Task area cross-satellite handover system of low-orbit satellite data chain and verification method

Abstract

The invention provides a task area cross-satellite handover system of a low-orbit satellite data link and a verification method, and belongs to the technical field of satellite communication. The system performs situation awareness on task area boundary, terminal distribution and link measurement to form task area coverage quality; determining a handover opportunity and selecting a target satellite based on factors such as a coverage trend, residual visible time and overlapping coverage; after wave beams, time slots and power resources are pre-allocated to a target satellite, a synchronous switching instruction is issued to a task area terminal, and non-inductive switching is completed according to pre-connection, double-path parallel transmission and elegant release; the digital twin environment performs three-dimensional visualization, index statistics and anomaly analysis on the whole process, and is used for online verification and parameter optimization.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, and in particular relates to a mission area inter-satellite handover system and verification method for low-orbit satellite data links. Background Technology

[0002] Low Earth Orbit (LEO) satellite data link systems can build satellite-to-ground and inter-satellite transmission channels based on LEO satellite constellations, network management stations, gateway stations, and user terminals, providing wireless access and relay transmission services for areas such as the air, the open sea, high mountains, and deserts. The application scope continues to expand as the communication and computing capabilities of the payloads improve.

[0003] Inter-satellite handover in existing low-Earth orbit satellite communication systems mostly adopts terminal-triggered mechanisms or hard handover methods. The terminal triggers the handover request based on thresholds such as received power or signal-to-noise ratio, or the terminal makes its own decision after the network provides neighbor cell information and completes the handover in a "disconnect first, reconnect later" manner, which is prone to causing communication interruptions.

[0004] The aforementioned approach, which primarily relies on single-user strategies and hard handover, typically suffers from issues such as inconsistent communication status within the mission area, the possibility that command and mission units may access different satellites, leading to disruptions in coordination, fragmented resource allocation that is difficult to dynamically adjust according to regional needs, data loss and latency uncertainties caused by hard handover, and a lack of monitoring of the overall service quality of the mission area. Consequently, it is difficult to meet the requirements for regionalized, coordinated, and highly reliable communication assurance. Summary of the Invention

[0005] In view of this, the present invention aims to propose a mission area inter-satellite handover system and verification method for low-Earth orbit satellite data links, so as to at least solve one of the problems in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A mission area inter-satellite handover system for low-Earth orbit (LEO) satellite data links includes a ground control center, at least two LEO satellites, and multiple user terminals located within the mission area; the ground control center communicates with the LEO satellites via a satellite-to-ground link, and the LEO satellites communicate with each other via an inter-satellite link; The mission area inter-satellite handover system includes a regional situational awareness module, an intelligent decision engine module, a resource collaborative scheduling module, and a handover execution control module; among which... The regional situation awareness module is used to acquire satellite ephemeris information, user terminal positioning information, link measurement reports and service traffic characteristics, construct and update the communication situation of the task area, and output the task area identification results and the task area coverage quality characterization. The intelligent decision engine module is used to make handover and trigger judgments and select target satellites based on the communication situation in the mission area, and generate a handover strategy for the mission area. The resource coordination scheduling module is used to pre-allocate the beam resources, time slot resources and power resources of the target satellite according to the switching strategy and form a resource allocation result; The handover execution control module is used to convert the handover strategy and the resource allocation result into synchronous handover control signaling for the task area, organize multiple user terminals in the task area to complete the soft handover from the current serving satellite to the target satellite in the same handover window, and release the resources occupied by the current serving satellite in the task area after the soft handover is completed.

[0007] Furthermore, the regional situation awareness module includes a task area dynamic identification unit and a coverage situation fusion unit; The task area dynamic identification unit is used to dynamically cluster user terminals based on their geographical distribution and communication correlation, thereby determining the task area boundary; The coverage situation fusion unit is used to fuse the link measurement report and service requirement information to generate a comprehensive coverage quality index for the mission area, which is used to evaluate the overall coverage effectiveness of the current service satellites for the mission area.

[0008] Furthermore, the coverage situation fusion unit is used to construct a terminal link quality index for a single user terminal, and to weight and aggregate the terminal link quality indices of multiple user terminals according to the terminal service weights to obtain a comprehensive coverage quality index for the task area.

[0009] Furthermore, the intelligent decision engine module includes an interaction triggering judgment unit and a target satellite selection unit; The handover triggering judgment unit is used to calculate the trigger value based on the comprehensive coverage quality index of the mission area, the coverage quality change trend, the remaining effective coverage time of the mission area, and the overlapping coverage capability of candidate satellites, and compare it with the preset threshold to determine whether to start the handover of the mission area. The target satellite selection unit is used to score candidate satellites based on multiple attributes, including at least coverage integrity, resource sufficiency, expected link quality, and handover cost, and selects the candidate satellite with the best comprehensive score as the target satellite.

[0010] Furthermore, the resource collaborative scheduling module is used to model the pre-allocation of resources in the task area as a constrained multi-objective optimization problem. The multi-objectives include at least the task area throughput objective, the coverage fairness objective, and the handover continuity objective. Under the conditions of satisfying the constraints of the maximum number of available beams, total power constraints, coverage constraints, link quality constraints, and interference coordination constraints, the module outputs a resource allocation matrix.

[0011] Furthermore, the switching execution control module includes a synchronization signaling distribution unit, an execution status monitoring unit, and an abnormal rollback unit; The synchronization signaling distribution unit is used to distribute handover commands to multiple user terminals within the task area using a reliable multicast method; The execution status monitoring unit is used to receive confirmation information reported by the user terminal and evaluate and switch the execution status accordingly. The abnormal backoff unit is used to trigger a backoff strategy when a soft handover failure or abnormal soft handover quality is detected, in order to maintain the original link or switch to a backup satellite.

[0012] Furthermore, the soft handover consists of a pre-connection phase, a dual-active parallel transmission phase, and a graceful resource release phase; The pre-connection phase is used to instruct user terminals to establish control plane connections with target satellites while maintaining user plane services carried by the current serving satellites. The dual-active parallel transmission phase is used to perform parallel transmission and fusion processing of data when the current serving satellite and the target satellite are simultaneously carrying user plane data transmission. The graceful resource release phase is used to release the control plane resources, user plane resources, and temporary status information of the currently serving satellite in the mission area in a preset order after the target satellite link is stable and meets the preset conditions.

[0013] Furthermore, this solution discloses an inter-satellite mission soft handover method, executed in the mission region, including: Acquire communication status data for the task area and generate comprehensive coverage quality indicators for the task area; Based on the comprehensive coverage quality index of the task area, the remaining effective coverage time, and the overlapping coverage capability, the handover triggering judgment is made, and the task area soft handover is initiated when the triggering conditions are met. Multiple candidate satellites are evaluated for multiple attributes to determine the target satellite and generate a list of alternative satellites; Perform resource pre-negotiation on the target satellite, pre-allocate beam resources, time slot resources and power resources for takeover mission area, and mark the pre-allocated resources as occupied; The system organizes multiple user terminals within the mission area to establish pre-connections with the target satellite, while maintaining the service connections between the user terminals and the currently serving satellites. After the pre-connection is completed, dual-active parallel transmission is entered, so that downlink data and uplink data form a parallel transmission path between the current serving satellite and the target satellite, and the parallel transmission data is deduplicated, sorted or fused. After detecting that the target satellite link meets the stability conditions, perform graceful resource release to release the resources currently occupied by the serving satellite in the mission area; Perform comprehensive verification of the soft handover process and output the verification results.

[0014] Furthermore, the acquisition of communication situation data in the task area includes acquiring satellite ephemeris, user terminal positioning information, link measurement reports, and service traffic characteristics; the comprehensive coverage quality index of the task area is obtained by weighted aggregation of the link quality index of multiple user terminals and service weights.

[0015] Furthermore, the cross-trigger judgment includes: constructing a trigger function based on the degree of coverage quality degradation, the trend of coverage quality degradation, the quality safety margin, the time urgency, and the overlapping coverage guarantee capability, and dynamically adjusting the weights or thresholds in the trigger function according to the task priority.

[0016] Furthermore, the multi-attribute evaluation includes at least: the coverage integrity index of candidate satellites to the mission area, the sufficiency index of available resources of candidate satellites, the expected index of link quality of candidate satellites, and the handover cost index; wherein, the handover cost index is composed of or derived from the time slot adjustment amount, frequency adjustment amount, and historical handover success rate.

[0017] Furthermore, the resource pre-negotiation includes: constructing a constrained optimization model for the joint allocation of time slots and beams, obtaining a resource allocation matrix using a heuristic solution method, and then sending the resource allocation matrix to the target satellite to complete resource reservation.

[0018] Furthermore, prior to the dual-active parallel transmission, the user terminal's user session context information on the current serving satellite is synchronized to the target satellite. The user session context information includes at least address information, security parameters, quality of service parameters, and sequence number status information.

[0019] Furthermore, the digital twin visualization verification method involved in this solution is used to verify the inter-satellite handover system and the inter-satellite mission soft handover process, including: Construct a digital twin of the satellite communication system, establish a mapping relationship between physical entities and virtual world models, and establish a real-time data synchronization channel; The system renders the low-Earth orbit satellite orbit, satellite model, mission area, beam coverage area, and user terminal distribution in a 3D Earth scene, and dynamically updates the satellite position, beam pointing, and coverage quality display based on synchronous data. The soft handover process is presented in a phased and detailed manner, according to the pre-connection phase, the dual-active parallel transmission phase, and the graceful release of resources phase. The resource reservation status, context synchronization status, and data stream transmission status are also displayed. Provides a dashboard of key performance indicators, displaying continuous indicators, data integrity indicators, and performance trend curves in real time; When an abnormal event is detected, anomaly detection and root cause analysis are performed, and anomaly alarm information is output. The anomaly-related entities, anomaly propagation paths and root cause analysis results are identified in the visualization interface. It provides interactive playback and analysis capabilities, supports playback of soft handover processes along a timeline, and enables multi-view linkage. The verification report is automatically generated and output based on the verification process data.

[0020] Furthermore, the real-time data synchronization channel adopts a message push mechanism to synchronize satellite location data, user terminal location data, link status data, resource status data, and performance index data to the visualization interface.

[0021] Furthermore, the anomaly detection includes at least two levels of detection: threshold detection, trend detection, and pattern recognition detection; the root cause analysis includes generating a cause tree structure and associating snapshots of key parameters before and after the anomaly occurred.

[0022] Furthermore, the verification report generation includes data collection, statistical analysis, result summarization, and formatted output, wherein the formatted output includes at least a web page display format and an exportable document format.

[0023] Compared with existing technologies, the mission area inter-satellite handover system and verification method for low-Earth orbit satellite data links described in this invention have the following advantages: (1) This invention takes the task area as the basic guarantee unit, and performs unified perception and modeling of the task area boundary, user distribution, service requirements and link measurement information through the network side. It also performs collaborative decision-making and resource scheduling with the overall regional efficiency as the goal, realizing the transformation from guaranteeing the connection of a single user to guaranteeing the communication of the entire task area. This can alleviate the collaborative risks caused by the task area coverage gap, inconsistent user status and cross-satellite separation of command and task units. (2) This invention proposes a soft handover process of pre-connection, dual-path parallel transmission and graceful release, which maintains the parallel carrying of the old and new links and performs session context security synchronization during the handover transition period, reduces the risk of communication interruption and data loss caused by handover, and improves the consistency and controllability of multi-user synchronous handover in the task area through reliable multicast distribution and execution status monitoring mechanisms. (3) This invention reduces resource conflicts and inefficient occupation caused by distributed switching by pre-allocating and coordinating the beam, time slot and power resources across satellites, so that resources can be aggregated and reserved according to the changes in the needs of the mission area, thereby improving the stability of mission area support and resource utilization efficiency. (4) This invention provides a digital twin visualization verification method, which displays the handover and soft switching process in three-dimensional spatiotemporal dimension through virtual-real mapping and real-time interaction. Combined with key indicator dashboards, anomaly detection and root cause analysis, playback comparison and automated report generation, it realizes online verification of strategy effects and parameter optimization, and improves the intuitiveness and operability of system evaluation. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the mission area inter-satellite handover system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the inter-satellite mission soft handover method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the digital twin visualization verification method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the method described in an embodiment of the present invention. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a mission area cross-satellite handover system for low-Earth orbit satellite data links, an inter-satellite mission soft handover and digital twin visualization verification method. It abandons the traditional single-user handover strategy and proposes the core design concept of mission area overall handover. The mission area is used as the basic unit for network resource scheduling, service quality assurance and performance evaluation. The network senses and serves the entire geographical mission area. The collaborative handover decision is triggered by the network based on the overall coverage status of the area. Resources are aggregated and scheduled on a mission area basis, realizing a fundamental shift from ensuring single user connection to ensuring communication of the entire mission area.

[0030] Specifically, the three-layer architecture of the collaborative handover process includes: a regional situational awareness layer, a collaborative intelligent decision-making layer, and a digital twin verification layer. The regional situational awareness layer perceives the mission area boundaries, user distribution, and service requirements in real time, accurately establishing a communication situational model for the mission area, used for communication situational prediction. The collaborative intelligent decision-making layer optimizes resource scheduling with the goal of maximizing overall regional efficiency, employing a three-stage process of pre-connection-dual transmission-graceful release for soft handover control. The digital twin verification layer establishes a high-fidelity digital twin of the satellite communication system through virtual-physical mapping, supporting real-time interaction, online strategy testing, and parameter tuning; its verification results automatically guide the optimization of the physical system.

[0031] The technical approach described in this invention possesses four innovative service capabilities: a regionalized service model, a collaborative soft handover mechanism, intelligent resource scheduling, and a digital twin verification method. These capabilities support collaborative, reliable, and secure continuous communication assurance services for applications. Specifically, the regionalized service model shifts the protection target from dispersed users to the entire task area, and the quality indicators change from individual QoS to regional coverage and coordination, providing deterministic communication assurance for tasks. The collaborative soft handover mechanism achieves zero-interruption handover through dual-path parallel transmission, ensuring synchronous handover for all users within the area. Intelligent resource scheduling supports dynamic aggregation of multi-satellite resources according to regional needs and allows for pre-reservation of resources based on predictions to avoid handover conflicts. The digital twin verification method supports full-element modeling, real-time situational awareness display, and visualized command and control, enabling continuous optimization of system performance through data-driven approaches.

[0032] The core value of this invention lies in the transformation from technological advantages to mission advantages. Through a three-in-one design of regional overall support, seamless collaborative switching, and twin intelligent verification, it not only solves the technical bottlenecks of low-orbit satellite applications, but also achieves technological breakthroughs in command post support, mission cluster collaborative communication, rapid deployment of emergency response, and rapid switching capability verification. It elevates satellite communication from a basic function of ensuring connectivity to a core capability that empowers missions, providing secure, reliable, continuous, and collaborative communication support for future intelligent warfare.

[0033] The technical solution of this invention includes: a mission area inter-satellite handover system, an inter-satellite mission soft handover method, and a digital twin visualization verification method, which are described in detail below: Mission Area Inter-Star Handover System The mission area cross-satellite handover system is a software-defined network control system operating at the ground control center or onboard processing nodes. It is responsible for the full-process management and control of regional communication assurance. Its specific functions include: a) unified situational awareness of mission area boundaries, user distribution, and service requirements; b) intelligent decision-making such as handover timing judgment and target satellite selection based on the global situation; c) cross-satellite coordinated scheduling and pre-allocation of onboard beams, time slots, and power resources; and d) issuing precise and synchronized handover control commands to all user terminals.

[0034] The mission area inter-satellite handover system adopts a centralized decision-making and distributed execution control architecture. The ground control center acts as the control center, responsible for global optimization calculations, while satellites and user terminals act as execution units, responsible for the precise and synchronous execution of handover commands. The system consists of a regional situational awareness module, an intelligent decision engine module, a resource collaborative scheduling module, and a handover execution module, such as... Figure 1 As shown, the specific functions are described below.

[0035] (1) Area Situation Awareness Module The regional situational awareness module is deployed on low-Earth orbit satellites and its function is to build and update a panoramic view of the communication situation in the mission area in real time. Its inputs are satellite ephemeris, terminal positioning information, link measurement reports (RSSI, SNR, BER), and traffic characteristics. Through the situational awareness algorithm engine, it calculates and outputs mission area identification and mission area coverage quality.

[0036] a) Optionally, the task area dynamic identification can use a dynamic region clustering algorithm, based on the improved DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm, to dynamically divide the task area according to the geographical distribution of the terminal and the communication correlation.

[0037] Adaptive adjustment of neighborhood radius based on terminal density Let the total number of terminals in the entire region be N, and the average distance between each terminal and its k nearest neighbors be... Then the neighborhood radius for: (1) In the formula, It is an adjustable coefficient, usually ranging from 1.5 to 2.

[0038] The minimum number of points, MinPts, is adjusted based on terminal density and task type, and is defined as follows: (2) In the formula, It is a scaling factor, and N is the total number of terminals in the region.

[0039] b) Optionally, the situation fusion algorithm can be a coverage situation fusion algorithm to generate a regional communication coverage situation map, and integrate the link quality and service requirements of each terminal into a regional comprehensive coverage quality index (CQI) to evaluate the overall coverage effectiveness of the current satellite in the mission area.

[0040] For each terminal i, its Terminal Link Quality Index (TQI) is defined as: (3) In the formula, This is the normalized quantization value of the signal-to-noise ratio (SNR). The normalized quantization value of the received signal strength RSSI; This is the normalized quantization value of the bit error rate (BER). This is the weighted sum of all indicators.

[0041] The Regional Comprehensive Coverage Quality Index (CQI) is defined as the weighted average of the Total Quality I (TQI) of all terminals. Assuming there are N terminals in the task area, the calculation formula is as follows: (4) In the formula, This is the service weight of terminal i, which is specified by the upper-layer application based on tactical importance; It is the link quality index of terminal i, which is obtained by fusing physical layer measurement indicators; N is the number of covered terminals; N is the total number of terminals in the area.

[0042] (2) Intelligent Decision Engine Module The intelligent decision engine module is deployed at the ground control center. Its function is to determine the handover timing and target satellite selection based on the situation, and generate the globally optimal handover strategy. It primarily uses handover trigger judgment algorithms and target satellite selection algorithms to make optimal handover strategy decisions.

[0043] a) Optionally, the cross-trigger decision algorithm uses a weighted comprehensive trigger function for decision-making, mathematically defined as follows: (5) In the formula, This is a weighted sum of the weights for each factor. The recommended task weights are set as follows: Coverage quality is the most important factor; The urgency of time is secondary; Consider overlapping protections.

[0044] In the formula, The coverage quality degradation function is defined as: (6) In the formula, This is an absolute quality decrease term. The regional baseline coverage quality is typically set to 0.8; This represents a trend of declining quality.

[0045] For quality and safety margin items, As an acceptable minimum quality threshold (e.g., 0.5), this value increases exponentially as the CQI approaches the minimum quality threshold, ensuring a switchover is triggered before a quality collapse.

[0046] This is a time urgency function that assesses the urgency of handover based on the remaining effective coverage time. (7) In the formula, The effective visibility time of the satellite to the center of the mission area can be determined by the elevation angle. calculate; The optimal handover lead is the time required for the soft handover process, where: Pre-connection time (typically 5-10 seconds); The execution time for dual-channel transmission (typical value 0.2-0.5 seconds); This is a safety buffer time (typically 3-5 seconds).

[0047] This is an overlap coverage guarantee function used to evaluate whether candidate satellites have sufficient overlap coverage capability. (8) In the formula, This is the ratio of the effective overlap area between candidate satellite k and the current satellite beam in the mission area; It is a unit step function; The minimum required overlap rate (range 0.2-0.3).

[0048] b) Optionally, the target satellite selection algorithm is based on multi-attribute decision-making, establishing a comprehensive score that includes coverage capability, resource status, link quality, and handover cost, and selecting the satellite with the highest overall score. The multi-attribute scoring model is as follows: (9) In the formula, M represents the number of evaluation attributes; For attribute weights; This is the attribute scoring function. Wherein, Attribute 1: Coverage Integrity Defined as: (10) Attribute 2: Resource Adequacy Defined as: (11) Attribute 3: Expected Link Quality Defined as: (12) In the formula, To predict the signal-to-noise ratio; This represents the link budget margin. Reference link margin; Attribute 4: Switching Cost Defined as: (13) In the formula, This is the time slot adjustment amount; This is the frequency adjustment amount; Historical switching success rate.

[0049] (3) Resource Coordination and Scheduling Module The resource collaborative scheduling module is deployed at the ground control center. Its function is to pre-allocate the required beam, time slot, and power resources to the satellite about to take over the mission, based on the switching instructions from the decision engine. It employs a joint time slot-beam allocation algorithm and uses a heuristic algorithm to quickly solve a constrained multi-objective optimization problem, outputting a resource allocation matrix.

[0050] Consider satellite ensemble Task Area Collection Frequency resource block Time slot resource block Given a set of resources, design a joint resource allocation algorithm.

[0051] The time slot-beam joint allocation algorithm is designed as a multi-objective weighted optimization function to balance system capacity, fairness, and handover continuity, and includes the following three optimization objectives: a) Optimization objective 1: Maximize the total system throughput (14) In the formula, For three-dimensional decision variables; The achievable rate is calculated using Shannon's formula: (15) In the formula, The signal-to-interference-plus-noise ratio (SINR) of the resource block; Let f be the bandwidth of frequency block f.

[0052] b) Optimization objective 2: Maximize coverage fairness (16) This is to ensure that all regions receive balanced services.

[0053] c) Optimization Objective 3: Ensure Continuity of Switching (17) Minimize changes in serving satellites between adjacent time slots to ensure service continuity.

[0054] d) Overall objective function: (18) In the formula, the weighting factor The normalization conditions are met; the weighting factors are dynamically adjusted according to the task types of capacity priority, fairness priority, and continuity priority.

[0055] Considering constraints such as the number of beams, total power limit, coverage constraint, link quality, and interference coordination, solving the above-mentioned comprehensive objective function requires taking into account the following constraints and solving within the feasible space: a) Maximum beam count constraint The number of beams activated by a single satellite in a single time slot cannot exceed its capacity limit: (19) b) Total power constraint The total transmit power of a single satellite in a single time slot shall not exceed its maximum power: (20) c) Full Coverage Constraint Each sub-region is covered by at least one effective beam in each time slot: (twenty one) d) Link quality constraints The signal-to-interference-to-noise ratio of the effective link must meet the minimum requirements: (twenty two) e) Interference Coordination Constraints If two satellites serve geographically close areas in the same time slot and on the same frequency, co-channel interference will occur. Interference coordination constraints ensure that this situation does not occur: (twenty three) In the formula, Interference indicator function: (twenty four) In the formula, It is the angular distance on the Earth's surface between the beams of satellite n pointing to region m and satellite k pointing to region l; It is the minimum beam isolation angle required to prevent interference, and is usually taken as... .

[0056] (4) Switching the execution control module The handover execution module is deployed on low-Earth orbit satellites and user terminals. Its function is to translate high-level policies into specific signaling sequences, ensuring that all terminals execute them synchronously and reliably. The core mechanism of the handover execution control module consists of three parts: a) Synchronous signaling distribution: A reliable multicast protocol is used to ensure that all terminals receive the handover command within ±1ms; b) Execution status monitoring: Real-time monitoring of execution status switching based on ACK / NACK reported by the terminal; c) Abnormal rollback mechanism: Pre-set rollback plan for soft handover failure, such as maintaining the original link or switching to a backup satellite.

[0057] The aforementioned mission area cross-satellite handover system adopts a regionalized communication guarantee and full-process control method, reducing the number of handover management objects from N users to M areas (M << N), greatly reducing management signaling overhead; centralized resource scheduling can avoid conflicts and improve the utilization rate of beam and time slot resources; global optimization decision-making can ensure the optimal overall performance of the area, guaranteeing the continuity of mission area coverage and service integrity.

[0058] Interstellar mission soft handover method The soft handover method for inter-satellite missions is the core execution logic of the cross-satellite handover system within the mission area. It aims to achieve a smooth, uninterrupted migration for all users within the area from their current serving satellite to their target serving satellite. It focuses on resolving the inherent communication interruptions and data loss in hard handover methods, ensuring the continuity of real-time services such as voice, video, and critical commands during handover, and guaranteeing that a large number of user terminals within the mission area complete handover actions synchronously within the same time window (on the order of tens of milliseconds), thus ensuring the uninterrupted operation of tactical collaborative missions.

[0059] The inter-satellite mission soft handover method adopts a three-stage progressive soft handover process, namely "pre-handover preparation, dual-active parallel transmission, and graceful resource release", to complete the cross-satellite migration of communication links without the user's awareness. It mainly includes the following 6 processing steps: (1) Judgment of area handover conditions The task of the area handover condition judgment step is to determine the optimal time to initiate the handover process, avoiding initiation too early or too late. This is achieved through comprehensive evaluation based on multi-dimensional predictions, enabling precise triggering of handover preparation and transforming passive response into proactive decision-making. The main processing steps include: a) Data acquisition: Real-time acquisition of comprehensive coverage quality (CQI), remaining satellite service time, overlap coverage rate, etc. in the mission area, as shown in formula (4); b) Comprehensive evaluation: using a weighted comprehensive trigger function Calculate the trigger value as shown in formula (5); c) Dynamic decision-making: Trigger value If the threshold is exceeded by comparing the value with a threshold that is dynamically adjusted according to task priority, a switchover preparation is triggered. (2) Optimal selection of target satellites The goal of target satellite optimization selection is to choose the best replacement satellite from multiple candidate satellites. This is achieved by establishing a multi-attribute decision model that balances multiple objectives such as coverage, resources, quality, and cost. The main processing steps include: a) Pre-screening: Filter candidate satellites based on hard constraints such as coverage integrity, resource sufficiency, and minimum elevation angle; b) Multi-attribute scoring: For candidate satellites, a multi-attribute weighted scoring algorithm is used to evaluate their coverage capability, link quality, load status, handover cost and other attributes to obtain a comprehensive score, as shown in formula (9); c) Final selection: Select the satellite with the highest overall score and generate a shortlist of candidates; (3) Resource pre-negotiation algorithm The goal of the resource negotiation algorithm is to pre-allocate the beam, time slot, and power resources required for the target satellite to take over the mission area, avoiding handover resource conflicts. This is achieved by modeling resource allocation as a constrained multi-objective optimization problem, enabling collaborative resource scheduling across satellites. The main processing steps are as follows: a) Optimization modeling: The joint allocation problem of time slots and beams is constructed as a mixed integer programming model with the goal of maximizing regional throughput and the conditions of satellite capability and interference constraints, as shown in formula (18); b) Solution algorithm: A heuristic algorithm (such as genetic algorithm or particle swarm optimization algorithm) is used to solve the resource allocation matrix quickly; c) Resource reservation: The allocation plan is sent to the target satellite to mark the resources for pre-occupancy; (4) Dual-active parallel transmission control The goal of dual-active parallel transmission control is to achieve zero service interruption and zero data loss during the handover transition period. The method is to maintain the old link while establishing the new link, so as to achieve dual-path data transmission and intelligent integration.

[0060] The current serving satellite (Sat_A) interacts with the target satellite (Sat_B) via inter-satellite links or ground gateways. According to the resource scheduling module's scheme, Sat_B marks the corresponding time slots and power resources for its beam coverage in this mission area as pre-occupied.

[0061] The ground control center or Sat_A uses signaling to instruct all user terminals within the mission area to establish low-rate, high-reliability control plane connections with Sat_B, including random access and RRC connections. User plane data streams are still primarily transmitted through Sat_A.

[0062] Securely synchronize user session context information (such as IP address, security key, QoS parameters, PDCP sequence number, etc.) on Sat_A to Sat_B to ensure seamless data transfer.

[0063] Downlink data can be simultaneously sent from the core network / command center to Sat_A and Sat_B, which will then distribute it separately. The terminal receiver will merge the two signals to improve reception reliability during handover.

[0064] (5) Resource release mechanism The goal of the graceful resource release mechanism is to safely and orderly release old satellite resources after confirming the stability of the new link. This is achieved by adopting a phased, verification-based release strategy to prevent service rollback due to misjudgment. The main processing steps are as follows: a) Stability confirmation: Monitor the quality of the new link, and trigger resource release when it is consistently and stably better than the old link for a period of time (e.g., 200ms); b) Batch release: Release resources in batches in the order of control plane resources, user plane backup resources, and temporary status information; c) Abnormal rollback: If an abnormality is detected during the release process, the process will be paused and a preset rollback plan will be activated.

[0065] (6) Complete the comprehensive verification after switching. The goal of the comprehensive verification upon successful switchover is to fully assess whether the switchover process was successful and whether various performance indicators met the standards. This is achieved by establishing a multi-dimensional quantitative indicator system and verifying it through real-time testing and statistical analysis. The processing steps include: a) Metric testing: Measure key metrics such as downtime, data loss rate, handover success rate, and user status synchronization rate; b) Data analysis: Use rule-based anomaly detection algorithms and statistical comparative analysis to determine whether the indicators meet the preset standards, such as interruption <10ms, packet loss rate <0.001%, etc. c) Report generation: Automatically outputs a switch verification report containing quantitative indicators and qualitative conclusions.

[0066] Digital Twin Visual Verification Method To support the comprehensive verification of the soft handover process and results of inter-satellite missions, and to present the invisible handover process intuitively in the spatiotemporal dimension, transform performance indicators into measurable values, and support root cause analysis when handover anomalies occur, the digital twin visualization verification method constructs a low-Earth orbit satellite data link digital twin verification environment that integrates virtual and real mapping, real-time interaction, and intelligent analysis. This method deeply integrates the physical world's low-Earth orbit satellites, user terminals, and satellite-to-ground links with the virtual world's simulation models, data visualization, and intelligent analysis algorithms, enabling full-element modeling, full-process visualization, and full-indicator evaluation of the inter-satellite mission soft handover process.

[0067] The implementation steps for digital twin visualization verification of the inter-satellite handover system and inter-satellite mission soft handover process are as follows: (1) Soft handover panoramic situation visualization The goal of soft handover panoramic situation visualization is to intuitively display the entire process of inter-satellite mission soft handover from a three-dimensional spatiotemporal perspective. The elements of the visualization design include: a) Construction of a 3D Earth Scene The Earth scene is constructed using the WebGL 3D rendering engine, and an Earth model is built based on the real geographic coordinate system (WGS-84), including terrain elevation data, atmospheric effects, and day-night illumination variations. Satellite orbits are dynamically calculated and rendered according to accurate ephemeris parameters, and the satellite model employs refined 3D modeling to accurately reflect the antenna structure. The beam coverage area is visualized in the form of a semi-transparent cone, with the base of the cone projected onto the Earth's surface to form the coverage area.

[0068] The beam coverage area is color-coded in real time based on service status: green for normal service, yellow for the pre-connection phase, blue for the dual-path transmission phase, and red for the resource release phase. The data stream animation is implemented using a particle system, dynamically flowing along the path from satellite to terminal, with uplink and downlink data streams distinguished by different colors.

[0069] b) Dynamic element synchronization mechanism A real-time data synchronization channel is established between the physical and virtual worlds, using the WebSocket protocol for real-time data updates. Satellite positions are calculated based on orbital dynamics equations to ensure consistency between satellite motion in the 3D scene and its actual orbit. User terminal positions are updated in real-time using BeiDou positioning data and displayed as icons in the 3D scene, labeled with the terminal number and communication status. Beam pointing and coverage are dynamically adjusted based on satellite attitude and antenna parameters. The coverage area is represented by gradient colors on the Earth's surface to indicate signal strength, forming a coverage quality heatmap.

[0070] c) Multi-view observation mode It offers three viewing perspectives: a first-person perspective that follows a specific satellite or terminal to observe its communication process; a global perspective that provides an overview of the entire constellation and mission area, showing the overall coverage situation; and a mission area close-up perspective that focuses on a specific mission area, magnifying the communication status and link connections of all terminals within that area. Smooth transitions between perspectives are supported, and users can freely control the movement, rotation, and zoom of the viewpoint using the mouse and keyboard.

[0071] (2) Detailed display during the switching phase The process of software switching for inter-satellite missions is presented in detail according to its three stages, mainly including: a) Visualization of the pre-connection establishment phase During the pre-connection establishment phase, the visual interface focuses on showcasing the control plane connection establishment process. A dashed line connects the target satellite and the mission area, indicating that the control link is being established. Reserved resources are highlighted in the resource panel, including beam number, time slot allocation, and power settings. The context synchronization process is displayed through animation, with data packets flowing from the current serving satellite to the target satellite, and synchronization progress shown as a percentage progress bar. In the terminal list view, the pre-connection status (established, establishing, failed) of each terminal is displayed as an icon.

[0072] b) Visualization of the dual-path parallel transmission stage The dual-path parallel transmission phase primarily demonstrates the simultaneous transmission of data through both the old and new paths. The primary path of the new satellite and the secondary path of the old satellite are distinguished by lines of different colors and widths; the primary path line is thicker and solid, while the secondary path line is thinner and dashed. The transmission process of each data packet on both paths is represented by particle animation, allowing users to observe the data packets passing through both links simultaneously. The data fusion process on the network side is visualized through data packet sequence numbers, with the receiving end displaying the deduplication and sorting process. The performance monitoring panel displays a real-time comparison of throughput, latency, and packet loss rate for both paths.

[0073] c) Visualization of the graceful resource release phase The graceful resource release phase focuses on showcasing the gradual release of old link resources, visualized in three batches. The first batch releases control plane resources, with the corresponding resource items in the resource panel changing from occupied to available. The second batch releases user plane backup resources. The third batch clears temporary state information. Stability verification is performed before each release, with verification results displayed as checkmarks or crosses. If an anomaly is detected during the release process, a rollback mechanism is triggered, and the relevant resources are remarked as occupied.

[0074] (3) Key performance indicator dashboard The key performance indicator dashboard mainly includes three categories: real-time display of continuous indicators, display of data integrity indicators, and plotting of performance trend curves.

[0075] a) Real-time display of continuous indicators The interruption time metric is displayed in both numerical and progress bar formats. The numerical value shows the current interruption time accurate to microseconds, while the progress bar shows the percentage relative to a threshold; the progress bar turns red when the threshold is exceeded. The interruption probability metric is calculated based on historical data, displaying the average interruption probability of the last 100 handovers. The service recovery time metric shows the timeline from the start of the handover to full service recovery, including the time consumed in each sub-stage. All metrics are updated once per second, and historical data is displayed as a line graph showing the trend over the last 60 seconds.

[0076] b) Display of data integrity metrics Data loss rate is calculated in real time by comparing the number of sent and received data packets and displayed as a percentage, along with the absolute number of lost packets. Sequence continuity check results are displayed as a visual sequence, with consecutively received data packet sequences shown as green bands and missing sequences shown as red gaps. Packet duplication rate displays the proportion of duplicate packets detected by the receiver. These metrics not only show current values ​​but also historical minimums, maximums, and averages, helping to analyze trends in data integrity.

[0077] c) Plotting performance trend curves Use Canvas drawing technology to plot real-time performance curves, with time on the horizontal axis and performance metric values ​​on the vertical axis. Plot at least three key curves: area coverage change curve, switchover interruption time curve, and system throughput change curve. Each curve is distinguished by a different color and supports showing / hiding. The graphs are interactive; hovering the mouse over a curve displays precise values ​​at specific times, and double-clicking a curve zooms in on that time period. Curve data is updated once per second, retaining historical data from the most recent 10 minutes.

[0078] (4) Anomaly detection and root cause analysis Anomaly detection and root cause analysis includes three functions: a multi-level anomaly detection mechanism, a visual root cause analysis tool, and interactive diagnostic functions.

[0079] a) Multi-level anomaly detection mechanism A three-tiered anomaly detection mechanism is established: the first tier is threshold-based detection, triggering a primary alarm when key indicators exceed preset thresholds; the second tier is trend-based detection, analyzing indicator trends to predict potential anomalies; and the third tier is pattern recognition, using machine learning algorithms to identify anomaly patterns. Detected anomalies are categorized into three levels: informational (blue), warning (yellow), and error (red). Anomaly information is displayed in a dedicated alarm panel, including the anomaly type, occurrence time, impact scope, and recommended handling measures.

[0080] b) Visual root cause analysis tools When an anomaly occurs, the system automatically initiates the root cause analysis process. First, the location of the anomaly and related entities, such as the anomalous satellite, terminal, or link, are highlighted in the spatiotemporal view. Then, the anomaly propagation path is displayed, showing how the anomaly spreads from one component to others. The root cause analysis results are presented in a tree diagram, with the root node representing the root cause and child nodes representing direct causes and impacts. A snapshot of the relevant system state is also provided, showing changes in key parameters before and after the anomaly, aiding in the analysis of the conditions under which the anomaly occurred.

[0081] c) Interactive diagnostic functions Users can manually trigger the diagnostic process by selecting a specific anomaly. The system will then replay the scene for 30 seconds before and after the anomaly occurred, showing the anomaly's development in slow motion. The diagnostic tool provides multiple analysis views: an event sequence view displays changes in relevant metrics, a topology view shows the relationships between affected components, and a log view displays relevant system logs. Users can add annotations to these views to record the analysis process and conclusions; these annotations can be saved to the validation report.

[0082] (5) Interactive playback and analysis The goal of interactive playback and analysis is to support the user's interactive playback switching process, and to conduct in-depth comparative analysis using timeline control components, multi-view synchronous playback tools, and other technologies.

[0083] a) Time axis control component The timeline controller provides complete playback control functions, including play, pause, fast forward, rewind, and single-frame forward / rewind. Playback speed is adjustable, supporting 0.1x to 10x speed. The timeline has multiple markers indicating the occurrence of key events, such as switch triggers, pre-connection completion, and dual-channel transmission initiation. Users can drag the event slider to jump to any point in time, or directly click on a marker to jump to the corresponding event. Below the timeline, a summary of the current system status is displayed, including the number of active satellites, the number of covered terminals, and system load.

[0084] b) Multi-view synchronous playback tool During playback, the 3D scene view, performance curve view, resource status view, and data flow view are updated synchronously, ensuring users can observe the system status at the same moment from different perspectives. A linkage is established between the views; selecting a satellite in the 3D view will highlight relevant information about that satellite in other views. Selecting a time point in the performance curve will jump to the 3D view's status at that moment. The view layout is customizable; users can adjust the size and position of each view and save the changes in their personal preferences.

[0085] c) Comparison and analysis function Two comparison modes are supported: time-based comparison and scenario-based comparison. Time-based comparison allows selection of two different time points within the same scenario, displaying the system status at both times side-by-side with differences highlighted. Scenario-based comparison allows loading switching process data under different parameter configurations, displaying the performance metrics of the two scenarios side-by-side, and automatically calculating and displaying the percentage improvement. Comparison results are presented in tabular and chart formats, including changes in each metric and statistical significance test results.

[0086] (6) Automated verification report generation The structured report generation process is fully automated, comprising four steps: data collection, analysis, summarization, and formatting. The data collection phase extracts all relevant data from the verification process from the digital twin system, including configuration parameters, process logs, performance metrics, and anomalies. The analysis phase performs statistical analysis on the data, calculating the average, maximum, minimum, and standard deviation of various metrics, and conducting trend and correlation analyses. The summarization phase organizes the analysis results into a report structure, including an executive summary, detailed analysis, and conclusions / recommendations. The formatting phase converts the report content to HTML, PDF, or Word format, adding charts, tables, and styles.

[0087] The generated validation report is presented in web page format, featuring rich visualization elements: key metrics are highlighted as information cards, important findings are emphasized with highlighted text boxes, and performance data is displayed as interactive charts. The report supports hierarchical navigation, allowing users to quickly jump to sections of interest via the left-hand navigation bar. All charts are interactive; hovering the mouse reveals detailed data, and clicking toggles the display of data series. Finally, a one-click export function is provided, allowing the complete report to be exported as a PDF document for archiving and sharing.

[0088] This digital twin visualization method constructs a high-fidelity virtual environment to achieve full-dimensional, end-to-end, and intelligent verification of the soft handover process for inter-satellite missions. It not only visually displays the handover process but also deeply analyzes performance indicators, automatically detects anomalies, and generates optimization suggestions, providing strong verification support for the optimization and deployment of soft handover algorithms. It is particularly suitable for the high reliability and high security verification requirements of communication systems.

[0089] Taking low-Earth orbit satellite communication support for cross-regional maneuver missions as an example, a specific embodiment of the mission area cross-satellite handover system, inter-satellite mission soft handover, and digital twin visualization verification method of the low-Earth orbit satellite data link described in this invention is illustrated in detail below: (1) Scene description A team is carrying out a cross-regional mobile mission. The team consists of: 1 mobile command vehicle, 3 A detachments (10 vehicles each), 2 B detachments (8 pieces of equipment each), and 1 squad each of C, D, E, and F.

[0090] Mission area: Initial area 50×50km, target area 80×60km, maneuver distance 200km.

[0091] Communication requirements: Command and control (low latency, high reliability), situation sharing (medium speed, medium latency), reconnaissance video (high speed), and logistical support (low speed, best effort).

[0092] Communication assurance requirements: Area coverage > 95%, handover success rate > 99.5%, service continuity: handover interruption < 20ms.

[0093] (2) System working process Step 1: Task Preparation (T-60 minutes) a) Mission planning: Input the maneuver route, mission area, and team composition, and the system generates a communication support plan, which is then pre-rehearsed and verified by the digital twin system; b) Resource pre-allocation: Reserve satellite resources according to predicted demand, configure beam pointing and time slot allocation, and establish initial communication links; c) System check: Check the status of all terminals, perform link quality tests, and prepare contingency plans; Step 2: Initial area communication establishment (T=0) a) Area awareness: Satellites detect the distribution of user terminals and establish a communication situation map of the mission area. Initial service satellite: Sat_A; b) Network establishment: All users access Sat_A to establish a command and communication network, and services are activated according to priority. c) Status monitoring: Real-time display of communication status, continuous monitoring of performance indicators, and timely alarms for abnormal situations; Step 3: Continuous support during the maneuver (T=0 to T=120 minutes) a) Key Event 1: First Satellite Switchover (T+18 minutes) The switching trigger condition is that Sat_A is about to leave, and the overlap coverage is 35%. The target selections are Sat_B (score 92) and Sat_B (score 85). When the soft handover process is executed according to the method described in this invention, all users successfully switch over without service interruption. b) Key Event 2: Mission Area Expansion (T+45 minutes) The mission area has been expanded 20km eastward, requiring additional Sat_D auxiliary coverage, increasing the coverage rate of the expanded area from 70% to 95%. c) Critical Event 3: High-speed maneuver of the command post (T+75 minutes) The command vehicle moves at a speed of 80 km / h. During the movement, it needs to switch between multiple satellites quickly. Based on the prediction-based beam pointing described in this invention, it can support continuous beam tracking and ensure uninterrupted command and communication throughout the entire process. Step 4: Target area communication reconstruction (T+120 minutes) a) Area transfer: The new mission area is identified and confirmed, the service satellites are re-planned with Sat_E as the primary satellite and Sat_F as the secondary satellite, and users are regrouped for access; b) Network optimization: Optimize resource allocation based on the characteristics of the new region; (3) Implementation effect The above embodiments illustrate the effectiveness of the inter-satellite mission soft handover method described in this invention. During continuous command post maneuvers, command communication remains uninterrupted, ensuring satellite communication continues while the commander is on the move. Commander decisions and command issuance are unaffected by satellite handover. All mission units achieve millisecond-level synchronization during satellite handover, resolving the previous problem of action disconnection caused by handover asynchrony and providing a reliable synchronous communication foundation for critical actions. After dynamic expansion of the mission area, the system, through intelligent scheduling, rapidly increases the coverage of the newly expanded area from 70% to 95%, verifying the system's rapid response and adaptive capabilities to changes in the battlefield situation.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A mission area inter-satellite handover system for low-Earth orbit satellite data links, characterized in that, It includes a ground control center, at least two low-Earth orbit satellites, and multiple user terminals located within the mission area; the ground control center communicates with the low-Earth orbit satellites via a satellite-to-ground link, and the low-Earth orbit satellites communicate with each other via an inter-satellite link; The mission area inter-satellite handover system includes a regional situational awareness module, an intelligent decision engine module, a resource collaborative scheduling module, and a handover execution control module; among which... The regional situation awareness module is used to acquire satellite ephemeris information, user terminal positioning information, link measurement reports and service traffic characteristics, construct and update the communication situation of the task area, and output the task area identification results and the task area coverage quality characterization. The intelligent decision engine module is used to make handover and trigger judgments and select target satellites based on the communication situation in the mission area, and generate a handover strategy for the mission area. The resource coordination scheduling module is used to pre-allocate the beam resources, time slot resources and power resources of the target satellite according to the switching strategy and form a resource allocation result; The handover execution control module is used to convert the handover strategy and the resource allocation result into synchronous handover control signaling for the task area, organize multiple user terminals in the task area to complete the soft handover from the current serving satellite to the target satellite in the same handover window, and release the resources occupied by the current serving satellite in the task area after the soft handover is completed.

2. The system according to claim 1, characterized in that, The regional situational awareness module includes a task area dynamic identification unit and a coverage situational fusion unit. The task area dynamic identification unit is used to dynamically cluster user terminals based on their geographical distribution and communication correlation, thereby determining the task area boundary; The coverage situation fusion unit is used to fuse the link measurement report and service requirement information to generate a comprehensive coverage quality index for the mission area, which is used to evaluate the overall coverage effectiveness of the current service satellites for the mission area; The coverage situation fusion unit is used to construct a terminal link quality index for a single user terminal, and to weight and aggregate the terminal link quality indices of multiple user terminals according to the terminal service weights to obtain a comprehensive coverage quality index for the task area.

3. The system according to claim 1, characterized in that, The intelligent decision engine module includes an interaction triggering judgment unit and a target satellite selection unit; The handover triggering judgment unit is used to calculate the trigger value based on the comprehensive coverage quality index of the mission area, the coverage quality change trend, the remaining effective coverage time of the mission area, and the overlapping coverage capability of candidate satellites, and compare it with the preset threshold to determine whether to start the handover of the mission area. The target satellite selection unit is used to score candidate satellites based on multiple attributes, including at least coverage integrity, resource sufficiency, expected link quality, and handover cost, and selects the candidate satellite with the best comprehensive score as the target satellite. The resource collaborative scheduling module is used to model the pre-allocation of resources in the task area as a constrained multi-objective optimization problem. The multi-objectives include at least the task area throughput objective, coverage fairness objective, and handover continuity objective. The module outputs a resource allocation matrix under the conditions of satisfying the constraints of maximum available beam count, total power, coverage, link quality, and interference coordination.

4. The system according to claim 1, characterized in that, The switching execution control module includes a synchronization signaling distribution unit, an execution status monitoring unit, and an abnormal rollback unit; The synchronization signaling distribution unit is used to distribute handover commands to multiple user terminals within the task area using a reliable multicast method; The execution status monitoring unit is used to receive confirmation information reported by the user terminal and evaluate and switch the execution status accordingly. The abnormal backoff unit is used to trigger a backoff strategy when a soft handover failure or abnormal soft handover quality is detected, in order to maintain the original link or switch to a backup satellite.

5. The system according to claim 1, characterized in that, The soft handover consists of a pre-connection phase, a dual-active parallel transmission phase, and a graceful resource release phase. The pre-connection phase is used to instruct user terminals to establish control plane connections with target satellites while maintaining user plane services carried by the current serving satellites. The dual-active parallel transmission phase is used to perform parallel transmission and fusion processing of data when the current serving satellite and the target satellite are simultaneously carrying user plane data transmission. The graceful resource release phase is used to release the control plane resources, user plane resources, and temporary status information of the currently serving satellite in the mission area in a preset order after the target satellite link is stable and meets the preset conditions.

6. A method for soft handover of inter-satellite missions, characterized in that, Execution is directed towards the task area, including: Acquire communication status data for the task area and generate comprehensive coverage quality indicators for the task area; Based on the comprehensive coverage quality index of the task area, the remaining effective coverage time, and the overlapping coverage capability, the handover triggering judgment is made, and the task area soft handover is initiated when the triggering conditions are met. Multiple candidate satellites are evaluated for multiple attributes to determine the target satellite and generate a list of alternative satellites; Perform resource pre-negotiation on the target satellite, pre-allocate beam resources, time slot resources and power resources for takeover mission area, and mark the pre-allocated resources as occupied; The system organizes multiple user terminals within the mission area to establish pre-connections with the target satellite, while maintaining the service connections between the user terminals and the currently serving satellites. After the pre-connection is completed, dual-active parallel transmission is entered, so that downlink data and uplink data form a parallel transmission path between the current serving satellite and the target satellite, and the parallel transmission data is deduplicated, sorted or fused. After detecting that the target satellite link meets the stability conditions, perform graceful resource release to release the resources currently occupied by the serving satellite in the mission area; Perform comprehensive verification of the soft handover process and output the verification results.

7. The method according to claim 6, characterized in that, The acquisition of communication situation data in the task area includes acquiring satellite ephemeris, user terminal positioning information, link measurement reports, and service traffic characteristics; The comprehensive coverage quality index of the task area is obtained by weighted aggregation of the link quality index of multiple user terminals and the service weight; The trigger determination for cross-coverage includes: constructing a trigger function based on the degree of coverage quality degradation, the trend of coverage quality degradation, the quality safety margin, the time urgency, and the overlapping coverage guarantee capability, and dynamically adjusting the weights or thresholds in the trigger function according to the task priority.

8. The method according to claim 6, characterized in that, The multi-attribute evaluation includes at least: the coverage integrity index of candidate satellites to the mission area, the sufficiency index of available resources for candidate satellites, the expected index of link quality of candidate satellites, and the handover cost index; wherein, the handover cost index is composed of or derived from the time slot adjustment amount, the frequency adjustment amount, and the historical handover success rate.

9. The method according to claim 6, characterized in that, The resource pre-negotiation includes: constructing a constrained optimization model for the joint allocation of time slots and beams, obtaining a resource allocation matrix using a heuristic solution method, and then sending the resource allocation matrix to the target satellite to complete resource reservation.

10. The method according to claim 6, characterized in that, Prior to the dual-active parallel transmission, the user terminal's user session context information on the current serving satellite is synchronized to the target satellite. The user session context information includes at least address information, security parameters, quality of service parameters, and sequence number status information.

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