Multi-connection management method suitable for high-low orbit fusion satellite communication terminal

Abstract

The application discloses a kind of multi-connection management methods suitable for high-low orbit fusion satellite communication terminal, comprising: with high-orbit satellite establishes communication connection, and obtains low-orbit satellite ephemeris information;Accordingly, the visible time window of target low-orbit satellite is predicted, and the composite link quality of future time is dynamically evaluated;Based on visible time window and composite link quality, prospective multi-connection state management is executed;Wherein, multi-connection state management includes the preparation state of triggering antenna pre-pointing before target low-orbit satellite is visible, and the transition state of triggering high-low orbit dual-link simultaneous transmission before low-orbit satellite coverage ends.The application overcomes the deficiency that traditional passive response type switching has communication blind area in link handover period, realizes first build and then break of cross-orbit link, effectively guarantees the continuity and high reliability of service data transmission in complex space network.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication, and in particular, it is a multi-connection management method applicable to high and low orbit integrated satellite communication terminals. Background Technology

[0002] With the development of integrated space-air-ground networks, satellite internet has become a core support for building a global wide-area information infrastructure. In modern communication networks, satellite systems at different orbital altitudes carry differentiated transmission tasks. High-orbit geostationary satellites have the advantage of wide-area coverage, while low-orbit constellation systems can provide low-latency and high-throughput data interaction. How to ensure the stability of data flow and access between different orbital links for terminal devices in a rapidly changing space network topology is a key technical issue in the current design of next-generation mobile communication system architecture.

[0003] Current satellite network terminals typically employ a passive hard handover mechanism based on physical layer signal strength when accessing multi-orbit systems. Under this mechanism, the terminal only triggers the signal search and link establishment process for satellites in the new orbit after the measured signal quality of the current working link has attenuated to a disconnection threshold. For example, in a scenario where a low-Earth orbit satellite is passing at high speed, the terminal relies on received signal strength indicators to determine the validity of the current connection. Once the signal drops below the threshold, the current connection is disconnected and a reconnection operation to other available network nodes is initiated. This passive response mechanism allocates new resources only after the physical link is actually disconnected, resulting in inherent communication blind spots during network node handover.

[0004] The aforementioned passive response-based access and reconnection mechanisms, when faced with scenarios involving high-speed movement of spatial nodes and limited coverage time, struggle to balance the continuity of service transmission with the efficiency of network resource switching. This can easily lead to frequent communication interruptions or ineffective signaling overhead during link handover periods. Therefore, it is necessary to investigate a method that can improve the robustness of data transmission and the continuity of service connections in complex heterogeneous spatial network scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-connection management method suitable for high- and low-orbit integrated satellite communication terminals, so as to solve the above-mentioned problems existing in the prior art.

[0006] The technical solution, applicable to multi-connection management methods for high- and low-Earth orbit integrated satellite communication terminals, includes:

[0007] Establish communication connections with high-orbit satellites and obtain ephemeris information from low-orbit satellites;

[0008] Based on low-Earth orbit satellite ephemeris information, the visible time window of the target low-Earth orbit satellite is predicted, and the composite link quality at future moments is dynamically evaluated.

[0009] Based on the visibility time window and composite link quality, a forward-looking multi-connection state management is performed. The multi-connection state management includes a preparatory state that triggers antenna pre-pointing before the target low-Earth orbit satellite becomes visible, and a transition state that triggers simultaneous transmission of high- and low-Earth orbit dual links before the low-Earth orbit satellite coverage ends.

[0010] Beneficial effects: This invention overcomes the shortcomings of traditional passive response switching, which has communication blind spots during link handover, and realizes the establishment and discontinuation of cross-track links, effectively ensuring the continuity and high reliability of business data transmission in complex space networks. Attached Figure Description

[0011] Figure 1 A flowchart illustrating the steps of a multi-connection management method for a high-low orbit fusion satellite communication terminal provided in this application embodiment.

[0012] Figure 2 A flowchart illustrating the steps for entering the sub-low orbit capture state, as provided in this application embodiment.

[0013] Figure 3 This is a flowchart illustrating the steps of merging data by the receiving end based on a unified serial number, as provided in an embodiment of this application.

[0014] Figure 4 This is a flowchart illustrating the power-on process of a converged terminal provided in an embodiment of this application.

[0015] Figure 5 A communication flowchart provided for an embodiment of this application. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] It should be noted that the terms include and have, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0018] like Figure 1 As shown, a multi-connection management method suitable for high-Earth orbit and low-Earth orbit integrated satellite communication terminals includes the following steps:

[0019] Establish communication connections with high-orbit satellites and obtain ephemeris information from low-orbit satellites.

[0020] In this embodiment, after the terminal is powered on and initialized, it prioritizes searching for and locking onto high-Earth orbit (GEO) satellites. Because GEO satellites have extremely wide beam coverage, the terminal can easily complete initial satellite and network registration at this stage, establishing a basic GEO communication connection. After establishing this connection, the terminal receives ephemeris information from low-Earth orbit (LEO) satellites currently operating in the network via the GEO link.

[0021] Specifically, ephemeris information is typically delivered in a two-line orbital element data format, containing key Keplerian orbital parameters such as orbital inclination, right ascension of the ascending node, eccentricity, and mean anomaly angle of the low-Earth orbit (LEO) satellite. After acquiring the LEO satellite ephemeris information, the terminal stores it in its local memory, serving as the fundamental data source for subsequent calculations of satellite trajectories. The wide-area coverage of high-Earth orbit (HEO) satellites ensures that the terminal can reliably and stably acquire the latest orbital data of all LEO satellites in the network, regardless of its geographical location.

[0022] Based on the ephemeris information of low-Earth orbit satellites, the visible time window of the target low-Earth orbit satellite is predicted, and the composite link quality at future moments is dynamically evaluated.

[0023] Specifically, the terminal's internal orbit calculation module, based on locally stored ephemeris information and the terminal's own geographical coordinates (latitude, longitude, and altitude), uses a standard orbit extrapolation model to calculate the elevation and azimuth trajectories of the target low-Earth orbit satellite relative to the terminal over a future time axis. By setting a minimum passable angle threshold, the terminal can accurately predict the visible time window from the target low-Earth orbit satellite's ascent to its descent.

[0024] Furthermore, based on the determined visible time window, the terminal dynamically and quantitatively assesses the composite link quality of the target low-Earth orbit satellite at various future moments. The assessment process does not rely solely on a single physical layer measured signal strength, such as the carrier-to-noise ratio (CNR), but comprehensively considers the predicted CNR derived from orbital parameters, the allocable service bandwidth of the satellite system, the predicted remaining coverage time derived from the visible time window, and the propagation delay determined by the physical distance between the satellite and the ground. By normalizing and weighting the multi-dimensional physical quantities, a composite quality score that comprehensively reflects the expected service capability of the link is obtained. This predictive assessment mechanism based on deterministic orbital mechanics enables the terminal to grasp the link quality change trend throughout its entire lifecycle before the low-Earth orbit satellite actually reaches its optimal communication position.

[0025] Based on the visibility time window and composite link quality, a forward-looking multi-connection state management is implemented. This multi-connection state management includes a preparatory state that triggers antenna pre-pointing before the target low-Earth orbit satellite becomes visible, and a transition state that triggers simultaneous transmission of high- and low-Earth orbit dual links before the low-Earth orbit satellite coverage ends, in order to ensure service continuity.

[0026] In this embodiment, the terminal's multi-connection management protocol stack drives the internal state machine to transition states based on the predicted visible time window and the composite link quality score. Unlike the passive response-based switching in traditional cellular or monorail satellite networks where signal degradation leads to link loss and subsequently triggers a new link search, a prediction-driven look-ahead management mechanism is preferred.

[0027] Specifically, before the target low-Earth orbit satellite enters the terminal's visible range (i.e., before the elevation angle reaches the minimum communication threshold), the state machine enters a standby state once the system clock reaches a specific lead calculated based on the prediction window. In the standby state, the terminal's main bearer services continue to be transmitted stably on the high-Earth orbit link, while the antenna control system utilizes this lead time to pre-align the idle radio frequency beam or mechanical antenna surface with the predicted azimuth of the target low-Earth orbit satellite's imminent appearance.

[0028] When the terminal is in low-Earth orbit (LEO) communication mode and the primary service is running on the LEO link, the protocol stack continuously monitors the predicted remaining coverage time of the LEO satellite and the degradation trend of the composite link quality. Before the LEO satellite leaves the coverage area or its quality drops below the threshold, the state machine proactively enters a transition state. During the transition state, the terminal not only wakes up in advance and restores the full-rate transmission capability of the high-Earth orbit (HEO) link, but also, under the scheduling of the network layer, concurrently transmits service data packets through both HEO and LEO physical paths—that is, dual-link simultaneous transmission. When the LEO satellite eventually moves out of the visible range, causing the physical link to disconnect, the service data stream has been smoothly and completely migrated to the HEO link during the transition state, achieving zero packet loss and zero interruption service continuity at the application layer.

[0029] It should be noted that the high-Earth orbit and low-Earth orbit fusion satellite communication terminal applicable to this embodiment typically includes a dual-RF front-end supporting dual-band (e.g., Ku band for high-Earth orbit and Ka band for low-Earth orbit) transmission and reception, as well as a phased array antenna or a high-dynamic mechanical servo antenna with fast beam switching capability. The terminal internally runs a multi-connection management protocol stack, capable of simultaneously maintaining or rapidly time-division multiplexing at least two satellite communication physical links.

[0030] This embodiment illustrates the forward-looking backbone process of high- and low-orbit integrated satellite communication terminals when performing network access and connection management. It solves the problems that a single orbital satellite cannot achieve full coverage and ultra-low latency, as well as the service interruption caused by traditional passive response switching.

[0031] In one possible implementation, multi-connection state management specifically includes the following transition states:

[0032] High-orbit acquisition status: After the terminal is powered on, it searches for and locks onto high-orbit satellite signals;

[0033] High-orbit communication status: Establish a high-orbit communication link to carry services and receive ephemeris information from low-orbit satellites;

[0034] Ready state: When the system clock reaches the ready trigger time determined based on the ephemeris information of the low-orbit satellite, maintain the high-orbit communication link active and control the antenna beam to be pre-pointed to the predicted azimuth of the target low-orbit satellite.

[0035] Low Earth Orbit Acquisition Status: After the target low Earth orbit satellite enters the visible range, low Earth orbit signal acquisition is initiated;

[0036] Low-Earth Orbit (LEO) communication status: After the LEO signal is locked, the LEO communication link is established to carry the main services, and the HEO communication link is downgraded to signaling hold-up mode.

[0037] Transition state: Triggered when the composite link quality meets the preset quality switching conditions, or when the visible time window is less than the preset transition duration, the high-orbit communication link is restored to full-rate communication mode, and high- and low-orbit dual-link simultaneous transmission is performed.

[0038] Abnormal recovery status: Triggered when a sudden abnormality occurs in the low-orbit communication link, the high-orbit emergency recovery process is initiated.

[0039] In other words, the abnormal recovery state is triggered when a sudden abnormality occurs in the low-orbit communication link, initiating the high-orbit emergency recovery process to restore the high-orbit communication link to full-rate communication mode to carry services.

[0040] Specifically, multi-connection state management constructs a complete closed-loop state transition. After the terminal completes hardware initialization upon power-on, it enters an idle state and then enters the high-orbit acquisition state to search for and lock onto a signal. Upon successful high-orbit acquisition, it enters the high-orbit communication state, where the high-orbit link acts as the primary bearer link to transmit service data and simultaneously extract ephemeris data. After entering the low-orbit communication state, the low-orbit communication link provides high-bandwidth and low-latency service transmission. At this time, the system controls the high-orbit communication link to enter signaling hold mode. For example, the signaling hold mode can specifically manifest as maintaining only a control channel with a rate of approximately 16kbps for transmitting periodic heartbeat signals and ephemeris update signaling, while reducing the transmit power to 1% of the full-rate communication mode to save terminal power consumption. If the low-orbit communication link detects an unpredictable sudden anomaly during operation, the state machine directly jumps to the anomaly recovery state, preventing the terminal from being offline for an extended period by urgently waking up the high-orbit link. For example, sudden anomalies include, but are not limited to: the low-orbit link physical layer continuously reporting frame synchronization loss within a preset detection window, or the received signal quality continuously dropping below the minimum communication threshold and this attenuation mode not matching the normal coverage exit mode based on ephemeris prediction. Upon detecting a sudden anomaly, the state machine immediately interrupts the low-Earth orbit (LEO) communication link, sends an emergency wake-up command to the high-Earth orbit (HEO) radio frequency front-end, requests the gateway to allocate uplink frequency and time domain resources, and restores the HEO communication link to full-rate communication mode to support services after power ramp-up is complete. It should be noted that during LEO acquisition, if LEO signal locking is not achieved within the preset signal acquisition timeout period, the state machine reverts to the HEO communication state and waits for the next visible time window of a LEO satellite. The preset quality switching condition can specifically be that the composite link quality of the LEO communication link is lower than the composite link quality of the HEO communication link at the same time, or lower than a preset absolute quality lower limit threshold. The specific judgment method and threshold value can be selected according to the reliability requirements of the actual service scenario.

[0041] In a further embodiment, the method for determining the pre-triggering time is as follows:

[0042] Obtain the start time when the target low-orbit satellite enters the visible range, predicted based on the low-orbit satellite ephemeris information; subtract the preset antenna repointing time and the preset expected low-orbit signal acquisition time from the start time to obtain the preparatory trigger time.

[0043] In this embodiment, the terminal can initiate beam switching preparation in advance using the orbital patterns determined by ephemeris data. The formula for calculating the pre-trigger time is as follows:

[0044] t prep =t start_LEO -Δ t_antenna -Δ t_acq ;

[0045] Among them, t prep To prepare for the triggering time, tstart_LEO Δ represents the predicted start time when a target low-Earth orbit satellite enters the visible range, based on low-Earth orbit satellite ephemeris information. t_antenna Δ is the preset antenna repointing time. t_acq The preset expected duration for capturing low-orbit signals.

[0046] In practice, the preset antenna repointing time depends on the type of antenna configured in the terminal. For example, when the terminal uses a phased array antenna, the antenna control module calculates the phase distribution matrix based on the azimuth angle predicted by the ephemeris and preloads the calculation result into the phase shifter register to perform electronic beam deflection. The antenna repointing time only covers the time for phase matrix calculation and beam calibration, and is usually set to about 3 seconds.

[0047] Furthermore, during the pre-pointing process of the phased array antenna, the main beam maintains the high-orbit communication link without interruption, ensuring uninterrupted service connectivity. As an alternative implementation, if the terminal is equipped with a mechanically servo parabolic antenna, the antenna repointing time corresponds to the physical rotation time of the servo motor from high-orbit pointing to the target low-orbit azimuth position, typically set between 14 and 20 seconds. In some implementations, during the mechanical rotation, the terminal pre-buffers the service data to be transmitted until the low-orbit link is established.

[0048] In a further embodiment, the preset transition duration is determined as follows:

[0049] Obtain the time required for the high-orbit communication link to recover from signaling hold-up mode to full-rate communication mode;

[0050] The preset transition time is obtained by adding the time required to restore to full-rate communication mode to the preset safety margin duration.

[0051] In this embodiment, determining the transition duration ensures that the high-orbit link has sufficient time to reconstruct the high-speed communication channel before the low-orbit satellite completely moves out of sight, guaranteeing a sufficient window for simultaneous dual-link transmission. For example, the formula for calculating the preset transition duration is as follows:

[0052] T transition =T prep_G +T margin ;

[0053] Among them, T transition T is the preset transition duration. prep_G T represents the time required for a high-orbit communication link to recover from signaling hold mode to full-rate communication mode. margin This is the preset safety margin duration.

[0054] Specifically, the recovery time of the high-orbit communication link from signaling hold mode to full-rate communication mode comprises four physical phases: the transmission time for the terminal to send the recovery request signaling, the interaction time for the gateway to issue frequency domain and time domain resource allocation responses, the terminal's closed-loop power ramp-up time, and the service layer bearer verification time. The typical recovery time obtained by superimposing these four phases is 5 seconds. The preset safety margin time is used to absorb gateway scheduling delays and ephemeris extrapolation errors, and can be set to 15 seconds. Under this parameter configuration, the preset transition time is 20 seconds, that is, 20 seconds before the expected end of low-orbit satellite coverage, the terminal begins to wake up the high-orbit full-rate service channel.

[0055] like Figure 2 As shown, in a further implementation, multi-connection state management also includes a sub-low orbit capture state;

[0056] When in low-Earth orbit communication mode, if the coverage window of the next target low-Earth orbit satellite is predicted to overlap with that of the current low-Earth orbit satellite based on the low-Earth orbit satellite ephemeris information, then the system enters the sub-low-Earth orbit acquisition mode.

[0057] In the sub-low orbit acquisition state, while maintaining the current low orbit communication link, it attempts to acquire the signal of the next target low orbit satellite, and after successful acquisition, it switches the service to the next target low orbit satellite.

[0058] In other words, during the sub-low Earth orbit acquisition state, while maintaining the current low Earth orbit communication link, it attempts to acquire the signal of the next target low Earth orbit satellite, and switches the service to the next target low Earth orbit satellite after successful acquisition; if the acquisition fails, it exits the sub-low Earth orbit acquisition state and enters the transition state.

[0059] Specifically, a relay mechanism is provided between low-Earth orbit (LEO) satellite constellations, either within or across orbits, to prevent terminals from frequently backing up to high-Earth orbit (HEO) satellites in areas with dense overlap in LEO satellite coverage. When the terminal is operating in LEO communication mode and the service is carried by the first LEO satellite, the control logic periodically compares the visibility time window of the current LEO satellite with that of the second LEO satellite about to rise in the sky. If the calculation determines that the overlap coverage duration of the two satellites is greater than or equal to the time required to acquire a new signal, the state machine switches to the next LEO acquisition mode.

[0060] In the sub-LEO acquisition state, the terminal uses a phased array antenna with multi-beam capability or an idle independent radio frequency channel to send acquisition and synchronization signaling to the second LEO satellite while maintaining uninterrupted service data flow from the first LEO satellite. Further, after successful acquisition and establishment of the second LEO communication link, the terminal control system updates the underlying routing table, seamlessly migrating data packets generated by upper-layer applications to the second LEO communication link, and disconnecting the first LEO communication link to release resources. If an acquisition timeout occurs in the sub-LEO acquisition state, the system determines that the inter-satellite relay has failed and enters a transition state, initiating a full-rate recovery process for the high-orbit communication link, using the high-orbit link as a bridging medium to prevent service interruption.

[0061] In one exemplary embodiment, obtaining low-Earth orbit satellite ephemeris information is specifically achieved through a combination of one or more of the following mechanisms:

[0062] Ephemeris data is extracted using the forward broadcast channel of high-orbit satellites;

[0063] Extract local cached historical ephemeris data and perform short-term extrapolation using a pre-configured orbit prediction model;

[0064] The latest ephemeris data is obtained through a ground network interface.

[0065] In other words, obtaining ephemeris information from low-Earth orbit satellites is achieved through a combination of one or more of the following mechanisms: extracting ephemeris information through the forward broadcast channel of high-Earth orbit satellites; extracting locally cached historical ephemeris information and using a pre-configured orbit prediction model for short-term extrapolation to obtain predicted ephemeris information; and obtaining the latest injected ephemeris information through a ground network interface.

[0066] Specifically, in a single high-orbit communication link scenario, if the high-orbit link becomes unavailable due to physical obstruction or fading, the entire low-orbit access link will break. To ensure the reliability of terminal access in various environments, this embodiment adopts a three-level ephemeris acquisition mechanism with decreasing priority. The main path is set to distribute and extract ephemeris data in real time through the forward broadcast channel of the high-orbit satellite. In the main path, ephemeris information is embedded in the forward broadcast channel data stream based on system standards in the form of a dedicated signaling table. The baseband processing module in the terminal extracts ephemeris data by parsing the specific group identifier configured in the forward stream. This provides basic data freshness.

[0067] Furthermore, when the primary path becomes unavailable, the system triggers a first-level backup path. The terminal retrieves the last valid and saved locally cached historical ephemeris data from its internal memory. Based on the Kepler orbital parameters contained in the historical ephemeris data, the orbit control module calls the built-in orbit prediction model to perform short-term extrapolation calculations. Preferably, the orbit prediction model adopts a standard orbit extrapolation algorithm model. The predicted ephemeris output by the extrapolation calculation is used to replace the real-time ephemeris data within a set validity period. The preset validity period can be configured to 48 hours. The local extrapolation mechanism maintains the ability to assess the visible time window of low-Earth orbit satellites.

[0068] In some optional implementations, the terminal is configured with a second-level backup path, which obtains the latest ephemeris data via a terrestrial network interface. When the terminal is in an area with internet connectivity, and both the high-orbit primary path and the first-level backup path are invalid or expired, the system connects to the cloud server via the terrestrial network interface to directly obtain the latest updated two-line orbital element format ephemeris file.

[0069] In summary, the three mechanisms described above constitute a mutually independent yet logically progressive safeguard system. The terminal adaptively switches between the primary path, the first-level backup path, and the second-level backup path based on the current network interface connectivity and the timestamp attribute of the local ephemeris file. This avoids single points of failure in connection management for the converged terminal and maintains the continuity of the underlying data source required for predictive state transitions.

[0070] This embodiment illustrates the multi-source acquisition and execution mechanism when a high-low orbit fusion satellite communication terminal obtains ephemeris information from low-orbit satellites, solving the problem of ephemeris interruption across the entire terminal system due to a single link failure.

[0071] According to one aspect of this application, the quality of a composite link at future moments is dynamically evaluated by weighted summation of the following normalized dimensions:

[0072] Normalized dimension of predicted carrier-to-noise ratio determined by predicted elevation angle and satellite-to-ground slant distance based on extrapolation of low-orbit satellite ephemeris information.

[0073] The available bandwidth normalization dimension is determined based on the available bandwidth of the target low-orbit satellite and the preset maximum system bandwidth;

[0074] Normalized dimension of predicted remaining coverage time determined based on the visible time window;

[0075] The normalized dimension of propagation delay is determined based on the round-trip propagation delay of the target satellite.

[0076] In this embodiment, the terminal performs calculations on four physical dimensions to quantify the expected link service. For example, the formula for calculating composite link quality is as follows:

[0077] Q i (t)=w1*(C i (t)-C th ) / (C max -C th )+w2*R i / R max +w3*T rem_i (t) / T ref +w4*(1-D i / D max );

[0078] Among them, Q i (t) represents the composite link quality of target satellite link i at time t, w1 represents the weight of the predicted carrier-to-noise ratio normalized dimension, and C i (t) represents the carrier-to-noise ratio based on ephemeris prediction, C th The minimum communicable carrier-to-noise ratio threshold set for the system, C max R represents the maximum achievable carrier-to-noise ratio of the system, w2 represents the weight of the normalized dimension of available bandwidth, and R... i R is the available bandwidth allocated to the terminal by the target satellite. max The maximum bandwidth of the system is given by w3, where w3 is the weight of the normalized dimension for the predicted remaining coverage time, and T is the maximum bandwidth of the system. rem_i (t) represents the predicted remaining coverage time, T ref For the normalized reference time, w4 represents the weight of the normalized dimension of propagation delay, and D... i For the link round-trip delay, D max C represents the maximum reference round-trip time. th and C max The link budget of the satellite communication system to which the terminal is connected is determined, and is an inherent parameter of the system that can be directly obtained according to the system design specifications.

[0079] Furthermore, the predicted carrier-to-noise ratio C i The calculation of (t) is based on the ratio of carrier power to noise power spectral density. When obtaining the predicted carrier-to-noise ratio (CNR), free-space propagation loss and atmospheric attenuation loss are calculated using a standard RF propagation model, combined with the satellite's equivalent isotropic radiated power and the terminal receiving antenna gain, and the system noise power spectral density is subtracted. The predicted CNR obtained here excludes the system bandwidth parameter because the system bandwidth characteristics have already been independently evaluated in the available bandwidth normalization dimension. Introducing a bandwidth term into the predicted CNR would cause the broadband advantage of low-Earth orbit satellites to cancel out in the first and second normalization dimensions, leading to distortion of the system evaluation results.

[0080] In one exemplary implementation, the calculation process for the normalized dimension of the predicted remaining coverage time, determined based on the visible time window, includes:

[0081] Based on low-Earth orbit satellite ephemeris information, the predicted elevation trajectory of the target low-Earth orbit satellite is deduced.

[0082] In the predicted elevation trajectory, find the boundary moment when the elevation angle drops to the preset minimum communication angle;

[0083] The time difference between the boundary time and the current time is calculated as the predicted remaining available time, and the predicted remaining available time is compared with the preset normalized reference time to obtain the normalized dimension of the predicted remaining coverage time.

[0084] Specifically, based on the deterministic laws of orbital mechanics, the terminal's internal processing module extrapolates the predicted elevation trajectory over a future period according to a set step size. After acquiring the trajectory sequence, it sequentially searches for nodes whose values ​​drop to the preset minimum pass angle, marking the timestamps corresponding to these nodes as boundary times. Subtracting the current time from the boundary time yields the predicted remaining available time. For low-Earth orbit (LEO) satellites, the calculated predicted remaining available time is divided by a preset normalized reference time to output a dimensionless ratio. The preset normalized reference time is the average visible time of a single LEO satellite transit, typically 600 seconds. In contrast, for high-Earth orbit (GEO) geostationary satellites, their relative position is constant, so their predicted remaining available time is directly assigned to the preset normalized reference time, resulting in a normalization dimension constant of 1.0.

[0085] Furthermore, before performing a weighted summation on the aforementioned normalized dimensions, the following is also included:

[0086] A preset clamping operation is performed on each normalized dimension to restrict the value of each normalized dimension to a closed interval between the minimum value of zero and the maximum value of one, thereby ensuring that the quality of the output composite link has bounded numerical stability.

[0087] In this embodiment, to prevent extreme physical conditions from causing the input variables to exceed the normal range, the terminal performs mathematical boundary truncation on the raw ratios of the four normalized dimensions obtained through calculation. The specific operational logic of the preset clamping operation is as follows:

[0088] y = min(max(x, 0), 1);

[0089] Where x is the original input value of a normalized dimension before the clamping operation is performed, and y is the dimensionless value output after the clamping operation.

[0090] Through clamping operations, the output value is limited to a maximum of 1 regardless of the size of the original variable, and truncated to a minimum of 0 regardless of the size or negative value of the original variable. Combined with the constraint that the sum of all weights equals 1, this ensures that the quality distribution of the final output composite link is within the numerical range of 0 to 1, facilitating threshold comparison by the state machine on a uniform scale.

[0091] In a further embodiment, when performing a weighted summation on the above-mentioned normalized dimensions, the weights of each normalized dimension are dynamically allocated according to the current service type being carried.

[0092] Among them, when the current service type is a real-time service, weights are allocated to the propagation latency normalization dimension to enhance the latency attribute;

[0093] When the current service type being carried is a high-bandwidth service, weights are allocated to the available bandwidth normalization dimension to enhance bandwidth attributes;

[0094] When the current service type is a high-reliability service, weights are assigned to the normalized dimension of the predicted remaining coverage time to strengthen the coverage time attribute.

[0095] Specifically, the terminal identifies the type of service it is currently carrying based on the service quality marker of the service layer, and calls the corresponding weight vector combination.

[0096] Furthermore, to verify the effectiveness of the business-aware weights, the following simplified normalized example is provided:

[0097] Assuming that after normalization and clamping, the evaluation parameters for the high-orbit satellite are: predicted carrier-to-noise ratio (CNR) normalized to 1.0, available bandwidth normalized to 0.04, predicted remaining coverage time normalized to 1.0, and propagation delay normalized to 0. Simultaneously, the evaluation parameters for the low-orbit satellite are: predicted CNR normalized to 1.0, available bandwidth normalized to 1.0, predicted remaining coverage time normalized to 1.0, and propagation delay normalized to 0.933.

[0098] In the first scenario, when the terminal detects that the currently carried service type is real-time voice service, the highest weight is assigned to the normalized propagation delay dimension. In this case, the weights w1 are 0.2, w2 is 0.1, w3 is 0.2, and w4 is 0.5. Substituting these values ​​into the composite link quality formula, the composite link quality of the high-orbit satellite is calculated to be 0.404, and the composite link quality of the low-orbit satellite is 0.967. The difference between the low-orbit satellite score and the high-orbit satellite score is 0.563. This difference is greater than the preset handover hysteresis of 0.05. The terminal determines that the target link quality is significantly better than the current link, triggering a handover to the low-orbit communication link.

[0099] In the second scenario, when the terminal detects that the currently carried service type is a high-reliability command service, the highest weight is assigned to the normalized dimension of the predicted remaining coverage time. In this case, the weights w1 are 0.3, w2 is 0.1, w3 is 0.5, and w4 is 0.1. Assuming the low-Earth orbit (LEO) satellite is about to leave the coverage area, its predicted remaining coverage time normalized value decays to 0.2. Substituting these values ​​into the composite link quality formula, the composite link quality for the high-Earth orbit (HEO) satellite is calculated to be 0.804, and the composite link quality for the LEO satellite is 0.593. At this point, the difference between the LEO satellite score and the HEO satellite score is -0.211, which is less than the preset handover hysteresis of 0.05, so the system determines to maintain the HEO link.

[0100] By using weight allocation logic, links that have high latency advantages but are about to fall out of service area are excluded, thus avoiding frequent network outages and reconnections for highly reliable services.

[0101] In one embodiment of this application, when performing forward-looking multi-connection state management, the terminal is allowed to switch from a high-orbit satellite to a target low-orbit satellite to carry services if and only if a preset anti-ping-pong protection condition is met;

[0102] The anti-ping-pong protection conditions include: the sum of the following three durations: the visible time window is longer than the preset low-orbit signal acquisition and link establishment time, the preset minimum effective service duration, and the preset high-orbit link recovery preparation time.

[0103] In specific implementations, traditional cellular networks typically employ a fixed trigger timer combined with hysteresis for statistical filtering to prevent the ping-pong effect. Since the coverage window of low-Earth orbit satellites possesses orbital dynamic determinism, this embodiment preferably uses a prediction inequality based on absolute time to construct the anti-ping-pong protection conditions. The specific inequality determination logic is as follows:

[0104] T rem_LEO ≥T acq_LEO +T min_svc +T prep_G ;

[0105] Among them, T rem_LEO For the visible time window, T acq_LEO T is the preset low-orbit signal acquisition and link establishment time. min_svc T is the preset minimum effective service duration. prep_G Pre-set preparation time for high-orbit link restoration.

[0106] The system calculates whether the remaining visibility time of the target low-Earth orbit (LEO) satellite is sufficient to cover the complete cycle of the three stages: signal search and synchronization establishment, execution of a minimum service transmission with actual benefits, and safe fallback to the high-Earth orbit (HEO) link. If the determination result satisfies the above inequality, the system issues a switching command and controls the state machine to enter the subsequent LEO transit process; if the determination result does not satisfy the above inequality, the system determines that the current transit of the target LEO satellite is a short-window transit, the terminal skips the target LEO satellite and maintains the current HEO communication link, waiting and calculating the time window parameters for the next LEO satellite.

[0107] In a further embodiment, in the scenario where the target low-orbit satellite is the next satellite in the same orbit to replace the current low-orbit satellite, the anti-ping-pong protection conditions also include overlapping window protection conditions for inter-satellite handover.

[0108] The overlap window protection condition is: the predicted overlap coverage window between the current low-Earth orbit satellite and the target low-Earth orbit satellite, based on the low-Earth orbit satellite ephemeris information, is greater than or equal to the low-Earth orbit signal acquisition and link establishment time.

[0109] In this embodiment, for scenarios involving continuous coverage by two satellites within the same orbital plane of a low-Earth orbit constellation, the terminal does not need to revert to a high-Earth orbit satellite for bridging; instead, it directly performs inter-satellite communication link switching. In this scenario, the logic for determining the inter-satellite overlap window protection inequality is as follows:

[0110] T overlap ≥T acq_LEO ;

[0111] Among them, T overlap T represents the predicted overlap coverage window between the current low-Earth orbit satellite and the target low-Earth orbit satellite. acq_LEO Link establishment time for low-orbit signal acquisition.

[0112] Furthermore, the calculation method for the predicted overlapping coverage window is as follows: Obtain the coverage end time of the current low-Earth orbit (LEO) satellite and the coverage end time of the target LEO satellite, and extract the minimum value between them; obtain the visibility start time of the current LEO satellite and the visibility start time of the target LEO satellite, and extract the maximum value between them; calculate the difference between the minimum and maximum values ​​to obtain the predicted overlapping coverage window. The system compares this difference with the preset LEO signal acquisition and link establishment time to determine whether the duration for which the two LEO satellites jointly cover the terminal in space supports the terminal in completing antenna beam switching and signal acquisition operations. If the difference is less than the LEO signal acquisition and link establishment time, it indicates that there is a spatial gap or insufficient overlap in the inter-satellite coverage, and the terminal executes a fallback mechanism to migrate the service to the high-Earth orbit (HEO) communication link.

[0113] In a preferred implementation, the minimum effective service duration is not a fixed constant, but is adaptively configured according to the type of service currently being carried by the terminal;

[0114] Configure a minimum effective service duration of the first duration for latency-sensitive services, and configure a minimum effective service duration of the second duration for high-throughput non-real-time services; wherein the first duration is shorter than the second duration.

[0115] Specifically, in a multi-service concurrent communication environment, different service types have varying expectations regarding the benefits of low latency and their tolerance for connection establishment overhead. Service-aware logic can be introduced to dynamically modulate the threshold parameters in the decision inequality.

[0116] As a specific configuration example, when the terminal is currently carrying a latency-sensitive service such as real-time voice or video calls, the service data packets are highly sensitive to round-trip propagation latency, and obtaining low-latency services from low-Earth orbit satellites has high priority benefits. In this scenario, the system configures the preset minimum effective service duration to a relatively short threshold of 30 seconds.

[0117] As an alternative implementation, when the terminal is currently carrying high-throughput, non-real-time services such as file downloads, the slow start phase after the Transmission Control Protocol (TCP) establishes a connection and the linear growth phase of the congestion window require a relatively long setup time. If the system frequently switches between extremely short low-Earth orbit (LEO) satellite coverage windows, the overall link throughput will decrease due to repeated resets of the TCP window. In this case, the system dynamically increases the preset minimum effective service duration to a longer threshold of 120 seconds, filtering out fragmented coverage windows at the visible time edge by setting a higher time threshold. This allows the terminal to adaptively adjust the handover defense strength according to the data flow characteristics of different services.

[0118] This embodiment illustrates the anti-ping-pong protection mechanism of the high-low orbit fusion satellite communication terminal when making link switching decisions, which solves the problems of invalid switching and wasted coverage window caused by the traditional timer-based anti-ping-pong mechanism in deterministic satellite orbit scenarios.

[0119] According to one aspect of this application, during the transition period, the terminal simultaneously maintains active communication links with both the high-orbit satellite and the target low-orbit satellite, and performs multipath service data simultaneous transmission.

[0120] The multi-path service data simultaneous transmission is as follows: the sending end assigns a unified sequence number to the service data packets to be transmitted, and sends the same service data packets carrying the unified sequence number to the receiving end simultaneously through the high-orbit communication link and the low-orbit communication link, and the receiving end performs merging processing based on the unified sequence number.

[0121] In this embodiment, the high-orbit and low-orbit communication links exhibit asymmetry in round-trip propagation delay. Specifically, the typical one-way propagation delay of the high-orbit communication link is 300 milliseconds, while that of the low-orbit communication link is 20 milliseconds, a difference of 280 milliseconds. When the multi-connection state management unit enters the transition state, the data packet aggregation layer protocol entity inside the terminal intercepts each service data packet entering the lower-layer physical channel and writes a continuously increasing unified sequence number to its packet header. The replication module clones the service data packet with the unified sequence number into two copies, which are then routed to the high-orbit and low-orbit radio frequency front-ends for concurrent transmission. Through multi-path data redundancy distribution, the system effectively reduces the probability of link interruption during handover. According to the independent failure probability model, assuming the packet loss rate of single-path transmission is p, the probability of simultaneous packet loss on both paths after multi-path service data transmission decreases to p. 2 It provides a highly reliable service transmission channel during the switching phase when the physical layer is unstable.

[0122] In one possible implementation, multi-path business data simultaneous transmission specifically adopts a full dual-transmission mode:

[0123] All service data packets to be transmitted are assigned a unified sequence number and sent simultaneously through both high-orbit and low-orbit communication links to achieve redundant transmission of all service data.

[0124] Specifically, if the terminal's network has ample bandwidth resources, or if the current service it carries includes highly reliable emergency communication data, the system defaults to full dual-transmission mode. The sending end does not distinguish between service flow identifiers in the service data packets; it clones and maps all service data packets sent from the application layer to a unified sequence number, and pushes them into the high-low track dual-link transmission queue. This consumes twice the spectrum and power resources in exchange for absolute data continuity and an extremely low transmission error rate within the switching window.

[0125] In another possible implementation, multi-path business data simultaneous transmission specifically adopts a selective dual-transmission mode:

[0126] The sending end performs flow classification based on the priority of the service data packets to be transmitted; it assigns a unified sequence number only to high-priority service data packets that meet the preset priority, and sends them simultaneously through both the high-orbit and low-orbit communication links; for low-priority service data packets, it sends them only through the current single main communication link.

[0127] As an alternative to the full dual-transmission mode described above, in scenarios where the terminal encounters uplink bandwidth limitations or needs to control RF transmission power consumption, the system invokes a selective dual-transmission mode based on Quality of Service (QoS) tags. Specifically, the sending end parses the header identifier of the service data packet to be transmitted and extracts its Distinguishing Service Code Point (DSC) or priority marker. When it is determined that the current service data packet contains high-priority service data packets such as real-time voice frames or control signaling, a unified sequence number allocation and dual-link transmission operation are performed. When it is determined that the current service data packet contains low-priority service data packets such as background file downloads or system periodic updates, the control system skips the copying operation and only routes the low-priority service data packet to the current low-orbit communication link for single-path transmission. While ensuring zero interruption of core sensitive services, this reduces the instantaneous encroachment on the high-orbit communication link bandwidth during the transition period.

[0128] like Figure 3 As shown, according to one aspect of this application, the receiving end performs merging processing based on a unified sequence number, specifically including:

[0129] The receiving end is configured with a ring-shaped deduplication buffer to adapt to the delay difference between high and low rail transmission, and extracts the unified sequence number carried by the service data packet after receiving the service data packet;

[0130] The unified sequence number is retrieved in the circular deduplication buffer. If it is the first time the data packet is received, the service data packet is delivered to the upper layer application, and a record is created in the circular deduplication buffer and a deduplication waiting timer is started.

[0131] If a matching unified sequence number already exists in the circular deduplication buffer, the current service data packet is determined to be a delayed duplicate data packet and is discarded.

[0132] Furthermore, when the deduplication waiting timer expires, the records with the corresponding unified sequence number in the circular deduplication buffer are cleared to release buffer resources.

[0133] In this embodiment, to cope with packet out-of-order and delayed arrival times of up to several hundred milliseconds, the receiving end allocates an independent circular deduplication buffer in memory. The formula for calculating the maximum number of packets that the circular deduplication buffer needs to hold is as follows:

[0134] B size =ceil(Δ D_max *R data_max / L pkt );

[0135] Among them, B size The circular deduplication buffer is the maximum number of data packets it needs to hold, ceil is the floor function, and Δ is the maximum number of data packets it needs to hold. D_max R represents the maximum one-way time delay difference between the high-orbit and low-orbit communication links.data_max L is the maximum data rate for the current business. pkt This represents the average data packet length.

[0136] For example, setting Δ D_max For 0.28 seconds, R data_max For 10,000,000 bits per second, L pkt The value is 12,000 bits. Substituting into the above formula, we get 0.28 * 10,000,000 / 12,000 = 233.33. After rounding up, the buffer capacity is determined to be 234 data packet nodes. When parsing data packets, the receiving end follows the principle of "first-come, first-served." When a service data packet from the low-track link arrives first, the system searches the circular deduplication buffer and finds no record of it. It immediately unpacks the packet and delivers it to the upper-layer application, recording the unique sequence number. After a period of time, when a delayed data packet carrying the same unique sequence number from the high-track link arrives, the system hits the historical record and directly erases it from memory. This achieves zero-awareness of the application layer regarding the switching of the underlying physical link, avoiding unnecessary fast retransmission congestion control mechanisms triggered by the transmission control protocol due to the detection of out-of-order packets.

[0137] In a further embodiment, the timeout duration of the deduplication waiting timer is set to be dynamically adjustable; during the transition period, the receiving end continuously calculates the delay difference distribution characteristics of the actual received data packets between the high-orbit communication link and the low-orbit communication link; based on the sliding window mean and standard deviation of the delay difference distribution characteristics, the timeout duration of the deduplication waiting timer is adaptively updated.

[0138] Specifically, during the transit of a low-Earth orbit (LEO) satellite, its elevation angle relative to the terminal exhibits a continuous nonlinear variation, rising from extremely low to extremely high and then falling back. This dynamic change in spatial geometry causes the satellite-to-ground slant range of the LEO communication link to constantly change, resulting in periodic jitter in the data packet delay arriving at the receiver. To prevent fixed timeout parameters from causing delayed data packets to fail to be intercepted in time or leading to prolonged invalidation of memory nodes, the system employs a dynamic adaptive mechanism to update the deduplication waiting timer in real time. The specific adaptive update formula is as follows:

[0139] T wait =Δ D_mean +3*σ Δ_D ;

[0140] Among them, T wait Δ is the timeout duration for the deduplication waiting timer. D_mean σ is the mean of the sliding window representing the time delay difference distribution characteristics. Δ_D The standard deviation represents the distribution characteristics of the time delay difference.

[0141] The system collects the latest delay difference sample points according to a preset time step and pushes them into the observation queue, calculating the current mean and standard deviation. By introducing three times the standard deviation as a tolerance margin, a delay fluctuation coverage area with an envelope exceeding 99% probability is constructed. This allows the deduplication waiting timer to accurately match the Doppler and propagation distance changes caused by the relative motion of the satellite, improving the execution efficiency of underlying memory reclamation and deduplication comparison.

[0142] This embodiment illustrates the data plane processing mechanism for dual-link simultaneous transmission during the transition state of the terminal, which solves the problems of service data packet loss caused by physical switching of links in high-orbit and low-orbit fusion scenarios, as well as out-of-order data at the receiving end caused by extreme propagation delay differences.

[0143] like Figure 4 and Figure 5 As shown in another embodiment of this application, the multi-connection management method applicable to high-Earth orbit (HEO) and low-Earth orbit (LEO) integrated satellite communication terminals can also be as follows: Before satellite terminal communication, it generally goes through a satellite pairing state and a communication state. Satellite link management is required in both states. HEO satellites generally use beacons or carrier waves for pairing, while LEO satellites generally use ephemeris pairing. The pairing module design needs to consider supporting both methods simultaneously. After pairing is completed and the communication state is established, the link status needs to be monitored, and there should be corresponding handling mechanisms for abnormal situations such as link disconnection. In the integrated terminal power-on process, after power-on, pairing is performed with HEO satellites via beacons or carrier waves, fully utilizing the wide coverage advantage of HEO satellites. After successful HEO satellite pairing, the system will broadcast LEO ephemeris information via forward DVB. When the terminal receives the complete ephemeris information, it will initiate the LEO ephemeris pairing process. That is, when the integrated terminal is within the coverage area of ​​LEO satellites, the LEO satellite link is used preferentially for service processing, fully utilizing the high bandwidth and low latency characteristics of LEO satellites to improve service QoS assurance. During communication, if low-Earth orbit (LEO) coverage is about to end or the LEO link is abnormal, based on ephemeris information, the high-Earth orbit (HEO) satellite pairing process will be initiated to fully utilize the link backup function of HEO satellites. Subsequently, the next LEO satellite coverage time will be calculated using ephemeris information, and the time for the next LEO satellite pairing will be set in conjunction with anti-ping-pong handover latency.

[0144] This invention introduces a multi-state connection management mechanism based on ephemeris prediction. It pre-points the antenna before the target satellite becomes visible and proactively constructs a dual-link simultaneous transmission channel before the current coverage ends. This overcomes the shortcomings of traditional passive-response handover, which suffers from communication blind spots during link handover. It eliminates the long-term offline waiting time during cross-orbit link handover, achieving a smooth data transition seamlessly at the application layer. A composite link evaluation function integrating predicted remaining coverage time and service awareness weights is constructed, coupled with adaptive anti-ping-pong protection constraints based on absolute time windows. This effectively filters fragmented invalid coverage windows, transforming network resource allocation logic from passive signal fading response to proactive and precise scheduling, reducing the trigger frequency of invalid handovers and the ping-pong reconnection rate. At the receiving end, a ring-shaped deduplication and merging mechanism based on a unified sequence number and adaptive dynamic timer is designed. Simultaneously, a multi-source, mutually redundant three-level ephemeris acquisition path is deployed at the access end. This not only efficiently deduplicates and reassembles parallel redundant data packets under extreme asymmetric propagation delays but also ensures the continuous availability of core prediction data sources in complex obstruction environments, improving the overall robustness of heterogeneous space network fusion transmission.

[0145] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A multi-connection management method applicable to high-Earth orbit and low-Earth orbit integrated satellite communication terminals, characterized in that, include: Establish communication connections with high-orbit satellites and obtain ephemeris information from low-orbit satellites; Based on low-Earth orbit satellite ephemeris information, the visible time window of the target low-Earth orbit satellite is predicted, and the composite link quality at future moments is dynamically evaluated. Based on the visibility time window and composite link quality, a forward-looking multi-connection state management is performed; wherein, the multi-connection state management includes a preparatory state that triggers antenna pre-pointing before the target low-Earth orbit satellite becomes visible, and a transition state that triggers simultaneous transmission of high- and low-Earth orbit dual links before the low-Earth orbit satellite coverage ends. When performing forward-looking multi-connection state management, the terminal is allowed to switch from high-orbit satellite to target low-orbit satellite to carry services if and only if the preset anti-ping-pong protection conditions are met. The anti-ping-pong protection conditions include: the visible time window being longer than the sum of the preset low-orbit signal acquisition and link establishment time, the preset minimum effective service duration, and the preset high-orbit link recovery preparation time; During the transition period, the terminal maintains active communication links with both the high-orbit satellite and the target low-orbit satellite, and performs multi-path service data simultaneous transmission. The multi-path service data simultaneous transmission is as follows: the sending end assigns a unified sequence number to the service data packets to be transmitted, and sends the same service data packets carrying the unified sequence number to the receiving end simultaneously through the high-orbit communication link and the low-orbit communication link, and the receiving end performs merging processing based on the unified sequence number; The receiving end performs merging processing based on a unified sequence number, specifically including: The receiving end is configured with a ring-shaped deduplication buffer to adapt to the delay difference between high and low rail transmission, and extracts the unified sequence number carried by the received service data packet. The unified sequence number is retrieved in the circular deduplication buffer. If it is the first time the data packet is received, the service data packet is delivered to the upper layer application, and a record is created in the circular deduplication buffer and a deduplication waiting timer is started. If a matching unified sequence number already exists in the circular deduplication buffer, the current service data packet is determined to be a delayed duplicate data packet and is discarded.

2. The method according to claim 1, characterized in that, Multi-connection state management specifically includes the following transition states: High-orbit acquisition status: After the terminal is powered on, it searches for and locks onto high-orbit satellite signals; High-orbit communication status: Establish a high-orbit communication link to carry services and receive ephemeris information from low-orbit satellites; Ready state: When the system clock reaches the ready trigger time determined based on the ephemeris information of the low-orbit satellite, maintain the high-orbit communication link active and control the antenna beam to be pre-pointed to the predicted azimuth of the target low-orbit satellite. Low Earth Orbit Acquisition Status: After the target low Earth orbit satellite enters the visible range, low Earth orbit signal acquisition is initiated; Low-Earth Orbit (LEO) communication status: After the LEO signal is locked, the LEO communication link is established to carry the main services, and the HEO communication link is downgraded to signaling hold-up mode. Transition state: Triggered when the composite link quality meets the preset quality switching conditions, or when the visible time window is less than the preset transition duration, the high-orbit communication link is restored to full-rate communication mode, and high- and low-orbit dual-link simultaneous transmission is performed. Abnormal recovery status: Triggered when a sudden abnormality occurs in the low-orbit communication link, the high-orbit emergency recovery process is initiated.

3. The method according to claim 2, characterized in that, Multi-connection state management also includes the sub-low orbit capture state; When in low-Earth orbit communication mode, if the coverage window of the next target low-Earth orbit satellite is predicted to overlap with that of the current low-Earth orbit satellite based on the low-Earth orbit satellite ephemeris information, then the system enters the sub-low-Earth orbit acquisition mode. In the sub-low orbit acquisition state, while maintaining the current low orbit communication link, it attempts to acquire the signal of the next target low orbit satellite, and after successful acquisition, it switches the service to the next target low orbit satellite.

4. The method according to claim 1, characterized in that, The quality of the composite link at future moments is dynamically evaluated by weighted summation of the following normalized dimensions: Normalized dimension of predicted carrier-to-noise ratio determined by predicted elevation angle and satellite-to-ground slant distance based on extrapolation of low-orbit satellite ephemeris information. The available bandwidth normalization dimension is determined based on the available bandwidth of the target low-orbit satellite and the preset maximum system bandwidth; Normalized dimension of predicted remaining coverage time determined based on the visible time window; The normalized dimension of propagation delay is determined based on the round-trip propagation delay of the target low-Earth orbit satellite.

5. The method according to claim 1, characterized in that, In the scenario where the target low-Earth orbit satellite is the next satellite in the same orbit to replace the current low-Earth orbit satellite, the anti-ping-pong protection conditions also include the overlapping window protection conditions for inter-satellite handover. The overlap window protection condition is: the predicted overlap coverage window between the current low-Earth orbit satellite and the target low-Earth orbit satellite, based on the low-Earth orbit satellite ephemeris information, is greater than or equal to the low-Earth orbit signal acquisition and link establishment time.

6. The method according to claim 1, characterized in that, The minimum effective service duration is adaptively configured based on the type of service currently being carried by the terminal; Configure a minimum effective service duration of the first duration for latency-sensitive services, and configure a minimum effective service duration of the second duration for high-throughput non-real-time services. The first duration is shorter than the second duration.

7. The method according to claim 1, characterized in that, Multi-path business data simultaneous transmission specifically adopts a full dual-transmission mode: All service data packets to be transmitted are assigned a unified sequence number and sent simultaneously through both high-orbit and low-orbit communication links to achieve redundant transmission of all service data.

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