario where the first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device, a new context-carrying NGAP signaling is provided. This allows the access network device to transmit the context of the terminal device served by the first core network device to the second core network device through the new NGAP signaling. Furthermore, by transmitting the context of the terminal device served by the first core network device through standard-specified NGAP signaling, signaling transmission overhead is reduced.

[0024] In one possible design, the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device. The first communication device obtains a context from the second communication device, including: receiving the context from the first access network device according to RRC release signaling. The context is the context of the terminal device served by the first core network device, and the RRC release signaling may carry downlink scheduling information.

[0025] Based on this possible design, a specific process is provided for a terminal device to obtain a context based on RRC release signaling, in a scenario where the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device. Furthermore, the terminal device can receive the context through RRC release signaling specified in the standard, further reducing signaling overhead for the first access network device.

[0026] In one possible design, a first communication device obtains a context from a second communication device, including: the first communication device sends a first request message for requesting a context to the second communication device, and further receives a context from the second communication device, wherein the context is a context of a terminal device served by the second communication device.

[0027] Based on this possible design, a specific process for a first communication device to obtain a context through a first request message is provided. A new first request message for requesting a context is also provided, allowing the first communication device to send this request message to a second communication device, thereby obtaining the context of the terminal device served by the second communication device.

[0028] In one possible design, the first request message is a handover request message, or the first request message is a context request message. The context request message may be NGAP signaling carried by a user equipment context retrieval request (UE context retrieve request).

[0029] Based on this possible design, specific first request messages for requesting context in different communication scenarios are provided. Specifically, when a terminal device performs a handover, the first request message is a handover request message; when an access network device performs a handover, the first request message is a context request message. This allows different request messages to request context in different scenarios, allowing for flexible and diverse application of this solution in various communication scenarios, improving its utilization.

[0030] In one possible design, the communication method described in the first aspect also includes: the first communication device receives update information from the third communication device, wherein the update information is used to update the context.

[0031] Based on this possible design, when the third communication device updates its context, the first communication device can obtain the updated context from the third communication device through the update information, and further enable the first communication device to successfully access the third communication device based on the updated context.

[0032] In one possible design, the communication method described in the first aspect further includes: the first communication device caching the context. Based on this possible design, the first communication device can cache the context locally, so that when the first communication device uses the context again, the first communication device can quickly obtain the context locally, thereby improving the response speed of the first communication device in obtaining the context.

[0033] In one possible design, the context includes a terminal key context, wherein the terminal key context is used to securely transmit the context. Based on this possible design, each communication device can securely transmit the context over the air interface.

[0034] In one possible design, the context does not include the terminal's key context, where the terminal's key context is generated by the core network device based on the terminal's geographic region. Based on this possible design, the core network device can generate the terminal's key context for the terminal based on geographic region, allowing the third communication device to obtain the terminal's key context in advance from the core network device based on the terminal's geographic region, thereby avoiding the terminal's key context from being transmitted over an open air interface and achieving the purpose of securely transmitting the terminal's key context.

[0035] In the second aspect, an embodiment of the present application provides a communication method, which can be executed by a second communication device and a functional module or chip within the second communication device. Taking the execution of the second communication device as an example, the second communication device is a communication device that provides services for the first communication device. The method includes: the second communication device obtains a context; and sends a context to the first communication device, where the context is the context of the terminal device served by the second communication device.

[0036] Based on the method described in the second aspect, the second communication device sends the acquired context to the first communication device, so that the first communication device can directly obtain the context of the terminal device served by the second communication device, and at the same time, no additional communication devices are added to relay the context of the terminal device served by the second communication device, so there is no additional delay in transmitting the context.

[0037] In one possible design, in the communication method described in the second aspect, the first communication device is a terminal device, and the second communication device is a first access network device.

[0038] Based on this possible design, an actual communication scenario applicable to the communication method provided in an embodiment of the present application is provided. For example, in a communication scenario where the first communication device is a terminal device and the second communication device is a first access network device, the first access network device obtains a context and further sends the context to the terminal device, wherein the first access network device is a communication device that provides services to the terminal device. As a result, the terminal device can directly obtain the context of the terminal device served by the first access network device, and at the same time, no additional communication device is added between the terminal device and the first access network device to relay the context of the terminal device served by the first access network device, thereby achieving the goal of not increasing the delay of transmitting additional context.

[0039] In one possible design, the first communication device is a terminal device, the second communication device is a first access network device, and the first access network device is a communication device that provides services for the terminal device. The method of the second aspect further includes: the first access network device sends RRC release signaling, where the RRC release signaling is used to instruct the terminal to receive a context. The context is the context of the terminal device served by the first access network device.

[0040] Based on this possible design, the first access network device instructs the terminal to receive the context through the RRC release signaling specified in the standard. On the one hand, this saves the signaling overhead of the first access network device, and on the other hand, it enables the terminal device to receive the context according to the instruction of the RRC release signaling, thereby saving the signaling overhead of the terminal device receiving the instruction.

[0041] In one possible design, in the communication method described in the second aspect, the first communication device is an access network device, and the second communication device is a first core network device.

[0042] Based on this possible design, a practical communication scenario applicable to the communication method provided in an embodiment of the present application is provided. For example, in a communication scenario where the first communication device is an access network device and the second communication device is a first core network device, the first core network device obtains a context and further sends the context to the access network device, where the context is the context of the terminal device served by the first core network device, and the first core network device is a communication device that provides services to the access network device. As a result, the access network device can directly obtain the context, and no additional communication devices are added between the access network device and the first core network device to relay the context, thereby achieving the goal of not increasing the delay of transmitting additional context.

[0043] In one possible design, the second communication device sending the context to the first communication device includes: the second communication device receiving a first request message for requesting the context from the first communication device, and sending the context to the first communication device.

[0044] Based on this possible design, a specific process for a second communication device to send a context to a first communication device via a first request message is provided. A new first request message for requesting a context is also provided, enabling the second communication device to send the context to the first communication device via the received first request message.

[0045] In one possible design, the first request message is a handover request message, or the first request message is a context request message. For example, the context request message is NGAP signaling carried by a UE context retrieve request.

[0046] Based on this possible design, specific first request messages for requesting context in different communication scenarios are provided. Specifically, when a terminal device performs a handover, the first request message is a handover request message; when an access network device performs a handover, the first request message is a context request message. This allows different request messages to request context in different scenarios, allowing for flexible and diverse application of this solution in various communication scenarios, improving its utilization.

[0047] In a third aspect, an embodiment of the present application provides a communication method, which can be executed by a third communication device and a functional module or chip within the third communication device. Taking the execution of the third communication device as an example, the third communication device is a communication device that provides services for the first communication device; the method includes: the third communication device receives a context from the first communication device; and provides services to the first communication device based on the context.

[0048] Based on the method described in the third aspect, the third communication device receives the context from the first communication device, so that the third communication device can successfully provide services for the first communication device; at the same time, the third communication device receives the context through the first communication device, so that the third communication device no longer needs to receive the relay context from the core network device or the off-orbit satellite base station, thereby reducing the delay in relaying the context and reducing the switching delay.

[0049] In one possible design, in the communication method described in the third aspect, the first communication device is a terminal device, and the third communication device is a second access network device.

[0050] Based on this possible design, an actual communication scenario applicable to the communication method provided in an embodiment of the present application is provided. For example, in a communication scenario where the first communication device is a terminal device and the third communication device is a second access network device, the second access network device receives a context from the terminal device, wherein the second access network device is a communication device that provides services to the terminal device. Thus, the second access network device can receive the context through the terminal device, which reduces the delay of the relay receiving the context compared to the second access network device receiving the context through a core network device or an off-orbit satellite base station, thereby reducing the switching delay.

[0051] In one possible design, the first communication device is a terminal device, the third communication device is a second access network device, and the third communication device receives the context from the first communication device, including: the second access network device sends first indication information for indicating first time-frequency resources to the terminal device, and receives the context from the terminal device through the first time-frequency resources.

[0052] Based on this possible design, in a communication scenario where the first communication device is a terminal device and the third communication device is a second access network device, a first indication information indicating a first time-frequency resource is given. The second access network device can receive the context from the terminal device through the first time-frequency resource indicated by the first indication information, thereby avoiding the problem of the second access network device blindly receiving the context and wasting transmission resources.

[0053] In one possible design, the first indication information is carried in a random access response, or the first indication information is carried in RRC signaling. Based on this possible design, messages that can carry the first indication information in different communication scenarios are given. Specifically, during random access of a terminal device, the first indication information can be carried in a random access response; during the process of an inactive terminal resuming a connection state, the first indication information can be carried in RRC signaling. In this way, different messages are used to carry the first indication information for different scenarios, and this solution can be flexibly and diversely applied to various communication scenarios, thereby improving the utilization rate of the solution.

[0054] In one possible design, the first communication device is a terminal device, the third communication device is a second access network device, and the third communication device receives the context from the first communication device, which also includes: the second access network device receives second indication information from the terminal, wherein the second indication information is used to indicate sending the context to the second access network device.

[0055] Based on this possible design, in a communication scenario where the first communication device is a terminal device and the third communication device is a second access network device, a second indication information is provided to instruct the sending of a context to the second access network device, so that the second access network device can receive the context from the terminal device in accordance with the indication of the second indication information, thereby achieving the purpose of receiving the context from the terminal device.

[0056] In one possible design, the second indication information is carried in a random access request, or the second indication information is carried in an RRC resume request message. For example, the second indication information can be carried in a radio resource control resume request (RRC resume request) signaling specified in an existing wireless communication protocol.

[0057] Based on this possible design, messages that can carry the second indication information in different communication scenarios are provided. Specifically, during random access by a terminal device, the second indication information can be carried in a random access request; during the process of an inactive terminal resuming a connected state, the second indication information can be carried in an RRC recovery request message. In this way, different messages are used to carry the second indication information in different scenarios, allowing for flexible and diverse application of this solution in various communication scenarios, thereby improving its utilization.

[0058] In one possible design, in the communication method described in the third aspect, the first communication device is an access network device, and the third communication device is a second core network device.

[0059] Based on this possible design, an actual communication scenario is provided to which the communication method provided in an embodiment of the present application is applicable. For example, in a communication scenario where the first communication device is an access network device and the third communication device is a second core network device, the second core network device receives the context from the access network device and further provides services to the access network device based on the context. The second core network device is a communication device that provides services to the access network device. Thus, the second core network device can obtain the context through the access network device, thereby achieving the purpose of successfully providing services to the access network device. Furthermore, the terminal device provided with services by the access network device does not need to re-initiate the process of applying to the second core network device for resource allocation from the second core network device, thereby saving resource overhead of the terminal device.

[0060] In one possible design, the first communication device is an access network device, the third communication device is a second core network device, a next-generation NG interface is established between the access network device and the second core network device, and the third communication device receives the context from the first communication device, including: receiving the next-generation access point NGAP signaling from the access network device through the aforementioned NG interface, wherein the NGAP signaling carries the context.

[0061] Based on this possible design, in a scenario where the first communication device is an access network device and the third communication device is a second core network device, a new NGAP signaling method for carrying context is provided. This allows the second core network device to receive context from the access network device via the new NGAP signaling method. Furthermore, receiving context via the standard-specified NGAP signaling method reduces signaling overhead.

[0062] In one possible design, the communication method described in the third aspect also includes: the third communication device sends update information to the first communication device, wherein the update information is used to update the context.

[0063] Based on this possible design, when the third communication device updates the context, update information of the updated context is sent to the first communication device, so that the first communication device can obtain the updated context in the third communication device through the update information, and further enable the third communication device to successfully replace the second communication device to provide services for the first communication device.

[0064] In a fourth aspect, the present application provides a first communication device, which may be a terminal device or a chip or system on chip in a terminal device, or a functional module in a terminal device for implementing the first aspect or any possible design of the first aspect. The communication device may implement the functions performed by the terminal device in the above-mentioned first aspect or any possible design of the first aspect, and the functions may be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. For example, the communication device may include a transceiver unit. Among them,

[0065] a transceiver unit configured to obtain a context from a second communication device; the second communication device being a communication device providing a service to the first communication device; and the context being a context of a terminal device provided by the second communication device;

[0066] The transceiver unit is further configured to send the context to a third communication device; the third communication device is a communication device that takes over the service provided by the second communication device to the first communication device.

[0067] Specifically, the execution actions of each unit of the communication device can refer to the first aspect or any possible design of the first aspect, and will not be repeated here.

[0068] In a fifth aspect, the present application provides a second communication device, which is a communication device that provides services for the first communication device. The second communication device can be a network device or a chip or system on chip in the network device, and can also be a functional module in the network device for implementing the second aspect or any possible design of the second aspect. The communication device can implement the functions performed by the network device in the above-mentioned second aspect or the possible design of the second aspect, and the functions can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. For example, the communication device may include a processing unit and a transceiver unit. Among them,

[0069] A processing unit, configured to obtain a context; the context being a context of a terminal device served by the second communication device;

[0070] The transceiver unit is configured to send the context to the first communication device.

[0071] Specifically, the execution actions of each unit of the communication device can refer to the second aspect or any possible design of the second aspect, and will not be repeated here.

[0072] In a sixth aspect, the present application provides a third communication device, which is a communication device that provides services for the first communication device. The third communication device can be a network device or a chip or system on chip in the network device, and can also be a functional module in the network device for implementing the third aspect or any possible design of the third aspect. The communication device can implement the functions performed by the network device in the above-mentioned third aspect or the possible design of the third aspect, and the functions can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. For example: the communication device may include a processing unit and a transceiver unit. Among them,

[0073] a processing unit, configured to receive a context from a first communication device;

[0074] The transceiver unit is configured to provide a service to the first communication device based on the context.

[0075] Specifically, the execution actions of each unit of the communication device can refer to the third aspect or any possible design of the third aspect, and will not be repeated here.

[0076] In a seventh aspect, the present application provides a communication device, which may be a first communication device, or a second communication device, or a third communication device, or a chip or system-on-chip in the first communication device, or a chip or system-on-chip in the second communication device, or a chip or system-on-chip in the third communication device. The communication device may implement the function performed by the first communication device in the first aspect or the possible design of the first aspect, or the communication device may implement the function performed by the second communication device in the second aspect or the possible design of the second aspect, or the communication device may implement the function performed by the third communication device in the third aspect or the possible design of the third aspect, and the function may be implemented by hardware. In one possible design, the communication device includes a processor and a communication interface. The processor and the communication interface are used to support the first communication device to perform the communication method in the first aspect or any possible design of the first aspect, or the processor and the communication interface are used to support the second communication device to perform the communication method in the second aspect or any possible design of the second aspect, or the processor and the communication interface are used to support the third communication device to perform the communication method in the third aspect or any possible design of the third aspect. In another possible design, the communication device may further include a memory for storing computer-executable instructions and data necessary for the communication device. When the communication device is running, the processor executes the computer-executable instructions stored in the memory to cause the communication device to perform the communication method described in the first aspect or any possible design of the first aspect, or to cause the communication device to perform the communication method described in the second aspect or any possible design of the second aspect, or to cause the communication device to perform the communication method described in the third aspect or any possible design of the third aspect.

[0077] In an eighth aspect, the present application provides a communication system, which includes the first communication device provided by the fourth aspect, the second communication device provided by the fifth aspect, and the third communication device provided by the sixth aspect; or, the communication system includes the first communication device provided by the fourth aspect, the second communication device provided by the fifth aspect, and the communication device provided by the seventh aspect; or, the communication system includes the first communication device provided by the fourth aspect, the communication device provided by the seventh aspect, and the third communication device provided by the sixth aspect; or, the communication system includes the communication device provided by the seventh aspect, the second communication device provided by the fifth aspect, and the third communication device provided by the sixth aspect.

[0078] In the ninth aspect, the present application provides a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer executes the first aspect or any possible communication method in the design of the first aspect; or, the computer executes the second aspect or any possible communication method in the design of the second aspect, or, the computer executes the third aspect or any possible communication method in the design of the third aspect.

[0079] In the tenth aspect, the present application provides a computer program product, which includes computer instructions. When the computer instructions are run on a computer, the computer executes the communication method in the first aspect or any possible design of the first aspect; or, the computer executes the communication method in the second aspect or any possible design of the second aspect, or, the computer executes the communication method in the third aspect or any possible design of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] FIG1 is a schematic diagram of a satellite communication network system architecture;

[0081] FIG2 is a schematic diagram of a communication system provided in an embodiment of the present application;

[0082] FIG3 is a schematic diagram of a satellite communication system provided in an embodiment of the present application;

[0083] FIG4 is a flow chart of a communication method provided in an embodiment of the present application;

[0084] FIG5 is a flow chart of a communication method provided in an embodiment of the present application;

[0085] FIG6 is a flow chart of a communication method provided in an embodiment of the present application;

[0086] FIG7 is a flow chart of a communication method provided in an embodiment of the present application;

[0087] FIG8 is a schematic structural diagram of a first communication device provided by the present application;

[0088] FIG9 is a schematic structural diagram of a second communication device provided by the present application;

[0089] FIG10 is a schematic structural diagram of a third communication device provided by the present application;

[0090] FIG11 is a schematic structural diagram of a communication device provided in this application. DETAILED DESCRIPTION

[0091] Before introducing the embodiments of the present application, some technical terms involved in the embodiments of the present application are explained. It should be noted that the following explanations are intended to make the embodiments of the present application easier to understand and should not be regarded as limiting the scope of protection claimed by the embodiments of the present application.

[0092] With the development of information technology, the demand for efficient, mobile, and diverse communications is becoming increasingly urgent. Currently, a key development focus in the communications system sector is global mobile communications, of which satellite communications are a crucial component. Satellite communications play an irreplaceable role in key areas such as space and aviation communications. Satellite communications offer long communication distances, wide coverage areas, and flexible networking, providing services for both fixed and mobile terminals.

[0093] The 3rd Generation Partnership Project (3GPP) standards organization has released the fifth-generation (5G) technical standards for mobile communications technology. The research focuses on integrating space-ground communication technologies, primarily by integrating existing 5G standards with satellite communication technologies to achieve full global coverage. 3GPP members have also integrated satellite communication and 5G technologies to propose a satellite communication network system architecture diagram, as shown in Figure 1. The satellite communication network system architecture shown in Figure 1 includes user equipment (UE), a 5G base station deployed on a satellite, a ground station, a 5G user plane processing unit, a 5G control plane processing unit, a data network, a 5G new air interface, an Xn interface, and a next-generation (NG) interface. The 5G control plane processing unit includes 5G access mobility management functions and 5G session management functions. As shown in Figure 1, the UE is connected to the 5G base station deployed on the satellite through the 5G new air interface. The 5G base station deployed on the satellite is connected to the ground station through the NG interface. The ground station is connected to the 5G user plane processing unit through the NG interface. The ground station is connected to the 5G control plane processing unit through the NG interface. At the same time, if there is an available wireless link between satellites, the 5G base stations deployed on different satellites can complete signaling interaction and user data transmission between base stations through the Xn interface.

[0094] In this application, the type of base station deployed on the satellite is not limited. It can be a 5G base station, or a base station in a future evolved communication system, etc. This application takes a 5G base station as an example for illustration, where the 5G base station deployed on the satellite can be alternatively described as a satellite base station, or a satellite access network device, or a satellite access network device or a satellite communication device, etc., without limitation.

[0095] Cell handover refers to the movement of a terminal from one cell to another while it is connected and maintaining data transmission services. Alternatively, when the original serving cell (source cell) can no longer provide services to the terminal due to factors such as wireless transmission service load adjustment, activation operation maintenance, or equipment failure, the wireless bearer system will search for the most suitable cell (target cell) or network to continue providing uninterrupted services to the terminal in order to maintain data transmission services and service quality, thus achieving mobility management with seamless wireless network coverage.

[0096] In the satellite communication network system architecture shown in Figure 1, cell handover includes intra-satellite cell handover and inter-satellite cell handover. Intra-satellite cell handover refers to a terminal switching between a source cell and a target cell, where the source cell and the target cell are within the coverage of the same satellite base station. In other words, the source cell and the target cell correspond to the same satellite base station. Inter-satellite cell handover refers to a terminal switching between a source cell and a target cell, where the source cell and the target cell are within the coverage of different satellite base stations. In other words, the source cell and the target cell correspond to different satellite base stations. The satellite base station to which the source cell belongs can be referred to as the source satellite base station, and the satellite base station to which the target cell belongs can be referred to as the target satellite base station.

[0097] In satellite communication network architectures, satellite base stations are deployed in satellite orbits. Within large-scale low-orbit (LEO) constellations, satellite orbits can be ascending or descending. LEO constellations refer to artificial satellite constellations orbiting Earth at altitudes below 1,000 km. When a satellite orbits from south to north, it's called an ascending satellite; when it orbits from north to south, it's called a descending satellite. The relative speed between ascending and descending satellites is extremely high, making it difficult to establish a usable intersatellite link between these two satellites.

[0098] An intersatellite link (ISL) is a link used for direct communication between satellite base stations, also known as an intersatellite link or a cross link. An ISL can be a wireless interface or an optical interface. If the ISL is a wireless interface, the Xn interface in Figure 1 can be referred to as the ISL.

[0099] Take the case where the terminal performs inter-satellite cell handover, and the source cell and the target cell belong to the coverage of different ascending and descending satellite base stations, that is, the source cell and the target cell correspond to different ascending and descending satellite base stations. For example, the source cell corresponds to the ascending satellite base station, and the target cell corresponds to the descending satellite base station; or, the source cell corresponds to the descending satellite base station, and the target cell corresponds to the ascending satellite base station. At this time, since the source cell and the target cell correspond to different ascending and descending satellite base stations, it is difficult to establish an available inter-satellite link between the source satellite base station and the target satellite base station, resulting in the inability to complete signaling interaction and user data transmission between the source satellite base station and the target satellite base station through the Xn interface, and thus the terminal cannot adopt inter-satellite cell handover based on the Xn interface. In the above case, the terminal can adopt inter-satellite cell handover based on the NG interface or the terminal can adopt inter-satellite cell handover based on the multi-hop Xn interface.

[0100] Among them, when the terminal adopts inter-satellite cell switching based on the NG interface, the source satellite base station needs to transmit the terminal context required for the inter-satellite cell switching in the source satellite base station to the core network device through the NG interface, and then the core network device forwards the terminal context to the target satellite base station. This method of forwarding the terminal context through the core network device causes a large transmission delay in the inter-satellite cell switching. Especially when the core network device is deployed on the ground, the satellite-to-ground transmission will further increase the transmission delay.

[0101] Among them, when the terminal adopts inter-satellite cell switching based on the multi-hop Xn interface, the source satellite base station needs to relay the terminal context required for the inter-satellite cell switching in the source satellite base station to the target satellite base station through the off-orbit satellite base station. There is an available Xn interface between the source satellite base station and the off-orbit satellite base station, and there is an available Xn interface between the target satellite base station and the off-orbit satellite base station. Obviously, the terminal adopts inter-satellite cell switching based on the multi-hop Xn interface, which also has a large transmission delay and low transmission reliability.

[0102] In order to solve the problem of large delay when a communication device (such as an access network device or a core network device) providing services to a terminal device switches from a source communication device to a target communication device, the source communication device relays the context to the target communication device through a core network device or an off-orbit satellite base station. The present application provides a communication method, the method comprising: a first communication device obtains a context from a second communication device providing services to the first communication device, and sends the context to a third communication device that replaces the second communication device to provide services to the first communication device, wherein the context is the context of the terminal device served by the second communication device. For example, taking the first communication device as a terminal, the second communication device as a source satellite base station, and the third communication device as a target satellite base station as an example, when an intersatellite link cannot be established between the source satellite base station and the target satellite base station, the source satellite base station can send the context of the terminal served by the source satellite base station to the terminal. After the terminal receives the context of the terminal served by the source satellite base station, it can send the context of the terminal served by the source satellite base station to the target satellite base station when communicating with the target satellite base station. There is no need to relay the context of the terminal served by the source satellite base station to the target satellite base station through a core network device or an off-orbit satellite base station, thereby reducing the delay in relaying the terminal context and achieving the goal of reducing the switching delay.

[0103] The communication method provided in the embodiments of the present application is described below with reference to the accompanying drawings.

[0104] The technical solutions of the embodiments of the present application can be used in various communication systems, which may be a third generation partnership project (3GPP) communication system, such as a long term evolution (LTE) system, or a fifth generation (5G) mobile communication system, a new radio (NR) system, a satellite communication system, a new radio vehicle to everything (NR V2X) system, and may also be applied to a system of LTE and 5G hybrid networking, or a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an Internet of Things (IoT), and other next-generation communication systems, and may also be a non-3GPP communication system without limitation.

[0105] The technical solutions of the embodiments of the present application can be applied to various communication scenarios, for example, one or more of the following communication scenarios: enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), machine type communication (MTC), massive machine type communication (mMTC), D2D, V2X, and IoT communication scenarios. The technical solutions of the embodiments of the present application can also be applied to long-distance communication scenarios, such as satellite communication scenarios where the distance between the terminal and the network device is constantly changing, or other long-distance communication scenarios, without limitation.

[0106] Figure 2 is a structural diagram of a communication system provided in an embodiment of the present application. As shown in Figure 2, the communication system may include a first communication device, a second communication device, and a third communication device. The first communication device in Figure 2 may be a communication device with a wireless communication function. The first communication device may have a mobile feature, and the first communication device may communicate and / or exchange data with the second communication device within the coverage area of ​​the second communication device, and receive services provided by the second communication device. The first communication device may move from the coverage area / service area of ​​the second communication device to the coverage area / service area of ​​the third communication device, and the first communication device may communicate and / or exchange data with the third communication device within the coverage area of ​​the third communication device, and receive services provided by the third communication device.

[0107] In this application, a second communication device is a communication device that provides services to a first communication device. A third communication device is a communication device that takes over the service provided by the second communication device to the first communication device. The second communication device can be referred to as a source communication device, and the third communication device can be referred to as a target communication device. A direct communication link may or may not be established between the second and third communication devices, without limitation.

[0108] It is understood that Figure 2 is merely a schematic diagram and does not limit the applicable scenarios of the technical solutions provided in this application. Those skilled in the art should understand that, in a specific implementation, the communication system shown in Figure 2 may include fewer devices than shown in Figure 2 , or the communication system shown in Figure 2 may include other devices. The number of devices in the communication system shown in Figure 2 may also be determined based on specific needs and is not limited. The devices in the system shown in Figure 2 are described below.

[0109] In the present application, the communication system shown in Figure 2 can be a satellite communication system. For example, it can be the satellite communication system shown in Figure 3. As shown in Figure 3, the satellite communication system may include: a terminal, a source satellite base station, a target satellite base station, a source core network device, and a target core network device. Among them, the terminal can be in a connected state or a deactivated state. When the terminal is in a connected state, connections are established between the terminal and the source satellite base station, and between the source satellite base station and the source core network device, and the terminal can access the network at any time. When the terminal is in a deactivated state, no connection is established between the terminal and the source satellite base station, but a connection is established between the source satellite base station and the source core network device. Therefore, when the terminal is in a deactivated state, it needs to be restored from the deactivated state to the connected state to further access the network.

[0110] The source satellite base station is a communication device that provides services to the terminal. The source satellite base station includes satellite cell 1 and satellite cell 2. Satellite cell 2 is the satellite cell that provides services to the terminal. Satellite cell 1 and satellite cell 2 are the areas covered by the source satellite base station. The source satellite base station can provide services to the terminal within both satellite cell 1 and satellite cell 2.

[0111] The target satellite base station is a communication device that takes over service for the terminal from the source satellite base station. The target satellite base station includes satellite cell 3 and satellite cell 4. Satellite cell 3 of the target satellite base station is the satellite cell that takes over service for the terminal from satellite cell 3. Satellite cell 3 and satellite cell 4 represent the areas covered by the target satellite base station. The target satellite base station can provide service to the terminal within both satellite cell 3 and satellite cell 4.

[0112] The source core network equipment is a communication device that provides services to the source satellite base station and the target satellite base station.

[0113] The target core network device is a communication device that takes over the service of the source core network device for the source satellite base station.

[0114] Taking a satellite communication system as an example, the first communication device involved in this application can be a terminal device or an access network device. When the first communication device is a terminal device, the second communication device can be a first access network device, and the third communication device can be a second access network device, wherein the first access network device is an access network device that provides services to the terminal device, and the second access network device is an access network device that replaces the first access network device in providing services to the terminal device. When the first communication device is an access network device, the second communication device can be a first core network device, and the third communication device can be a second core network device, wherein the first core network device is a core network device that provides services to the access network device, and the second core network device is a core network device that replaces the first core network device in providing services to the access network device.

[0115] The terminal device involved in this application can be terminal equipment or a functional module / chip in the terminal equipment, or it can be user equipment (UE), mobile station (MS), or mobile terminal (MT), etc. Specifically, the terminal can be a mobile phone, tablet computer, or computer with wireless transceiver function, and can also be a virtual reality (VR) terminal, augmented reality (AR) terminal, wireless terminal in industrial control, wireless terminal in unmanned driving, wireless terminal in telemedicine, wireless terminal in smart grid, wireless terminal in smart city, smart home, vehicle-mounted terminal, etc.

[0116] The access network device involved in this application can be an access network device or a functional module / chip in an access network device. It is a device in a radio access network (RAN) that connects a terminal to a wireless network. The RAN can be connected to a core network (for example, it can be an LTE core network or a 5G core network). The access network device can be a satellite base station (or flying platform) in an NTN scenario, an evolutionary Node B (eNB or eNodeB) in LTE, or a base station in a 5G network or a future evolved public land mobile network (PLMN), a broadband network gateway (BNG), an aggregation switch or a non-3GPP access device; or the access network device in the embodiment of this application can also be a wireless controller in a cloud radio access network (CRAN); or a transmission and reception point (TRP), or a device including a TRP, etc., which is not specifically limited in this embodiment of the application. Optionally, the base station in the embodiment of the present application may include various forms of base stations, such as: macro base stations, micro base stations (also called small stations), relay stations, access points, etc., and the embodiment of the present application does not make specific limitations on this.

[0117] The access network device in the embodiment of the present application can be mounted or deployed on a flight platform, such as a low-altitude flight platform, a high-altitude flight platform, or a satellite. When the access network device is mounted on the flight platform, the access network device moves synchronously with the flight platform.

[0118] The core network device involved in this application can be a core network device or a functional module / chip in a core network device, such as an access and mobility management function (AMF) or a functional module / chip in an AMF, which is responsible for the central point of most control plane function interactions, mainly used for registration management, connection management, access management, mobility management, and various functions related to security and access management and authorization.

[0119] Optionally, each device in Figure 2 (such as the first communication device, the second communication device, and the third communication device) can also be referred to as a communication device, which can be a general device or a dedicated device. The embodiments of the present application do not specifically limit this.

[0120] Optionally, the related functions of each device in FIG2 of the present application can be implemented by a single device, or by multiple devices together, or by one or more functional modules within a single device, and the embodiments of the present application do not specifically limit this. It is understood that the above functions can be network elements in a hardware device, software functions running on dedicated hardware, or a combination of hardware and software, or virtualized functions instantiated on a platform (e.g., a cloud platform).

[0121] The following describes the communication method provided in the embodiments of the present application in conjunction with the communication system shown in Figure 2. The actions and terms involved in the following embodiments can be referenced to each other. The names of messages exchanged between devices in each embodiment or the names of parameters in the messages are only examples, and other names can also be used in specific implementations. For example, the word "corresponding" in the following embodiments can be replaced by "associating", and the word "sending" in the following embodiments can be replaced by "transmitting".

[0122] FIG4 is a flow chart of a communication method provided in an embodiment of the present application. As shown in FIG4 , the method may include steps S401 to S403:

[0123] S401: The second communication device obtains a context and sends the context to the first communication device.

[0124] The second communication device may be a communication device providing services to the first communication device, and the second communication device may be a communication device corresponding to the cell where the terminal is located. For example, the first communication device may be the terminal in Figure 3 , and the second communication device may be the source satellite base station in Figure 3 . For another example, the first communication device may be the source satellite base station in Figure 3 , and the second communication device may be the source core network device in Figure 3 .

[0125] The context is the context of the terminal device served by the second communication device; the context of the terminal device refers to the relevant information of the terminal device. The context can be used by the communication device to serve the terminal device.

[0126] In one example, the context includes the key context of the terminal device and other information. The other information may be information specified in the existing 3GPP protocol and will not be described in detail. The key context of the terminal device refers to information used to securely transmit the context. In different communication scenarios, the context may include different information. For example, in a scenario where the terminal performs inter-satellite cell switching, the context includes information used by the target satellite base station to complete switching preparations, such as terminal user security configuration (such as encryption algorithm, etc.), air interface configuration information, user capability information, etc. For another example, in a scenario where an inactive terminal restores the connection state, the context includes information used by the inactive terminal to access the target base station, such as the terminal's session information, security information (such as encryption algorithm, etc.), mobility management information, etc.

[0127] In another example, the context may include information specified in the existing 3GPP protocol, but does not include the key context of the terminal device. In this case, the key context of the terminal device is generated by the core network device according to the geographical area where the terminal device is located and stored in the core network device. For example, the key context of the terminal device can be stored in the core network device in correspondence with the geographical area. Subsequently, the third communication device can obtain the key context of the terminal device corresponding to the geographical area where the terminal device is located from the core network device based on the geographical area where the terminal device is located. There is no need to obtain the context through the first communication device, and the key context of the terminal is obtained from the context, thereby avoiding the air interface transmission of the key context of the terminal device between the first communication device and the third communication device, thereby improving the security of the terminal device accessing the network.

[0128] The context is stored in the second communication device, such as in a local cache of the second communication device. The second communication device acquiring the context may include: the second communication device acquiring the context from the local cache.

[0129] In one example, the second notification device may actively obtain the context from a local cache.

[0130] For example, after the second communication device sends a radio resource control (RRC) release signaling to the first communication device to instruct the first communication device to receive the context, the second communication device can obtain the context from the local cache and send the context to the first communication device. For specific implementation methods, please refer to the embodiment corresponding to Figure 6.

[0131] In another example, the second communication device may receive a first request message from the first communication device for a context. In response to the first request message, the second communication device retrieves the context from a local cache and sends the context to the first communication device. Specifically, this implementation may refer to the embodiments corresponding to FIG. 5 or FIG. 7 .

[0132] Optionally, when the first communication device is a terminal device and the second communication device is a first access network device providing services for the terminal, the first request message may be a handover request message; when the first communication device is an access network device and the second communication device is a first core network device providing services for the access network device, the first request message may be a context request message. It should be understood that any message used to request a context in this application may be referred to as a first request message, and this application does not limit the specific information format of the first request message.

[0133] S402: The first communication device obtains a context from the second communication device.

[0134] The first communication device acquiring the context from the second communication device may be alternatively described as the first communication device receiving the context from the second communication device.

[0135] In one example, obtaining a context from a second communication device by a first communication device may include: the first communication device sending a first request message to the second communication device requesting the context, and further receiving the context from the second communication device. The first request message is described in S401 and is not further described here. For specific implementations, refer to the embodiments corresponding to FIG. 5 or FIG. 7 .

[0136] In another example, where the first communication device is a terminal device and the second communication device is a first access network device providing services for the terminal device, the first communication device obtaining a context from the second communication device may include: the first communication device receiving RRC release signaling from the second communication device, and further receiving the context from the second communication device based on the RRC release signaling, wherein the RRC release signaling is used to instruct the first communication device to receive the context. For specific implementation methods, reference may be made to the embodiment corresponding to FIG6 .

[0137] Further optionally, when the first communication device obtains the context of the second communication device, the first communication device may cache the context. In this way, when the first communication device uses the context again, the first communication device can quickly obtain the context locally, thereby improving the response speed of the first communication device in obtaining the context.

[0138] S403: The first communication device sends the context to the third communication device. Correspondingly, the third communication device receives the context from the first communication device.

[0139] The third communication device is a communication device that takes over the service provided by the second communication device to the first communication device. For example, the first communication device may be the terminal in Figure 3, the second communication device may be the source satellite base station in Figure 3, and the third communication device may be the target satellite base station in Figure 3. For another example, the first communication device may be the source satellite base station in Figure 3, the second communication device may be the source core network device in Figure 3, and the third communication device may be the target core network device in Figure 3.

[0140] The first communication device sending the context to the third communication device can be divided into the following two examples:

[0141] In one example, the first communication device is a terminal device, the second communication device is a first access network device, and the third communication device is a second access network device. In this case, the first communication device sending the context to the third communication device may include:

[0142] The terminal device receives first indication information indicating a first time-frequency resource from the second access network device, and in response to the first indication information, the terminal device sends a context to the second access network device using the first time-frequency resource. The first indication information may be carried in a random access response or in RRC signaling.

[0143] In this example, before the terminal device sends the context to the second access network device, the terminal device may send second indication information to the second access network device. The second indication information is used to instruct the second access network device to send the context, and the second indication information may be carried in a random access request or an RRC recovery request message.

[0144] Specifically, the implementation of this example may refer to the embodiment corresponding to FIG5 or FIG6 .

[0145] In another example, the first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device. In this case, the first communication device sending the context to the third communication device may include:

[0146] When an NG interface is established between the access network device and the second core network device, the access network device sends a Next Generation Access Protocol (NGAP) signaling message carrying the context to the second core network device via the NG interface. The specific implementation method can be found in the embodiment corresponding to FIG. 7 .

[0147] Further optionally, after receiving the context from the first communication device, the third communication device provides services to the first communication device based on the context. Specifically, this process can refer to the existing technology and will not be described in detail here.

[0148] Based on the communication method shown in Figure 4, when a second communication device is the communication device providing services to a first communication device and a third communication device takes over the service provided by the second communication device, the first communication device obtains a context from the second communication device and then sends the context to the third communication device. The context is the context of the terminal device served by the second communication device. This allows the second communication device to relay the context to the third communication device without having to use core network equipment or an off-orbit satellite base station if an intersatellite link cannot be established between the second and third communication devices. This reduces the latency of relaying the context and further reduces the handover latency when the first communication device switches from the second to the third communication device.

[0149] Optionally, when the third communication device updates the context, the third communication device may send update information for updating the context to the first communication device based on the updated context. Accordingly, the first communication device receives the update information from the third communication device and updates its own context based on the update information. Optionally, the update information may include, but is not limited to, full context update information or incremental context update information. The full context update information may refer to the context updated by the third communication device, and the incremental context update information may refer to the difference between the context updated by the third communication device and the context before the update.

[0150] In this way, the third communication device can provide services to the first communication device through the updated context. Accordingly, the first communication device can successfully access the third communication device through the updated context received from the third communication device.

[0151] In the following, with reference to the satellite communication system shown in FIG3 , the first communication device is the terminal in FIG3 , the second communication device is the source satellite base station in FIG3 , and the third communication device is the target satellite base station in FIG3 . The source satellite base station is the communication device that provides services to the terminal, and the target satellite base station is the communication device that takes over the service provided by the source satellite base station to the terminal. The communication method shown in FIG4 is described in conjunction with FIG5 . FIG5 is a schematic flow diagram of a communication method provided in an embodiment of the present application. As shown in FIG5 , the method may include:

[0152] S500: The core network device generates a terminal key context for the terminal according to the geographical area where the terminal is located.

[0153] Among them, the core network device generates a terminal key context for the terminal according to the geographical area where the terminal is located, including: the terminal and the core network device derive a specific area key (area-specific key, Karea) based on the terminal's root key K, and further derive other keys based on the specific area key. The root key is the basis of the cryptographic system and is used to generate other keys. Other keys may include at least one of the following types of keys: a key K used for secure transmission between the access network device and the core network device; gNB , the secret key K used to securely transmit RRC signaling RRC , secret key K used for secure transmission of user plane services UP It should be understood that other keys are generated based on the key of a specific area, so other keys of the same type generated by the core network device based on the key of the same specific area are the same. For example, the K generated by the core network device based on the same Karea gNB The same K enables terminals to use the same K between different base stations in the same geographical area. gNB .

[0154] Further optionally, the core network device may store the generated terminal key context locally, such as in the context of the terminal.

[0155] It should be understood that S500 is an optional execution step. For example, in response to the context not including the terminal's key context, the core network device may execute S500 to generate the terminal's key context. In this way, after the target satellite base station begins to cover the geographical area where the terminal is located, the terminal's key context can be obtained through the NG interface between the target satellite base station and the core network device, avoiding air interface transmission of the terminal's key context between the terminal and the target satellite base station, thereby improving the security of the terminal's access to the network. In the case where the context includes the terminal's key context, the core network device may not execute S500 to generate the terminal's key context for the terminal based on the terminal's geographical area, and may directly use existing technologies to generate the terminal's key context.

[0156] S501: The terminal sends a handover request message to a source satellite base station. Correspondingly, the source satellite base station receives the handover request message.

[0157] The handover request message may request to switch the satellite base station providing service for the terminal or switch the serving cell of the terminal, etc. In the present application, the handover request may also be used to request a context. The handover request message may be a handover request signaling specified in a wireless communication protocol.

[0158] Among them, the terminal sends a switching request message to the source satellite base station, which may include: when the source satellite base station cannot continue to provide services to the terminal or the signal quality provided by the source satellite base station to the terminal is too low, the terminal sends a switching request message to the source satellite base station to request switching to the satellite base station that provides services to the terminal, and requesting the context of the terminal.

[0159] S502: In response to the handover request message, the source satellite base station sends a context to the terminal, and the terminal receives the context accordingly.

[0160] In the embodiment of the present application, the context is the context of the terminal served by the source satellite base station.

[0161] Further, optionally, in response to the handover request message, the source satellite base station may also determine a candidate target satellite base station for the terminal and send relevant information about the candidate target satellite base station to the terminal, such as an identifier of the candidate target satellite base station. Specifically, the candidate target satellite base station may include one or more. The process by which the source satellite base station determines the candidate target satellite base station may refer to existing technologies and is not described in detail here.

[0162] The context includes at least the information required by the candidate target satellite base station to complete handover preparations, such as user security configuration information, air interface configuration information, and user capability information. User security configuration information refers to the configuration information that ensures secure network access for terminal users, such as encryption algorithms. Air interface configuration information refers to the configuration information for wireless transmission between the terminal and the base station, such as the time domain resources, frequency domain resources, or coding methods used for each wireless channel. User capability information refers to the communication capabilities supported by the terminal, such as paging capabilities.

[0163] Specifically, when the source satellite base station determines one candidate target satellite base station for the terminal, the context may include information required for the candidate target satellite base station to complete handover preparation. When the source satellite base station determines multiple candidate target satellite base stations for the terminal, the context may include information required for the multiple candidate target satellite base stations to complete handover preparation.

[0164] Among them, the source satellite base station sending the context to the terminal may include: the source satellite base station detects that there is no available inter-satellite link between the source satellite base station and the target satellite base station, or the Xn interface load between the source satellite base station and the target satellite base station is large. At this time, the source satellite base station determines that it cannot send the context directly to the target satellite base station, or cannot send the context to the target satellite base station in a timely and effective manner. The source satellite base station sends the context to the terminal so that the terminal can send the context to the target satellite base station.

[0165] The source satellite base station sending the context to the terminal may include: the source satellite base station obtaining the context from a local cache of the source satellite base station and sending the context to the terminal.

[0166] Further optionally, the terminal receives the context and caches the context locally, so that when the terminal uses the context again, it can quickly obtain the context locally, thereby improving the response speed of the terminal in obtaining the context.

[0167] S503: The terminal sends a random access request message to the target satellite base station. Correspondingly, the target satellite base station receives the random access request message.

[0168] The target satellite base station may be a satellite base station that takes over the service provided to the terminal from the source satellite base station.

[0169] In one example, when the source satellite base station determines a candidate target satellite base station for the terminal, the terminal can determine the candidate target satellite base station as the target satellite base station to replace the source satellite base station, determine the target satellite base station based on the identifier of the target satellite base station sent by the source satellite base station, and send a random access request message to the target satellite base station.

[0170] In another example, when the source satellite base station determines multiple candidate target satellite base stations for the terminal, the terminal can select a target satellite base station to replace the source satellite base station from the multiple candidate satellite base stations, determine the target satellite base station based on the identifier of the target satellite base station, and send a random access request message to the target satellite base station.

[0171] In this application, the random access request information may be alternatively described as message 1 (MSG1), or a preamble, or a random access preamble, or a random access preamble sequence. The random access request may be used to request access to a target satellite base station, and may also be used to instruct a terminal to send a context to a target satellite base station.

[0172] In one example, the random access request may carry second indication information, which may be used to instruct the terminal to send the terminal context to the target satellite base station, that is, a direct indication method may be used to indicate to the target satellite base station that the terminal will send the terminal context to it.

[0173] In another example, when sending a random access request, the terminal selects a predefined preamble to initiate random access (RA), and / or when sending a random access request, the terminal sends the preamble on a predefined time-frequency resource. The predefined preamble and / or the predefined time-frequency resource can be used to instruct the terminal to send a context to a target satellite base station, i.e., an implicit indication can be used to indicate to the target satellite base station that the terminal will send the context to it.

[0174] For example, the preamble code set includes preamble codes 1-3, where preamble code 2 is predefined to instruct the terminal to send a context to the target satellite base station. At this time, if the terminal sends a random access request carrying preamble code 2 to the target satellite base station, the terminal is instructed to send the context to the target satellite base station. Conversely, if the terminal sends a random access request carrying preamble code 1 or carrying preamble code 3 to the target satellite base station, the terminal is instructed not to send the context to the target satellite.

[0175] S504: The target satellite base station sends a random access response carrying the first indication information to the terminal. Correspondingly, the terminal receives the random access response carrying the first indication information.

[0176] The random access response (RAR) is used to respond to the random access request for accessing the network, and may also be referred to as message 2 (MSG2). The random access response may carry first indication information, which may be used to indicate the available time-frequency resources allocated by the target satellite base station to the terminal.

[0177] Exemplarily, when sending a random access request, a terminal sends a predefined preamble to a target satellite base station, where the predefined preamble indicates that the terminal's purpose of initiating random access includes transmitting a context. Accordingly, after receiving and successfully parsing the predefined preamble, the target satellite base station allocates available time-frequency resource 1 to the terminal and further sends a random access response carrying first indication information to the terminal, where the first indication information indicates the available time-frequency resource 1 allocated by the target satellite base station to the terminal.

[0178] Optionally, to improve the success rate of the terminal randomly accessing the target satellite base station, the following design can be performed:

[0179] (1) The target satellite base station indicates the dedicated contention random access resource and the new cell-radio network temporary identifier (C-RNTI) paired with it in the system message. The system message refers to the message sent by the base station, which contains the information required for terminal initialization and related information of some other functions / features. C-RNTI refers to the dynamic identifier assigned to the terminal by the base station, which uniquely identifies the terminal under the air interface of a cell. In this way, the terminal can initiate random access to the target satellite base station on the dedicated contention random access resource indicated by the system message, and will not cause resource competition or resource conflict with other terminals initiating random access to the target satellite base station, thereby increasing the success rate of the terminal's random access to the target satellite base station.

[0180] Exemplarily, the target satellite base station sends a system message to terminal 1 in the form of a broadcast, where the system message indicates that the dedicated random access resource allocated by the target satellite base station to terminal 1 is resource 1, as well as C-RNTI_1. Further, terminal 1 uses C-RNTI_1 to initiate random access to the target satellite base station in resource 1.

[0181] (2) The source satellite base station schedules the random access sequence of the handover terminal, enabling the handover terminal to initiate contention-free random access to the target satellite base station. Contention-free random access means that the terminal uses the dedicated random access preamble allocated by the base station to initiate random access to the base station. In this case, the probability of the terminal successfully accessing the network is high.

[0182] Exemplarily, the source satellite base station is a communication device that provides services for terminal 1 and terminal 2. The random access order of terminal 1 initially assigned by the source satellite base station precedes the random access order of terminal 2. However, due to movement, the source satellite base station can no longer provide communication services to terminal 2, so the target satellite base station needs to take over the service of terminal 2 from the source satellite base station. Therefore, the source satellite base station switches the random access order of terminal 1 and terminal 2 through scheduling, that is, the source satellite base station configures the random access order of terminal 2 to precede the random access order of terminal 1, so that the timing of terminal 2 initiating random access to the target satellite base station will not conflict with the timing of terminal 1 initiating random access to the target satellite base station, thereby achieving the effect of terminal 2 initiating non-contention random access to the target satellite base station.

[0183] S505: The terminal sends a context to the target satellite base station on the time-frequency resource indicated by the first indication information. Correspondingly, the target satellite base station receives the context sent by the terminal.

[0184] The first indication information and the random access response carrying the first indication information are described in S504 , and the context is described in S502 , which will not be repeated here.

[0185] Exemplarily, the time-frequency resource indicated by the first indication information in the random access response received by the terminal is time-frequency resource 1, the context includes the terminal's security configuration information, air interface configuration information, etc., and the terminal further sends the context to the target satellite base station on time-frequency resource 1.

[0186] S506: The target satellite base station provides services to the terminal based on the context.

[0187] Specifically, after receiving the context, the target satellite base station provides services to the terminal based on the context, allowing the target satellite base station to successfully take over services for the terminal from the source satellite base station. Furthermore, after the target satellite base station successfully takes over services for the terminal from the source satellite base station, the terminal completes handover from the source satellite base station to the target satellite base station. The terminal can then send a handover confirmation message to the source satellite base station, allowing the source satellite base station to release the context and conserve resources of the source satellite base station.

[0188] Optionally, when the terminal's key context is not included in the context and the terminal's key context is generated by the core network device according to the geographical area where the terminal is located, the target satellite base station can obtain the terminal's key context through the NG interface between the target satellite base station and the core network device after receiving the context sent by the terminal, so that the terminal and the target satellite base station can securely transmit data based on the terminal's key context.

[0189] Further, optionally, if the target satellite base station updates the context, for example, if the target satellite base station has more suitable new air interface parameters that can be configured for the terminal, S507 is executed. In this case, the update information sent by the target satellite base station to the terminal includes the new air interface parameters assigned to the terminal by the target satellite base station. If the target satellite base station does not update the context, for example, if all configuration information in the context received by the target satellite base station is applicable to the target satellite base station, S507 is not executed.

[0190] S507: The target satellite base station sends update information to the terminal. Correspondingly, the terminal receives the update information sent by the target satellite base station and updates the context in the terminal based on the update information.

[0191] The update information is used to update the context, and the update information may include the updated context of the target satellite base station; or may include different information between the updated context of the target satellite base station and the context before the update.

[0192] Based on the communication method shown in FIG5 , when the target satellite base station takes over the service for the terminal from the source satellite base station and there is no available inter-satellite link (e.g., Xn interface) between the source satellite base station and the target satellite base station, the terminal context of the source satellite base station is sent by the terminal to the target satellite base station, without the need to relay the terminal context of the source satellite base station through a core network device or other off-orbit satellite base stations, thereby reducing the delay in relaying the terminal context of the source satellite base station and further reducing the switching delay of the terminal from the source satellite base station to the target satellite base station. At the same time, a design is provided in which a core network device generates a terminal key context for the terminal based on the geographical area where the terminal is located, so that the target satellite base station can obtain the terminal key context from the core network device in advance based on the geographical area where the terminal is located, avoiding the transmission of the terminal key context over an open air interface, thereby achieving the purpose of securely transmitting the terminal key context.

[0193] In conjunction with the satellite communication system shown in FIG3 , the following takes the first communication device as the terminal in FIG3 , the second communication device as the source satellite base station in FIG3 , and the third communication device as the target satellite base station in FIG3 as an example, wherein the source satellite base station can also be called the last serving gNB, and the target satellite base station is the one that takes over the service for the terminal. The communication method shown in FIG4 is described in conjunction with FIG6 . FIG6 is a flow chart of a communication method provided in an embodiment of the present application. As shown in FIG6 , the method may include:

[0194] S601: The previous serving satellite base station sends an RRC release signaling to the terminal. In response, the terminal receives the RRC release signaling and enters a deactivated state.

[0195] Among them, RRC release signaling (for example, RRC release with DL scheduling) is used to trigger the terminal to enter the deactivated state from the connected state, etc. In the present application, the RRC release signaling can also be used to instruct the terminal to receive the context from the previous serving satellite base station. In the embodiment of the present application, the context is the context of the terminal served by the previous serving base station. The connected state means that connections are established for the terminal between the terminal and the base station, and between the base station and the core network, and data transmission can be performed at any time. This state does not require establishment of a delay, so the delay is the shortest. The deactivated state means that there is no connection between the terminal and the base station, but a connection is established between the base station and the core network for the terminal. When there is data to be sent to the terminal, the base station will send a paging call. After receiving the paging call, the terminal quickly establishes a connection with the base station (10ms fast recovery), so that the terminal recovers from the deactivated state to the connected state.

[0196] In one example, the previous serving satellite base station sends an RRC release signaling to the terminal, which may include: the previous serving satellite base station sends an RRC release signaling carrying downlink scheduling resources to the terminal, where the downlink scheduling resources are time-frequency resources allocated by the previous serving satellite base station to the terminal for transmitting the context.

[0197] In another example, the previous serving satellite base station sending RRC release signaling to the terminal may include: the previous serving satellite base station sending RRC release signaling carrying downlink scheduling resource indication information to the terminal, where the downlink scheduling resource indication information indicates a time-frequency resource for monitoring downlink control information (DCI). The DCI is used to schedule the terminal to receive a context from the previous serving satellite base station.

[0198] S602: In response to the instruction of the RRC release signaling, the previous serving satellite base station sends a context to the terminal. Correspondingly, the terminal receives the context from the previous serving satellite base station.

[0199] The previous serving satellite base station sending the context to the terminal includes: the previous serving satellite base station sending the context to the terminal on a downlink scheduling resource. The downlink scheduling resource is a time-frequency resource allocated by the previous serving satellite base station to the terminal for transmitting the context in the previous serving satellite base station.

[0200] The context includes the terminal's session parameters, security parameters, and mobility management parameters. Session parameters refer to the parameters of the data transmission channel between the terminal and the data network. Security parameters are parameters that ensure secure network access for terminal users. Mobility management parameters are parameters that ensure continuous communication services for mobile terminals.

[0201] Optionally, after sending a context to the terminal on the downlink scheduling resources, the previous serving satellite base station no longer provides services to the terminal, releases the context, and conserves its own resources. For example, the previous serving base station triggers the terminal to enter a deactivated state from a connected state. When the deactivated terminal resumes a connected state, the communication device providing service to it is no longer the previous serving base station. Therefore, to conserve its own resources, the previous serving base station releases the context after sending the context.

[0202] Further optionally, when the context does not include the terminal's key context, and the terminal's key context is generated by the core network device according to the geographical area where the terminal is located, the previous serving satellite base station sends the context in the previous serving satellite base station on the downlink scheduling resources. Further, the previous serving satellite base station transmits the terminal's key context to the core network device (for example, AMF network element) in the geographical area where the terminal is located. The terminal's key context is used for secure transmission of the context. Specifically, the terminal's key context is generated by the core network device according to the geographical area where the terminal is located. Please refer to the aforementioned S500 step and will not be repeated here.

[0203] Further optionally, the terminal receives the context from the previous serving satellite base station and caches the context locally, so that when the terminal uses the context again, it can quickly obtain the context locally, thereby improving the response speed of the terminal in obtaining the context.

[0204] S603: The terminal sends an RRC recovery request to the target satellite base station. In response, the target satellite base station receives the RRC recovery request.

[0205] The target satellite base station is a satellite base station that takes over the service from the previous serving satellite base station to provide services to the terminal. The target satellite base station can also be understood as a satellite base station that restores the deactivated terminal from the deactivated state to the connected state.

[0206] In this application, the RRC recovery request can be used to request the restoration of the connection state of the deactivated terminal. It can also be used to instruct the terminal to send a context to the target satellite base station. That is, the purpose of the terminal initiating the RRC recovery request this time is to instruct the target satellite base station: the terminal will send the context to it.

[0207] In one example, the RRC recovery request carries second indication information, and the second indication information is used to instruct the terminal to send a context to the target satellite base station.

[0208] For example, the RRC resume request is a radio resource control request (RRC resume request) signaling specified in a wireless communication protocol, and the terminal sends the RRC resume request signaling carrying the second indication information to the target satellite base station.

[0209] S604: The target satellite base station sends an RRC signaling carrying the first indication information to the terminal. Correspondingly, the terminal receives the RRC signaling carrying the first indication information.

[0210] The RRC signaling is used to send radio resource control related information, such as handover related information. The RRC signaling may carry first indication information, which may be used to indicate available time-frequency resources allocated by the target satellite base station to the terminal.

[0211] For example, taking the RRC resume request as an example, the terminal sends an RRC resume request carrying second indication information to the target satellite base station, where the second indication information instructs the terminal to send a context to the target satellite base station. Accordingly, the target satellite base station receives the RRC resume request and allocates available time-frequency resource 1 to the terminal. Furthermore, the target satellite base station sends an uplink context grant (UL grant for UE context) carrying first indication information to the terminal, where the first indication information indicates the time-frequency resource 1 allocated by the target satellite base station to the terminal.

[0212] S605: The terminal sends a context to the target satellite base station using the time-frequency resource indicated by the first indication information. Correspondingly, the target satellite base station receives the context.

[0213] The related description of the first indication information and the RRC signaling carrying the first indication information is shown in S604 , and the related description of the context is shown in S602 , which will not be repeated here.

[0214] For example, assume that the RRC signaling carrying the first indication information sent by the target satellite base station to the terminal is UL grant for UE context signaling, where the time-frequency resource indicated by the first indication information is time-frequency resource 1. Accordingly, the terminal receives the UL grant for UE context signaling carrying the first indication information, and further, the terminal sends a context to the target satellite base station in time-frequency resource 1.

[0215] S606: The target satellite base station restores the terminal from the deactivated state to the connected state based on the context.

[0216] Specifically, the target satellite base station receives the context sent by the terminal and reconfigures local parameters so that the target satellite base station can provide services to the terminal. Accordingly, the terminal returns from the deactivated state to the connected state.

[0217] Optionally, when the terminal's key context is not included in the context and the terminal's key context is generated by the core network device according to the geographical area where the terminal is located, the target satellite base station can obtain the terminal's key context through the NG interface between the target satellite base station and the core network device after receiving the context sent by the terminal, so that the terminal and the target satellite base station can securely transmit data based on the terminal's key context.

[0218] S607: The target satellite base station sends update information to the terminal. Correspondingly, the terminal receives the update information and updates the context in the terminal based on the update information.

[0219] For the description of S607 , reference may be made to the description of S507 , which will not be repeated here.

[0220] S608: The target satellite base station sends RRC recovery information to the terminal. Correspondingly, the terminal receives the RRC recovery information.

[0221] S609: The terminal sends RRC recovery completion information to the target satellite base station based on the RRC recovery information. Correspondingly, the target satellite base station receives the RRC recovery completion information.

[0222] The detailed steps of S608 and S609 may refer to existing communication protocols, such as TS38.331.5.3.13.1.

[0223] Based on the communication method shown in Figure 6, when the previous serving satellite base station is providing services to the terminal and the target satellite base station is taking over the services for the terminal from the previous serving satellite base station, during the process of the terminal recovering from the deactivated state to the connected state, the target satellite base station no longer needs to obtain the context of the previous serving base station from the anchor satellite base station, thereby reducing the delay of relay transmission context and the complexity of context maintenance of network equipment, thereby further reducing the delay of the deactivated terminal recovering from the deactivated state to the connected state.

[0224] In conjunction with Figure 3, the following takes the first communication device as the source satellite base station in Figure 3, the second communication device as the source core network device in Figure 3, and the third communication device as the target core network device as an example, wherein the source core network device can also be referred to as the previous serving core network device. The target core network device is a communication device that takes over the service provided by the previous serving core network device to the source satellite base station. The communication method shown in Figure 4 is described in conjunction with Figure 7. Figure 7 is a flow chart of a communication method provided in an embodiment of the present application. As shown in Figure 7, the method may include:

[0225] S701: The source satellite base station determines the core network device providing service for it and switches from the previous serving core network device to the target core network device.

[0226] The source satellite base station refers to the satellite base station that provides services to the terminal. For example, in Figure 3, the source satellite base station is the satellite base station that provides services to the terminal. The previous serving core network device is the core network device that provides services to the source satellite base station and the terminals served by the source satellite base station. The target core network device is the core network device that takes over the service provided by the previous serving core network device to the source satellite base station and the terminals served by the source satellite base station.

[0227] Specifically, the source satellite base station determines that the core network device providing service for it will be switched from the previous serving core network device to the target core network device based on the relative position relationship between the source satellite base station and the previous serving core network device.

[0228] S702: The source satellite base station sends a context request message to the previous serving core network device. In response, the previous serving core network device receives the context request message.

[0229] The context request message is used to request a context. In the embodiment of the present application, the context refers to the context of the terminal previously served by the serving core network device. The context request message is NGAP signaling, which may carry an NG interface terminal identifier. The NG interface terminal identifier is used to identify the terminal.

[0230] Specifically, the source satellite base station sends a context request message to the previous service core network device through the NG interface, where the context request message carries the NG interface terminal identifier of the connected terminal served by the source satellite base station (for example, the NG interface radio access network side user identifier (RAN UE NGAP ID), or the NG interface access and mobility management function side user identifier (AMF UE NGAP ID)).

[0231] For example, assuming that the context request message is NGAP signaling of UE context retrieve request, the source satellite base station sends NGAP signaling of UE context retrieve request to the previous serving core network device through the NG interface. The NGAP signaling carries the AMF UE NGAP ID of connected terminal 1 served by the source satellite base station. The AMF UE NGAP ID is the unique identifier of the terminal on the NG interface of the AMF network element. Accordingly, the source core network device receives the NGAP signaling of UE context retrieve request, which carries the AMF UE NGAP ID of connected terminal 1 served by the source satellite base station.

[0232] S703: The previous serving core network device sends a context response to the source satellite base station. In response, the source satellite base station receives the context response.

[0233] The context response is used to respond to the context request message. The context response carries the terminal context indicated by the NG interface terminal identifier. The context includes the terminal identifier, security parameters, and mobility management parameters. The terminal identifier refers to information identifying the terminal. Security parameters refer to parameters used by the terminal to securely transmit the context. Mobility management parameters refer to parameters required by the terminal to perform mobility management operations, such as the terminal's air interface configuration parameters when performing cell handover.

[0234] Optionally, after the previous serving core network device sends a context response to the source satellite base station, the context of the terminal indicated by the NG interface terminal identifier may be released to save resources of the previous serving core network device.

[0235] For example, it is assumed that the context request message is the NGAP signaling of UE context retrieve request, and the context response is the NGAP signaling of UE context response. The source satellite base station sends the NGAP signaling of UE context retrieve request to the previous serving core network device through the NG interface, and the NGAP signaling carries the AMF UE NGAP ID of the connected terminal 1 served by the source satellite base station. The AMF UE NGAP ID is the unique identifier of the terminal on the NG interface of the AMF network element. Accordingly, the source core network device receives the NGAP signaling of UE context retrieve request, and further, the source core network device sends the NGAP signaling of UE context response to the source satellite base station, wherein the NGAP signaling of UE context response carries the context of the terminal identified by the AMF UE NGAP ID.

[0236] S704: The source satellite base station and the target core network device initiate NG interface establishment.

[0237] The NG interface is an interface for data exchange between the source satellite base station and the target core network device. The process of starting the establishment of the NG interface between the source satellite base station and the target core network device can refer to the existing technology and will not be described in detail.

[0238] Optionally, the source satellite base station receives the context in the context response and further caches the context locally, so that when the source satellite base station uses the context again, it can quickly obtain the context locally, thereby improving the response speed of the source satellite base station in obtaining the context.

[0239] S705: The source satellite base station sends NGAP signaling carrying the context to the target core network device. Correspondingly, the target core network device receives the NGAP signaling carrying the context.

[0240] Among them, NGAP signaling refers to the information used by access network devices in 5G networks to communicate with AMF network elements in core network devices. In this application, NGAP signaling carries context.

[0241] Exemplarily, an available NG interface is established between the source satellite base station and the target core network device, and the source satellite base station sends an NGAP signaling of upload UE context to the target core network device through the NG interface, where the NGAP signaling carries the context.

[0242] S706: The target core network device provides services to the source satellite base station based on the context.

[0243] Specifically, after the target core network device receives the context of the terminal, it provides services to the source satellite base station and the terminal served by the source satellite base station based on the context of the terminal, so that the target core network device successfully takes over the previous service core network device to provide services to the source satellite base station and the terminal served by the source satellite base station.

[0244] Further optionally, in the case where the target core network device updates the context, for example, the target core network device allocates a new NG interface identifier (RAN UE NGAP ID or AMF UE NGAP ID) to the terminal, S707 is executed. In this case, the update information sent by the target core network device to the source satellite base station includes the new NG interface identifier allocated to the terminal by the target core network device. In the case where the target core network device does not update the context of the terminal, for example, all configuration information in the context received by the target core network device is applicable to the target core network device, S707 is not executed.

[0245] S707: The target core network device sends update information to the source satellite base station. Correspondingly, the source satellite base station receives the update information and updates the context based on the update information.

[0246] The update information is used to update the context, and the update information may include the updated context of the target core network device; or may include different information between the context of the terminal after the target core network device is updated and the context of the terminal before the update.

[0247] S708: The source satellite base station sends update information to the terminal. In response, the terminal receives the update information and updates the context in the terminal based on the updated update information.

[0248] Based on the communication method shown in Figure 7, when the target core network device is taking over the service of the previous serving core network device to provide services for the source satellite base station, and there is no available interface between the previous serving core network device and the target core network device, the context of the terminal served by the previous serving core network device can be relayed to the target core network device through the source satellite base station, so that the target core network device can successfully take over the service of the previous serving core network device to provide services for the source satellite base station, reducing the overhead of the terminal re-initiating the core network device parameter application, and further reducing the switching delay of the source satellite base station from the previous serving core network device to the target core network device.

[0249] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of interaction between various devices. It can be understood that each device, such as a first communication device (for example, a terminal, a source satellite base station), a second communication device (for example, a target satellite base station, a source core network device), a third communication device (for example, a target satellite base station, a target core network device), etc., in order to realize the above functions, includes a hardware structure and / or software module corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0250] In the embodiment of the present application, the functional modules of the first communication device, the second communication device, the third communication device, etc. can be grouped according to the above method example. For example, each functional module can be grouped according to each function, or two or more functions can be integrated into one processing module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the grouping of modules in the embodiment of the present application is schematic and is only a logical functional grouping. In actual implementation, there may be other grouping methods.

[0251] FIG8 shows a structural diagram of a first communication device 800, which can be used to perform the functions of the first communication device involved in the above embodiment. As an implementation method, the first communication device 800 shown in FIG8 includes: a transceiver unit 8001;

[0252] The transceiver unit 8001 is configured to obtain a context from a second communication device; the second communication device is a communication device providing a service to the first communication device; the context is the context of the terminal device served by the second communication device; and is further configured to send the context to a third communication device; the third communication device is a communication device that takes over the service provided by the second communication device to the first communication device. For example, the transceiver unit 8001 may support the first communication device 800 in executing S501 to S503 and S505, or support the first communication device 800 in executing S601 to S603 and S605, or support the first communication device 800 in executing S702 to S703 and S705.

[0253] For the description of the first communication device, the second communication device, the third communication device, and the context, reference may be made to that in the above method embodiment.

[0254] Specifically, all relevant content related to each step involved in the method embodiments shown in Figures 5, 6, and 7 can be referenced in the functional descriptions of the corresponding functional modules and will not be repeated here. The first communication device 800 is used to perform the functions of the terminal in the communication method shown in Figures 5 or 6, thereby achieving the same effects as the above communication methods. The first communication device 800 is used to perform the functions of the source satellite base station in the communication method shown in Figure 7, thereby achieving the same effects as the above communication methods.

[0255] FIG9 shows a structural diagram of a second communication device 900, which can be used to perform the functions of the second communication device involved in the above embodiment. As an implementation method, the second communication device 900 shown in FIG9 includes: a processing unit 9001, a transceiver unit 9002;

[0256] The processing unit 9001 is configured to obtain a context, where the context is a context of a terminal device served by the second communication device. For example, the processing unit 9001 may be configured to support the second communication device 900 in executing S501, S601, or S702.

[0257] The transceiver unit 9002 is configured to send the context to the first communication device. For example, the transceiver unit 9002 may be configured to support the second communication device 900 in executing S502, S602, or S703.

[0258] For the description of the first communication device, the second communication device, and the context, reference may be made to that in the above method embodiment.

[0259] Specifically, all relevant contents of each step involved in the method embodiments shown in Figures 5, 6, and 7 can be referred to the functional description of the corresponding functional modules and will not be repeated here. The second communication device 900 is used to perform the function of the source satellite base station in the communication method shown in Figure 5, thereby achieving the same effect as the above-mentioned communication method. The second communication device 900 is used to perform the function of the previous service base station in the communication method shown in Figure 6, thereby achieving the same effect as the above-mentioned communication method. The second communication device 900 is used to perform the function of the previous service core network device in the communication method shown in Figure 7, thereby achieving the same effect as the above-mentioned communication method.

[0260] FIG10 shows a structural diagram of a third communication device 1000, which can be used to perform the functions of the third communication device involved in the above embodiment. As an implementation method, the third communication device 1000 shown in FIG10 includes: a transceiver unit 1001, a processing unit 1002;

[0261] The transceiver unit 1001 is configured to receive a context from the first communication device. For example, the transceiver unit 1001 may be configured to support the third communication device 1000 in executing S505, S605, or S705.

[0262] The processing unit 1002 is configured to provide a service for the first communication device based on the context. For example, the processing unit 1002 may be configured to support the third communication device 1000 in executing S506, S606, or S706.

[0263] For the description of the first communication device, the third communication device, and the context, reference may be made to that in the above method embodiment.

[0264] Specifically, all relevant content related to each step involved in the method embodiments shown in Figures 5, 6, and 7 can be referenced in the functional descriptions of the corresponding functional modules and will not be repeated here. The third communication device 1000 is used to perform the functions of the target satellite base station in the communication method shown in Figures 5 or 6, thereby achieving the same effects as the above communication methods. The third communication device 1000 is used to perform the functions of the target core network device in the communication method shown in Figure 7, thereby achieving the same effects as the above communication methods.

[0265] The processing unit mentioned above can be a processing module, or a processor or a controller. It can implement or execute the various exemplary logical blocks, modules and circuits described in conjunction with the contents disclosed in this application. The processor can also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc. The transceiver unit can be a communication module, or a transceiver circuit or a communication interface, etc. Any of the communication devices mentioned above can also include a storage unit, which is used to store program code and data of any communication device. The storage unit can be a storage module or a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the first communication device 800, the second communication device 900, and the third communication device 1000 involved in the embodiment of the present application can be the communication device 1100 shown in Figure 11. For example, the terminal, source satellite base station, target satellite base station, source core network device, and target core network device mentioned above can adopt the structure shown in Figure 11 or include the components shown in Figure 11. FIG11 is a schematic diagram of the composition of a communication device 1100 provided in an embodiment of the present application. As shown in FIG11 , the communication device 1100 may include a processor 1101 , a communication line 1102 , and a communication interface 1103 .

[0266] Furthermore, the communication device 1100 may further include a memory 1104 . The processor 1101 , the memory 1104 and the communication interface 1103 may be connected via a communication line 1102 .

[0267] The processor 1101 may be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. The processor 1101 may also be other communication devices with processing capabilities, such as circuits, devices, or software modules.

[0268] The communication line 1102 is used to transmit information between the components included in the communication device 1100.

[0269] The communication interface 1103 is used to communicate with other devices or other communication networks. The other communication network can be Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc. The communication interface 1103 can be a radio frequency module, a transceiver, or any communication device capable of achieving communication. The embodiment of the present application is described using the communication interface 1103 as an example of a radio frequency module, wherein the radio frequency module may include an antenna, a radio frequency circuit, etc., and the radio frequency circuit may include a radio frequency integrated chip, a power amplifier, etc.

[0270] The memory 1104 is used to store instructions, where the instructions may be computer programs.

[0271] Among them, the memory 1104 can be a read-only memory (ROM) or other types of static storage devices that can store static information and / or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and / or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage, magnetic disk storage media or other magnetic storage devices, and optical disc storage includes compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.

[0272] It should be noted that the memory 1104 can exist independently of the processor 1101 or can be integrated with the processor 1101. The memory 1104 can be used to store instructions, program code, or some data. The memory 1104 can be located within the communication device 1100 or outside the communication device 1100, without limitation. The processor 1101 is configured to execute the instructions stored in the memory 1104 to implement the random access procedure preamble transmission method provided in the following embodiments of the present application.

[0273] In one example, the processor 1101 may include one or more CPUs, such as CPU0 and CPU1 in FIG. 11 .

[0274] As an optional implementation, the communication device 1100 includes multiple processors. For example, in addition to the processor 1101 in FIG. 11 , it may also include a processor 1107 .

[0275] As an optional implementation, the communication apparatus 1100 further includes an output device 1105 and an input device 1106. The input device 1106 is a keyboard, a mouse, a microphone, or a joystick, and the output device 1105 is a display screen, a speaker, or other devices.

[0276] It should be noted that the communication device 1100 may be a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system, or a device having a structure similar to that shown in FIG11 . Furthermore, the component structure shown in FIG11 does not limit the communication device. In addition to the components shown in FIG11 , the communication device may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0277] In the embodiment of the present application, the chip system can be composed of chips, or can include chips and other discrete devices.

[0278] The embodiments of the present application also provide a computer-readable storage medium. All or part of the processes in the above-mentioned method embodiments can be completed by a computer program to instruct the relevant hardware. The program can be stored in the above-mentioned computer-readable storage medium. When the program is executed, it can include the processes of the above-mentioned method embodiments. The computer-readable storage medium can be a terminal device of any of the above-mentioned embodiments, such as: an internal storage unit including a data transmission end and / or a data receiving end, such as a hard disk or memory of the terminal device. The above-mentioned computer-readable storage medium can also be an external storage device of the above-mentioned terminal device, such as a plug-in hard disk, a smart memory card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the above-mentioned terminal device. Furthermore, the above-mentioned computer-readable storage medium can also include both the internal storage unit of the above-mentioned terminal device and an external storage device. The above-mentioned computer-readable storage medium is used to store the above-mentioned computer program and other programs and data required by the above-mentioned terminal device. The above-mentioned computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0279] It should be understood that the collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in the technical solution of this application complies with relevant laws and regulations and does not violate public order and good morals. For example, in the technical solution of this application, the processing of user personal information is carried out with the user's authorization, and the same description is not repeated here.

[0280] It should be noted that the terms "first" and "second" in the specification, claims, and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products, or devices.

[0281] It should be understood that in the present application, "at least one (item)" refers to one or more, "more than one" refers to two or more, "at least two (items)" refers to two or three and more than three, and "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0282] It should be understood that in the embodiments of the present application, "B corresponding to A" means that B is associated with A. For example, B can be determined based on A. It should also be understood that determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information. In addition, the "connection" in the embodiments of the present application refers to various connection methods, such as direct connection and indirect connection, to achieve communication between devices, and the embodiments of the present application do not impose any limitations on this.

[0283] Unless otherwise specified, the "transmission" (transmit / transmission) appearing in the embodiments of the present application refers to bidirectional transmission, including the actions of sending and / or receiving. Specifically, the "transmission" in the embodiments of the present application includes the sending of data, the receiving of data, or the sending of data and the receiving of data. In other words, the data transmission here includes uplink and / or downlink data transmission. Data may include channels and / or signals, uplink data transmission is uplink channel and / or uplink signal transmission, and downlink data transmission is downlink channel and / or downlink signal transmission. The "network" and "system" appearing in the embodiments of the present application express the same concept, and the communication system is the communication network.

[0284] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the grouping of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be grouped into different functional modules to complete all or part of the functions described above.

[0285] In the several embodiments provided in this application, it should be understood that the disclosed communication devices and methods can be implemented in other ways. For example, the communication device embodiments described above are merely illustrative. For example, the grouping of the modules or units is merely a logical functional grouping. In actual implementation, there may be other grouping methods, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0286] The units described as separate components may or may not be physically separate, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0287] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0288] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a device, such as a single-chip microcomputer, a chip, etc., or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media for storing program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0289] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that, Applied to a first communication device; the method includes: Obtain context from a second communication device; the second communication device is a communication device that provides services to the first communication device; the context is the context of a terminal device served by the second communication device; Send the context to a third communication device; the third communication device is a communication device that takes over from the second communication device to provide services to the first communication device.

2. The method according to claim 1, wherein: The first communication device is the terminal device, the second communication device is a first access network device, and the third communication device is a second access network device.

3. The method according to claim 2, wherein The sending the context to the third communication device includes: Receive first indication information from the second access network device, the first indication information being used to indicate a first time-frequency resource; Send the context to the second access network device through the first time-frequency resource.

4. The method according to claim 2 or 3, wherein: The first indication information is carried in a random access response, or The first indication information is carried in radio resource control (RRC) signaling.

5. The method according to any one of claims 2 to 4, characterized in that, The method further includes: Send second indication information to the second access network device, the second indication information being used to indicate sending the context to the second access network device.

6. The method according to claim 5, wherein: The second indication information is carried in a random access request, or The second indication information is carried in an RRC resume request message.

7. The method according to claim 1, wherein The first communication device is an access network device, the second communication device is a first core network device, and the third communication device is a second core network device.

8. The method according to claim 7, wherein An next generation (NG) interface is established between the access network device and the second core network device; the sending the context to the third communication device includes: Send next generation application protocol (NGAP) signaling carrying the context to the second core network device through the NG interface.

9. The method according to claim 2, characterized in that, The obtaining the context from the second communication device includes: Receive the context from the first access network device according to an RRC release signaling.

10. The method according to any one of claims 1-9, characterized in that, The obtaining the context from the second communication device includes: Send a first request message to the second communication device, the first request message being used to request the context; Receive the context from the second communication device.

11. The method according to claim 10, wherein: The first request message is a handover request message, or The first request message is a context request message.

12. The method according to any one of claims 1-11, characterized in that, The method further includes: Receive update information from the third communication device, the update information being used to update the context.

13. The method according to any one of claims 1-12, characterized in that, The method further includes: Cache the context.

14. A communication method, characterized in that, Applied to a second communication device; the second communication device is a communication device that provides services to a first communication device, the method includes: Obtain context; the context is the context of a terminal device served by the second communication device; Send the context to the first communication device.

15. The method according to claim 14, wherein: The first communication device is the terminal device, and the second communication device is the first access network device.

16. The method according to claim 15, wherein The method further includes: Sending a Radio Resource Control (RRC) release signaling, where the RRC release signaling is used to instruct the first communication device to receive the context.

17. The method according to claim 14, wherein, The first communication device is an access network device, and the second communication device is the first core network device.

18. The method according to claim 14 or 17, characterized in that The sending the context to the first communication device includes: Receiving a first request message from the first communication device, where the first request message is used to request the context; Sending the context to the first communication device.

19. The method according to claim 18, wherein, The first request message is a handover request message, or The first request message is a context request message.

20. A communication method, characterized in that, Applied to a third communication device; the third communication device is a communication device that provides services for the first communication device; the method includes: Receiving a context from the first communication device; Providing services for the first communication device based on the context.

21. The method according to claim 20, wherein, The first communication device is a terminal device, and the third communication device is a second access network device.

22. The method according to claim 21, wherein The receiving the context from the first communication device includes: Sending first indication information to the terminal, where the first indication information is used to indicate a first time-frequency resource; Receiving the context from the terminal device through the first time-frequency resource.

23. The method according to claim 21 or 22, wherein, The first indication information is carried in a random access response, or The first indication information is carried in a Radio Resource Control (RRC) signaling.

24. The method according to any one of claims 21-23, characterized in that, The method further includes: Receiving second indication information from the terminal, where the second indication information is used to indicate sending the context to the second access network device.

25. The method according to any one of claims 21-24, wherein, The second indication information is carried in a random access request, or The second indication information is carried in an RRC resume request message.

26. The method according to claim 20, wherein The first communication device is an access network device, and the third communication device is a second core network device.

27. The method according to claim 26, wherein An Next Generation (NG) interface is established between the access network device and the second core network device; the receiving the context from the first communication device includes: Receiving Next Generation Application Protocol (NGAP) signaling from the access network device through the NG interface, where the NGAP signaling carries the context.

28. The method according to claim 20, wherein The method further includes: Sending update information to the first communication device, where the update information is used to update the context.

29. A first communication device, characterized in that, The first communication device includes: A transceiver unit, configured to obtain a context from a second communication device; the second communication device is a communication device that provides services for the first communication device; the context is a context of a terminal device served by the second communication device; The transceiver unit is further configured to send the context to a third communication device, where the third communication device is a communication device that takes over the second communication device to provide services for the first communication device.

30. A second communication device, characterized in that, The second communication device is a communication device that provides services for the first communication device; The second communication device includes: A processing unit, configured to obtain a context, where the context is the context of a terminal device served by the second communication device; A transceiver unit, configured to send the context to the first communication device.

31. A third communication device, characterized in that, The third communication device is a communication device that provides services for the first communication device; The third communication device includes: A transceiver unit, configured to receive the context from the first communication device; A processing unit, configured to provide services for the first communication device based on the context.

32. A communication device, characterized in that, The communication device includes a processor and a communication interface, where the processor and the communication interface are used to support the communication device to execute the communication method according to any one of claims 1-13, or execute the method according to any one of claims 14-19; or execute the communication method according to any one of claims 20-28.

33. A communication system, characterized in that, The communication system includes the first communication device according to claim 29, the second communication device according to claim 30, and the third communication device according to claim 31.

34. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the method according to any one of claims 1-13, or the computer is caused to execute the method according to any one of claims 14-19, or the computer is caused to execute the method according to any one of claims 20-28.

35. A computer program product, characterized in that, The computer program product includes computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the method according to any one of claims 1-13, or the computer is caused to execute the method according to any one of claims 14-19, or the computer is caused to execute the method according to any one of claims 20-28.

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