Communication method, communication device and communication system

Abstract

The invention provides a communication method, a communication device and a communication system. The method comprises: a first access network device on a satellite determines that an RNA of a terminal device is to be moved out or has been moved out of the RNA of the terminal device within a first duration, wherein the terminal device is in an RRC inactive state or an RRC idle suspended state; and sending a first message to ground equipment, wherein the first message comprises the context of the terminal equipment. According to the scheme, when the first access network device is about to move out of the RNA of the terminal device, the context of the terminal device is actively sent to the ground device for storage, so that when other access network devices need to use the context of the terminal device, if the context of the terminal device cannot be obtained from the first access network device, the context of the terminal device can be obtained. If yes, the context of the terminal equipment can be requested from the ground equipment, so that the success rate of acquiring the context of the terminal equipment is increased, and better communication service can be provided for the terminal equipment.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a communication method, a communication device, and a communication system. Background Art

[0002] The fifth-generation mobile communication system (5GS) boasts high bandwidth, high reliability, and low latency. With the advancement of satellite communication technology, the bandwidth capacity of communication satellites has increased significantly while costs have decreased. The convergence of satellite networks and fifth-generation (5G) networks is emerging. Their powerful coverage capabilities will enable 5G networks to reach remote, sparsely populated areas, as well as areas difficult to reach by terrestrial networks, such as oceans and isolated islands.

[0003] When a terminal device in a radio resource control (RRC) inactive state or an RRC idle suspended state wants to restore the RRC connection, the terminal device can initiate an RRC recovery process to an access network device on a satellite currently covering the terminal device (hereinafter referred to as access network device 1). Then, the access network device 1 obtains the context of the terminal device from an access network device on another satellite (hereinafter referred to as access network device 2) and restores the terminal device to an RRC connected state based on the context of the terminal device. Here, access network device 2 can be the access network device that releases the terminal device to the RRC inactive state or the RRC idle suspended state, or it can be another access network device.

[0004] However, since the satellite is always moving, access network device 1 may not be able to connect to access network device 2, resulting in the inability to obtain the context of the terminal device from access network device 2, and therefore the inability to restore the terminal device to the RRC connection state, affecting the normal communication of the terminal device. Summary of the Invention

[0005] The embodiments of the present application provide a communication method, a communication device, and a communication system to provide better communication services for terminal devices.

[0006] In a first aspect, an embodiment of the present application provides a communication method, which can be performed by a first access network device on a satellite or a module (such as a chip) in the first access network device on a satellite. The method includes: determining that the first access network device will move out of a radio access network-based notification area (RAN-based notification area, RNA) of a terminal device within a first time period or has already moved out of the RNA of the terminal device, and the terminal device is in an RRC inactive state or an RRC idle suspended state; and sending a first message to a ground device, where the first message includes a context of the terminal device.

[0007] In the above scheme, when the first access network device is about to remove the RNA of the terminal device, it actively sends the context of the terminal device to the ground device for storage, so that when other access network devices need to use the context of the terminal device, if they cannot obtain the context of the terminal device from the first access network device, they can request the ground device to obtain the context of the terminal device, thereby increasing the success rate of obtaining the context of the terminal device and helping to provide better communication services for the terminal device.

[0008] In one possible implementation method, the first message also includes a first identifier associated with the context of the terminal device; wherein, the terminal device is in an RRC inactive state, and the first identifier is an inactive radio network temporary identifier (I-RNTI); or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0009] In a possible implementation method, the first message also includes indication information, and the indication information indicates to release the user plane connection of the terminal device.

[0010] In a second aspect, an embodiment of the present application provides a communication method, which can be performed by a second access network device on a satellite or a module (such as a chip) in the second access network device on a satellite. The method includes: receiving a first request message from a terminal device, the first request message being used to request restoration of an RRC connection, the first request message including a first identifier; when the first access network device corresponding to the first identifier has been removed from the RNA of the terminal device, sending a second request message to a ground device, the second request message being used to request a context for the terminal device; and receiving the context of the terminal device from the ground device.

[0011] In the above solution, if the second access network device cannot obtain the context of the terminal device from the first access network device, it can request the ground device to obtain the context of the terminal device, thereby increasing the success rate of obtaining the context of the terminal device and helping to provide better communication services for the terminal device.

[0012] In a possible implementation method, the method further includes: sending an RRC recovery message to the terminal device, where the RRC recovery message is used to trigger the terminal device to enter an RRC connected state.

[0013] In a possible implementation method, the method further includes: sending indication information to the terminal device, wherein the indication information instructs the terminal device to remain in an RRC inactive state.

[0014] In a possible implementation method, the method further includes: determining, based on ephemeris information, that the first access network device has been moved out of the RNA of the terminal device.

[0015] In a possible implementation method, the second request message also includes the first identifier, and the second request message is used to request the context of the terminal device associated with the first identifier.

[0016] In a possible implementation method, the method further includes: sending a path switching request message to a mobility management network element, where the path switching request message is used to instruct the second access network device to provide service for the terminal device.

[0017] In a possible implementation method, the method further includes: sending a third request message to the ground device, where the third request message is used to request the ground device to release the context of the terminal device.

[0018] In the above solution, after the second access network device has successfully acquired the context of the terminal device from the ground device, the ground device can release the stored context of the terminal device, thereby saving storage space.

[0019] In one possible implementation method, the terminal device is in an RRC inactive state, and the first identifier is an I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0020] In a third aspect, an embodiment of the present application provides a communication method, which can be executed by a ground device or a module (such as a chip) in the ground device. The method includes: receiving trigger information, the trigger information including signaling or data to be sent to a terminal device, the terminal device being in an RRC inactive state or an RRC idle suspended state; determining the RNA of the terminal device according to a first area, the first area being the area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; sending a paging message to at least one access network device in the RNA, the paging message being used to page the terminal device.

[0021] In the above solution, the ground device stores the terminal device's context and can proactively send a paging message to at least one access network device within the terminal device's RNA. If one or more of these access network devices pages the terminal device based on the paging message, the ground device can request the terminal device's context from the ground device. This solution increases the success rate of obtaining the terminal device's context, helping to provide better communication services for the terminal device.

[0022] In one possible implementation method, the method further includes: receiving a request message from a second access network device among the at least one access network device, the request message being used to request the context of the terminal device; and sending the context of the terminal device to the second access network device.

[0023] In a possible implementation method, the request message further includes a first identifier, and the request message is used to request the context of the terminal device associated with the first identifier.

[0024] In one possible implementation method, the terminal device is in an RRC inactive state, and the first identifier is an I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0025] In a possible implementation method, the method further includes: determining the at least one access network device based on the ephemeris information and the RNA.

[0026] In a fourth aspect, an embodiment of the present application provides a communication method, which can be executed by a ground device or a module (such as a chip) in the ground device. The method includes: receiving trigger information, the trigger information including signaling or data to be sent to a terminal device, the terminal device being in an RRC inactive state or an RRC idle suspended state; determining the RNA of the terminal device based on a first area, the first area being the area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; and sending the context of the terminal device to a second access network device within the RNA.

[0027] In the above solution, the ground device stores the terminal device's context and can proactively send the terminal device's context to the second access network device within the terminal device's RNA. This solution, in which the ground device proactively sends the terminal device's context to the second access network device, increases the success rate of the second access network device acquiring the terminal device's context, helping to provide better communication services for the terminal device.

[0028] In a possible implementation method, the method further includes: determining the second access network device based on the ephemeris information and the RNA.

[0029] In a fifth aspect, an embodiment of the present application provides a communication device, which may be a first access network device on a satellite, or a module (such as a chip) in the first access network device on a satellite. The device has the function of implementing any implementation method of the first aspect described above. The function may be implemented by hardware, or by hardware executing corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

[0030] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a second access network device on a satellite, or a module (such as a chip) in the second access network device on a satellite. The device has the function of implementing any implementation method of the second aspect described above. The function may be implemented by hardware, or by hardware executing corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

[0031] In a seventh aspect, an embodiment of the present application provides a communication device, which can be a ground device or a module (such as a chip) in the ground device. The device has the function of implementing any of the implementation methods of the third to fourth aspects above. The function can be implemented by hardware or by hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above functions.

[0032] In an eighth aspect, an embodiment of the present application provides a communication device, comprising a unit or means for executing each step of any implementation method in the above-mentioned first to fourth aspects.

[0033] In a ninth aspect, an embodiment of the present application provides a communication device, comprising a processor and an interface circuit, wherein the processor is configured to communicate with other devices via the interface circuit and execute any of the implementation methods described in the first to fourth aspects. The processor comprises one or more.

[0034] Optionally, the communication device may further include a memory for storing computer instructions, the memory being coupled to a processor, and the processor executing the computer instructions stored in the memory so that the device executes any implementation method in the above-mentioned first to fourth aspects.

[0035] In the tenth aspect, an embodiment of the present application also provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are run by a communication device, any implementation method in the above-mentioned first to fourth aspects is executed.

[0036] In the eleventh aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, which, when run on a communication device, enables any implementation method in the above-mentioned first to fourth aspects to be executed.

[0037] In the twelfth aspect, the present application provides a chip (or chip system), which includes a processor, the processor is coupled to a memory, and the memory stores a computer program; the processor is used to call part or all of the computer program in the memory, so that any implementation method of the above-mentioned first to fourth aspects is executed.

[0038] In the thirteenth aspect, the present application provides a communication system, including a ground device and a first access network device on a satellite; the first access network device is used to execute any implementation method of the first aspect; the ground device is used to receive a first message from the first access network device, and the first message includes the context of the terminal device.

[0039] In the fourteenth aspect, the present application provides a communication system, including a ground device and a second access network device on a satellite; the second access network device is used to execute any implementation method of the second aspect; the ground device is used to receive a second request message from the second access network device, the second request message is used to request the context of the terminal device; and send the context of the terminal device to the second access network device.

[0040] In the fifteenth aspect, the present application provides a communication system comprising a ground device and at least one access network device; the ground device is used to execute any implementation method of the third aspect; the at least one access network device is used to receive a paging message from the ground device, and the paging message is used to page a terminal device.

[0041] In the sixteenth aspect, the present application provides a communication system, including a ground device and a second access network device; the ground device is used to execute any implementation method of the fourth aspect; the second access network device is used to receive the context of the terminal device from the ground device. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the 5G network architecture based on service-oriented architecture;

[0043] Figure 2 This is a schematic diagram of a satellite access scenario where a satellite-borne base station is deployed on a satellite;

[0044] Figure 3 This is an example image of satellite coverage;

[0045] Figure 4(a) to Figure 4(d) A flow chart of a communication method provided in an embodiment of the present application;

[0046] Figures 5 to 7 A flow chart of a communication method provided in an embodiment of the present application;

[0047] Figures 8 and 9 A schematic diagram of the structure of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] Figure 1 Schematic diagram of 5G network architecture based on service-oriented architecture. Figure 1The 5G network architecture shown includes a data network (DN) and a carrier network. The following briefly describes the functions of some of these network elements.

[0049] The operator network includes one or more of the following network elements: authentication server function (AUSF) network element, unified data repository (UDR) network element, policy control function (PCF) network element, unified data management (UDM) network element, access and mobility management function (AMF) network element, application function (AF) network element, session management function (SMF) network element, network repository function (NRF) network element, network exposure function (NEF) network element, user plane function (UPF) network element, access network (AN) equipment (in the figure, the AN equipment is a radio access network (RAN) equipment as an example), etc. In the above operator network, network elements or equipment other than the access network equipment can be referred to as core network network elements or core network equipment.

[0050] Access network equipment includes wired access network equipment and wireless access network equipment. Among them, the wireless access network equipment can be a base station, an evolved base station (eNodeB), a transmission reception point (TRP), a next-generation base station (next generation NodeB, gNB) in a 5G mobile communication system, a next-generation base station in a sixth-generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a wireless fidelity (WiFi) system, etc.; it can also be a module or unit that completes part of the functions of a base station, for example, it can be a centralized unit (CU) or a distributed unit (DU). The embodiments of the present application do not limit the specific technology and specific equipment form adopted by the access network equipment.

[0051] Terminal devices that communicate with access network devices include terminals, user equipment (UE), mobile stations, mobile terminals, etc. The figure takes the terminal device as an example of UE. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. The terminal can be a mobile phone, tablet computer, computer with wireless transceiver function, wearable device, vehicle, drone, helicopter, airplane, ship, robot, robotic arm, smart home device, etc. The embodiments of this application do not limit the specific technology and specific device form adopted by the terminal device.

[0052] Access network equipment and terminal devices can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water; or in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of access network equipment and terminal devices.

[0053] The mobility management network element is mainly used for the attachment, mobility management, and tracking area update (TAU) processes of terminal devices in mobile networks. The access management network element terminates the non-access stratum (NAS) message, completes registration management, connection management, reachability management, and mobility management, allocates the tracking area list (TAlist), and transparently routes the session management (SM) message to the session management network element. In 5G communications, the mobility management network element can be an AMF network element. In future communications such as the 6th generation (6G) communications, the mobility management network element can still be an AMF network element, or have other names, which are not limited in this application.

[0054] The session management network element is a control plane network element provided by the operator network, which is responsible for managing the protocol data unit (PDU) session of the terminal device. The PDU session is a channel for transmitting PDUs, and the terminal device transmits PDUs to each other with the DN through the PDU session. The SMF network element is responsible for establishing, maintaining and deleting the PDU session. The session management network element includes session management (such as session establishment, modification and release, including tunnel maintenance between user plane network elements and access network equipment), selection and control of user plane network elements, service and session continuity (SSC) mode selection, roaming and other session-related functions. In 5G communications, the session management network element can be an SMF network element. In future communications such as 6G communications, the session management network element can still be an SMF network element, or have other names, which are not limited in this application.

[0055] The user plane network element is a gateway provided by the operator and serves as the gateway for communication between the operator network and the DN. The user plane network element includes user plane related functions such as data packet routing and transmission, packet detection, service usage reporting, quality of service (QoS) processing, lawful interception, uplink packet detection, downlink data packet storage, etc. In 5G communications, the user plane network element can be a UPF network element. In future communications such as 6G communications, the user plane network element can still be a UPF network element or have other names, which are not limited in this application.

[0056] The unified data management network element is a control plane network element provided by the operator, responsible for storing information such as the subscriber permanent identifier (SUPI), credentials, security context, and subscription data of subscribers in the operator's network. This information stored by the data management network element can be used for authentication and authorization of terminal devices accessing the operator's network. Specifically, subscribers of the operator's network may be users who use services provided by the operator's network, such as users who use China Telecom's mobile phone SIM cards or users who use China Mobile's mobile phone SIM cards. The SUPI of the subscriber may be the number of the mobile phone SIM card, etc. The credentials and security context of the subscriber may be small files storing the encryption key of the mobile phone SIM card or information related to the encryption of the mobile phone SIM card, used for authentication and / or authorization. The security context may be data (cookie) or token stored on the user's local terminal (such as a mobile phone). The subscription data of the subscriber may be the supporting services of the mobile phone SIM card, such as the data package or network usage of the mobile phone SIM card. It should be noted that SUPI, credentials, security context, authentication data (cookie), and token are equivalent to authentication and authorization-related information. In this application document, for the sake of convenience of description, no distinction or restriction is made. Unless otherwise specified, the embodiments of this application will be described using security context as an example, but the embodiments of this application are also applicable to authentication and / or authorization information expressed in other ways. In 5G communications, the unified data management network element can be a UDM network element. In future communications such as 6G communications, the unified data management network element can still be a UDM network element, or have other names, which are not limited in this application.

[0057] The unified database network element is a control plane network element provided by the operator, which includes the access function of executing contract data, policy data, application data, and other types of data. In 5G communications, the unified database network element can be a UDR network element. In future communications such as 6G communications, the unified database network element can still be a UDR network element or have other names, which are not limited in this application.

[0058] The network open network element is a control plane network element provided by the operator. The network open network element opens the external interface of the operator network to a third party in a secure manner. When the session management network element needs to communicate with the network element of a third party, the network open network element can serve as a relay for the communication between the session management network element and the network element of the third party. When the network open network element acts as a relay, it can translate the identification information of the subscriber, as well as the identification information of the third-party network element. For example, when the network open network element sends the SUPI of the subscriber from the operator network to the third party, the SUPI can be translated into its corresponding external identity. Conversely, when the network open network element sends the external ID (the network element ID of the third party) to the operator network, it can be translated into SUPI. In 5G communication, the network open network element can be a NEF network element. In future communications such as 6G communication, the network open network element can still be a NEF network element, or have other names, which are not limited in this application.

[0059] The application function network element is used to convey the requirements of the application side to the network side, such as quality of service (QoS) requirements or user status event subscriptions. The application function network element can be a third-party functional entity or an application server deployed by the operator. In 5G communication, the application function network element can be an AF network element. In future communications such as 6G communication, the application function network element can still be an AF network element or have other names, which are not limited in this application.

[0060] The policy control network element is a control plane function provided by the operator, including user subscription data management, policy control, charging policy control, QoS control, etc. In 5G communications, the policy control network element can be a PCF network element. In future communications such as 6G communications, the policy control network element can still be a PCF network element or have other names, which are not limited in this application.

[0061] The network storage function network element can be used to provide network element discovery function, and provide network element information corresponding to the network element type based on the request of other network elements. The network storage function network element also provides network element management services, such as network element registration, update, deregistration, and network element status subscription and push. In 5G communication, the network storage function network element can be an NRF network element. In future communications such as 6G communication, the network storage function network element can still be an NRF network element, or have other names, which are not limited in this application.

[0062] A DN is a network located outside of a carrier network. A carrier network can connect to multiple DNs, and a variety of services can be deployed on the DN, providing data and / or voice services to terminal devices. For example, a DN is the private network of a smart factory. Sensors installed in the workshop can be terminal devices. The DN houses a sensor control server, which provides services to the sensors. Sensors can communicate with the control server, receive instructions from the control server, and transmit collected sensor data to the control server based on the instructions. Another example is a DN that is a company's internal office network. An employee's mobile phone or computer can be a terminal device, allowing them to access information and data resources on the company's internal office network.

[0063] Figure 1 Nausf, Npcf, Nudr, Nudm, Naf, Namf, Nsmf, Nnrf, and Nnef are service-oriented interfaces provided by the above-mentioned AUSF network element, PCF network element, UDR network element, UDM network element, AF network element, AMF network element, SMF network element, NRF network element, and NEF network element, respectively, and are used to call corresponding service-oriented operations. N1, N2, N3, N4, and N6 are interface serial numbers, and their meanings are as follows:

[0064] 1) N1: The interface between the AMF network element and the terminal device, which can be used to transmit non-access stratum (NAS) signaling (such as QoS rules from the AMF network element) to the terminal device.

[0065] 2) N2: The interface between the AMF network element and the radio access network equipment, which can be used to transmit radio bearer control information from the core network side to the radio access network equipment.

[0066] 3) N3: The interface between the wireless access network equipment and the UPF network element, mainly used to transmit uplink user plane data and / or downlink user plane data between the wireless access network equipment and the UPF network element.

[0067] 4) N4: The interface between the SMF network element and the UPF network element, which can be used to transmit information between the control plane and the user plane, including controlling the issuance of forwarding rules, QoS rules, traffic statistics rules, etc. for the user plane and reporting information on the user plane.

[0068] 5) N6: The interface between the UPF network element and the DN, used to transmit uplink user data flow and / or downlink user data flow between the UPF network element and the DN.

[0069] It is understood that the above-mentioned network element or function can be a network element in a hardware device, a software function running on dedicated hardware, or a virtualized function instantiated on a platform (e.g., a cloud platform). Optionally, the above-mentioned network element or function can be implemented by a single device, or by multiple devices, or can be a functional module within a single device, and this is not specifically limited in the embodiments of the present application.

[0070] For ease of explanation, in the embodiments of this application, a base station is used as an example of an access network device for explanation, and any base station appearing anywhere in the following can be replaced with an access network device. A UE is used as an example of a terminal device for explanation, and any UE appearing anywhere in the following can be replaced with a terminal device.

[0071] To facilitate understanding of the content of this application, the nouns or terms involved in this application are introduced below.

[0072] 1. 5GS

[0073] 5GS boasts high bandwidth, high reliability, and low latency. With the development of satellite communication technology, the bandwidth capacity of communication satellites has increased significantly, while costs have decreased. The integration of satellite networks with 5G networks is emerging, and their powerful coverage capabilities can help 5G networks reach remote areas with sparse populations, as well as areas such as oceans and isolated islands that are difficult for terrestrial networks to reach.

[0074] 2. Integration of Satellite Communications and 5GS

[0075] The 3rd Generation Partnership Project (3GPP) already supports the use of satellites as radio frequency modules for ground base stations, providing transparent forwarding capabilities. In addition, 3GPP also considers satellites to support data processing, that is, considering satellites to provide non-transparent forwarding capabilities (or called renewable capabilities). Specifically, it considers deploying base stations on satellites. This application assumes that satellites have renewable capabilities, and considers that satellites are deployed with onboard base stations, and UEs can access the 5G core network through onboard base stations. Among them, onboard base stations are also called onboard RAN, base stations on satellites, base stations deployed on satellites, or satellite base stations, etc. For the sake of convenience, this application will refer to them as onboard base stations.

[0076] Figure 2This diagram illustrates a satellite access scenario with a satellite-based base station deployed on a satellite. A base station deployed on a satellite, also called a satellite-based base station, provides data processing and storage and forwarding capabilities. The link between the satellite and the UE is called the service link. The interface between the UE and the satellite-based base station corresponds to the Uu interface defined by 3GPP. The link between the satellite and the 5GC is called the feeder link. This feeder link carries interfaces between the satellite-based base station and the terrestrial 5GC, including N2 and N3.

[0077] 3. Radio Resource Control (RRC) Inactive State

[0078] Compared to the fourth generation (4G) long term evolution (LTE), 5G new radio (NR) adds an RRC inactive state (also called RRC inactive state). When the UE enters the RRC inactive state from the RRC connected state, both the UE and the base station save the UE context. The UE context refers to the UE access stratum (AS) context.

[0079] In the RRC inactive state, the UE can be quickly restored to the RRC connected state through the RRC resume process, which reduces the RRC reconfiguration process, security mode configuration process, UE context establishment process and authentication process, thereby reducing a large amount of signaling interaction.

[0080] To further reduce the transmission overhead of paging messages for UEs in the RRC inactive state, the concept of "RNA" (tracking area) is introduced. RNA is managed by the base station, and the base station can page the UE based on the RNA to find the UE.

[0081] In one implementation method, the base station may provide a cell ID list to the UE, the cell ID list including one or more cell IDs, and the cell ID list serves as the UE's RNA. Based on this implementation method, the RNA includes one or more cell IDs.

[0082] In another implementation method, the base station may provide a RAN area identifier list to the UE, where the RAN area identifier list includes identifiers of multiple RAN areas (RAN area IDs). Each RAN area identifier uniquely identifies a RAN area, and the RAN area may be a subset of a TA or equal to a TA. Therefore, each RAN area corresponds to one or more cells. Based on this implementation method, the RNA includes identifiers of one or more RAN areas. Exemplarily, the cell under the base station may carry the identifier of the RAN area to which the cell belongs (i.e., the RAN area ID) in the broadcast system message. For example, RAN area 1 includes cell 1, cell 2, and cell 3, and RAN area 2 includes cell 4 and cell 5. Then, the system messages broadcast by cells 1, 2, and 3 include the identifier of RAN area 1, and the system messages broadcast by cells 4 and 5 include the identifier of RAN area 2.

[0083] When the RNA timer of the UE times out, or the UE moves out of the RNA, the UE initiates a RAN-based notification area update (RNAU) process to the base station currently covering the UE (hereinafter referred to as base station #2). Among them, the UE will provide the inactive radio network temporary identifier (I-RNTI) to base station #2, and then base station #2 will send the UE's context extraction request to the last serving base station (Last ServinggNodeB, hereinafter referred to as base station #1). The UE's context extraction request contains I-RNTI. Base station #1 obtains the UE's context locally based on I-RNTI and sends the UE's context to base station #2. Base station #2 will subsequently manage the UE's context. Furthermore, base station #2 can also send a path switch request (PathSwitch request) message to the AMF network element to inform the core network that the base station providing services for the UE has changed. Among them, the last serving base station refers to the base station that last provided services to the UE before the UE entered the RRC inactive state, or it can be understood as the last serving base station before the UE entered the RRC inactive state.

[0084] Figure 3This diagram illustrates satellite coverage. At time T1, the satellite signal from satellite 1 covers a UE on the ground. The UE subsequently enters the RRC inactive state, and the base station on satellite 1 is called the last serving base station. At time T2, after T1, satellite 1 moves out of the UE's satellite coverage area, and the satellite signal from satellite 2 covers the UE. At this point, satellite 2 becomes the current satellite covering the UE. When the UE initiates an RNAU procedure with the base station on satellite 2, the base station on satellite 2 triggers a request from the base station on satellite 1 for the UE's context.

[0085] 4. Internet of Things (IoT) User Plane Optimization

[0086] For IoT applications, since UEs are typically limited in terms of battery life, 5G communication systems have designed mechanisms to support UE energy conservation and high-latency communications. For example, the UE's "user plane optimization" feature allows the UE to establish a UE context (also known as the UE's AS context) between the UE and the base station when in idle state without initiating a service request process. This allows the UE to wake up from energy-saving sleep mode and resume the RRC connected state.

[0087] The UE can be suspended in the idle state, which is called the UE being in the idle suspended state. Similar to the aforementioned RRC inactive state, in IoT application scenarios, before the UE enters the idle suspended state, at least one PDU session has been established through an activated user plane connection, and a UE context has been established between the base station and the UE. Subsequently, when the UE is in the idle suspended state and receives a NAS trigger message, the UE can perform the idle state connection suspension recovery process. In order to ensure the normal use of user plane optimization when the UE moves between different base stations, the UE context is supported to be transferred between different base stations.

[0088] For a UE in an idle suspended state, when the UE's periodic timer expires or the UE enters a new registration area, the UE initiates a tracking area update (TAU) procedure or a registration update procedure. At this time, if the UE is covered by a new base station, the new base station can obtain the UE context from the old base station (i.e., the base station that provided services to the UE before the UE entered the idle suspended state).

[0089] In addition, for IoT scenarios, 3GPP has also designed technology for IoT UE to access 5GS via satellite.

[0090] Currently, the division of RNA can be bound to geographical areas. When a satellite moves over a certain ground geographical area, the onboard base station on the satellite can broadcast an RNA identifier (RNAID) corresponding to the geographical area. The RNA indicated by the RNA identifier is the RNA configured for the UE in the geographical area.

[0091] When a UE in an RRC inactive state requests to restore the RRC connection at a certain moment, the satellite base station currently covering the UE does not have the context of the UE. In addition, since the UE has not moved or has not moved out of a certain geographical area, the UE will not trigger the RNAU process, and will not trigger the satellite base station currently covering the UE to request the last satellite base station serving the UE to obtain the context of the UE in advance. Subsequently, when the RNA timer times out or the UE moves out of the RNA and triggers the UE to initiate RNAU, the satellite base station currently covering the UE will be triggered to request the last satellite base station serving the UE to obtain the context of the UE. At this time, the last satellite base station serving the UE may have moved to a very long distance, resulting in the satellite base station currently covering the UE being unable to request the context of the UE from the last satellite base station serving the UE, which in turn causes the UE to fail to restore the RRC connection, affecting the communication performance of the UE.

[0092] by Figure 3 For example, the onboard base station on satellite 1 is the last onboard base station that provided services to the UE before it entered the RRC inactive state. As the satellite moves, the UE is updated from being covered by the satellite signal of satellite 1 to being covered by the satellite signal of satellite 2. When the UE wants to enter the RRC connected state from the RRC inactive state, the onboard base station of satellite 2 is triggered to request the onboard base station of satellite 1 to obtain the context of the UE. However, at this time, satellite 1 may have moved far away, resulting in the onboard base station of satellite 2 being unable to obtain the context of the UE from the onboard base station of satellite 1. As a result, the UE fails to restore the RRC connection, affecting the communication performance of the UE.

[0093] In addition, similar issues also exist for UEs in idle and suspended states in IoT application scenarios. The difference is that the RNAU process described above is replaced by a TAU process or a registration update process.

[0094] To address this issue, one possible approach is to determine the next satellite covering a UE based on ephemeris information when the satellite no longer covers the UE, and proactively send the UE's context to the next satellite covering the UE. However, this approach requires a high level of continuous relaying of UE context between satellites. This is especially true if a large number of UEs enter the RRC Inactive state, requiring a large amount of UE context to be transmitted between satellites, resulting in significant signaling overhead.

[0095] To address the above issue, another possible implementation method is to set the UE's RNA timer based on ephemeris information. This RNA timer will time out before the satellite-based base station that last served the UE leaves the UE's RNA, causing the UE to trigger the RNAU process. This allows the satellite-based base station of the satellite currently covering the UE to obtain the UE's context from the satellite-based base station that last served the UE before the satellite-based base station that last served the UE leaves the UE's RNA. A problem with this method is that low-orbit satellites move quickly and can quickly move out of the UE's RNA. Therefore, the RNA timer must be set very small, causing the UE to frequently initiate RNAUs, which increases the UE's power consumption.

[0096] To this end, the embodiments of the present application provide corresponding solutions, which can achieve fast and accurate acquisition of UE context without increasing additional signaling overhead and UE power consumption.

[0097] Figure 4(a) is a schematic flow chart of a communication method provided in an embodiment of the present application. The method is executed by a first base station (or a module within the first base station, such as a chip) and a ground device (or a module within the ground device, such as a chip). The following description uses the first base station and the ground device executing the method as an example.

[0098] The method comprises the following steps:

[0099] In step 401a, the first base station determines that it will remove the RNA of the UE within a first time period, or has already removed the RNA of the UE.

[0100] The UE is in an RRC inactive state or an RRC idle suspended state.

[0101] The first base station is a base station on a satellite. For example, the first base station may be the last base station to provide services to the UE before the UE enters the RRC inactive state or the RRC idle suspended state, or it can be understood that the first base station is the base station that releases the UE to the RRC inactive state or the RRC idle suspended state. Figure 3 In the example, the first base station can be a base station on satellite 1.

[0102] Among them, the first duration can be a pre-set duration, such as 5 seconds, 10 seconds or 2 minutes, etc. This application does not limit the specific length of the first duration.

[0103] It should be noted that the above-mentioned RNA that will be removed from the UE within the first period of time can be replaced by: RNA that is about to be removed from the UE, without limitation.

[0104] The first base station may determine, based on the ephemeris information and the RNA of the UE, that the first base station will be moved out of the RNA of the UE within a first time period, or has already been moved out of the RNA of the UE. Specifically, the first base station determines its own position or area based on the ephemeris information, and determines, in combination with the RNA of the UE, whether it is about to be moved out of the RNA of the UE or has already been moved out of the RNA of the UE.

[0105] In step 402a, the first base station sends a first message to the ground device, and the ground device receives the first message accordingly.

[0106] Specifically, if the first base station will remove the RNA of the UE or has already removed the RNA of the UE within the first time period, step 402a is performed. Specifically, the following situations may occur:

[0107] In one case, when the first base station determines that it will move out of the RNA of the UE within a first time period, step 402a is executed.

[0108] In another case, step 402a is performed when the first base station moves out of the RNA of the UE.

[0109] In another case, when the first base station determines that it has been removed from the UE's RNA, step 402a is executed. For example, the first base station executes step 402a within the second time period after removing the UE's RNA. The embodiment of the present application does not impose strict restrictions on the timing of the first base station executing step 402a.

[0110] The first message includes the context of the UE.

[0111] The ground device is deployed on the ground. Specifically, the ground device can be a device between the first base station and the core network. The ground device can be configured independently or integrated with a core network device. This application does not limit the specific type of ground device. The explanation of the ground device is provided here for a unified explanation, and will not be repeated in other subsequent embodiments.

[0112] In the above scheme, when the first base station is about to move out the RNA of the UE, it will actively send the UE context to the ground equipment for storage. When other base stations need to use the UE context, if they cannot obtain the UE context from the first base station, they can request the ground equipment to obtain the UE context, thereby increasing the success rate of obtaining the UE context and helping to provide better communication services for the UE.

[0113] Optionally, in one implementation method of the above solution, the above first message may further include a first identifier associated with the UE's context, so that the ground equipment associates the first identifier with the UE's context and stores the first identifier and the UE's context. It can be understood that the first identifier is an index of the UE's context. Exemplarily, if the UE is in an RRC inactive state, the first identifier is an I-RNTI; or if the UE is in an RRC suspended state, the first identifier is a resume ID.

[0114] Optionally, in an implementation method of the above solution, the first message further includes indication information, where the indication information indicates to release the user plane connection of the UE. The ground equipment releases the user plane connection of the UE according to the indication information.

[0115] The embodiment of Figure 4(a) above introduces the process of storing the UE context in the ground device. The following embodiments of Figures 4(b), 4(c) and 4(d) introduce the specific implementation process of the UE context provided by the ground device.

[0116] Figure 4(b) is a flow chart of a communication method provided in an embodiment of the present application. The method is executed by a second base station (or a module within the second base station, such as a chip) and a ground device (or a module within the ground device, such as a chip). The following description uses the second base station and the ground device executing the method as an example.

[0117] The method comprises the following steps:

[0118] Step 401b: The UE sends a first request message to the second base station. Correspondingly, the second base station receives the first request message.

[0119] The first request message may be used to request restoration of the RRC connection, and the first request message may include a first identifier.

[0120] The UE is in an RRC inactive state or an RRC idle suspended state. Exemplarily, the UE is in an RRC inactive state, and the first identifier is an I-RNTI; or the UE is in an RRC suspended state, and the first identifier is a resume identifier.

[0121] The second base station may be a base station on a satellite that currently covers the UE, or a base station on a satellite that currently provides services to the UE, that is, a serving base station for the UE. Figure 3 Base station on satellite 2 in .

[0122] Step 402b: When the first base station corresponding to the first identifier has been removed from the RNA of the UE, the second base station sends a second request message to the ground device. Correspondingly, the ground device receives the second request message.

[0123] The second request message is used to request the context of the UE. The second request message may include a first identifier, and the second request message is used to request the context of the UE associated with the first identifier.

[0124] Specifically, after receiving the first request message, the second base station may first determine the first base station corresponding to the first identifier according to the first identifier (for example, the first identifier includes the identifier of the first base station). The first base station may be the last base station that provides service to the UE before the UE enters the RRC inactive state or the RRC idle suspended state (for example, Figure 3 If the first base station has not yet been removed from the UE's RNA, the second base station may request the first base station to obtain the UE's context. If the first base station has already been removed from the UE's RNA, the second base station cannot obtain the UE's context from the first base station. In this case, the second base station requests the UE's context by sending a second request message to the ground base station.

[0125] As an implementation method, the second base station may determine that the first base station has moved out of the UE's RNA based on ephemeris information, where the ephemeris information may be used to indicate information such as the flight speed and motion trajectory of the satellite to which the first base station belongs.

[0126] Step 403b: The ground device sends the UE context to the second base station. Correspondingly, the second base station receives the UE context.

[0127] In the above solution, if the second base station cannot obtain the UE context from the first base station, it can request the ground equipment to obtain the UE context, thereby increasing the success rate of obtaining the UE context and helping to provide better communication services for the UE.

[0128] Optionally, in an implementation method of the above solution, if the second base station determines to restore the UE to the RRC connected state, an RRC recovery message is sent to the UE, where the RRC recovery message is used to trigger the UE to enter the RRC connected state.

[0129] Optionally, in an implementation method of the above solution, if the second base station determines to keep the UE in the RRC inactive state, indication information is sent to the UE, where the indication information instructs the UE to keep the RRC inactive state.

[0130] Optionally, in one implementation method of the above solution, the second base station also sends a path switching request message to a mobility management network element (such as an AMF network element or a mobility management entity (MME), etc.), and the path switching request message is used to indicate that the second base station provides service for the UE.

[0131] Optionally, in one implementation of the above solution, after step 403b, the second base station further sends a third request message to the ground device, requesting the ground device to release the UE context. That is, after the second base station has successfully acquired the UE context from the ground device, the ground device may release the stored UE context, thereby saving storage space.

[0132] Figure 4(c) is a schematic flow chart of a communication method provided in an embodiment of the present application. This method is executed by at least one base station (or at least one module within a base station, such as a chip) and ground equipment (or a module within a ground equipment, such as a chip). The following description uses at least one base station and ground equipment executing this method as an example.

[0133] The method comprises the following steps:

[0134] Step 401c: The ground device receives the trigger information.

[0135] The trigger information may be used to trigger paging of the UE. Specifically, the trigger information may include signaling or data to be sent to the UE, or the trigger information may be a downlink data notification message, etc., without limitation. For example, the ground equipment may receive data to be sent to the UE from a UPF network element of the core network, or receive signaling to be sent to the UE from an AMF network element.

[0136] The UE is in an RRC inactive state or an RRC idle suspended state.

[0137] Step 402c: The ground equipment determines the RNA of the UE according to the first area.

[0138] It can be understood that when the ground device receives the trigger information, it triggers the ground device to execute step 402c.

[0139] The first area may be the area where the first base station is located when the ground device receives the context of the UE from the first base station. The area may be a geographical area, or a TA, etc., without limitation. The first base station may be the last base station to provide services to the UE before the UE enters the RRC inactive state or the RRC idle suspended state, and the first base station is deployed on a satellite. Exemplarily, the first base station may be the first base station described in the embodiment of Figure 4(a). For example, the first base station sends the context of the UE to the ground device at time t1, and the ground device receives the context of the UE at time t2, then the first area refers to the area where the first base station is located at time t2.

[0140] Step 403c: The ground device sends a paging message to at least one base station in the RNA. Correspondingly, the at least one base station receives the paging message.

[0141] Exemplarily, the ground device may determine the at least one base station based on the ephemeris information and the RNA of the UE. The at least one base station refers to a base station within the RNA of the UE, and the at least one base station is a base station on the satellite. The signal of the at least one base station may cover the UE, so the at least one base station has a chance of successfully paging the UE.

[0142] The ground device sends a paging message to the at least one base station, where the paging message is used to page the UE. Accordingly, after receiving the paging message, the at least one base station can page the UE based on the paging message.

[0143] In the above solution, the ground device stores the UE's context and can proactively send a paging message to at least one base station within the UE's RNA. If one or more base stations within the at least one base station pages the UE based on the paging message, the ground device can request the UE's context. This solution increases the success rate of obtaining the UE's context, helping to provide better communication services for the UE.

[0144] Optionally, in an implementation method of the above scheme, if the second base station among the at least one base station successfully pages the UE, the second base station may send a request message to the ground device, and the request message is used to request the context of the UE. The ground device obtains the context of the UE locally and sends the context of the UE to the second base station. Exemplarily, the request message also includes a first identifier, and the request message is used to request the context of the UE associated with the first identifier. Based on the first identifier, the ground device obtains the context of the UE corresponding to the first identifier locally and sends the context of the UE to the second base station. Exemplarily, if the UE is in an RRC inactive state, the first identifier is an I-RNTI; or, if the UE is in an RRC suspended state, the first identifier is a recovery identifier.

[0145] Figure 4(d) is a flow chart of a communication method provided in an embodiment of the present application. The method is executed by a second base station (or a module within the second base station, such as a chip) and a ground device (or a module within the ground device, such as a chip). The following description uses the second base station and the ground device executing the method as an example.

[0146] The method comprises the following steps:

[0147] Step 401d: The ground equipment receives the trigger information.

[0148] The trigger information may be used to trigger paging of the UE, and may specifically include signaling or data to be sent to the UE, or the trigger information may be a downlink data notification message, etc., without limitation. For example, the ground equipment may receive data to be sent to the UE from a UPF network element in the core network, or receive signaling to be sent to the UE from an AMF network element.

[0149] The UE is in an RRC inactive state or an RRC idle suspended state.

[0150] Step 402d: The ground equipment determines the RNA of the UE according to the first area.

[0151] It can be understood that when the ground device receives the trigger information, it triggers the ground device to execute step 402d.

[0152] The first area is the area where the first base station is located when the ground device receives the context of the UE from the first base station. The first base station may be the last base station to provide services to the UE before the UE enters the RRC inactive state or the RRC idle suspended state, and the first base station is deployed on the satellite. Exemplarily, the first base station may be the first base station described in the embodiment of Figure 4(a). For example, the first base station sends the context of the UE to the ground device at time t1, and the ground device receives the context of the UE at time t2, then the first area refers to the area where the first base station is located at time t2.

[0153] Step 403d: The ground equipment sends the UE context to the second base station in the RNA of the UE. Correspondingly, the second base station receives the UE context.

[0154] For example, the ground device can determine a second base station based on the ephemeris information and the UE's RNA. The second base station can be a base station within the UE's RNA, and the second base station is a base station on the satellite. The signal of the second base station can cover the UE, so the second base station has a chance to successfully page the UE.

[0155] The second base station may actively page the UE, and at the same time, the second base station may also notify other base stations (such as a third base station, etc.) within the RNA of the UE to page the UE.

[0156] Based on the above solution, the ground device stores the UE's context and can proactively send the UE's context to the second base station within the UE's RNA. This solution, in which the ground device proactively sends the UE's context to the second base station, increases the success rate of the second base station acquiring the UE's context, helping to provide better communication services for the UE.

[0157] Optionally, in one implementation method of the above scheme, if the second base station successfully pages the UE, the second base station can notify the UE to restore to the RRC connected state based on the UE context obtained from the ground equipment, or can also notify the UE to continue to remain in the RRC inactive state or the RRC idle suspended state.

[0158] Optionally, in one implementation method of the above scheme, if other base stations within the RNA (for example, a third base station) successfully pages the UE, the third base station can request the second base station to obtain the UE's context, and notify the UE to restore to the RRC connected state based on the UE's context, or it can also notify the UE to continue to remain in the RRC inactive state or the RRC idle suspended state.

[0159] Combined with the following Figures 5 to 7 Specific embodiment, for the above Figure 4(a) to Figure 4(d) The following examples are described. Figure 5 The embodiment is a specific example of the embodiment of FIG. 4 (a) and FIG. 4 (b) above. Figure 6 The embodiment is a specific example of the embodiment of FIG4(c) above. Figure 7 The embodiment of is a specific example of the embodiment of FIG4(d) above. Figures 5 to 7 In the embodiment, base station #1 and base station #2 are respectively Figure 4(a) to Figure 4(d) Specific examples of the first base station and the second base station in the embodiment. Figures 5 to 7 In the embodiment, the UE is in an RRC inactive state as an example for description.

[0160] Figure 5 This is a flow chart of a communication method provided in an embodiment of the present application. The method includes the following steps:

[0161] Step 501: Base station #1 sends an RRC release message to UE. Correspondingly, the UE receives the RRC release message.

[0162] Exemplarily, the base station #1 is Figure 3 The shown satellite base station is on satellite 1. The base station #1 may be the last base station to provide services to the UE before the UE enters the RRC inactive state.

[0163] The RRC release message includes the I-RNTI and the UE's RNA.

[0164] After receiving the RRC release message, the UE enters the RRC inactive state. As the satellite 1 moves, the base station #1 may move outside the RNA.

[0165] Step 502: Base station #1 sends a UE context transfer request message to the ground device. Correspondingly, the ground device receives the UE context transfer request message.

[0166] For example, before base station #1 moves outside the RNA, it sends a UE Context Transfer Request message to the ground device. Alternatively, base station #1 sends a UE Context Transfer Request message to the ground device immediately after it moves out of the RNA. This UE Context Transfer Request message is a specific example of the first message in the embodiment of FIG. 4( a ).

[0167] The UE context transfer request message includes the I-RNTI and the UE context. Exemplarily, the UE context transfer request message includes a user plane resource release indication, and the user plane resource release indication is used to instruct the release of the UE's user plane resources.

[0168] Step 503: The ground equipment stores the I-RNTI and the UE context.

[0169] Exemplarily, if the context transfer request message of the UE further includes a user plane resource release indication, the ground equipment further releases the user plane resources of the UE according to the user plane resource release indication.

[0170] Step 504: The UE sends an RRC recovery request message to base station #2. Correspondingly, base station #2 receives the RRC recovery request message.

[0171] Base station #2 is the satellite-borne base station on satellite 2 that currently covers the UE. That is, the satellite signal from base station #2 covers the geographic area where the UE is located. Alternatively, base station #2 is the base station on the satellite currently serving the UE, i.e., the UE's serving base station.

[0172] Exemplarily, when the RNA timer of the UE times out, or the UE moves out of the RNA, or the UE is ready to send data, the UE is triggered to send an RRC recovery request message to base station #2.

[0173] The RRC recovery request message includes the I-RNTI.

[0174] Step 505: Base station #2 sends a UE context request message to the ground device. Correspondingly, the ground device receives the UE context request message.

[0175] For example, base station #2 determines base station #1 based on I-RNTI, and determines that base station #1 is not in the RNA based on ephemeris information and the UE's RNA, and then sends a UE context request message to the ground device.

[0176] The UE context request message includes the I-RNTI. The UE context request message is used to request to obtain the UE context.

[0177] After acquiring the UE context, base station #2 can allow the UE to restore the RRC connection (corresponding to the following scenario 1), or continue to maintain the UE in the RRC inactive state (corresponding to the following scenario 2), or allow the UE to enter the idle state (corresponding to the following scenario 3). The following describes each of these.

[0178] Scenario 1 (involving steps 506a to 511a below)

[0179] In step 506a, the ground device sends an N2 message to base station #2. Accordingly, base station #2 receives the N2 message.

[0180] The N2 message includes the UE context.

[0181] The N2 message may be a UE context transfer message.

[0182] In step 507a, base station #2 decides to restore the UE to the RRC connected state, and sends an RRC resume message to the UE. Accordingly, the UE receives the RRC resume message.

[0183] After receiving the RRC recovery message, the UE enters the RRC connected state.

[0184] In step 508a, after entering the RRC connected state, the UE sends a recovery complete message to base station #2. Accordingly, base station #2 receives the recovery complete message.

[0185] In step 509a, base station #2 sends a path switch request message to the AMF network element. Correspondingly, the AMF network element receives the path switch request message.

[0186] The path switch request message is used to indicate that a path switch occurs, that is, base station #2 provides service to the UE.

[0187] In step 510a, the AMF network element sends a path switch response message to base station #2. Accordingly, base station #2 receives the path switch response message.

[0188] In step 511a, base station #2 sends a UE context release message to the ground device. Correspondingly, the ground device receives the UE context release message.

[0189] The ground equipment releases the stored UE context according to the UE context release message.

[0190] Scenario 2 (involving steps 506b to 510b below)

[0191] In step 506b, the ground device sends an N2 message to base station #2. Accordingly, base station #2 receives the N2 message.

[0192] The N2 message includes the UE context.

[0193] The N2 message may be a UE context transfer message.

[0194] In step 507b, base station #2 decides to keep the UE in the RRC inactive state, and sends an RRC release suspension indication to the UE. Accordingly, the UE receives the RRC release suspension indication.

[0195] After receiving the RRC release suspension indication, the UE remains in the RRC inactive state.

[0196] In step 508b, base station #2 sends a path switch request message to the AMF network element. In response, the AMF network element receives the path switch request message.

[0197] The path switch request message is used to indicate that a path switch occurs, that is, the path is switched to be served by base station #2.

[0198] In step 509b, the AMF network element sends a path switch response message to base station #2. Accordingly, base station #2 receives the path switch response message.

[0199] In step 510b, base station #2 sends a UE context release message to the ground device. Correspondingly, the ground device receives the UE context release message.

[0200] The ground equipment releases the stored UE context according to the UE context release message.

[0201] Scenario 3 (involving steps 506c to 507c below)

[0202] In step 506c, the ground device sends an N2 message to base station #2. Accordingly, base station #2 receives the N2 message.

[0203] The N2 message includes an RRC release indication, and the RRC release indication is used to instruct base station #2 to release the UE to the RRC idle state.

[0204] The N2 message may be a UE context transmission failure message.

[0205] In step 507c, base station #2 decides to let the UE enter the RRC idle state, and sends an RRC release message to the UE. Accordingly, the UE receives the RRC release message.

[0206] The UE enters the RRC idle state according to the RRC release message.

[0207] In the above scheme, when base station #1 is about to move out the RNA of the UE, it will actively send the UE context to the ground equipment for storage. When other base stations (such as base station #2) need to use the UE context, if they cannot obtain the UE context from base station #1, they can request the ground equipment to obtain the UE context, thereby increasing the success rate of obtaining the UE context and helping to provide better communication services for the UE.

[0208] Figure 6 This is a flow chart of a communication method provided in an embodiment of the present application. The method includes the following steps:

[0209] Step 601: Ground equipment receives trigger information.

[0210] The trigger information may be, for example, signaling from an AMF network element or data from a UPF network element. The trigger information triggers the ground equipment to page the UE. The trigger information is also called an N2 UE Context Transfer Trigger.

[0211] Before step 601, the UE is in RRC inactive state and does not initiate RNAU for a long time. For example, the UE always moves freely in the RNA area and does not move out of the RNA, so RNAU is not triggered. In addition, base station #1 has sent the UE context to the ground equipment for storage. For details, please refer to Figure 5 The base station #1 may be a satellite-borne base station on satellite 1. The base station #1 may be the last base station to provide service to the UE before the UE enters the RRC inactive state.

[0212] Step 602: The ground equipment determines the RNA of the UE according to the first area.

[0213] The first area is the area where base station #1 is located when the ground device receives the context of the UE from base station #1.

[0214] In step 603, the ground equipment sends a paging message to the base stations in the RNA (eg, base station #2 and base station #3).

[0215] Exemplarily, the paging message includes a paging identifier and an RNA identifier.

[0216] In step 603, the ground equipment may send the paging message to all or some of the base stations in the RNA. Figure 6 In the example, the ground device sends a paging message to base station #2 and base station #3. Assume that base station #2 is a base station on satellite 2 and base station #3 is a base station on satellite 3.

[0217] Step 604: Base station #2 and base station #3 page the UE.

[0218] Exemplarily, base station #2 and base station #3 page the UE within the RNA based on the paging identifier.

[0219] Assuming that the satellite signal of base station #2 covers the geographical area where the UE is located and base station #2 successfully pages the UE, after step 604, the following steps 605 to 611 may be executed.

[0220] Step 605: The UE sends an RRC recovery request message to base station #2. Correspondingly, base station #2 receives the RRC recovery request message.

[0221] Exemplarily, when the UE receives a paging message from base station #2, it triggers the UE to send an RRC recovery request message to base station #2.

[0222] The RRC recovery request message includes the I-RNTI.

[0223] Step 606: Base station #2 sends a UE context request message to the ground device. Correspondingly, the ground device receives the UE context request message.

[0224] For example, base station #2 determines base station #1 based on I-RNTI, and determines that base station #1 is not in the RNA based on ephemeris information and the UE's RNA, and then sends a UE context request message to the ground device.

[0225] The UE context request message includes the I-RNTI. The UE context request message is used to request to obtain the UE context.

[0226] Step 607: The ground device sends an N2 message to base station #2. Accordingly, base station #2 receives the N2 message.

[0227] The N2 message includes the UE context.

[0228] The N2 message may be a UE context transfer message.

[0229] In step 608, base station #2 decides to restore the UE to the RRC connected state, and sends an RRC resume message to the UE. Accordingly, the UE receives the RRC resume message.

[0230] After receiving the RRC recovery message, the UE enters the RRC connected state.

[0231] Step 609: After entering the RRC connected state, the UE sends a recovery complete message to base station #2. Correspondingly, base station #2 receives the recovery complete message.

[0232] In step 610, base station #2 sends a path switch request message to the AMF network element. Accordingly, the AMF network element receives the path switch request message.

[0233] The path switch request message is used to indicate that a path switch occurs, that is, base station #2 provides service to the UE.

[0234] In step 611, the AMF network element sends a path switch response message to base station #2. Accordingly, base station #2 receives the path switch response message.

[0235] In step 612, base station #2 sends a UE context release message to the ground device. Correspondingly, the ground device receives the UE context release message.

[0236] The ground equipment releases the stored UE context according to the UE context release message.

[0237] In the above solution, when base station #1 is about to be removed from the UE's RNA, it proactively sends the UE's context to the ground device for storage. Based on the trigger information, the ground device can proactively notify the base stations within the UE's RNA to page the UE. When a base station (for example, base station #2) successfully pages the UE, base station #2 can request the UE's context from the ground device. Since the UE's context can be obtained from the ground device, the situation where base station #1 is removed from the RNA and thus unable to obtain the UE's context can be avoided. This increases the success rate of obtaining the UE's context and helps provide better communication services for the UE.

[0238] Figure 7 This is a flow chart of a communication method provided in an embodiment of the present application. The method includes the following steps:

[0239] Step 701: Ground equipment receives trigger information.

[0240] The trigger information may be, for example, signaling from an AMF network element or data from a UPF network element. The trigger information triggers the ground equipment to page the UE. The trigger information is also called an N2 UE Context TransferTrigger.

[0241] Before step 701, the UE is in RRC inactive state and does not initiate RNAU for a long time. For example, the UE always moves freely in the RNA area and does not move out of the RNA, so RNAU is not triggered. In addition, base station #1 has sent the UE context to the ground equipment for storage. For details, please refer to Figure 5 The base station #1 may be a satellite-borne base station on satellite 1. The base station #1 may be the last base station to provide service to the UE before the UE enters the RRC inactive state.

[0242] Step 702: The ground equipment determines the RNA of the UE according to the first area, and selects base station #2 within the RNA according to the ephemeris information.

[0243] The first area is the area where base station #1 is located when the ground device receives the context of the UE from base station #1.

[0244] The base station #2 is an onboard base station on satellite 2 and is currently located in RNA.

[0245] It should be noted that the ground equipment can also select other base stations in the RNA. This embodiment takes the selection of base station #2 as an example for explanation.

[0246] Step 703: The ground device sends an N2 message to base station #2. Accordingly, base station #2 receives the N2 message.

[0247] The N2 message includes the I-RNTI and the UE context.

[0248] That is, the ground equipment actively sends the I-RNTI and UE context to base station #2.

[0249] Step 704: Base station #2 pages the UE in the RNA.

[0250] In step 705, base station #2 sends a paging message to other base stations in the RNA (eg, base station #3). Correspondingly, base station #3 receives the paging message.

[0251] The base station (eg, base station #3) that receives the paging message pages the UE within the RNA.

[0252] In the first scenario, if base station #2 pages the UE, then the following steps 706a to 711a are executed. In the second scenario, if a base station other than base station #2 (e.g., base station #3) pages the UE, then the following steps 706b to 712b are executed. Each step is described below.

[0253] Scenario 1 (involving steps 706a to 711a below)

[0254] Step 706a: The UE sends an RRC recovery request message to base station #2. In response, base station #2 receives the RRC recovery request message.

[0255] Exemplarily, when the UE receives a paging message from base station #2, it triggers the UE to send an RRC recovery request message to base station #2.

[0256] The RRC recovery request message includes the I-RNTI.

[0257] In step 707a, base station #2 decides to restore the UE to the RRC connected state, and sends an RRC resume message to the UE. Accordingly, the UE receives the RRC resume message.

[0258] Base station #2 receives the RRC Resume Request message and, based on the I-RNTI in the RRC Resume Request message, determines that it has a local UE context corresponding to the I-RNTI. Base station #2 decides to restore the UE to an RRC connected state and sends an RRC Resume message to the UE.

[0259] After receiving the RRC recovery message, the UE enters the RRC connected state.

[0260] Step 708a: After entering the RRC connected state, the UE sends a recovery complete message to base station #2. Correspondingly, base station #2 receives the recovery complete message.

[0261] In step 709a, base station #2 sends a path switch request message to the AMF network element. In response, the AMF network element receives the path switch request message.

[0262] The path switch request message is used to indicate that a path switch occurs, that is, base station #2 provides service to the UE.

[0263] In step 710a, the AMF network element sends a path switch response message to base station #2. In response, base station #2 receives the path switch response message.

[0264] In step 711a, base station #2 sends a UE context release message to the ground device. Correspondingly, the ground device receives the UE context release message.

[0265] The ground equipment releases the stored UE context according to the UE context release message.

[0266] Scenario 2 (involving steps 706b to 712b below)

[0267] Step 706b: The UE sends an RRC recovery request message to base station #3. In response, base station #3 receives the RRC recovery request message.

[0268] Exemplarily, when the UE receives a paging message from base station #3, it triggers the UE to send an RRC recovery request message to base station #3.

[0269] The RRC recovery request message includes the I-RNTI.

[0270] In step 707b, base station #3 sends a UE context request message to base station #2. Accordingly, base station #2 receives the UE context request message.

[0271] For example, base station #3 determines base station #3 according to the I-RNTI, and determines that base station #2 is within the RNA according to the ephemeris information and the RNA of the UE, and then sends a UE context request message to base station #2.

[0272] The UE context request message includes the I-RNTI. The UE context request message is used to request to obtain the UE context.

[0273] In step 708b, base station #2 sends an N2 message to base station #3. Accordingly, base station #3 receives the N2 message.

[0274] The N2 message includes the UE context.

[0275] The N2 message may be a UE context transfer message.

[0276] In step 709b, base station #3 decides to restore the UE to the RRC connected state, and sends an RRC resume message to the UE. Accordingly, the UE receives the RRC resume message.

[0277] After receiving the RRC recovery message, the UE enters the RRC connected state.

[0278] In step 710b, after entering the RRC connected state, the UE sends a recovery complete message to base station #3. Accordingly, base station #3 receives the recovery complete message.

[0279] In step 711b, base station #3 sends a path switch request message to the AMF network element. Accordingly, the AMF network element receives the path switch request message.

[0280] The path switch request message is used to indicate that a path switch occurs, that is, base station #3 provides service to the UE.

[0281] In step 712b, the AMF network element sends a path switch response message to base station #3. Accordingly, base station #3 receives the path switch response message.

[0282] In the above solution, when base station #1 is about to be removed from the UE's RNA, it proactively sends the UE's context to the ground device for storage. Based on the trigger information, the ground device proactively sends the UE's context to base station #2 within the UE's RNA. Since the UE's context can be obtained from the ground device, the situation where base station #1 is removed from the RNA and thus cannot obtain the UE's context is avoided. This increases the success rate of obtaining the UE's context and helps provide better communication services for the UE.

[0283] above Figures 5 to 7In the embodiment of the present invention, the implementation process of the ground equipment storing the UE context and providing the UE context to the base station is introduced by taking the UE in the RRC inactive state as an example. In actual use, the above embodiment is also applicable to the UE in the RRC idle suspended state. Figures 5 to 7 In the embodiment, the I-RNTI is replaced by a recovery identifier, the RRC recovery request message is replaced by an RRC connection recovery message, the RNA is replaced by the service area of ​​the ground device, and corresponding adjustments are made elsewhere.

[0284] It is understood that, in order to implement the functions in the above-described embodiments, the first access network device, the second access network device, or the ground device includes hardware structures and / or software modules corresponding to the respective functions. Those skilled in the art should readily appreciate that, in conjunction with the various exemplary units and method steps 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 implemented in hardware or in a hardware-driven manner by computer software depends on the specific application scenario and design constraints of the technical solution.

[0285] Figure 8 and Figure 9 Schematic diagram of the structure of possible communication devices provided for embodiments of the present application. These communication devices can be used to implement the functions of the first access network device, the second access network device, or the ground device in the above-mentioned method embodiments, thereby also achieving the beneficial effects of the above-mentioned method embodiments. In the embodiments of the present application, the communication device can be the first access network device, the second access network device, or the ground device, and can also be a module (such as a chip) applied to the first access network device, the second access network device, or the ground device.

[0286] Figure 8 The communication device 800 shown includes a processing unit 810 and a transceiver unit 820. The communication device 800 is used to implement the functions of the first access network device, the second access network device or the ground device in the above method embodiment.

[0287] When the communication device 800 is used to implement the function of the first access network device in the above method embodiment, the processing unit 810 is used to determine that the first access network device will move out of the RNA of the terminal device within a first time period or has already moved out of the RNA of the terminal device, and the terminal device is in an RRC inactive state or an RRC idle suspended state; the transceiver unit 820 is used to send a first message to the ground device, and the first message includes the context of the terminal device.

[0288] In one possible implementation method, the first message also includes a first identifier associated with the context of the terminal device; wherein, the terminal device is in an RRC inactive state, and the first identifier is an I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0289] In a possible implementation method, the first message also includes indication information, and the indication information indicates to release the user plane connection of the terminal device.

[0290] When the communication device 800 is used to implement the function of the second access network device in the above method embodiment, the transceiver unit 820 is used to receive a first request message from the terminal device, the first request message is used to request the restoration of the RRC connection, and the first request message includes a first identifier; when the processing unit 810 determines that the first access network device corresponding to the first identifier has been moved out of the RNA of the terminal device, a second request message is sent to the ground device, the second request message is used to request the context of the terminal device; and the context of the terminal device is received from the ground device.

[0291] In a possible implementation method, the transceiver unit 820 is further used to send an RRC recovery message to the terminal device, and the RRC recovery message is used to trigger the terminal device to enter the RRC connected state.

[0292] In a possible implementation method, the transceiver unit 820 is further used to send indication information to the terminal device, where the indication information instructs the terminal device to remain in the RRC inactive state.

[0293] In a possible implementation method, the processing unit 810 is specifically configured to determine, based on the ephemeris information, that the first access network device has been removed from the RNA of the terminal device.

[0294] In a possible implementation method, the second request message also includes the first identifier, and the second request message is used to request the context of the terminal device associated with the first identifier.

[0295] In a possible implementation method, the transceiver unit 820 is further configured to send a path switching request message to the mobility management network element, where the path switching request message is used to instruct the second access network device to provide service for the terminal device.

[0296] In a possible implementation method, the transceiver unit 820 is further configured to send a third request message to the ground device, where the third request message is used to request the ground device to release the context of the terminal device.

[0297] In one possible implementation method, the terminal device is in an RRC inactive state, and the first identifier is an I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0298] When the communication device 800 is used to implement the functions of the ground equipment in the above method embodiment, the transceiver unit 820 is used to receive trigger information, and the trigger information includes signaling or data to be sent to the terminal device, and the terminal device is in an RRC inactive state or an RRC idle suspended state; the processing unit 810 is used to determine the RNA of the terminal device based on the first area, and the first area is the area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; the transceiver unit 820 is also used to send a paging message to at least one access network device in the RNA, and the paging message is used to page the terminal device.

[0299] In one possible implementation method, the transceiver unit 820 is further used to receive a request message from a second access network device among the at least one access network device, where the request message is used to request the context of the terminal device; and send the context of the terminal device to the second access network device.

[0300] In a possible implementation method, the request message further includes a first identifier, and the request message is used to request the context of the terminal device associated with the first identifier.

[0301] In one possible implementation method, the terminal device is in an RRC inactive state, and the first identifier is an I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

[0302] In a possible implementation method, the processing unit 810 is further configured to determine the at least one access network device according to the ephemeris information and the RNA.

[0303] When the communication device 800 is used to implement the functions of the ground equipment in the above method embodiment, the transceiver unit 820 is used to receive trigger information, and the trigger information includes signaling or data to be sent to the terminal device, and the terminal device is in an RRC inactive state or an RRC idle suspended state; the processing unit 810 is used to determine the RNA of the terminal device based on the first area, and the first area is the area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; the transceiver unit 820 is also used to send the context of the terminal device to the second access network device in the RNA.

[0304] In a possible implementation method, the processing unit 810 is further configured to determine the second access network device according to the ephemeris information and the RNA.

[0305] For a more detailed description of the processing unit 810 and the transceiver unit 820, reference can be made to the relevant description in the above method embodiment, which will not be repeated here.

[0306] Figure 9 The communication device 900 shown includes a processor 910 and an interface circuit 920. The processor 910 and the interface circuit 920 are coupled to each other. It will be appreciated that the interface circuit 920 may be a transceiver or an input / output interface. Optionally, the communication device 900 may further include a memory 930 for storing instructions executed by the processor 910, input data required by the processor 910 to execute instructions, or data generated by the processor 910 after executing instructions.

[0307] When the communication device 900 is used to implement the above method embodiment, the processor 910 is used to implement the functions of the above processing unit 810 , and the interface circuit 920 is used to implement the functions of the above transceiver unit 820 .

[0308] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0309] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disk, mobile hard disk, compact disc read-only memory (CD-ROM) or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in the first access network device, the second access network device or the ground device. Of course, the processor and the storage medium can also exist as discrete components in the access network device or the terminal device.

[0310] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. A computer program refers to a set of instructions that instruct an electronic computer or other device with message processing capabilities to perform each step of the action, usually written in a certain programming language and running on a certain target architecture. When the computer program or instruction is loaded and executed on a computer, the process or function described in the embodiment of the present application is executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable device. The computer program or instruction can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instruction can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired or wireless means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; an optical medium, such as a digital video disk; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0311] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0312] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next related objects are in an "or" relationship; in the formulas of this application, the character " / " indicates that the previous and next related objects are in a "division" relationship.

[0313] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

Claims

1. A communication method, characterized in that: The method applied to a first access network device or a module of the first access network device on a satellite includes: Determining that the first access network device will move out of the notification area RNA based on the radio access network of the terminal device within a first time period or has moved out of the RNA of the terminal device, and the terminal device is in a radio resource control RRC inactive state or an RRC idle suspended state; A first message is sent to a ground device, where the first message includes the context of the terminal device.

2. The method according to claim 1, wherein The first message further includes a first identifier associated with the context of the terminal device; The terminal device is in an RRC inactive state, and the first identifier is an inactive radio network temporary identifier I-RNTI; or the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

3. The method according to claim 1 or 2, wherein: The first message also includes indication information, where the indication information indicates to release the user plane connection of the terminal device.

4. A communication method, characterized in that: The method applied to a second access network device or a module of the second access network device on a satellite includes: Receiving a first request message from a terminal device, where the first request message is used to request restoration of a radio resource control (RRC) connection, and the first request message includes a first identifier; When the first access network device corresponding to the first identifier has moved out of the notification area RNA based on the wireless access network of the terminal device, sending a second request message to the ground device, where the second request message is used to request the context of the terminal device; A context of the terminal device is received from the ground device.

5. The method according to claim 4, wherein The method further comprises: An RRC recovery message is sent to the terminal device, where the RRC recovery message is used to trigger the terminal device to enter an RRC connected state.

6. The method according to claim 4, wherein The method further comprises: Send indication information to the terminal device, wherein the indication information instructs the terminal device to remain in the RRC inactive state.

7. The method according to any one of claims 4 to 6, characterized in that The method further comprises: According to the ephemeris information, it is determined that the first access network device has been removed from the RNA of the terminal device.

8. The method according to any one of claims 4 to 7, characterized in that The second request message also includes the first identifier, and the second request message is used to request the context of the terminal device associated with the first identifier.

9. The method according to any one of claims 4 to 8, characterized in that The method further comprises: A path switching request message is sent to the mobility management network element, where the path switching request message is used to indicate that the second access network device provides services for the terminal device.

10. The method according to any one of claims 4 to 9, characterized in that The method further comprises: A third request message is sent to the ground device, where the third request message is used to request the ground device to release the context of the terminal device.

11. The method according to any one of claims 4 to 10, characterized in that The terminal device is in an RRC inactive state, and the first identifier is an inactive radio network temporary identifier I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

12. A communication method, characterized in that: Applied to ground equipment or a module of ground equipment, the method comprises: Receiving trigger information, the trigger information including signaling or data to be sent to a terminal device, the terminal device being in an RRC inactive state or an RRC idle suspended state; Determining, according to the first area, a notification area RNA based on a radio access network of the terminal device, wherein the first area is an area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; A paging message is sent to at least one access network device in the RNA, where the paging message is used to page the terminal device.

13. The method according to claim 12, wherein: The method further comprises: receiving a request message from a second access network device among the at least one access network device, where the request message is used to request a context of the terminal device; Send the context of the terminal device to the second access network device.

14. The method according to claim 13, wherein The request message further includes a first identifier, and the request message is used to request the context of the terminal device associated with the first identifier.

15. The method according to claim 14, wherein The terminal device is in an RRC inactive state, and the first identifier is an inactive radio network temporary identifier I-RNTI; or, the terminal device is in an RRC suspended state, and the first identifier is a recovery identifier.

16. The method according to any one of claims 12 to 15, characterized in that The method further comprises: The at least one access network device is determined according to the ephemeris information and the RNA.

17. A communication method, characterized in that: Applied to ground equipment or a module of ground equipment, the method comprises: Receiving trigger information, the trigger information including signaling or data to be sent to a terminal device, the terminal device being in an RRC inactive state or an RRC idle suspended state; Determining, according to the first area, a notification area RNA based on a radio access network of the terminal device, wherein the first area is an area where the first access network device is located when the ground device receives the context of the terminal device from the first access network device; The context of the terminal device is sent to the second access network device in the RNA.

18. The method according to claim 17, wherein The method further comprises: The second access network device is determined according to the ephemeris information and the RNA.

19. A communication device, characterized in that: The method comprises a unit for performing the method according to any one of claims 1 to 3, or performing the method according to any one of claims 4 to 11, or performing the method according to any one of claims 12 to 16, or performing the method according to claim 17 or 18.

20. A communication device, characterized in that: The method comprises a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method described in any one of claims 1 to 3, or the method described in any one of claims 4 to 11, or the method described in any one of claims 12 to 16, or the method described in claim 17 or 18.

21. A computer program product, characterized in that The computer program product comprises instructions which, when executed on a processor, cause the processor to execute the method according to any one of claims 1 to 3, or the method according to any one of claims 4 to 11, or the method according to any one of claims 12 to 16, or the method according to claim 17 or 18.

22. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction. When the computer program or instruction is executed by the communication device, it implements the method described in any one of claims 1 to 3, or the method described in any one of claims 4 to 11, or the method described in any one of claims 12 to 16, or the method described in claim 17 or 18.

23. A communication system, characterized in that: Including ground equipment and first access network equipment on the satellite; The first access network device is configured to perform the method according to any one of claims 1 to 3; The ground device is used to receive a first message from the first access network device, where the first message includes the context of the terminal device.

24. A communication system, characterized in that: Including ground equipment and second access network equipment on satellite; The second access network device is configured to perform the method according to any one of claims 4 to 11; The ground device is configured to receive a second request message from the second access network device, where the second request message is used to request the context of the terminal device; and send the context of the terminal device to the second access network device.

25. A communication system, characterized in that: including ground equipment and at least one access network device; The ground equipment is used to perform the method according to any one of claims 12 to 16; The at least one access network device is used to receive a paging message from the ground device, where the paging message is used to page the terminal device.

26. A communication system, characterized in that: Including ground equipment and second access network equipment; The ground equipment is used to perform the method according to claim 17 or 18; The second access network device is configured to receive the context of the terminal device from the ground device.

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