Power emergency network-oriented low-orbit broadband satellite terminal switching method

Abstract

The invention discloses a low-orbit broadband satellite terminal switching method for an electric power emergency network, which belongs to the technical field of electric power, and comprises the following steps: setting a multi-stage switching trigger mechanism including normal switching trigger and abnormal switching trigger; aiming at a normal switching scene, selecting a target satellite by adopting a multi-attribute decision satellite switching strategy based on a directed graph, and aiming at an abnormal switching or new call access scene, selecting the target satellite by adopting the multi-attribute decision satellite switching strategy based on a combined weight; and when channel resources are in shortage, a priority queuing access mechanism is executed. The method effectively solves the problems of frequent satellite switching, easy link interruption, intense resource competition and the like in an electric power emergency scene, and remarkably improves the communication continuity and service quality of the low-orbit broadband satellite terminal in a complex emergency environment.

Description

Technical Field

[0001] This invention relates to the field of power technology, and specifically to a low-orbit broadband satellite terminal switching method for power emergency networks. Background Technology

[0002] The safe and stable operation of modern power systems is directly related to public safety. However, natural disasters such as earthquakes, typhoons, and floods, as well as major equipment failures, occur frequently, easily causing damage to power grid facilities and interrupting ground communication networks, creating "information silos" that seriously affect the timeliness of emergency repairs and command and dispatch. Therefore, building a power emergency communication system that does not rely on ground infrastructure, has wide-area coverage, can be deployed rapidly, and offers high reliability and business continuity has become an urgent need.

[0003] Traditional emergency communication methods, such as fiber optics, microwave, and cellular mobile networks, suffer from drawbacks such as strong reliance on ground infrastructure, numerous coverage blind spots, and long post-disaster recovery cycles, which are particularly pronounced in extreme disaster scenarios. While geostationary satellites offer some backup capabilities, their end-to-end latency exceeds 500ms, bandwidth resources are limited, and construction and maintenance costs are high, making it difficult to meet the real-time interaction and high-capacity data transmission requirements in power emergency scenarios.

[0004] The development of low-Earth orbit (LEO) broadband satellite technology offers a novel solution to the aforementioned problems. These satellites operate in orbits approximately 500 to 2000 kilometers above the Earth's surface, achieving end-to-end communication latency of 20 to 50 milliseconds, approaching the level of terrestrial fiber optic networks, and enabling user access rates of hundreds of megabits per second (Mbps) or even gigabits per second. Furthermore, LEO constellations provide seamless global coverage, completely eliminating communication blind spots in remote areas and disaster zones. Satellite links are independent of terrestrial networks, possessing inherent resilience and high survivability; emergency communication terminals can be activated within minutes, significantly improving the agility of emergency response.

[0005] Integrating low-orbit broadband satellite technology into the power emergency network not only fills the coverage gaps of traditional communication methods, but also supports new services such as real-time video transmission from drone inspections and AR / VR remote assisted maintenance with its high bandwidth. Furthermore, its low latency characteristics ensure the timely issuance and execution of critical services such as dispatch instructions and protection signals, thereby comprehensively improving the intelligence, visualization, and collaboration of emergency response.

[0006] However, the power emergency communication puts forward significant differentiated requirements for the quality of service of the network, which constitutes a fundamental challenge to the existing switching mechanism. For example: real-time control type business (such as relay protection, dispatching instruction) requires extremely low delay (<50ms), high reliability (bit error rate <1e-6), zero interruption; non-real-time monitoring type business (such as environmental sensor data, log back transmission) can tolerate certain delay and short interruption; audio and video type business (such as on-site monitoring, remote consultation) needs to ensure bandwidth and smoothness, but is not sensitive to instantaneous jitter.

[0007] The current mainstream satellite switching mechanism is based on a single signal strength threshold to switch immediately, and this "passive response" strategy has serious defects: it cannot distinguish the service level of different business flows, and in the case of channel resource shortage or sudden interference, high-priority business may be interrupted due to the lack of resources, while low-priority business continuously occupies the link. Essentially, it is a "signal-driven" rather than "business-driven" switching mode, which is difficult to meet the rigid requirements of "absolute priority of key business and high continuity of communication link" in the power emergency scene. Therefore, it is crucial to establish an intelligent switching technology for low-orbit broadband satellite terminals specially for power emergency networks.

[0008] Based on this, the present application designs a low-orbit broadband satellite terminal switching method for power emergency networks to solve the above problems. SUMMARY

[0009] In view of the above shortcomings of the prior art, the present application provides a low-orbit broadband satellite terminal switching method for power emergency networks. It is particularly suitable for power key business communication scenarios with multi-level quality of service (QoS) guarantee requirements.

[0010] To achieve the above purpose, the present application is realized by the following technical scheme: A low-orbit broadband satellite terminal switching method for power emergency networks, comprising the following steps: Step 1, constructing a candidate satellite list, the candidate satellite list comprising: satellite number, current signal strength, elevation angle, remaining service time, number of idle channels and accessible time window; Step 2, setting a multi-level switching trigger mechanism, including normal switching trigger and abnormal switching trigger; if it is determined as a normal switching scenario, go to step 3, if it is determined as an abnormal switching scenario, go to step 5; Step 3, for normal switching scenario, a multi-attribute decision satellite switching strategy based on directed graph is used to select target satellite: the ground gateway station constructs a time window T=T x , according to the terminal position, satellite ephemeris and business duration statistical characteristics T xThe service satellite sequence inside is generated, and a weighted directed graph G(V, E) is generated: wherein the vertex set V represents all satellite nodes that can provide services for terminals within T time, the edge set E represents a feasible switching path from satellite i to satellite j, and there is a directed edge (i, j) only when the service end time of satellite i is earlier than the service start time of satellite j; a comprehensive weight is assigned to each directed edge, and the calculation method is as follows: ; wherein: is the directed edge weight of satellite , is the total number of channels of each satellite, is the minimum elevation angle at which the user terminal and the satellite can establish communication, is the idle channel prediction value of satellite at the time of switching, is the elevation angle between the user terminal and satellite at the time of switching, , , are the weighting coefficients of the idle channel prediction value and the elevation angle between the user and the satellite, respectively; The minimum weight path from the current satellite node to the end node in the graph is solved by Dijkstra algorithm, and the optimal switching path Handover_Path is obtained; Step 4, based on the optimal switching path, the gateway station reserves channel resources on each target satellite in time sequence for the terminal, establishes a “satellite channel reservation information table”, and ensures that the target channel is available at the time of switching; the reservation strategy adopts a dynamic time slot allocation mechanism, and the same physical channel can be shared by multiple switching users in different time periods; then step 7 is entered; Step 5, for abnormal switching or new call access scenarios, a multi-attribute decision satellite switching strategy based on combined weights is used to select the target satellite: first, the signal strength S pred and the number of idle channels C pred of the adjacent satellites in the future time period are predicted by using the grey prediction model GM(1, 1); combined with the current remaining service time T, a standardized evaluation matrix X of the candidate satellites is constructed; the AHP method is used to determine the subjective weight W=(w1, w2, w3), w1, w2, w3 respectively corresponding to the subjective weights of signal strength, number of idle channels and remaining service time; the entropy method is used to calculate the objective weight H=(h1, h2, h3), h1, h2, h3 respectively corresponding to the objective weights of signal strength, number of idle channels and remaining service time; the combined weight V=(v1, v2, v3) is obtained by the weighted integration method, v1, v2, v3 respectively corresponding to the combined weights of signal strength, number of idle channels and remaining service time; finally, the relative closeness E i of each candidate satellite to the ideal solution is calculated by using the TOPSIS method, and E iThe largest one is selected as the target satellite; Step 6: When channel resources are scarce, implement a priority queuing access mechanism; Step 7: After the handover is complete, release the used channel resources.

[0011] Furthermore, step 1 specifically involves: during communication, the terminal continuously measures the signal strength of the currently accessed satellite beam and the beams of neighboring satellites, and simultaneously receives satellite broadcast channel information to obtain the orbital parameters, nadir position, and channel resource usage status of each visible satellite; combined with the terminal's positioning information, the terminal calculates the elevation angle, distance, and remaining service time between the terminal and each visible satellite, and constructs a candidate satellite list.

[0012] Furthermore, in step 2, normal handover is triggered when the elevation angle between the terminal and the currently serving satellite is lower than the preset minimum communication angle. If the current beam signal strength is consistently below the "switching threshold" and the neighboring beam signal strength is above the "increase channel threshold", it is determined to be a normal handover scenario, and proceed to step 3.

[0013] Furthermore, in step 2, abnormal handover is triggered when the current link signal strength suddenly drops above the "receiver threshold" due to environmental factors, but the bit error rate (BER) is greater than BER. th When the current service satellite load exceeds the threshold and load balancing is required, it is determined to be an abnormal handover scenario, and proceed to step 5.

[0014] Furthermore, step 6 specifically involves: classifying users into "emergency handover users," "emergency new call users," and "non-emergency users," and classifying service types into "real-time control" and "non-real-time monitoring"; setting four priority levels: emergency handover + real-time service, emergency handover + non-real-time service, emergency new call + real-time service, and others; when the target satellite has no free channel, users are queued according to priority, and the queuing time depends on the superimposed coverage duration between two adjacent satellites on the same orbital plane in the low-Earth orbit satellite network; otherwise, access is deemed to have failed.

[0015] Furthermore, step 7 specifically involves: after the handover is completed, updating the channel reservation information table and releasing the used channel resources; if the access satellite is the end node of the handover path, recalculating the handover path for the next stage; and clearing all reserved records after the terminal communication ends.

[0016] Furthermore, in step 3, the service satellite sequence is jointly generated by the ground gateway station and the network control center. The specific process is as follows: The ground gateway station receives real-time location information reported by user terminals, calculates the latitude and longitude, velocity, and direction of motion of each low-orbit satellite at any given time based on satellite ephemeris data, and then calculates the start and end times of coverage for each satellite to the user terminal by combining the user terminal location and satellite orbit parameters, ultimately forming a service satellite list in the following format: ; in: For access to the low-Earth orbit satellite communication system, the number is i The user terminal, Let n be the satellite numbers that can provide services to user terminals. There are a total of n satellites. The satellite is numbered as The moment when services can begin to be provided to user terminals. The satellite is numbered as The moment when services to user terminals cease.

[0017] Furthermore, in step 3, the process for constructing the directed graph is as follows: The service satellite list is arranged according to... Arrange in ascending order; starting with the first satellite, compare them sequentially. With subsequent satellites If satisfied Then add directed edges to the graph. Repeat the above process until all satellite comparisons are completed.

[0018] Furthermore, in step 5, the corresponding satellite standardized evaluation matrix is ​​constructed. The method is as follows: For signal strength prediction value and remaining service time Standardization was performed using trigonometric function transformation: ; ; Among them, T n It is the remaining service duration of a certain satellite to a user at time n, i.e., t max S n That is, the predicted signal strength value S i T is the predicted signal strength value at time i; i It is the remaining service duration at time i; and These are the predicted signal strength and the final standardized indicator values ​​for remaining service time, respectively.

[0019] For the predicted value of the idle channel The range transformation method is used for standardization to reflect its sensitivity within the interval: ; Where: C all This represents the total number of satellite channels. After standardizing each indicator, a corresponding satellite standardization evaluation matrix is ​​constructed. : ; in: , , These represent the standardized values ​​of the predicted signal quality of the first accessible satellite, the standardized value of the remaining service duration, and the standardized value of the predicted idle channel, respectively.

[0020] To better achieve the objectives of this invention, this invention also provides a system utilizing the aforementioned low-orbit broadband satellite terminal handover method for power emergency networks, comprising a signal acquisition module, a candidate list generation module, a handover trigger judgment module, a path optimization module, a resource reservation module, a multi-attribute decision-making module, a priority queue module, and a resource release module; The signal acquisition module is used to acquire terminal location and link status information and output it to the candidate list generation module; The candidate list generation module is used to generate a candidate satellite list by combining ephemeris data and send it to the switch trigger judgment module; The switching trigger judgment module is used to divert traffic to the path optimization module or the multi-attribute decision module based on threshold conditions; The path optimization module is used to generate the optimal handover path and hand it over to the resource reservation module for channel pre-allocation. The multi-attribute decision module is used to queue the target satellites after they are output into the priority queue module. The resource release module is used to reclaim resources after the switch is completed.

[0021] Compared to existing technologies, this invention offers the following advantages: It proposes a low-Earth orbit (LEO) satellite terminal handover method that integrates path planning and dynamic decision-making, addressing the specific requirements of high reliability and low interruption rate in power emergency communications. By constructing a weighted directed graph to achieve global optimization of the handover path, the number of handovers is significantly reduced. A channel reservation mechanism is introduced to ensure the success rate of handovers for critical services. For sudden environmental interference and load fluctuations, a fast handover strategy based on grey prediction and multi-attribute decision-making is adopted to improve system robustness. Furthermore, a queuing mechanism based on power service priorities ensures priority access for emergency communications. This method effectively solves problems such as frequent satellite handovers, easy link interruptions, and intense resource competition in power emergency scenarios, significantly improving the communication continuity and service quality of LEO broadband satellite terminals in complex emergency environments. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0023] Figure 1 This is a schematic diagram of the system architecture and business flow of the present invention; Figure 2 This is a flowchart of a low-orbit broadband satellite terminal switching method for power emergency networks according to the present invention; Figure 3 Flowchart for constructing a directed graph for satellites; Figure 4 This is a flowchart of a multi-attribute decision-making satellite handover strategy based on a directed graph. Figure 5 This is a flowchart of a multi-attribute decision-making satellite switching strategy based on combined weights. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Please refer to the accompanying drawings in the instruction manual. Figure 1 In emergency communication systems, the low-Earth orbit (LEO) satellite constellation layer, as space infrastructure, provides the sole backup communication link for power communication islands created by disasters. It establishes connections with dedicated ground-based power gateway stations through multiple satellite-to-ground links, undertaking the tasks of uploading power service data and issuing control commands. The ground network layer demonstrates deep coupling with the power dispatch automation system. After receiving various power service data relayed by satellites, the ground gateway stations perform service identification and priority scheduling by the network management center, ultimately delivering the data to the production control area of ​​the power grid dispatch center, providing dispatchers with decision-making support.

[0026] The core of this system lies in a cluster of dedicated terminals deployed at the forefront of power production and emergency repair. Various terminals maintain two-way communication with the terrestrial network via satellite links: substation intelligent terminals carry hard real-time services with extreme requirements for latency and reliability, such as relay protection and safety and stability control, serving as the first line of defense for ensuring the safety of the main power grid; emergency power command vehicles, as mobile hubs for regional fault handling, must simultaneously process video conferencing and multiple fault data streams; intelligent inspection personnel and power-specific drones are respectively designed for distribution network field operations and transmission line inspection scenarios, achieving precise fault location and refined equipment status perception. These terminals are closely integrated with the core business of power grid safe operation, and their communication needs directly determine that the switching strategy must shift from general signal-driven to specific service-driven, ensuring that critical services such as dispatch instructions and protection signals can be transmitted preferentially, reliably, and continuously under any circumstances.

[0027] This invention uses a power emergency communication task triggered by a regional power grid failure as its implementation background. A landslide caused by torrential rain in a mountainous area resulted in power outages at multiple substations, interruption of the main optical fiber communication cable, and failure of conventional communication methods. To quickly restore dispatch command and on-site information transmission capabilities, the power emergency command center activated its satellite communication contingency plan, dispatching multiple repair teams equipped with low-orbit broadband satellite terminals to the scene. The terminals were deployed at the mountain substation repair sites, mobile emergency command vehicles, and drone inspection platforms, located at the edge of the low-orbit satellite network coverage area, where communication links were susceptible to factors such as terrain obstruction and rain attenuation. In this context, the terminals needed to achieve stable, low-interruption satellite access in a complex and dynamic environment, ensuring differentiated service quality for different types of services. If a switchover occurred, selecting the target satellite solely based on signal strength might lead to interruptions in dispatch command transmission due to a lack of consideration for resource allocation. Therefore, a service-oriented intelligent switchover strategy was necessary to ensure the communication continuity of high-priority services. The specific implementation process of the following steps is based on this emergency scenario.

[0028] Define the currently serving satellite as Sat j The set of nearby visible satellites is {Sat} i The terminal position is P, and the minimum communication angle is θ. min The signal strength switching threshold is Th ho Increase the channel threshold to Th add The receiver's minimum operating threshold is Th rx The bit error rate threshold is BER th The satellite load threshold is L th The duration of the service is T. x Then the candidate satellite list, handover trigger conditions, optimal handover path, and target satellite selection are all generated and updated based on the above parameters.

[0029] Please refer to the accompanying drawings in the instruction manual. Figure 2A method for switching low-Earth orbit broadband satellite terminals for power emergency networks includes the following steps: Step 1: During terminal communication, continuously measure the pilot signal strength of the currently accessed satellite beam and neighboring satellite beams, and simultaneously receive orbital parameters, nadir position, and channel resource usage status of each visible satellite from the satellite broadcast channel; combine the real-time positioning information output by the terminal to calculate the spatial geometric relationship between the terminal and each visible satellite, and further obtain the elevation angle, distance, and remaining service duration; integrate the above information to form a candidate satellite list, which includes fields such as satellite number, current signal strength, elevation angle, remaining service duration, number of idle channels, and available access time window, as the basic input data for subsequent handover decisions.

[0030] The methods for obtaining signal strength, satellite elevation angle, remaining service duration, and number of idle channels are as follows: (1) Signal strength Because satellites are constantly moving, the signal strength received by user terminals varies with elevation angle and is affected by environmental factors such as rain attenuation and signal blockage, exhibiting uncertainty. Using only the maximum elevation angle or the current instantaneous signal strength as the basis for switching is insufficient to guarantee link quality and the stability of subsequent communication. In low-Earth orbit satellite communication systems, a method can be adopted where the terminal periodically measures the signal strength of each visible satellite and predicts its changing trends. Grey theory is suitable for small-sample, incomplete-information systems, effectively modeling and predicting sequences containing uncertainties, requiring minimal data, and is suitable for short-term signal strength prediction.

[0031] This invention uses a grey GM(1,1) model to predict signal strength. This model first considers the user terminal's signal strength over a given time period. Signal intensity sequence acquired internally As the original data set, its length is Then, a new data sequence is constructed by accumulating the data to reduce random fluctuations in the original data and enhance its regularity.

[0032] Specifically, in grey modeling, the cumulative generation method is used to generate the original signal intensity sequence. Convert to a new sequence The calculation formula is as follows: ; Where i represents the original signal strength data sequence The i-th element in the array; k represents the index of the data point currently being accumulated, i.e., from s1 to s2. k The sum of the first k data points is used to generate a sequence. The position index of the k-th item in the middle.

[0033] The new sequence obtained As input data for the gray model.

[0034] Next, we establish the GM(1,1) model, which is a first-order linear differential equation model: ; in, and Let be the parameter to be estimated. After discretization, it can be expressed as: ; joint The signal strength values ​​at k and k+1, combined with the previous two formulas, yield: ; Transform the above equation into matrix form: ; in: ; Solving for the parameter vector using the least squares method Approximate solution : ; After obtaining the parameter estimates, the predicted values ​​can be obtained by substituting them into the differential equation. Furthermore, by performing a cumulative subtraction operation on the accumulated sequence, the predicted values ​​of the original signal strength can be obtained. ; (2) Satellite elevation angle Satellite elevation angle is defined as the angle between the horizon at the user terminal's location and the satellite. In low-Earth orbit satellite communication systems, the minimum elevation angle is... This is a key parameter used to define the satellite's coverage area for ground users. (When the actual elevation angle...) Less than the set minimum elevation angle When this occurs, the user terminal cannot establish a valid communication link with the satellite, thus this parameter directly affects the availability and continuity of communication.

[0035] Let the Earth's radius be... The satellite's orbital altitude is The spatial distance between the user terminal and the satellite is ,point For the projection of the satellite onto the Earth's surface, point For the user terminal location, For the Earth's core, This refers to the satellite position. The elevation angle between the user terminal and the satellite is then calculated. It can be derived from spatial geometric relationships.

[0036] According to the geometric relationships of a triangle, the angle of elevation... The following relationship must be satisfied: ; in, The geocentric angle between the user terminal and the sub-satellite point. The angle between the line of sight between the satellite and the nadir point.

[0037] From the relationship of right triangles, we can obtain: ; in, It is a triangle Centrally located at the Earth's center The angle at a point can be calculated using the Law of Cosines: ; At the same time, in the triangle Middle, Angle It can be represented as: ; Combining the four equations above, we can obtain the elevation angle between the user terminal and the satellite. The final expression is: ; Where: r is the Earth's radius, h is the distance from the satellite to the nadir point, and d is the distance between the user terminal and the satellite. This formula can be used to calculate the elevation angle between the user terminal and any visible satellite in real time, serving as the basis for judging communication feasibility and planning handover paths.

[0038] (3) Remaining service time In large-scale low-Earth orbit (LEO) satellite communication systems, due to the low orbital altitude and high relative speed of the satellites, each satellite can only provide users with a service duration of a few minutes to a dozen minutes. Therefore, user terminals need to continuously monitor the availability of the currently serving satellite during communication and plan handover strategies in advance to ensure communication continuity. Frequent handovers between different satellites can lead to adverse effects such as signal interruption and increased latency; therefore, reducing unnecessary handovers is an important goal for improving communication quality.

[0039] The remaining service time of the satellite to be connected is one of the key indicators for user terminals when selecting a handover target. This parameter reflects the satellite's ability to provide effective communication to users for a period of time in the future, and directly affects the rationality of the handover timing and path planning.

[0040] Maximum remaining service duration of satellite for user terminals It can be represented as: ; in: The maximum service duration (from the time the user terminal can establish communication with the satellite until the satellite can no longer provide services to the user due to motion). and These are correlation constants within the same satellite network. Let be the arc distance between the user terminal and the satellite's nadir at time t. By comparing the trend of elevation angle changes measured at different times, it can be determined whether the satellite is approaching or moving away from the user terminal: if the elevation angle increases with time, it indicates that the satellite is approaching; if the elevation angle decreases, it indicates that the satellite is moving away. Based on this, the value of the "±" sign in the formula can be determined—"+" when the satellite is approaching the user terminal, and "-" when it is moving away, thus calculating the maximum remaining service time at the current time.

[0041] (4) Number of idle channels In large low-Earth orbit (LEO) satellite constellations, the sheer number of satellites and the large user base mean that multiple satellites can simultaneously cover a single terminal. Without proper resource allocation, some satellites can become overloaded while others remain idle, leading to localized congestion or even system-wide congestion and impacting service quality. Therefore, when making handover decisions, the number of idle channels on the target satellite should be considered a key indicator to reflect its resource availability, avoid connecting to overloaded satellites, and improve network efficiency and communication stability.

[0042] Terminals can obtain their real-time channel occupancy status by parsing satellite broadcast information; ground gateways can also calculate the number of available satellite channels for a terminal to access by combining the terminal's location and access request. However, due to random user access, the channel status changes drastically, making it difficult to accurately predict future resource availability based solely on current observations.

[0043] Therefore, the aforementioned grey prediction model (GM(1,1)) can be used to predict future channel usage. While periodically measuring signal strength, the user terminal simultaneously obtains idle channel count data from satellite broadcast information, denoted as a time series: ; in Indicates the first The number of idle channels measured at each sampling time.

[0044] Based on this sequence, the number of idle channels at the next time step can be predicted using the grey modeling method. According to the cumulative reduction formula of the grey model, the predicted value is: ; in: The generated predicted values ​​are summed up. and These are the model parameters obtained by the least squares method. This represents the total number of observed samples.

[0045] The terminal is deployed at a substation repair site in a mountainous area, located at the edge of the low-Earth orbit satellite network coverage area. It collects downlink pilot signal strength data from the currently serving satellite and surrounding satellites at intervals of t seconds, and obtains the TLE orbital elements and channel load information of each satellite via a broadcast channel. Based on its own latitude and longitude coordinates and the satellite's nadir position, the terminal calculates the elevation angle θ with each satellite.j Simultaneously, it predicts the remaining service time for the terminal based on the relative motion speed and direction. All measurement and calculation results are packaged into a structured data table, i.e., a candidate satellite list, and uploaded to the ground gateway station for global decision support. This list is updated in real time to ensure the accuracy and timeliness of state awareness.

[0046] A candidate satellite list can be used as the input for multi-attribute decision-making to determine whether the handover trigger conditions are met. If they are met, the corresponding handover process is initiated; otherwise, the current connection is maintained and the list is updated periodically.

[0047] Step 2: Based on the communication characteristics and service quality requirements of power emergency services, a multi-level handover trigger mechanism is set up, specifically including two scenarios: normal handover triggering and abnormal handover triggering. When the elevation angle between the terminal and the currently serving satellite is lower than the preset minimum communication angle θ... min Or the current beam signal strength remains below the switching threshold Th ho When the signal strength of the neighboring cell beam is higher than the increased channel threshold Thadd, it is determined to be a normal handover scenario, and the multi-attribute decision-making handover process based on the directed graph is initiated. When the signal strength of the current link suddenly drops to the receiver threshold Thadd due to environmental factors such as rain attenuation or obstruction, the handover process is initiated. rx However, if communication quality deteriorates or the current service satellite load exceeds the threshold L, the above applies. th When load balancing is required, if an abnormal switching scenario is identified, a multi-attribute decision-making switching process based on combined weights is initiated. This hierarchical mechanism ensures that the system can select the optimal response strategy based on the predictability of the event.

[0048] Step 3: For normal handover scenarios, the ground gateway station uses the terminal location, satellite ephemeris, and statistical characteristics of service duration (T) to determine the handover process. x Construct a time window T=T x The service satellite sequence is generated, and a weighted directed graph G(V,E) is constructed. The directed graph construction process is as follows: Figure 3 As shown, this is used to model the satellite handover relationship of user terminals during the communication process.

[0049] Serving satellite sequence refers to the sequence of satellites within a time window. The set of all satellites that can provide effective communication services to user terminals and their service time intervals.

[0050] The service satellite sequence is jointly generated by the ground gateway station and the network control center. The specific process is as follows: The ground gateway station receives real-time location information reported by user terminals, calculates the latitude, longitude, velocity, and direction of motion of each low-Earth orbit satellite at any given time based on satellite ephemeris data, and then calculates the start and end times of coverage for each user terminal by combining the user terminal's location and satellite orbit parameters. Finally, a service satellite list is formed, in the following format: ; in: For access to the low-Earth orbit satellite communication system, the number is i The user terminal, Let n be the satellite numbers that can provide services to user terminals. There are a total of n satellites. The satellite is numbered as The moment when services can begin to be provided to user terminals. The satellite is numbered as The moment when services to user terminals cease.

[0051] In this invention, a directed graph is used. To represent the handover relationship of a user terminal between multiple satellites, where: vertex set Indicates within the time window All satellite nodes within the system that can provide services to user terminals, i.e. Edge set Indicates from satellite arrive A feasible switching path.

[0052] The process of constructing a directed graph is as follows: The service satellite list is arranged according to... Arrange in ascending order; starting with the first satellite, compare them sequentially. With subsequent satellites If satisfied Then add directed edges to the graph. Repeat the above process until all satellite comparisons are completed.

[0053] This process ensures that the generated directed graph accurately reflects all potential switching paths of the user terminal in the time dimension.

[0054] To achieve multi-attribute decision-making, each directed edge needs to be assigned a comprehensive weight to reflect the overall performance of switching to the target satellite in terms of communication quality, resource availability, etc. The weight calculation formula is as follows: ; in: For satellite Pointing to satellite The weight of the directed edge. The total number of channels for each satellite. The minimum elevation angle at which communication can be established between the user terminal and the satellite. For satellites during handover Idle channel prediction value, For user terminals and satellites during handover The angle of elevation, , These are the predicted values ​​for the idle channel and the weighting coefficients for the elevation angle between the user and the satellite, respectively.

[0055] The gateway station uses the current moment as a starting point to query future T. y Within a given time, establish a vertex set V for all satellites capable of covering the terminal's location. Establish an edge set E based on the time sequence of each satellite entering and exiting the coverage area. Substitute these values ​​into the measured values. and Let α and β be the values, calculate the weights of each side, run Dijkstra's algorithm, and output the optimal switching path, denoted as Handover_Path.

[0056] ; This approach balances maximizing elevation angle with resource availability, reducing the total number of handovers.

[0057] When the terminal communication duration exceeds T x At that time, the gateway station uses the currently accessed satellite as the starting point to reconstruct the time window as 0.5T. x The weighted directed graph dynamically updates and switches paths to ensure the continuity of long-term communication. For example, when the original T... x =T y The window has closed, but the terminal is still transmitting disaster video. The system will use the currently accessed satellites as a starting point to re-plan the next 0.5T. y Service sequences within seconds to avoid path breaks.

[0058] Step 4: Based on the optimal handover path, the gateway station reserves communication channel resources for the terminal on each target satellite in chronological order, establishing a "Satellite Channel Reservation Information Table" to ensure that the target channel is available at the handover time. The reservation strategy adopts a dynamic time slot allocation mechanism, allowing multiple users in non-overlapping time periods to share the same physical channel, avoiding the resource waste caused by traditional fixed reservations. This mechanism significantly improves the handover success rate of emergency services, and is especially suitable for emergency repair sites with multiple terminals accessing concurrently. Then proceed to Step 7.

[0059] Step 5: For abnormal handover or new call access scenarios where the terminal cannot predict the handover time, a multi-attribute decision-making satellite handover strategy based on combined weights is adopted to select the target satellite. First, the grey prediction model GM(1,1) is used to assess the signal strength S of neighboring satellites in the future time period. pred and the number of idle channels C pred Make predictions. For the terminal in [t] g ,t n The signal sequence S'={s1',s2',...,sn'} measured internally is accumulated to generate a first-order linear differential equation. Solving for parameters using the least squares method , Thus, the predicted value is obtained: ; Spred This refers to the sequence of predicted signal strength values ​​for neighboring satellites. This represents the predicted signal strength of a specific satellite, i.e., S. pred It is composed of various neighboring satellites Composed of.

[0060] This is used for subsequent standardization processing and decision-making. A standardized evaluation matrix X for candidate satellites is constructed based on the current remaining service duration T. The subjective weights W=(w1,w2,w3) are determined using the AHP method, where w1, w2, and w3 correspond to the subjective weights of signal strength, number of idle channels, and remaining service duration, respectively. The objective weights H=(h1,h2,h3) are calculated using the entropy method, where h1, h2, and h3 correspond to the objective weights of signal strength, number of idle channels, and remaining service duration, respectively. The combined weights V=(v1,v2,v3) are obtained through a weighted integration method, where v1, v2, and v3 correspond to the combined weights of signal strength, number of idle channels, and remaining service duration, respectively. Finally, the TOPSIS method is used to calculate the relative proximity E between each candidate satellite and the ideal solution. i Select E i The largest one will be selected as the target satellite.

[0061] Specifically, the methods for determining the weights of each indicator are as follows: (1) Indicator standardization During satellite handover, evaluation criteria for different indicators vary. To achieve unified comparison in multi-attribute decision-making, it is necessary to classify each indicator according to its nature and process it using appropriate standardization methods. In multi-attribute decision-making, attributes can generally be divided into three categories: benefit-type: the larger the value, the more beneficial it is to system performance; cost-type: the smaller the value, the more beneficial it is to system performance; and interval-type: the closer the value is to a specific interval, the greater its positive impact on the system.

[0062] Signal strength prediction value in this method and remaining service time The selection of target satellites has a positive promoting effect, meaning that the higher the value, the better; therefore, it belongs to the benefit-oriented attribute. The number of idle channels... When resources are scarce, it should be a key consideration; however, when resources are abundant, its importance is comparable to the other two indicators. Considering that in actual communication, when the number of idle channels is below 20% of the total number of channels, the handover success rate drops significantly, while the handover effect tends to stabilize above this threshold, the number of idle channels is defined as a range-type attribute, with its effective range set as follows: ,in This represents the total number of satellite channels.

[0063] For signal strength prediction value and remaining service time Standardization was performed using trigonometric function transformation: ; ; Among them, T n It is the remaining service duration of a certain satellite to a user at time n, i.e., t max S n That is, the predicted signal strength value S i T is the predicted signal strength value at time i; i It is the remaining service duration at time i; and These are the predicted signal strength and the final standardized indicator values ​​for remaining service time, respectively.

[0064] For the predicted value of the idle channel The range transformation method is used for standardization to reflect its sensitivity within the interval: ; Where: C all This represents the total number of satellite channels. When the number of idle channels is higher than 20% of the total number of channels, the handover success rate difference is not significant, and they are almost the same. However, when it falls below 20%, the handover success rate drops sharply. Therefore, a standardized range is set as follows: After standardizing each indicator, a corresponding satellite standardization evaluation matrix is ​​constructed. : ; in: , , These represent the standardized values ​​of the predicted signal quality of the first accessible satellite, the standardized value of the remaining service duration, and the standardized value of the predicted idle channel, respectively.

[0065] (2) Determination of the weights of each indicator In multi-attribute decision-making, subjective weighting methods offer greater flexibility, but their results are heavily influenced by the decision-maker's experience, exhibiting a degree of subjectivity and arbitrariness. While objective weighting methods can reflect the inherent differences in the data, they overlook the decision-maker's emphasis on each attribute. Therefore, relying solely on a single method is insufficient to fully reflect actual needs.

[0066] The combined weighting method integrates the advantages of both subjective and objective weighting approaches. It considers the influence of objective factors while also taking into account the decision-maker's preference for each attribute, making it a more scientific and reasonable method for determining weights. This paper uses the combined weighting method to determine the multi-attribute decision weights during satellite handover.

[0067] 1. Determining Subjective Weights (AHP Method) This paper employs the Analytic Hierarchy Process (AHP) to subjectively weight the metrics involved in the handover process. The specific steps are as follows:

[0068] a. Construct a hierarchical model: Decompose the problem into three levels: target layer (selecting the best access satellite); criterion layer (signal strength, number of idle channels, remaining service time); and scheme layer (candidate satellites).

[0069] b. Constructing a comparison matrix: Based on the decision-maker's professional knowledge and past experience, a judgment matrix is ​​constructed through pairwise comparisons. Its form is as follows: ; in, Indicates the first The first indicator is relative to the first The importance ratios of each indicator range from 1 to 9, and their specific meanings are shown in Table 1-1 below.

[0070] Table 1-1 Meaning of Scale in Comparison Matrices

[0071] For the scenario in this study, the main objective is to ensure a high success rate of access while also considering communication performance. Therefore, the comparison matrix is ​​shown in Table 1-2.

[0072] Table 1-2 Satellite Selection Criteria Layer Decision Matrix

[0073] c. Normalization and weight calculation Comparison Matrix Each row of elements in the matrix is ​​normalized to obtain a normalized matrix. Its elements are defined as: ; Then calculate the subjective weight of each indicator. ,Right now: ; Then Normalization yields the final subjective weight vector: ; 2. Determination of objective weights (entropy method) To reflect the differences in the amount of information contained in the data for each indicator, the entropy method is used to determine the objective weights. The specific steps are as follows:

[0074] a. Normalize the standardized evaluation matrix: Normalize the satellite evaluation matrix. Normalization is performed to obtain the normalized matrix. The calculation formula is as follows: ; b. Calculate the information entropy of each attribute: Based on the normalized data, calculate the information entropy of the first attribute. Information entropy of each attribute : ; Where, constant This is used to ensure the dimensionless nature of entropy. When At that time, it was stipulated .

[0075] c. Calculate objective weights: Calculate the objective weights of each attribute based on information entropy. : ; From this, we can obtain the objective weight vector. .

[0076] 3. Generation of combined weights: Combining subjective weights With objective weight Combined, forming a combined weight vector The calculation formula is as follows: ; in: , , Representing the first i The combined weights, subjective weights, and objective weights of each indicator. It is a relaxation factor less than 1, used for linear adjustment of the objective weights.

[0077] (3) TOPSIS method Obtain the combined weight vector of each indicator Subsequently, the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method is used to make an optimal selection of candidate satellites. This method achieves the optimal selection in multi-attribute decision-making by calculating the relative similarity between each candidate scheme and the ideal solution. The specific selection process is as follows:

[0078] First, the standardized evaluation matrix Combined weight vector Perform weighted calculations to obtain the weighted standardized evaluation matrix. The calculation formula is as follows: ; in, Indicates the first The candidate satellites in The weighted standardized value of each indicator.

[0079] Next, based on the weighted matrix Identify the positive ideal solution (best ideal switching satellite) and the negative ideal solution (worst ideal switching satellite). Positive ideal solution and negative ideal solution Each value is composed of the maximum value of each indicator, as defined below:

[0080] ; ; Then, the weighted Euclidean distance between each candidate satellite and the positive and negative ideal solutions is calculated. Let the... The distance between each candidate satellite and the ideal solution is The distance to the negative ideal solution is The calculation formulas are as follows:

[0081] ; ; in: For the first The candidate satellites in Weighted values ​​on each indicator; and The first The corresponding values ​​of each index in the positive and negative ideal solutions.

[0082] Finally, the relative proximity of each candidate satellite to the positive and negative ideal solutions is calculated. Its definition is: ; This value reflects how close the candidate satellite is to the ideal state: The larger the value, the closer the satellite is to the ideal solution, and the better its overall performance. Among all candidate satellites, the one with the highest relative proximity is selected. The largest satellite is used as the final target for satellite switching.

[0083] Specific implementation example: An emergency command vehicle temporarily activated its communication system without prior route planning. The terminal reported the most recent x sets of signal measurements. Using a GM(1,1) model, these measurements were accumulated and fitted with a differential equation to obtain the values ​​of a and u, and the signal at the next moment was predicted. Similarly, the idle channel C of a candidate satellite was predicted. pred The value of E is combined with its elevation angle and remaining service duration to form an evaluation matrix with other candidate satellites. After weighting using AHP and entropy methods, TOPSIS calculations show E... i The satellite with the highest value is selected as its access target.

[0084] Step 6: When channel resources are scarce, implement a priority queuing access mechanism. Users are categorized into "emergency handover users," "emergency new call users," and "non-emergency users," and service types are divided into "real-time control" and "non-real-time monitoring." Four priority levels are set: emergency handover + real-time services, emergency handover + non-real-time services, emergency new call + real-time services, and others. When the target satellite has no available channel, users are queued according to priority. The queuing time depends on the overlap coverage duration between two adjacent satellites on the same orbital plane in the low-Earth orbit satellite network; otherwise, access is considered unsuccessful.

[0085] For example, in a multi-point concurrent failure, multiple terminals simultaneously request access to a satellite. The system detects that the channel is full and initiates a queuing mechanism. A scheduling instruction transmission task (emergency handover + real-time control) is assigned priority 4 and given priority channel allocation; a video transmission task (emergency new call + non-real-time) is assigned priority 2 and must wait for higher-priority tasks to release resources. If the queuing timeout occurs (e.g., exceeding the overlap time of adjacent satellites), the system attempts to retry using a suboptimal satellite or at a lower transmission rate.

[0086] Step 7: After the handover is completed, update the channel reservation information table and release the used channel resources; if the access satellite is the end node of the handover path, recalculate the handover path for the next stage; after the terminal communication ends, clear all reserved records. This closed-loop management mechanism ensures efficient resource flow and avoids deadlock or leakage.

[0087] The method provided by this invention can also be implemented as a corresponding system using modular design technology. A terminal handover control system can be established, comprising a signal acquisition module, a candidate list generation module, a handover trigger judgment module, a path optimization module, a resource reservation module, a multi-attribute decision module, a priority queue module, and a resource release module. These modules are connected sequentially and work collaboratively. The signal acquisition module acquires terminal location and link status information and outputs it to the candidate list generation module. The candidate list generation module combines ephemeris data to generate a candidate satellite list, which is then sent to the handover trigger judgment module. The handover trigger judgment module routes the signal to either the path optimization module or the multi-attribute decision module based on threshold conditions. The path optimization module generates the optimal handover path and submits it to the resource reservation module for channel pre-allocation. The multi-attribute decision module outputs the target satellite and then queues it in the priority queue module. Finally, the resource release module reclaims resources after the handover is completed. The entire system can be deployed in a software-defined manner at a ground gateway station or edge cloud platform, exhibiting good scalability and engineering applicability.

[0088] This invention addresses the specific requirements of power emergency communication for high reliability and low interruption rate by proposing a low-Earth orbit (LEO) satellite terminal handover method that integrates path planning and dynamic decision-making. By constructing a weighted directed graph to achieve global optimization of the handover path, the number of handovers is significantly reduced. A channel reservation mechanism is introduced to ensure the success rate of handovers for critical services. To address sudden environmental interference and load fluctuations, a fast handover strategy based on grey prediction and multi-attribute decision-making is adopted to improve system robustness. Furthermore, a queuing mechanism based on power service priorities ensures priority access for emergency communications. This method effectively solves the problems of frequent satellite handovers, easy link interruptions, and intense resource competition in power emergency scenarios, significantly improving the communication continuity and service quality of LEO broadband satellite terminals in complex emergency environments.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for switching a low earth orbit broadband satellite terminal for a power emergency network, characterized in that, The method comprises the following steps: Step 1, constructing a candidate satellite list, which comprises satellite number, current signal strength, elevation angle, remaining service time, number of idle channels and accessible time window; Step 2, setting a multi-stage switching trigger mechanism, including normal switching trigger and abnormal switching trigger; when determining as a normal switching scenario, entering step 3; when determining as an abnormal switching scenario, entering step 5; Step 3, for normal handover scenario, adopt the multi-attribute decision satellite handover strategy based on directed graph to select target satellite: the ground gateway station constructs the service satellite sequence within the time window T=T x based on the terminal location, satellite ephemeris and service duration statistical characteristics T x , and generates a weighted directed graph G(V,E): where the vertex set V represents all satellite nodes that can provide services for the terminal within T time, and the edge set E represents the feasible handover path from satellite i to satellite j, and there is a directed edge (i,j) if and only if the service end time of satellite i is earlier than the service start time of satellite j; a comprehensive weight is assigned to each directed edge, and the calculation method is as follows: ; in: For satellite Pointing to satellite The weight of the directed edge. The total number of channels for each satellite. The minimum elevation angle at which communication can be established between the user terminal and the satellite. For satellites during handover Idle channel prediction value, For user terminals and satellites during handover The angle of elevation, , These are the predicted idle channel values ​​and the weighting coefficients for the elevation angle between the user and the satellite, respectively. Step 3, obtaining the optimal switching path Handover_Path by solving the minimum weight path from the current satellite node to the end node in the graph by Dijkstra algorithm; Step 4, based on the optimal switching path, the gateway station reserves channel resources on each target satellite in time sequence for the terminal, establishes a "satellite channel reservation information table", and ensures that the target channel is available at the switching time; the reservation strategy adopts a dynamic time slot allocation mechanism, and the same physical channel can be shared by multiple switching users in different time periods; then entering step 7; Step 5, for abnormal handover or new call access scenarios, a multi-attribute decision satellite handover strategy selection target satellite based on combination weight is adopted: first, the signal strength S pred and the number of idle channels C pred of the adjacent satellites in the future time period are predicted by using the grey prediction model GM(1, 1); combined with the current remaining service time T, the normalized evaluation matrix X of the candidate satellites is constructed; the AHP method is used to determine the subjective weight W=(w1, w2, w3), w1, w2, w3 respectively correspond to the subjective weight of signal strength, the number of idle channels, and the remaining service time; the entropy method is used to calculate the objective weight H=(h1, h2, h3), h1, h2, h3 respectively correspond to the objective weight of signal strength, the number of idle channels, and the remaining service time; the weighted integration method is used to obtain the combination weight V=(v1, v2, v3), v1, v2, v3 respectively correspond to the combination weight of signal strength, the number of idle channels, and the remaining service time; finally, the TOPSIS method is used to calculate the relative closeness E i of each candidate satellite to the ideal solution, and the maximum E i is selected as the target satellite; Step 6, when the channel resource is tight, executing a priority queuing access mechanism; Step 7, after completing the switching, releasing the used channel resources. 2.The method for power emergency network oriented LEO broadband satellite terminal handover according to claim 1, characterized in that, Step 1 is specifically: the terminal continuously measures the signal strength of the current access satellite beam and the adjacent satellite beam in the communication process, and synchronously receives the satellite broadcast channel information, obtains the orbital parameters, the sub-satellite point position and the channel resource use state of each visible satellite; Combining the terminal positioning information, the elevation angle, the distance and the remaining service time between the terminal and each visible satellite are calculated to construct the candidate satellite list. 3.The LEO broadband satellite terminal handover method for power emergency network according to claim 2, characterized in that, In Step 2, normal handoff trigger: when the terminal's elevation angle with the current serving satellite is lower than a pre-set minimum communication elevation angle or the current beam signal strength continuously is lower than a "handoff threshold" and the neighbor beam signal strength is higher than an "add channel threshold", the normal handoff scenario is determined and Step 3 is entered. 4.The method for LEO broadband satellite terminal handover for power emergency network according to claim 3, wherein, In step 2, abnormal handoff trigger: When the current link signal strength drops to above the "receiver threshold" due to environmental factors but the bit error rate BER > BER th threshold, or the current serving satellite load exceeds the threshold and needs to be load balanced, it is determined that the abnormal handoff scenario is entered into step 5.

5. The method of claim 4, wherein, Step 6 is specifically: the users are divided into "emergency switching users", "emergency new call users" and "non-emergency users", and the service types are divided into "real-time control type" and "non-real-time monitoring type"; four levels of priority are set: emergency switching + real-time service, emergency switching + non-real-time service, emergency new call + real-time service and others; when there is no idle channel in the target satellite, the users are queued in the order of priority, and the value of the queuing waiting time depends on the superposition coverage time length between two adjacent satellites in the same orbital plane in the low-orbit satellite network, otherwise it is determined that the access fails.

6. The method of claim 5, wherein, Step 7 is specifically: after completing the switching, updating the channel reservation information table and releasing the used channel resources; if the access satellite is the end node of the switching path, the next stage switching path is recalculated; after the terminal communication is completed, all the reservation records are cleared.

7. The method of claim 6, wherein, In step 3, the service satellite sequence is generated by the ground gateway station and the network management center jointly, and the specific process is as follows: the ground gateway station receives the real-time position information reported by the user terminal, calculates the subsatellite point longitude and latitude, speed and motion direction of each low earth orbit satellite at any time according to the satellite ephemeris data, and then combines the user terminal position with the satellite orbit parameters to calculate the coverage start and end time of each satellite to the user terminal, and finally forms a service satellite list, which is in the form of: ; wherein: is the user terminal numbered i in the low-orbit satellite communication system, is the satellite numbered that can provide services for the user terminal, and there are n satellites in total, is the satellite numbered is the time when the satellite can start to provide services for the user terminal, is the satellite numbered is the time when the satellite stops providing services for the user terminal.

8. The method of claim 7, wherein, In step 3, the directed graph construction process is as follows: The service satellite list is arranged according to... Arrange in ascending order; starting with the first satellite, compare them sequentially. With subsequent satellites If satisfied Then add directed edges to the graph. Repeat the above process until all satellite comparisons are completed. 9.The LEO broadband satellite terminal handover method for power emergency network according to claim 8, wherein, In step 5, the corresponding satellite standardized evaluation matrix is constructed The method is as follows: For signal strength prediction value And the remaining service duration Standardization processing is performed by using a trigonometric function transformation method: ； ； Wherein, T n is the remaining service time of a satellite to a user at the nth moment, that is, t max ; S n is the signal strength prediction value ; S i is the signal strength prediction value at the ith moment; T i is the remaining service time at the ith moment; and are the final standardized index values of the signal strength prediction value and the remaining service time, respectively; For the idle channel prediction value , the range transformation method is used for standardization processing to reflect its sensitivity in the interval: ; Where: C all is the total number of channels for the satellite; After the standardization of each index, the corresponding satellite standardization evaluation matrix is constructed : ; wherein: , , respectively represent the normalized value of the first accessible satellite signal quality prediction value, the normalized value of the remaining service duration, and the normalized value of the idle channel prediction value.

10. A system for low earth orbit broadband satellite terminal handover for power contingency network using the method of claim 9, wherein The method comprises a signal acquisition module, a candidate list generation module, a switching trigger judgment module, a path optimization module, a resource reservation module, a multi-attribute decision module, a priority queue module and a resource release module; The signal acquisition module is used for obtaining the terminal position and link state information and outputting to the candidate list generation module; The candidate list generation module is used for generating the candidate satellite list in combination with the ephemeris data and sending to the switching trigger judgment module; The switching trigger judgment module is used for shunting to the path optimization module or the multi-attribute decision module according to the threshold condition; The path optimization module is used for generating the optimal switching path and handing over to the resource reservation module for executing channel pre-allocation; The multi-attribute decision module is used for outputting the target satellite and then entering the priority queue module for queuing; The resource release module is used for recycling the resources after the switching is completed.

Images