An Inter-satellite Handover Method for Space-ground Collaboration Oriented to Giant Satellite Constellations

Abstract

The present invention provides an inter-satellite handover method for space-ground joint of a giant satellite constellation, including a handover trigger process, a handover decision process, a handover execution process, and a routing redirection process. The present invention adopts a staring beam satellite mode to reduce the handover times of users. The satellite triggers a handover request to reduce unnecessary handovers and avoid the ping-pong effect from affecting the user experience. Moreover, the functional entity for processing handover signaling is deployed on LEO satellites, MEO satellites, and GS ground stations. The LEO satellite is responsible for user access, and the MEO satellite and the GS ground station jointly make handover decisions for the users on the satellite that triggers the handover request. This not only reduces the dependence on the GS ground station and avoids long-distance and frequent space-ground signaling interactions, but also the MEO satellite and the GS ground station jointly serve as handover decision-makers, can obtain global information, and have high execution efficiency. In the context of a giant satellite constellation, it not only ensures the complete data communication of users during the handover process, but also can significantly reduce the handover delay and signaling overhead of inter-satellite handovers.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite network communication, and particularly relates to an inter-satellite handover method for satellite-ground integration facing a giant satellite constellation. Background Art

[0002] With the development of satellite communication, in order to meet the growing demand for broadband wireless access, satellite constellations are gradually becoming large-scale, and ultimately a giant satellite constellation composed of tens of thousands of satellites will be formed. Typical constellation representatives include Space-X. At the same time, the integration of satellite communication and terrestrial mobile communication has become increasingly important. The terrestrial mobile communication system provides convenient services for users. However, in areas such as mountains, deserts, and oceans, due to the difficulty of setting up base stations, satellites have become a supplement to the terrestrial network. With the generation change of the terrestrial mobile communication system, the integration of satellites and the ground has also been continuously developing. As one of the first batch of "Science and Technology Innovation - 2030 Major Projects" in China, the space-ground integrated network is an important informatization infrastructure in China, which will realize the transition from the interconnection of all things to the intelligent connection of all things.

[0003] Satellite networks have become an important part of the space-ground integrated network due to their advantages such as wide coverage, strong bearing capacity, and high robustness. With the continuous development of phased array technology, various types of satellites have gradually begun to attempt to adopt the staring technology. By adjusting the aerial attitude of the satellite and the phased array parameters, the time for the satellite to serve the user terminal is increased, effectively reducing the number of handovers. In recent years, many scholars have proposed many mature research results for the inter-satellite handover method in the fixed beam satellite mode. However, for a giant satellite constellation, how to design a complete and efficient inter-satellite handover method in the staring beam satellite mode needs to be further studied.

[0004] Zhu Hongtao and Guo Qing, in their published literature "Multi-satellite handover strategy for low-earth orbit satellite networks based on user groups", proposed a multi-satellite handover strategy for low-earth orbit satellite networks based on user groups to solve the problems of decreased handover success rate and excessive signaling overhead caused by a large number of users frequently performing concurrent handovers in large-scale low-earth orbit satellite networks. When a terrestrial user triggers a handover, it sends the candidate handover satellite information that meets its own communication requirements to the access satellite. The access satellite groups the users under the conditions of considering the user handover success rate, satellite throughput, and satellite load balancing to complete the entire handover process. A signaling interaction process based on user group handover is designed. A large number of mobile users periodically measure the signal strength of the current access satellite. When the signal strength is lower than the handover threshold, they measure and calculate the set of candidate handover satellites, and then send the information of the candidate handover satellites to the current access satellite. The satellite groups the users with a large number of concurrent handovers, initiates a handover request in a group manner, and updates the context information.

[0005] The 54th Research Institute of China Electronics Technology Group Corporation discloses a low-earth orbit satellite communication system and a CPE handover method applicable to this system in its patent document "Satellite Communication System and Terminal Handoff Method Based on 5G Lan Architecture" (application date: September 26, 2021, application number: 202111126440.8, application publication number: CN113852407A). This invention refers to the ground 5G lan network architecture, and based on the 5G mobile communication system, it conducts space-ground function allocation, deploys network elements such as 5G base stations and PSA on the spaceborne platform. The tunnel link between the CPE and the PSA, and the tunnel link between PSAs together constitute a local private network directly connected by PC terminals, providing the possibility for customizing the local private network of the low-earth orbit satellite mobile communication system. In the CPE handover method applicable to the low-earth orbit satellite communication system designed in this invention, the CPE can be connected to multiple PC terminals. The CPE makes handover decisions for the PC terminals and sends a handover request message to the source spaceborne base station, including information about the target spaceborne base station. The PC terminals can achieve single-hop communication from terminal to satellite and then to terminal in the local private network of the 5G low-earth orbit satellite communication system.

[0006] In the existing technical document "Multi-satellite Handoff Strategy for Low-Earth Orbit Satellite Networks Based on User Groups", the method based on user group handover is mainly designed for the fixed-beam satellite mode. First, the satellite moves at a relatively high speed, which will cause frequent handovers of user terminals in this mode. Frequent handover failures during the handover process will lead to a relatively high call drop rate. Second, in this document, the user periodically measures the signal strength of the accessed satellite, and when it is lower than the handover threshold, a handover request is triggered. However, in actual applications, due to unreasonable setting of the handover threshold, unnecessary handovers of users may occur, or the signal strength of the satellite received by users may change violently due to external signal interference, which is prone to ping-pong effects, etc., resulting in an increase in signaling overhead and exacerbating the signaling load of the network.

[0007] In the existing technical document "Multi-satellite Handoff Strategy for Low-Earth Orbit Satellite Networks Based on User Groups", the method based on user group handover mainly focuses on the signaling interaction process during the user handover process, only considering the user handover process, and does not further design the signaling interaction process for correctly forwarding user data communication services during the handover process. The user handover method designed in this technical document lacks integrity and cannot guarantee complete data communication of users during the handover process.

[0008] In the existing technical patent document "Satellite Communication System Based on 5G Lan Architecture and Terminal Handoff Method", a low-earth orbit satellite communication system and a CPE handoff method applicable to this system are disclosed. Although this invention conducts space-ground function allocation, deploying network elements such as 5G base stations and PSA on the spaceborne platform, the tunnel link between the CPE and the PSA, and the tunnel links between PSAs together constitute a local private network directly connected by PC terminals, conforming to the development of future space-ground integrated networks. However, this invention only provides the possibility for the customization of the local private network of the low-earth orbit satellite mobile communication system, with a relatively narrow scope of applicability. At the same time, in the existing technical document "Multi-satellite Handoff Strategy for Low-earth Orbit Satellite Networks Based on User Groups", the functional entities responsible for processing handoff signaling are mainly deployed on LEO satellites and GS ground stations. Deploying the functional entity for processing handoff decisions on LEO satellites results in complex signaling interactions, inconsistent query information due to the propagation delay of signaling, and low execution efficiency. Moreover, the limited deployment of GS ground stations will lead to long-distance space-ground signaling interactions, thereby increasing handoff delay and signaling overhead. And with the large-scale expansion of the satellite constellation, the handoff delay and signaling overhead will increase significantly. Summary of the Invention

[0009] To solve the above problems existing in the prior art, the present invention provides an inter-satellite handoff method for space-ground integration of a giant satellite constellation. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0010] The present invention provides an inter-satellite handoff method for space-ground integration of a giant satellite constellation, which is applied to an inter-satellite handoff architecture. The inter-satellite handoff architecture includes multiple user terminals, and the user terminals are divided into source-end session users and destination-end session users, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations. The inter-satellite handoff method for space-ground integration of a giant satellite constellation includes:

[0011] Handoff trigger process: Each LEO satellite determines whether the user terminals in the location area associated with itself in the next time slot need to be handed off to a new LEO satellite. If so, it selects an MEO satellite or a GS ground station as its management and control center, and sends a handoff request signaling to the management and control center.

[0012] Handoff decision process: The management and control center counts the user information requesting handoff in the location area associated with the original LEO satellite and queries the available handoff channel information of the new LEO satellite, makes a handoff decision, and generates a user allocation signaling for the new LEO satellite according to the handoff decision.

[0013] Handover execution process: The management and control center sends a handover request response signaling to the original LEO satellite, and the original LEO satellite sends an RRC connection reconfiguration signaling to the user terminal requesting handover, so that the user terminal connects to the new LEO satellite and the handover channel of the LEO satellite, and feeds back an RRC connection reconfiguration completion signaling to the new LEO satellite;

[0014] Routing redirection process: The new LEO satellite of the destination session user selects a management and control center for itself and sends a path handover request signaling to the management and control center; The management and control center instructs the new LEO satellite of the source session user to change the session path, and informs the new LEO satellite of the destination session user that the session path of the source session user has been updated; The new LEO satellite instructs the original LEO satellite to delete the context information of the handover user terminal.

[0015] The present invention provides an inter-satellite handover architecture for space-ground integration of a giant satellite constellation, including: multiple user terminals, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations;

[0016] Among them, the multiple user terminals, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations interact with each other to implement an inter-satellite handover method for space-ground integration of a giant satellite constellation.

[0017] Advantages of the present invention:

[0018] First, the inter-satellite handover method proposed by the present invention is mainly designed for the staring beam satellite mode. Compared with the existing inter-satellite handover method based on the fixed beam satellite mode, in the staring beam satellite mode, the time for the satellite to serve the user terminal becomes longer, which can effectively reduce the number of handovers and the call drop rate caused by handover failures. In the staring beam satellite mode, the satellite periodically calculates whether the staring area has changed. If it has changed, a handover request is triggered; otherwise, no handover request is triggered. Compared with the existing method in which the user terminal periodically measures the signal strength of the currently accessed satellite in the fixed beam satellite mode and triggers a handover request when it drops to a preset handover threshold, unnecessary handovers can be reduced, and the ping-pong effect can be avoided from affecting the user experience.

[0019] Second, the inter-satellite handover method proposed by the present invention includes a handover trigger process, a handover decision process, a handover execution process, and a routing redirection process. Compared with the existing inter-satellite handover methods, the signaling interaction process for correct forwarding of user data packets during the handover process is further designed, realizing the integrity of the inter-satellite handover method and ensuring complete data communication of users during the handover process.

[0020] Third, compared with the prior art in which the functional entity for processing handover signaling is deployed on LEO satellites and GS ground stations, the functional entity for processing handover signaling is mainly deployed on LEO satellites, MEO satellites, and GS ground stations. Among them, LEO satellites are responsible for user access, and MEO satellites and GS ground stations jointly make handover decisions for users on the satellite that triggers the handover request. This not only reduces the dependence on GS ground stations and avoids long-distance and frequent satellite-ground signaling interactions, but also MEO satellites and GS ground stations jointly as handover decision-makers can obtain global information and have high execution efficiency, which can significantly reduce the handover delay and signaling overhead of inter-satellite handovers in the face of giant satellite constellations.

[0021] The following will further elaborate on the present invention in conjunction with the accompanying drawings and embodiments. Brief Description of the Drawings

[0022] Figure 1 is a partial schematic diagram of the inter-satellite handover application scenario of the present invention;

[0023] Figure 2 is a flowchart of the method for associating LEO satellites with location areas of the present invention;

[0024] Figure 3 is a signaling interaction flowchart of the inter-satellite handover method of the present invention. Detailed Embodiments

[0025] The following further describes the present invention in detail with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0026] First, a brief introduction to the technical concept and inventive value of the present invention is given.

[0027] (1) Inter-satellite handover technology is a key technology for ensuring the continuity of user services in satellite communication networks. The existing inter-satellite handover methods are mainly designed for the fixed beam satellite mode. First, the moving speed of satellites is relatively fast, which will cause frequent handovers of user terminals in the fixed beam satellite mode. In the process of frequent handovers, handover failures will lead to a high call drop rate. Second, in the fixed beam satellite mode, user terminals periodically measure the signal strength of the currently accessed satellite. When it drops to a preset handover threshold, a handover request is triggered, which will not only cause unnecessary handovers, but also easily cause the ping-pong effect and affect the experience of user terminals. In the staring beam satellite mode, the time for satellites to serve user terminals increases, which can reduce the number of handovers and the call drop rate caused by handover failures. Therefore, how to design an inter-satellite handover method suitable for the staring beam satellite mode to effectively reduce the number of handovers and avoid the ping-pong effect has become a key issue.

[0028] (2) The existing inter-satellite handover methods mainly focus on the signaling interaction process during the user handover process, only considering the user handover process, and do not design the signaling interaction process for the correct forwarding of user data communication services during the handover process, thus unable to guarantee the complete data communication of users during the handover process. Therefore, after solving the problem in (1), the key problem now becomes how to design a complete inter-satellite handover method applicable to the staring beam satellite mode to ensure the complete data communication of users during the handover process.

[0029] (3) With the development of satellite communication, the scale of the satellite constellation has become larger, and the integration of satellites and the ground has also been continuously developing. The space-ground integrated network has become an important informatization infrastructure in our country. First of all, in the existing inter-satellite handover methods, the functional entities responsible for processing handover signaling are mainly deployed in LEO satellites and GS ground stations. Deploying the functional entity for processing handover decisions in LEO satellites leads to complex signaling interactions, inconsistent query information due to the propagation delay of signaling, and low execution efficiency. The limited deployment of GS ground stations will lead to long-distance space-ground signaling interactions, thus increasing the handover delay and signaling overhead. Moreover, with the scaling of the satellite constellation, the handover delay and signaling overhead will increase significantly. Therefore, after solving the problem in (2), for a giant satellite constellation, how to design a complete and efficient inter-satellite handover method applicable to the staring beam satellite mode to reduce the handover delay and signaling overhead of inter-satellite handover has become an important issue.

[0030] The present invention provides an inter-satellite handover method for space-ground integration of a giant satellite constellation, which is applied to the inter-satellite handover architecture. Refer to Figure 1 , the inter-satellite handover architecture includes multiple user terminals, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations. The LEO satellite includes a gNB-L on-board base station and a UPF-L user plane function module; the MEO satellite includes a gNB-CU-M on-board base station central module, an AMF-M access and mobility management function module, and an SMF-M session management function module; the GS ground station includes a gNB-CU-G base station central module, an AMF-G access and mobility management function module, and an SMF-G session management function module.

[0031] The user terminal, which is the starting point and receiving point of the data communication service, uploads the data communication service to the user's access LEO satellite. The UPF-L of this LEO satellite analyzes the data communication service to obtain the destination session user address and the LEO satellite to which the user is connected. Then, it forwards the data communication service to the LEO satellite to which the destination session user is connected through the inter-satellite link. After receiving the data communication service, this LEO satellite analyzes it, obtains the destination session user address, and then downloads the data communication service to the user. The user terminal is also used to receive the broadcast signaling from the original LEO satellite, determine whether the LEO satellite to which the user is connected is the original LEO satellite that sends the broadcast signaling. If so, it feeds back a broadcast response signaling to the original LEO satellite to inform the original LEO satellite that the user is ready to switch. It is also used to receive the RRC connection reconfiguration signaling from the original LEO satellite, notify the user to switch according to the newly allocated LEO satellite and the handover channel of this LEO satellite, and then feed back the RRC connection reconfiguration completion signaling to inform the new LEO satellite that the handover has been completed.

[0032] The gNB-L, if it acts as the original on-board base station, is used to send broadcast signaling to the user terminal. It is also used to receive the broadcast response signaling fed back by the user terminal. When the gNB-L of the original LEO satellite calculates that the staring area of the next time slot has changed, it then calculates its control center MEO satellite or GS ground station, and sends a handover request signaling to this control center, which is sent to its control center through the inter-satellite link. It is also used to receive the handover request response signaling sent by the gNB-CU-M or gNB-CU-G of its control center, and then send an RRC connection reconfiguration signaling to its connected users, notifying the users to switch according to the newly allocated LEO satellite and the handover channel of this LEO satellite. If it acts as the new on-board base station, it is used to receive the resource query request signaling sent by the gNB-CU-M or gNB-CU-G of the control center to query the available handover channel information of the new LEO satellite, and then feed back a resource query response signaling to the control center to feed back its available handover channel information to the control center. It is also used to receive the user allocation signaling sent by the gNB-CU-M or gNB-CU-G of the control center to update the handover channel information of the new LEO satellite. It is also used to receive the RRC connection reconfiguration completion signaling fed back by the user terminal to inform the new LEO satellite that the handover has been completed, and then send a path handover request signaling to its control center.

[0033] UPF-L, if it is the original on-board UPF-L, is used to receive the data communication services sent by users, parse them, obtain the destination session user address and the LEO satellite accessed by the user, and forward them to the LEO satellite accessed by the user through the inter-satellite link; it is also used to receive the session modification request signaling sent by SMF-M of the MEO satellite or SMF-G of the GS ground station, and is used to update the transmission path of the data communication service to ensure that the data communication service can be correctly forwarded during the user handover process; if it is the new on-board UPF-L, it is used to receive the data communication services sent by the original on-board UPF-L, parse the data communication services, obtain the destination session user address and download the data communication services to the user.

[0034] gNB-CU-M or gNB-CU-G is used to receive the handover request signaling sent by gNB-L of the original LEO satellite, parse the handover request signaling, obtain the location area associated with the original LEO satellite, count the handover user information in the location area, calculate the new LEO satellite associated with the location area in the next time slot, and send a resource query request signaling to all new LEO satellites; it is also used to receive the resource query response signaling fed back by gNB-L of the new LEO satellite associated with the location area, parse the resource query response signaling, obtain the available handover channel information of all new LEO satellites, generate a handover table according to the available handover channel information of all new LEO satellites in the location area and the handover user information, and send a user allocation signaling to all new LEO satellites in the location area to update their handover channel information; it is also used to send a handover request response signaling to the original LEO satellite to inform the original LEO satellite that it has decided on a new LEO satellite for its access user and the handover channel of the LEO satellite.

[0035] AMF-M or AMF-G is used to receive the path handover request signaling sent by gNB-L of the new LEO satellite and send a session update request signaling to SMF-M or SMF-G to update the transmission path of the data communication service; it is also used to receive the session update response signaling sent by SMF-M or SMF-G. At this time, the source-end user has completed the session update, and send a path handover response signaling to the new LEO satellite.

[0036] SMF-M or SMF-G is used to receive the session update request signaling sent by AMF-M or AMF-G, and then send a session modification request signaling to the peer LEO satellite to update the transmission path of the data communication service; it is also used to receive the session modification response signaling sent by the peer LEO satellite and send a session update response signaling to AMF-M or AMF-G, where the peer LEO satellite is the new LEO satellite of the source-end session user.

[0037] The inter-satellite handover method for space-ground integration of the giant satellite constellation provided by the present invention is divided into four processes, including a handover trigger process, a handover decision process, a handover execution process, and a routing redirection process. The handover trigger process, the handover decision process, the handover execution process, and the routing redirection process are all execution processes of the inter-satellite handover method in the staring beam satellite mode. In the staring beam satellite mode, the ground location area is used to simulate the staring area of the LEO satellite. All LEO satellites achieve full coverage of the location area within each time slot, and the location area associated with each LEO satellite is obtained by querying the satellite-location area association table.

[0038] During the communication between the source session user and the destination session user, both the source session user and the destination session user may undergo handovers, triggering the handover trigger process, the handover decision process, and the handover execution process. When the destination session user undergoes a handover, it also triggers the routing redirection process, which is used to inform the new LEO satellite of the source session user to change the session path, thereby ensuring complete data communication between the source session user and the destination session user throughout the session.

[0039] Reference Figure 3 , the inter-satellite handover method for space-ground integration of the giant satellite constellation provided by the present invention includes:

[0040] Handover trigger process: Each LEO satellite determines whether the user terminal within its associated location area needs to be handed over to a new LEO satellite in the next time slot. If so, it selects the MEO satellite or the GS ground station as its management and control center, and sends a handover request signaling to the management and control center.

[0041] Handover decision process: The management and control center counts the user information requesting handover within the location area associated with the original LEO satellite and queries the available handover channel information of the new LEO satellite, makes a handover decision, and generates a user allocation signaling for the new LEO satellite according to the handover decision.

[0042] Handover execution process: The management and control center feeds back a handover request response signaling to the original LEO satellite. The original LEO satellite sends an RRC connection reconfiguration signaling to the user terminal requesting handover. The user terminal connects to the new LEO satellite and its handover channel, and feeds back an RRC connection reconfiguration completion signaling to the new LEO satellite.

[0043] Routing redirection process: The new LEO satellite of the destination session user selects its own management and control center and sends a path handover request signaling to the management and control center. The management and control center informs the new LEO satellite of the source session user to change the session path, and informs the new LEO satellite of the destination session user that the session path of the source session user has been updated. The new LEO satellite informs the original LEO satellite to delete the context information of the handover user terminal.

[0044] It should be noted that in the gimbal beam satellite mode, the time for the satellite to serve the user terminal becomes longer, and the present invention effectively reduces the number of handovers. In this mode, the satellite periodically calculates whether the location area associated with it has changed. If it has changed, a handover request is triggered; otherwise, no handover request is triggered. This method can reduce unnecessary handovers and avoid the ping-pong effect from affecting the user experience. The present invention not only designs the signaling interaction process for the user handover process, but also further designs the signaling interaction process for the correct forwarding of user data communication services during the handover process, realizing the integrity of the inter-satellite handover method and ensuring the complete data communication of users during the handover process. The functional entity for processing handover signaling is mainly deployed in LEO satellites, MEO satellites, and GS ground stations. The LEO satellite is responsible for user access, and the MEO satellite and GS ground station jointly make handover decisions for the users on the satellite that triggers the handover request. This not only reduces the dependence on the GS ground station and avoids long-distance and frequent satellite-ground signaling interactions, but also the MEO satellite and GS ground station jointly acting as handover decision-makers can obtain global information and have high execution efficiency, significantly reducing the handover delay and signaling overhead of inter-satellite handovers in the face of a giant satellite constellation.

[0045] As Figure 2 shown, Figure 2 is the flowchart of the LEO satellite - location area association method of the present invention. The gimbal beam satellite mode can reduce the number of handovers and the call drop rate caused by handover failures. In order to simulate and implement the association relationship between the satellite and the location area. The satellite - location area association table is formed by the management and control center through the following steps:

[0046] (1) Obtain the center longitude and latitude information of each location area and each location area;

[0047] (2) Traverse all location areas within the current time slot. According to the trajectory files of all satellites, among the LEO satellites whose sub-satellite points of the LEO satellite are within the current location area in the current time slot, the LEO satellite with the shortest distance to the location area is designated as the LEO satellite associated with each location area according to the principle of the shortest distance between the LEO satellite and the location area, and mark the location area and the LEO satellite designated for this location area;

[0048] (3) Determine whether each location area within the current time slot has an associated LEO satellite. If not, for the location area without a designated LEO satellite, the LEO satellite with the largest elevation angle among the unmarked LEO satellites visible within the minimum elevation angle range of this location area is designated as the LEO satellite associated with this location area, and mark the location area and the LEO satellite designated for this location area;

[0049] (4) For the remaining unmarked LEO satellites, the LEO satellites are designated to the associated location areas according to the principle of the shortest distance between the LEO satellite and the center of the location area;

[0050] (5) Take the next time slot as the current time slot, and return to (2) to obtain the association result between the LEO satellite and the location area within the predetermined duration, and form the LEO satellite-location area association table, as shown in Table 1.

[0051] Table 1 LEO satellite-location area association table

[0052]

[0053] In the actual program process, the specific process of forming the association between the LEO satellite and the location area in the present invention is as follows:

[0054] (1) According to the global longitude and latitude and the location area division situation, obtain the central longitude and latitude information C of each location area a ={lat a , lon a}, The longitude and latitude range R where each location area is located a ={lat1 a , lat2 a lon1 a , lon2 a},

[0055] (2) Traverse the nth time slot, where The duration of each time slot is t n seconds. Determine whether all time slots have been traversed. If so, the LEO satellite-location area association method ends, and the "LEO satellite-location area association table" as shown in Table 1 above is formed. Otherwise, execute (3);

[0056] (3) Traverse the a-th location area, where Determine whether all location areas have been traversed. If so, execute (7). Otherwise, execute (4);

[0057] (4) Traverse the i-th LEO satellite, where Determine whether all LEO satellites have been traversed. If so, then execute (6). Otherwise, execute (5);

[0058] (5) According to the satellite trajectory file, obtain the longitude, latitude and altitude information S of the currently traversed LEO satellite in the current time slot i,n ={lat i,n , lon i,n , alt i,n}, Furthermore, obtain the sub-satellite point longitude and latitude information SP of the currently traversed LEO satellite in the current time slot i,n ={lat i,n , lon i,n}, Judge

[0059] (lat1 a ≤lat i,n ≤lat2 a )∩(lon1 a ≤lon i,n ≤lon2 a ) holds. If so, calculate the distance between the currently traversed LEO satellite and the center of the currently traversed location area in the current time slot, and return (4). Otherwise, set the distance between the currently traversed LEO satellite and the center of the currently traversed location area in the current time slot to -1, and return (4);

[0060] (6) According to the distances between all LEO satellites and the center of the currently traversed location area calculated in the fifth step, if there is a LEO satellite with a non - negative distance and the shortest distance, designate this LEO satellite as the associated satellite of the currently traversed location area, mark this location area and this LEO satellite, and return (3). Otherwise, do not mark this location area and this LEO satellite, and return (3);

[0061] (7) Traverse the remaining unmarked location areas. The set of remaining unmarked location areas is Judge whether all the remaining unmarked location areas have been traversed. If so, execute (11). Otherwise, execute (8);

[0062] (8) Traverse the remaining unmarked LEO satellites. The set of remaining unmarked LEO satellites is Judge whether all the remaining unmarked LEO satellites have been traversed. If so, execute (10). Otherwise, execute (9);

[0063] (9) According to the longitude and latitude information of the center of the currently traversed location area and the longitude, latitude and altitude information of the LEO satellite traversed in the current time slot calculate the elevation angle between the currently traversed location area and the LEO satellite traversed in the current time slot Judge whether it holds, where is the minimum elevation angle between the location area and the LEO satellite. If so, return (8). Otherwise, set the elevation angle between the currently traversed location area and the currently traversed LEO satellite to -1, and return (8);

[0064] Among them, is calculated by the following formula:

[0065]

[0066] Among them, Re is the radius of the earth,

[0067] (10) For all the elevation angles between the LEO satellites calculated according to (9) and the currently traversed location area, if there is a LEO satellite with an elevation angle not equal to -1 and the maximum elevation angle, then use this LEO satellite as the associated satellite for this location area, mark this LEO satellite, and return to (7); otherwise, do not mark this LEO satellite and return to (7);

[0068] (11) Traverse the remaining unmarked LEO satellites. The set of the remaining unmarked LEO satellites is Determine whether all the remaining unmarked LEO satellites have been traversed. If so, execute (15); otherwise, execute (12);

[0069] (12) Traverse the a-th location area, where Determine whether all location areas have been traversed. If so, execute (14); otherwise, execute (13);

[0070] (13) Calculate the distance between the currently traversed LEO satellite and the currently traversed location area in the current time slot, and return to (12);

[0071] (14) According to the distances between the currently traversed LEO satellite and all location areas calculated in (13), use the location area with the shortest distance as the location area associated with this satellite, and return to (11);

[0072] (15) The association between the LEO satellite and the location area in the current time slot ends, ensuring that the coverage rate of the location area in the current time slot is 100%.

[0073] As Figure 3 shown, Figure 3 is the signaling interaction flowchart of the inter-satellite handover protocol in the staring beam satellite mode of the present invention,

[0074] Handover trigger process:

[0075] Each LEO satellite determines whether to trigger a handover request according to whether the location area associated with itself in the current time slot is the same as the location area associated with it in the next time slot; if a handover request is triggered, a broadcast signaling is sent to the user terminal to inform the accessed user terminal to prepare to hand over to the new LEO satellite;

[0076] The user terminal that receives the broadcast signaling determines whether the LEO satellite it accesses is the LEO satellite that sends the broadcast signaling. If so, a broadcast response signaling is fed back to the LEO satellite to inform the LEO satellite that the user terminal is ready to hand over;

[0077] Each LEO satellite selects an MEO satellite or a GS ground station as its control center according to the principle of minimizing the number of relay satellites, and sends a handover request signaling to the control center;

[0078] Handover decision-making process:

[0079] The control center of the original LEO satellite obtains the location area associated with the LEO satellite from the handover request signaling, obtains the LEO satellites associated with this location area in the next time slot, and forms a handover user table with the user information of all users requesting handover in this location area; sends a resource query request signaling to the new LEO satellite associated with this location area in the next time slot;

[0080] The new LEO satellite feeds back a resource query response signaling to the control center of the original LEO satellite;

[0081] The control center of the original LEO satellite makes a handover decision according to the resource query response signaling and the handover user table, and sends a user allocation signaling to the new LEO satellite.

[0082] Handover execution process:

[0083] The control center of the original LEO satellite feeds back a handover request response signaling to the original LEO satellite;

[0084] The original LEO satellite sends an RRC connection reconfiguration signaling to the user terminal requesting handover, to inform the accessing user terminal to perform handover according to the allocated new LEO satellite and the handover channel of this LEO satellite;

[0085] The user terminal feeds back an RRC connection reconfiguration complete signaling to the new LEO satellite, to inform the new LEO satellite that the user has completed the handover.

[0086] Routing redirection process:

[0087] After receiving the RRC connection reconfiguration complete signaling of the destination user, the new LEO satellite selects a control center for itself according to the principle of minimizing the number of relay satellites, and sends a path handover request signaling to its own control center;

[0088] The control center of the new LEO satellite sends a session modification request signaling to the peer LEO satellite, to update the destination LEO satellite of the source session user;

[0089] The peer LEO satellite updates the destination LEO satellite of the source session user according to the session modification request signaling, and feeds back a session modification response signaling to the control center of the new LEO satellite;

[0090] The control center of the new LEO satellite feeds back a path handover response signaling to the new LEO satellite, to inform the new LEO satellite that the data transmission path of each source session user has been updated;

[0091] The new LEO satellite feeds back and releases context signaling to the original LEO satellite so that the original LEO satellite deletes the context information of the switched user terminal.

[0092] Specifically, as Figure 3 shown, the main steps of the handover triggering process of the present invention are as follows:

[0093] (1) Figure 3 Step 1 in : The original LEO satellite periodically calculates, according to the obtained LEO satellite - location area association table, whether the location area associated in the current time slot is the same as the location area associated in the next time slot. If so, the original LEO satellite does not trigger a handover request. Otherwise, the original LEO satellite triggers a handover request, and the gNB-L of this LEO satellite sends broadcast signaling to the user terminal to inform the access user to prepare for handover;

[0094] (2) Figure 3 Step 2 in : The user terminal receives the broadcast signaling sent by the gNB-L of the original LEO satellite. After receiving the broadcast signaling sent by the gNB-L of the original LEO satellite, it judges whether the LEO satellite accessed by the user terminal is the original LEO satellite that sent the broadcast signaling. If so, it returns a broadcast response signaling to the original LEO satellite to feedback to the original LEO satellite that its access user is ready for handover. Otherwise, this user terminal does not give feedback;

[0095] (3) Figure 3 Step 3 in : The gNB-L of the original LEO satellite receives the broadcast response signaling fed back by its access user terminal, selects its control center for the original LEO satellite according to the principle of the minimum number of relay satellites, and then sends a handover request signaling to its control center to inform its control center that the access users on the original LEO satellite need to hand over to the new LEO satellite;

[0096] Among them, the handover request signaling includes the location area associated with the original LEO satellite in the current time slot and the access user information on the original LEO satellite in the current time slot. The access user information includes the user's data transmission rate requirement, remaining session duration, longitude, and latitude.

[0097] Specifically, as Figure 3 shown, the main steps of the handover decision-making process of the present invention are as follows:

[0098] (1) Figure 3 Step 4 in : If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M receives the handover request signaling sent by the gNB-L of the original LEO satellite. If the control center of the original LEO satellite is a GS ground station, its gNB-CU-G receives the handover request signaling sent by the gNB-L of the original LEO satellite;

[0099] After the control center of the original LEO satellite receives the handover request signaling sent by gNB-L of the original LEO satellite, it obtains the location area associated with the original LEO satellite in the current time slot from the handover request signaling; it determines whether it has received all the handover request signaling sent by the original LEO satellites that triggered handover requests in this location area. If so, it counts the access user information on all the original LEO satellites that triggered handover requests in this location area to form handover user table information. Otherwise, it continues to receive the handover request signaling sent by the original LEO satellites that trigger handover requests in this location area;

[0100] Among them, the handover user table information includes the data transmission rate requirements, remaining call duration, longitude, and latitude of the users;

[0101] The control center of the original LEO satellite obtains the new LEO satellite associated with this location area in the next time slot according to the LEO satellite - location area association table, and sends a resource query request signaling to the new LEO satellite;

[0102] (2) Figure 3 Step 5 in (2): gNB-L of the new LEO satellite receives the resource query request signaling sent by the control center of the original LEO satellite, and returns a resource query response signaling to the control center of the original LEO satellite;

[0103] Among them, the resource query response signaling includes the available handover channel information of the new LEO satellite, and the handover channel information includes the number of handover channels and the data transmission rate that each channel can support;

[0104] (3) Figure 3 Step 6 in (3): If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M receives the resource query response signaling fed back by gNB-L of the new LEO satellite. If the control center of the original LEO satellite is a GS ground station, its gNB-CU-G receives the resource query response signaling fed back by gNB-L of the new LEO satellite;

[0105] After the control center of the original LEO satellite receives the resource query response signaling fed back by gNB-L of the new LEO satellite, according to the obtained location area, it determines whether it has received all the resource query response signaling fed back by the new LEO satellites in this location area. If so, it generates handover table information according to the handover user table information and the available handover channel information of all the new LEO satellites; and sends a user allocation signaling to the new LEO satellite to inform the new LEO satellite to update its handover channel information in time;

[0106] Among them, the user allocation signaling includes the handover table information; the handover table information includes the data transmission rate requirements, remaining session duration, new LEO satellite to which the handover is made, and the handover channel of this LEO satellite.

[0107] Specifically, such asFigure 3 As shown in the figure, the main steps of the handover execution process of the present invention are as follows:

[0108] (1) Figure 3 Step 7 in [description]: If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M feeds back a handover request response signaling to the original LEO satellite; if the control center of the original LEO satellite is a GS ground station, its gNB-CU-G feeds back a handover request response signaling to the original LEO satellite, so as to inform the original LEO satellite that its control center has made a decision on a new LEO satellite and the handover channel of this LEO satellite for all access users, and it can be ready to access;

[0109] (2) Figure 3 Step 8 in [description]: The gNB-L of the original LEO satellite receives the handover request response signaling fed back by its control center. After receiving the handover request response signaling, the gNB-L of the original LEO satellite sends an RRC connection reconfiguration signaling to its access users, so as to inform its access users of the new LEO satellite assigned to them and the handover channel of this LEO satellite;

[0110] Among them, the RRC connection reconfiguration signaling contains handover table information;

[0111] (3) Figure 3 Step 9 in [description]: The user terminal receives the RRC connection reconfiguration signaling sent by the gNB-L of the original LEO satellite, obtains the handover table information from the RRC connection reconfiguration signaling, obtains the new LEO satellite assigned to this user and the handover channel of this LEO satellite according to the handover table information, and returns an RRC connection reconfiguration complete signaling to the new LEO satellite.

[0112] Specifically, as Figure 3 shown, the main steps of the routing redirection process of the present invention are as follows:

[0113] (1) Figure 3 Step 10 in [description]: The gNB-L of the new LEO satellite receives the RRC connection reconfiguration complete signaling of the destination session user, selects its control center for the new LEO satellite according to the principle of minimizing the number of relay satellites, and then sends a path handover request to its control center, so as to inform the peer LEO satellite to update the data transmission path for each source session user, and ensure that after the destination session user makes a handover, the data communication service sent by the source user can be correctly sent to the destination LEO satellite and downloaded to the destination session user;

[0114] (2) Figure 3Step 11: If the control center of the new LEO satellite is a MEO satellite, its gNB-CU-M receives the path switching request signaling sent by the gNB-L of the new LEO satellite. After receiving the path switching request signaling sent by the gNB-L of the new LEO satellite, its AMF-M sends a session update request signaling to the SMF-M of this control center to inform the SMF-M of this control center to perform session update. If the control center of the new LEO satellite is a GS ground station, its gNB-CU-G receives the path switching request signaling sent by the gNB-L of the new LEO satellite. After receiving the path switching request signaling sent by the gNB-L of the new LEO satellite, its AMF-G sends a session update request signaling to the SMF-G of this control center to inform the SMF-G of this control center to perform session update;

[0115] Among them, the session update request signaling includes the destination LEO satellite that the source session user needs to update;

[0116] (3) Figure 3 Step 12: If the control center of the new LEO satellite is a MEO satellite, its SMF-M receives the session update request signaling sent by its AMF-M. After receiving the session update request signaling sent by its AMF-M, its SMF-M sends a session modification request signaling to the peer LEO satellite to inform the peer LEO satellite to update the destination LEO satellite of the source session user. If the control center of the new LEO satellite is a GS ground station, its SMF-G receives the session update request signaling sent by its AMF-G. After receiving the session update request sent by its AMF-G, its SMF-G sends a session modification request signaling to the peer LEO satellite to inform the peer LEO satellite to update the destination LEO satellite of the source session user;

[0117] (4) Figure 3 Step 13: The UPF-L of the peer LEO satellite receives the session modification request signaling sent by the control center of the new LEO satellite. After receiving the session modification request signaling sent by the control center of the new LEO satellite, this LEO satellite updates the destination LEO satellite of the source session user and feeds back a session modification response signaling to the control center of the new LEO satellite;

[0118] (5) Figure 3Step 14: If the control center of the new LEO satellite is a MEO satellite, its SMF-M receives the session modification response signaling fed back by the UPF-L of the peer LEO satellite. After receiving the session modification response signaling fed back by the UPF-L of the peer LEO satellite, it feeds back the session update response signaling to its AMF-M to inform its AMF-M that the session update has been completed. If the control center of the new LEO satellite is a GS ground station, its SMF-G receives the session modification response signaling fed back by the UPF-L of the peer LEO satellite. After receiving the session modification response signaling fed back by the UPF-L of the peer LEO satellite, it feeds back the session update response signaling to its AMF-G to inform its AMF-G that the session update has been completed.

[0119] (6) Figure 3 Step 15: If the control center of the new LEO satellite is a MEO satellite, its AMF-M receives the session update response signaling fed back by its SMF-M. After receiving the session update response signaling fed back by its SMF-M, it feeds back the path switch response signaling to the new LEO satellite to inform the new LEO satellite that the destination LEO satellite of each source session user has been updated. If the control center of the new LEO satellite is a GS ground station, its AMF-G receives the session update response signaling fed back by its SMF-G. After receiving the session update response signaling fed back by its SMF-G, it feeds back the path switch response signaling to the new LEO satellite to inform the new LEO satellite that the destination LEO satellite of each source session user has been updated.

[0120] (7) Figure 3 Step 16: The gNB-L of the new LEO satellite receives the path switch response signaling fed back by its control center. After receiving the path switch response signaling fed back by its control center, it feeds back the context release signaling to the original LEO satellite, and the gNB-L of the original LEO satellite receives the context release signaling to inform the original LEO satellite to delete the context information of its handover users.

[0121] Among them, the context information includes the user's subscription information, service priority, and authentication information.

[0122] The present invention provides an inter-satellite handover method for space-ground integration of a giant satellite constellation, including a handover triggering process, a handover decision-making process, a handover execution process, and a routing redirection process. The present invention adopts the staring beam satellite mode to reduce the number of handovers of users. The satellite triggers a handover request to reduce unnecessary handovers and avoid the ping-pong effect from affecting the user experience. Moreover, the functional entity for processing handover signaling is deployed on LEO satellites, MEO satellites, and GS ground stations. The LEO satellite is responsible for user access, and the MEO satellite and the GS ground station jointly make handover decisions for users on the satellite that triggers the handover request. This not only reduces the dependence on the GS ground station and avoids long-distance and frequent space-ground signaling interactions, but also the MEO satellite and the GS ground station jointly serve as handover decision-makers, can obtain global information, and have high execution efficiency. In the context of a giant satellite constellation, it not only ensures complete data communication for users during handover, but also significantly reduces the handover delay and signaling overhead of inter-satellite handovers. Finally, this inter-satellite handover method details the deployment of functional entities and how handover signaling interacts between functional entities, providing strong support for future inter-satellite handover methods under a giant satellite constellation.

[0123] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0124] Although the present application has been described in conjunction with various embodiments herein, however, in the process of implementing the claimed present application, those skilled in the art can understand and achieve other variations of the disclosed embodiments by viewing the accompanying drawings, the disclosure content, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality of cases.

[0125] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. An inter-satellite handover method for space-ground integration in a giant satellite constellation, characterized in that Applied to the inter-satellite handover architecture, the inter-satellite handover architecture includes multiple user terminals, and the user terminals are divided into source session users and destination session users, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations. The inter-satellite handover method for the space-ground integration of a giant satellite constellation includes: Handover trigger process: Each LEO satellite determines whether the user terminals within the location area associated with itself in the next time slot need to be handed over to a new LEO satellite. If so, it selects an MEO satellite or a GS ground station as its management and control center, and sends a handover request signaling to the management and control center. Handover decision process: The management and control center counts the user information requesting handover within the location area associated with the original LEO satellite and queries the available handover channel information of the new LEO satellite, makes a handover decision, and generates a user allocation signaling for the new LEO satellite according to the handover decision. Handover execution process: The management and control center feeds back a handover request response signaling to the original LEO satellite. The original LEO satellite sends an RRC connection reconfiguration signaling to the user terminal requesting handover, so that the user terminal connects to the new LEO satellite and the handover channel of this LEO satellite, and feeds back an RRC connection reconfiguration completion signaling to the new LEO satellite. Routing redirection process: The new LEO satellite of the destination session user selects a management and control center for itself and sends a path handover request signaling to the management and control center; the management and control center tells the new LEO satellite of the source session user to change the session path, and tells the new LEO satellite of the destination session user that the session path of the source session user has been updated; the new LEO satellite tells the original LEO satellite to delete the context information of the handover user terminal.

2. The inter-satellite handover method for space-ground integration of a giant satellite constellation according to claim 1, wherein The handover trigger process, the handover decision process, the handover execution process, and the routing redirection process are all the execution processes of the inter-satellite handover method in the staring beam satellite mode.

3. The inter-satellite handover method for space-ground integration of a giant satellite constellation according to claim 2, characterized in that, In the staring beam satellite mode, the ground location area is used to simulate the staring area of the LEO satellite. All LEO satellites achieve full coverage of the location area within each time slot. The location area associated with each LEO satellite is obtained by querying the LEO satellite - location area association table. The LEO satellite - location area association table is formed by the management and control center through the following steps: (1) Obtain each location area and the central longitude and latitude information of each location area; (2) Traverse all location areas within the current time slot. According to the trajectory files of all satellites, among the LEO satellites whose sub-satellite points are within the current location area in the current time slot, a LEO satellite associated with each location area is demarcated according to the principle of the shortest distance between the LEO satellite and the location area, and the location area and the demarcated LEO satellite for this location area are marked; (3) Judge whether each location area within the current time slot has an associated LEO satellite. If not, for the location area without a demarcated LEO satellite, the LEO satellite with the largest elevation angle among the unmarked LEO satellites visible within the minimum elevation angle range within this location area is demarcated as the LEO satellite associated with this location area, and the location area and the demarcated LEO satellite for this location area are marked; (4) For the remaining unlabeled LEO satellites, the LEO satellites are delimited to the associated location area according to the principle of the shortest distance between the LEO satellite and the center of the location area; (5) Take the next time slot as the current time slot and return to (2) to obtain the association result between the LEO satellite and the location area within a predetermined duration, and form an LEO satellite - location area association table.

4. The inter-satellite handover method for space-ground integration of a giant satellite constellation according to claim 1, characterized in that, The LEO satellite includes a gNB-L on-board base station and a UPF-L user plane function module; the MEO satellite includes a gNB-CU-M on-board base station center module, an AMF-M access and mobility management function module, and an SMF-M session management function module; the GS ground station includes a gNB-CU-G base station center module, an AMF-G access and mobility management function module, and an SMF-G session management function module.

5. The inter-satellite handover method for space-ground integration facing a giant satellite constellation according to claim 4, characterized in that Handover trigger process: Each LEO satellite determines whether to trigger a handover request according to whether the location area associated with itself in the current time slot is the same as the location area associated with it in the next time slot; If a handover request is triggered, a broadcast signaling is sent to the user terminal to inform the accessed user terminal to prepare to hand over to the new LEO satellite; The user terminal that receives the broadcast signaling determines whether the LEO satellite it accesses is the LEO satellite that sends the broadcast signaling. If so, a broadcast response signaling is fed back to the LEO satellite to inform the LEO satellite that the user terminal is ready for handover; Each LEO satellite selects a MEO satellite or a GS ground station as the control center for itself according to the principle of the minimum number of relay satellites, and sends a handover request signaling to the control center; Handover decision process: The control center of the original LEO satellite obtains the location area associated with the LEO satellite from the handover request signaling, and obtains the LEO satellite associated with this location area in the next time slot, and forms a handover user table with all the user information requesting handover in this location area; sends a resource query request signaling to the new LEO satellite associated with this location area in the next time slot; The new LEO satellite feeds back a resource query response signaling to the control center of the original LEO satellite; The control center of the original LEO satellite makes a handover decision according to the resource query response signaling and the handover user table, and sends a user allocation signaling to the new LEO satellite; Handover execution process: The control center of the original LEO satellite feeds back a handover request response signaling to the original LEO satellite; The original LEO satellite sends an RRC connection reconfiguration signaling to the user terminal requesting handover to inform the accessed user terminal to perform a handover according to the allocated new LEO satellite and the handover channel of this LEO satellite; The user terminal feeds back an RRC connection reconfiguration completion signaling to the new LEO satellite to inform the new LEO satellite that the user has completed the handover; Routing redirection process: After receiving the RRC connection reconfiguration completion signaling of the destination user, the new LEO satellite selects a control center for itself according to the principle of the minimum number of relay satellites, and sends a path handover request signaling to its own control center; The control center of the new LEO satellite sends a session modification request signaling to the peer LEO satellite to update the destination LEO satellite of the source session user; The peer LEO satellite updates the destination LEO satellite of the source session user according to the session modification request signaling and feeds back a session modification response signaling to the control center of the new LEO satellite; The control center of the new LEO satellite feeds back a path switching response signaling to the new LEO satellite to inform the new LEO satellite that the data transmission path of each source session user has been updated; The new LEO satellite feeds back a release context signaling to the original LEO satellite to enable the original LEO satellite to delete the context information of the switched user terminal.

6. The inter-satellite handover method for space-ground integration for a giant satellite constellation according to claim 5, wherein Handover trigger process: The original LEO satellite periodically calculates whether the location area associated in the current time slot is the same as the location area associated in the next time slot according to the obtained LEO satellite - location area association table. If so, the original LEO satellite does not trigger a handover request. Otherwise, the original LEO satellite triggers a handover request, and the gNB-L of this LEO satellite sends a broadcast signaling to the user terminal to inform its access users to prepare for handover; The user terminal receives the broadcast signaling sent by the gNB-L of the original LEO satellite. After receiving the broadcast signaling sent by the gNB-L of the original LEO satellite, it judges whether the LEO satellite accessed by the user terminal is the original LEO satellite that sent the broadcast signaling. If so, it returns a broadcast response signaling to the original LEO satellite to feedback to the original LEO satellite that its access users are ready for handover. Otherwise, this user terminal does not feedback; The gNB-L of the original LEO satellite receives the broadcast response signaling fed back by its access user terminal, selects its control center for the original LEO satellite according to the principle of the minimum number of relay satellites, and then sends a handover request signaling to its control center to inform its control center that the access users on the original LEO satellite need to handover to the new LEO satellite; Among them, the handover request signaling includes the location area associated with the original LEO satellite in the current time slot and the access user information on the original LEO satellite in the current time slot. The access user information includes the user's data transmission rate requirement, remaining session duration, longitude and latitude.

7. The inter-satellite handover method for space-ground integration for a giant satellite constellation according to claim 5, wherein Handover decision process: If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M receives the handover request signaling sent by the gNB-L of the original LEO satellite. If the control center of the original LEO satellite is a GS ground station, its gNB-CU-G receives the handover request signaling sent by the gNB-L of the original LEO satellite; After receiving the handover request signaling sent by the gNB-L of the original LEO satellite, the control center of the original LEO satellite obtains the location area associated with the original LEO satellite in the current time slot from the handover request signaling; judges whether it has received all the handover request signals sent by the original LEO satellites that triggered the handover request in this location area. If so, it statistically calculates the access user information on all the original LEO satellites that triggered the handover request in this location area to form handover user table information; Otherwise, continue to receive the handover request signaling sent by the original LEO satellites that triggered the handover request in this location area; Among them, the switched user table information includes the user's data transmission rate requirement, remaining call duration, longitude, and latitude; The control center of the original LEO satellite obtains the new LEO satellite associated with this location area in the next time slot according to the LEO satellite - location area association table, and sends a resource query request signaling to the new LEO satellite; The gNB-L of the new LEO satellite receives the resource query request signaling sent by the control center of the original LEO satellite, and returns a resource query response signaling to the control center of the original LEO satellite; Among them, the resource query response signaling includes the available handover channel information of the new LEO satellite, and the handover channel information includes the number of handover channels and the data transmission rate supported by each channel; If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M receives the resource query response signaling fed back by the gNB-L of the new LEO satellite. If the control center of the original LEO satellite is a GS ground station, its gNB-CU-G receives the resource query response signaling fed back by the gNB-L of the new LEO satellite; After the control center of the original LEO satellite receives the resource query response signaling fed back by the gNB-L of the new LEO satellite, it determines whether it has received the resource query response signaling fed back by all the new LEO satellites in this location area according to the obtained location area. If so, it generates handover table information according to the switched user table information and the available handover channel information of all the new LEO satellites; and sends a user allocation signaling to the new LEO satellite to inform the new LEO satellite to update its handover channel information in a timely manner; Among them, the user allocation signaling includes the handover table information; the handover table information includes the user's data transmission rate requirement, remaining session duration, the new LEO satellite to which the user is switched, and the handover channel of this LEO satellite.

8. The inter-satellite handover method for space-ground integration of a giant satellite constellation according to claim 5, characterized in that Handover execution process: If the control center of the original LEO satellite is a MEO satellite, its gNB-CU-M feeds back a handover request response signaling to the original LEO satellite. If the control center of the original LEO satellite is a GS ground station, its gNB-CU-G feeds back a handover request response signaling to the original LEO satellite to inform the original LEO satellite that its control center has made a decision on the new LEO satellite and the handover channel of this LEO satellite for all the access users, and they can be ready to access; The gNB-L of the original LEO satellite receives the handover request response signaling fed back by its control center. After receiving the handover request response signaling, the gNB-L of the original LEO satellite sends an RRC connection reconfiguration signaling to its access users to inform its access users of the new LEO satellite assigned to them and the handover channel of this LEO satellite; Among them, the RRC connection reconfiguration signaling includes the handover table information; The user terminal receives the RRC connection reconfiguration signaling sent by the gNB-L of the original LEO satellite, obtains the handover table information from the RRC connection reconfiguration signaling, obtains the new LEO satellite assigned to this user and the handover channel of this LEO satellite according to the handover table information, and returns an RRC connection reconfiguration complete signaling to the new LEO satellite.

9. The inter-satellite handover method for space-ground integration for a giant satellite constellation according to claim 5, wherein Routing redirection process: The gNB-L of the new LEO satellite receives the RRC connection reconfiguration complete signaling of the session user at the receiving end, selects its control center for the new LEO satellite according to the principle of minimizing the number of relay satellites, and then sends a path switching request to its control center to inform the peer LEO satellite to update the data transmission path for each source session user, ensuring that after the destination session user switches, the data communication service sent by the source user can be correctly sent to the destination LEO satellite and downlinked to the destination session user; If the control center of the new LEO satellite is a MEO satellite, its gNB-CU-M receives the path switching request signaling sent by the gNB-L of the new LEO satellite. After receiving the path switching request signaling sent by the gNB-L of the new LEO satellite, its AMF-M sends a session update request signaling to the SMF-M of this control center to inform the SMF-M of this control center to perform session update. If the control center of the new LEO satellite is a GS ground station, its gNB-CU-G receives the path switching request signaling sent by the gNB-L of the new LEO satellite. After receiving the path switching request signaling sent by the gNB-L of the new LEO satellite, its AMF-G sends a session update request signaling to the SMF-G of this control center to inform the SMF-G of this control center to perform session update; Among them, the session update request signaling contains the destination LEO satellite that the source session user needs to update; If the control center of the new LEO satellite is a MEO satellite, its SMF-M receives the session update request signaling sent by its AMF-M. After receiving the session update request signaling sent by its AMF-M, its SMF-M sends a session modification request signaling to the peer LEO satellite to inform the peer LEO satellite to update the destination LEO satellite of the source session user. If the control center of the new LEO satellite is a GS ground station, its SMF-G receives the session update request signaling sent by its AMF-G. After receiving the session update request sent by its AMF-G, its SMF-G sends a session modification request signaling to the peer LEO satellite to inform the peer LEO satellite to update the destination LEO satellite of the source session user; The UPF-L of the peer LEO satellite receives the session modification request signaling sent by the control center of the new LEO satellite. After receiving the session modification request signaling sent by the control center of the new LEO satellite, this LEO satellite updates the destination LEO satellite of the source session user and feeds back a session modification response signaling to the control center of the new LEO satellite; If the control center of the new LEO satellite is a MEO satellite, its SMF-M receives the session modification response signaling fed back by the UPF-L of the peer LEO satellite. After receiving the session modification response signaling fed back by the UPF-L of the peer LEO satellite, it feeds back the session update response signaling to its AMF-M to inform its AMF-M that the session update has been completed. If the control center of the new LEO satellite is a GS ground station, its SMF-G receives the session modification response signaling fed back by the UPF-L of the peer LEO satellite. After receiving the session modification response signaling fed back by the UPF-L of the peer LEO satellite, it feeds back the session update response signaling to its AMF-G to inform its AMF-G that the session update has been completed. If the control center of the new LEO satellite is a MEO satellite, its AMF-M receives the session update response signaling fed back by its SMF-M. After receiving the session update response signaling fed back by its SMF-M, it feeds back the path switch response signaling to the new LEO satellite to inform the new LEO satellite that the destination LEO satellite of each source session user has been updated. If the control center of the new LEO satellite is a GS ground station, its AMF-G receives the session update response signaling fed back by its SMF-G. After receiving the session update response signaling fed back by its SMF-G, it feeds back the path switch response signaling to the new LEO satellite to inform the new LEO satellite that the destination LEO satellite of each source session user has been updated. The gNB-L of the new LEO satellite receives the path switch response signaling fed back by its control center. After receiving the path switch response signaling fed back by its control center, it feeds back the context release signaling to the original LEO satellite, and the gNB-L of the original LEO satellite receives the context release signaling to inform the original LEO satellite to delete the context information of its handover user. Among them, the context information includes the user's subscription information, service priority, and authentication information.

10. An inter-satellite handover architecture for space-ground integration of a giant satellite constellation, characterized in that Including: Multiple user terminals, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations; Among them, the multiple user terminals, multiple LEO satellites, multiple MEO satellites, and multiple GS ground stations interact with each other to implement the inter-satellite handover method for satellite-ground joint of a giant satellite constellation described in any one of claims 1 to 9.

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