Cooperative networking method and system for high and low orbit satellites

Abstract

The invention relates to the technical field of satellite communication, and discloses a high-orbit and low-orbit satellite collaborative networking method and system, and the method comprises the steps: obtaining the orbit number of high-orbit and low-orbit satellites and the current phase of a low-orbit satellite, and predicting a future phase sequence based on an orbit dynamics model; a link quality prediction curve is generated in combination with a preset phase-link quality mapping relation, so that it is judged that a coverage blind area is about to enter before the link quality is lower than a service threshold value, and a compensation process is triggered; the compensation process comprises the following steps: predicting a departure moment, screening candidate high-orbit satellites and pre-allocating resources to a standby link before the departure moment, and then carrying out availability verification on the standby link; and after the verification is passed, migrating the service to the standby link before the separation moment, and releasing the original link resource. The system corresponds to the method. According to the invention, the active prediction and compensation of the coverage blind area are realized, and the service interruption caused by the high-speed movement of the low-orbit satellite is avoided.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, specifically a method and system for high and low orbit satellite collaborative networking. Background Technology

[0002] In high-Earth orbit (HEO) and low-Earth orbit (LEO) satellite collaborative networking, the inter-satellite links between LEO satellites and HEO satellites are significantly affected by relative motion due to the low orbital altitude and high speed. Link quality dynamically degrades with orbital phase, easily creating coverage blind spots when LEO satellites cross the edge of HEO satellite coverage areas, leading to communication interruptions. Existing networking technologies mostly employ a passive handover mechanism triggered by link quality degradation, lacking the ability to proactively predict coverage blind spots. On the one hand, a quantitative correlation model between orbital phase and link quality degradation has not been established, making it impossible to accurately identify coverage blind spots before link quality drops to the service assurance threshold. On the other hand, resource allocation and link verification are coupled, resulting in a time-consuming handover process. In scenarios with high-speed LEO satellite motion, reliable handover cannot be completed within a limited window period, causing service transmission interruptions, data retransmissions, and wasted onboard resources. Therefore, how to proactively predict and seamlessly compensate for coverage blind spots based on the orbital motion characteristics of LEO satellites, ensuring continuous and uninterrupted service during link handover, has become a core technical problem that urgently needs to be solved in HEO and LEO satellite collaborative networking. Summary of the Invention

[0003] Therefore, it is necessary to provide a method and system for high and low orbit satellite collaborative networking that can ensure uninterrupted service during link switching, addressing the aforementioned technical issues.

[0004] On the one hand, this application provides a method for high- and low-Earth orbit satellite cooperative networking, including the following steps: Obtain the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites; Based on the orbital elements and the current orbital phase, the orbital phase sequence of the low-Earth orbit satellite within a future preset time window is calculated using an orbital dynamics model; Based on the orbital phase sequence and the preset orbital phase-link quality mapping relationship, an inter-satellite link quality prediction curve is generated. The orbital phase-link quality mapping relationship characterizes the link quality attenuation law caused by relative motion of low-Earth orbit satellites under different orbital phases. When the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, it is determined that the low-Earth orbit satellite is about to enter the coverage blind zone of the high-Earth orbit satellite, and the coverage blind zone compensation process is triggered. The coverage blind zone compensation process includes: predicting the departure time of the low-Earth orbit satellite from the current high-Earth orbit satellite coverage area based on the orbital phase sequence; within a first preset time window before the departure time, selecting multiple candidate high-Earth orbit satellites that meet the orbital phase matching conditions from the high-Earth orbit satellite constellation, and pre-allocating bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-Earth orbit satellite and the low-Earth orbit satellite; after the end of the first preset time window and within a second preset time window before the departure time, performing link availability verification on the backup inter-satellite link. Once the link availability verification is successful, services will be migrated to the backup inter-satellite link before the decommissioning time. After the service migration is completed, the resources of the inter-satellite link are released.

[0005] In one embodiment, the process of constructing the orbital phase-link quality mapping relationship includes: The measured bit error rate and signal-to-noise ratio of the inter-satellite link were collected for different orbital phases of low-Earth orbit satellites during their complete orbital period. The orbital period is divided into multiple phase intervals. The measured bit error rate and signal-to-noise ratio in each phase interval are statistically aggregated to generate a table corresponding to the phase interval and link quality parameters. The correspondence table between the phase interval and the link quality parameters is used as the mapping relationship between the track phase and the link quality.

[0006] In one embodiment, the orbital phase matching condition in the coverage blind spot compensation process includes: the absolute value of the orbital phase difference between the candidate high-orbit satellite and the low-orbit satellite at the time of separation is less than a preset phase tolerance threshold, and the nadir point trajectory of the candidate high-orbit satellite covers the predicted position of the low-orbit satellite after the time of separation.

[0007] In one embodiment, the process of pre-allocating bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-orbit satellite and the low-orbit satellite includes: The basic bandwidth requirement is calculated based on the data volume of the service to be migrated and the predicted duration of the backup inter-satellite link. The retransmission redundancy coefficient is calculated based on the predicted bit error rate in the link quality prediction curve of the backup inter-satellite link. The retransmission redundancy coefficient increases as the predicted bit error rate increases. Multiply the basic bandwidth requirement by the retransmission redundancy coefficient to obtain the pre-allocated bandwidth; The predicted duration of the backup inter-satellite link is divided into multiple transmission time slots, and the number of transmission time slots is determined based on the pre-allocated bandwidth and the amount of data of the service to be migrated.

[0008] In one embodiment, the process of performing link availability verification on the backup inter-satellite link includes: Within the second preset time window, the high-orbit satellite sends test data packets to the low-orbit satellite; After receiving the test data packet, the low-orbit satellite calculates the received bit error rate and received signal-to-noise ratio of the test data packet. When the received bit error rate is lower than the preset verification bit error rate threshold and the received signal-to-noise ratio is higher than the preset verification signal-to-noise ratio threshold, the link availability verification is deemed successful.

[0009] In one embodiment, the coverage blind spot compensation process further includes: When the link availability verification fails, the candidate high-orbit satellite that failed the verification is removed from the multiple candidate high-orbit satellites. The remaining candidate high-orbit satellites with the highest orbit phase matching condition satisfaction are re-selected as the new candidate high-orbit satellites. The pre-allocated bandwidth resources, transmission time slots and link availability verification steps are repeated until the link availability verification passes or the candidate high-orbit satellites are exhausted.

[0010] In one embodiment, the method further includes a pre-network time synchronization step: High-orbit satellite broadcasting includes a time synchronization signal with a transmission timestamp; After receiving the signal, the low-Earth orbit satellite returns a response signal containing the reception timestamp. The high-orbit satellite calculates the clock deviation value based on the transmission timestamp, the reception timestamp in the response signal, its own secondary reception timestamp, and the inter-satellite distance calculated based on the orbital elements; Low-Earth orbit satellites correct their local clocks based on the aforementioned clock deviation value; In the calculation of the inter-satellite distance, only the orbital elements of low-Earth orbit satellites are subject to J2 perturbation correction, while the orbital elements of high-Earth orbit satellites are calculated based on the two-body problem model.

[0011] In one embodiment, the pre-network time synchronization step is performed before each triggering of the coverage blind spot compensation process, and the calculation result of the clock deviation value is used to correct the prediction accuracy of the orbit phase sequence.

[0012] In one embodiment, during the service migration process, the low-Earth orbit satellite caches the service data to be migrated to its onboard storage. After the backup inter-satellite link is established, the low-Earth orbit satellite reads cached data from the onboard memory and transmits it to the high-Earth orbit satellite through the backup inter-satellite link. After receiving the data, the high-Earth orbit satellite sends an acknowledgment command to the low-Earth orbit satellite. Upon receiving the acknowledgment command, the low-Earth orbit satellite clears the cached data in the onboard memory.

[0013] On the other hand, this application provides a high-low orbit satellite cooperative networking system, which applies the high-low orbit satellite cooperative networking method described above. The system includes: The data acquisition module is configured to acquire the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites. The orbit prediction module is configured to calculate the orbital phase sequence of the low-Earth orbit satellite within a future preset time window based on the orbital elements and the current orbital phase using an orbital dynamics model. The link quality prediction module is configured to generate a link quality prediction curve for inter-satellite links based on the orbit phase sequence and a preset orbit phase-link quality mapping relationship. The orbit phase-link quality mapping relationship characterizes the link quality attenuation law caused by relative motion of low-Earth orbit satellites under different orbit phases. The coverage blind spot determination module is configured to determine that a low-orbit satellite is about to enter the coverage blind spot of a high-orbit satellite when the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, and to trigger the coverage blind spot compensation process. The coverage blind spot compensation module is configured to, after triggering the coverage blind spot compensation process, predict the departure time of the low-Earth orbit satellite from the current high-Earth orbit satellite coverage area based on the orbital phase sequence; within a first preset time window before the departure time, select multiple candidate high-Earth orbit satellites that meet the orbital phase matching conditions from the high-Earth orbit satellite constellation, and pre-allocate bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-Earth orbit satellites and the low-Earth orbit satellites; after the first preset time window ends and within a second preset time window before the departure time, perform link availability verification on the backup inter-satellite link; when the link availability verification passes, migrate services to the backup inter-satellite link before the departure time; and release the resources of the inter-satellite link after the service migration is completed.

[0014] The aforementioned high-Earth orbit (HEO) and low-Earth orbit (LEO) satellite collaborative networking method and system acquire the current orbital phase of LEO satellites and generate an orbital phase sequence using an orbital dynamics model. It then uses a pre-defined orbital phase-link quality mapping relationship to generate a link quality prediction curve, achieving accurate quantitative prediction of inter-satellite link quality degradation trends. When the predicted link quality is below the service guarantee threshold, a coverage blind spot compensation process is triggered in advance. Within a first pre-defined time window before the departure time, multiple candidate HEO satellites meeting the orbital phase matching conditions are selected and bandwidth resources and transmission time slots are pre-allocated. Within a second pre-defined time window, link availability verification is specifically performed to ensure that service migration to a verified backup inter-satellite link is completed before the departure time, and the original link resources are released promptly after migration. This transforms link management from a post-interruption response to proactive pre-degradation compensation. Through an orbital phase-driven prediction mechanism and a phased resource scheduling verification process, it avoids the risk of service interruption caused by coverage blind spots due to the high-speed movement of LEO satellites, improving the continuity of network communication, handover reliability, and on-board resource utilization efficiency. Simultaneously, it avoids the problem of excessive handover delay caused by the coupling of link verification and resource allocation. Attached Figure Description

[0015] Figure 1 A flowchart illustrating the high- and low-Earth orbit satellite cooperative networking method provided in this application embodiment; Figure 2 This is a structural block diagram of a high- and low-orbit satellite collaborative networking system provided in an embodiment of this application. Detailed Implementation

[0016] To facilitate understanding of the technical solutions provided in the embodiments of this application, the background technology involved in the embodiments of this application will be described below.

[0017] In the high-Earth orbit (HEO) and low-Earth orbit (LEO) satellite collaborative networking architecture, HEO satellites (such as geostationary orbit satellites) provide wide-area coverage and backbone transmission capabilities, while LEO satellites (such as low Earth orbit satellites) achieve low-latency access and dynamic blind spot filling due to their low orbital altitude. However, LEO satellites operate at speeds as high as 7.5 km / s, and their relative geometric relationship with HEO satellites continuously and dynamically changes with orbital phase. When LEO satellites travel along their orbits to the edge of the HEO satellite beam coverage area, the inter-satellite link is affected by antenna pointing angle offset, Doppler frequency shift accumulation, and Earth's obstruction effect. The link quality (signal-to-noise ratio, bit error rate) exhibits significant periodic decay, forming a HEO satellite coverage blind spot.

[0018] Existing networking technologies generally employ a passive response mechanism after link quality deterioration. This involves the system continuously monitoring the real-time signal-to-noise ratio (SNR) of the current inter-satellite links. When the monitored value falls below the service guarantee threshold, a handover process is triggered, followed by candidate high-orbit satellite search, resource negotiation, link establishment, and service migration. This mechanism has fundamental flaws: link quality monitoring has an inherent lag; when handover is triggered, low-orbit satellites have typically entered the critical area of ​​coverage blind spots, leaving an extremely short remaining effective handover window (often less than 2 seconds). Furthermore, candidate satellite selection, bandwidth resource negotiation, and link verification must be performed sequentially. In scenarios involving the high-speed movement of low-orbit satellites, it is difficult to complete the entire process within the window, leading to service interruptions, data retransmissions, and wasted onboard computing resources. More critically, existing technologies cannot utilize the periodicity of low-orbit satellite orbital motion for forward-looking prediction. Handover decisions rely entirely on real-time measurement data, lacking the ability to proactively predict coverage blind spots. Simultaneously, resource allocation and link verification are coupled; if verification fails, candidate satellites must be re-screened, further compressing the handover time window and reducing network reliability.

[0019] Therefore, based on the above problems, this implementation proposes a technical solution that uses the orbital motion characteristics of low-Earth orbit satellites to achieve accurate prediction and forward-looking compensation of coverage blind spots, and completes resource pre-allocation and link verification before link quality deteriorates, so as to ensure that services are continuous and uninterrupted during inter-satellite link switching.

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] Firstly, this embodiment provides a method for high- and low-orbit satellite cooperative networking, such as... Figure 1 As shown, the method includes the following steps in sequence: S1: Obtain the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites; S1: Based on the orbital elements and the current orbital phase, calculate the orbital phase sequence of the low-Earth orbit satellite within a preset time window using an orbital dynamics model; S3: Based on the orbit phase sequence and the preset orbit phase and link quality mapping relationship, generate the link quality prediction curve of the inter-satellite link. The orbit phase and link quality mapping relationship characterizes the link quality attenuation law caused by the relative motion of low-Earth orbit satellites under different orbit phases. S4: When the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, it is determined that the low-Earth orbit satellite is about to enter the coverage blind zone of the high-Earth orbit satellite and the coverage blind zone compensation process is triggered. The coverage blind zone compensation process includes: predicting the departure time of the low-Earth orbit satellite from the current high-Earth orbit satellite coverage area based on the orbit phase sequence; within the first preset time window before the departure time, selecting multiple candidate high-Earth orbit satellites that meet the orbit phase matching conditions from the high-Earth orbit satellite constellation, and pre-allocating bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-Earth orbit satellite and the low-Earth orbit satellite; after the end of the first preset time window and within the second preset time window before the departure time, performing link availability verification on the backup inter-satellite link. S5: Once the link availability verification is successful, migrate the service to the backup inter-satellite link before the decommissioning time; after the service migration is completed, release the resources of the inter-satellite link.

[0022] Specifically, the number of orbital elements includes the semi-major axis. (Unit: meters), Eccentricity (Dimensionless), orbital inclination (Unit: degrees), Right Ascension of Ascending Node (Unit: degrees) Argument of perigee (Unit: degrees) and the angle of approach. (Unit: degrees), obtained from ephemeris data uploaded by satellite navigation systems or ground tracking and control stations.

[0023] Current orbital phase Defined as the angular position of a low-Earth orbit satellite relative to the ascending node in the orbital plane (unit: degrees, range [0°, 360°)), it is obtained by solving the orbital elements using the Kepler equations.

[0024] The orbital dynamics model employs a two-body problem equation combined with J2 term perturbation correction: for the low-Earth orbit satellite position vector Solving differential equations ,in The Earth's gravitational constant is 3.986 × 10¹⁴ m. 3 / s 2 ), For the J2 perturbation acceleration term, numerical integration was performed using the fourth-order Runge-Kutta method with a step size of 1 second to generate an orbital phase sequence for 600 time points within the next 10 minutes. , For the first The orbital phase at each time point; the orbital calculation of high-orbit satellites uses a simplified two-body model (due to the weak influence of high-orbit perturbations, the correction amount of the J2 term is less than 10). −6 ).

[0025] The mapping relationship between orbital phase and link quality is based on a pre-defined data model. The link quality prediction curve is obtained by mapping the orbital phase sequence. Each Substituting the mapping relationship, linear interpolation is used to obtain the corresponding predicted bit error rate. With prediction signal-to-noise ratio Connect all or The points form a continuous curve (the interpolation point is the midpoint obtained by linearly interpolating the endpoint parameter values ​​of adjacent phase intervals, which is a well-known interpolation method in the field of orbit mechanics).

[0026] Service assurance thresholds are set according to service type: signal-to-noise ratio thresholds for voice services. dB, the bit error rate threshold for data services Escape time Defined as the first time the link quality prediction curve meets the condition. or The first preset time window is set to [time point]. The second preset time window is set to The window duration is dynamically adjusted based on the low-Earth orbit satellite's altitude (55 seconds at 500 km altitude, 80 seconds at 1200 km altitude; adjustment coefficients are obtained via table lookup). Service migration is performed via data stream redirection through the satellite communication protocol stack (using the CCSDSAOS protocol), and resource release includes disconnecting physical link connections and reclaiming bandwidth and time slot resources.

[0027] Based on the above, this method obtains the current orbital phase of low-Earth orbit (LEO) satellites and generates an orbital phase sequence using an orbital dynamics model. It then uses a pre-defined orbital phase-link quality mapping relationship to generate a link quality prediction curve, achieving accurate quantitative prediction of inter-satellite link quality degradation trends. When the predicted link quality is lower than the service guarantee threshold, a coverage blind spot compensation process is triggered in advance. Within a first pre-defined time window before the departure time, multiple candidate high-Earth orbit (HEO) satellites that meet the orbital phase matching conditions are selected and bandwidth resources and transmission time slots are pre-allocated. Within a second pre-defined time window, link availability verification is specifically performed to ensure that service migration to a verified backup inter-satellite link is completed before the departure time, and the original link resources are released promptly after migration. This transforms link management from a post-interruption response to proactive compensation before degradation. Through an orbital phase-driven prediction mechanism and a phased resource scheduling verification process, it avoids the risk of service interruption caused by coverage blind spots due to the high-speed movement of LEO satellites, improving the continuity of network communication, handover reliability, and on-board resource utilization efficiency. Simultaneously, it avoids the problem of excessive handover delay caused by the coupling of link verification and resource allocation.

[0028] To achieve accurate link quality prediction, in one embodiment, the process of constructing the orbital phase-link quality mapping relationship includes: The measured bit error rate and signal-to-noise ratio of the inter-satellite link were collected for different orbital phases of low-Earth orbit satellites during their complete orbital period. The orbital period is divided into multiple phase intervals. The measured bit error rate and signal-to-noise ratio in each phase interval are statistically aggregated to generate a table corresponding to the phase interval and link quality parameters. The correspondence table between phase intervals and link quality parameters is used as the mapping relationship between track phase and link quality.

[0029] Specifically, data acquisition occurs over the complete orbital period (duration) of a low-Earth orbit satellite. From the semi-major axis of the track (Confirmed) The process continues at 1-second intervals, synchronously recording the orbital phase. Inter-satellite link measured bit error rate and measured signal-to-noise ratio All collected data is stored in the onboard secure storage area after being anonymized with user authorization. The orbital period is evenly divided into 360 phase intervals (each interval being 1°) according to the orbital phase. Phase intervals Internal collection Group Calculate the arithmetic mean of each data point: , In practical applications, the number of phase intervals and the statistical method can be adjusted according to the orbital characteristics; this embodiment does not limit this. The correspondence table between phase intervals and link quality parameters is stored in key-value pairs: the key is the center value of the phase interval. The value is Tuples; This table is updated periodically (once every 7 track cycles) to adapt to changes in the link environment.

[0030] Based on the above, this construction process establishes a quantitative correlation between orbital phase and link quality attenuation (mapping physical orbital positions into calculable link parameters), providing a high-precision data foundation for link quality prediction, avoiding the problem of delayed handover decisions caused by missing prediction models, and improving the accuracy of coverage blind spot identification.

[0031] When selecting candidate high-orbit satellites, clear and quantifiable matching conditions are needed to ensure that the selected candidate satellites have the potential to provide stable and continuous service in their geometric location at the time of handover and for a period of time thereafter. Therefore, in one embodiment, the orbital phase matching conditions in the coverage blind spot compensation process include: the absolute value of the orbital phase difference between the candidate high-orbit satellite and the low-orbit satellite at the time of separation is less than a preset phase tolerance threshold, and the nadir trajectory of the candidate high-orbit satellite covers the predicted position of the low-orbit satellite after the time of separation.

[0032] Specifically, a preset phase tolerance threshold Set to 15°, based on the orbital inclination of low-Earth orbit satellites. Dynamic correction: when hour, Orbital phase difference ,in , These represent the orbital phases (in degrees) of the candidate high-orbit and low-orbit satellites at the time of separation. The nadir trajectory coverage determination uses a spherical geometry method: calculating the nadir trajectory of the high-orbit satellite within 30 seconds after the separation time. Predicted position of low-Earth orbit satellites spherical distance ,in, For the Earth's radius, , (respectively latitude and longitude); when It is determined to be covered at that time. The coverage radius of a high-orbit satellite beam (determined by the antenna beamwidth) With orbital height calculate: .

[0033] Based on the above, the matching condition integrates the dual constraints of orbital phase difference and nadir trajectory to ensure that candidate high-orbit satellites have continuous coverage capability after the departure time (avoiding rapid link failure after handover due to geometric mismatch), thereby improving the availability of handover links and service continuity.

[0034] Resource pre-allocation requires precise calculations to ensure that backup links have sufficient capacity to reliably transmit service data within the predicted duration, while avoiding under-allocation leading to transmission failures or over-allocation causing waste of valuable on-board resources. Therefore, in one embodiment, the process of pre-allocating bandwidth resources and transmission time slots for backup inter-satellite links between candidate high-orbit and low-orbit satellites includes: Calculate the basic bandwidth requirements based on the data volume of the services to be migrated and the predicted duration of the backup inter-satellite links; The retransmission redundancy coefficient is calculated based on the predicted bit error rate in the link quality prediction curve of the backup inter-satellite link. The retransmission redundancy coefficient increases as the predicted bit error rate increases. Multiply the basic bandwidth requirement by the retransmission redundancy factor to obtain the pre-allocated bandwidth; The predicted duration of the backup inter-satellite link is divided into multiple transmission time slots, and the number of transmission time slots is determined based on the pre-allocated bandwidth and the amount of data of the services to be migrated.

[0035] Specifically, basic bandwidth requirements Through formula Calculation, where The amount of data to be migrated (unit: bits). The predicted duration of the backup inter-satellite link (in seconds, the duration for which the link quality remains above a threshold after the disconnection time). Retransmission redundancy factor. According to the formula Calculation, where This represents the predicted bit error rate at the decoupling time in the link quality prediction curve. To ensure the business operates within a certain bit error rate threshold (e.g., 10), −5 ), proportionality coefficient (Verified by Monte Carlo simulation, in) Within a certain range, retransmission overhead and reliability can achieve an optimal balance. When At that time, take Pre-allocated bandwidth Number of transmission time slots Through formula Calculations show that each transmission slot carries a data frame of fixed length 1024 bytes.

[0036] Based on the above, this pre-allocation method dynamically incorporates the predicted link quality into resource calculation. and (Proportional to the error rate) When the predicted bit error rate increases, the bandwidth redundancy is automatically increased to ensure transmission reliability; avoid data retransmission and service delay due to insufficient resources, and prevent resource waste caused by over-allocation.

[0037] Resource pre-allocation is based on prediction, while the actual link status may be affected by transient space environment interference (such as ionospheric scintillation, transient obstruction, etc.). Therefore, it is necessary to verify the actual availability of the backup link before switching to ensure that the switching decision is based on real and reliable link performance. To this end, in one embodiment, the process of performing link availability verification on the backup inter-satellite link includes: Within the second preset time window, the high-orbit satellite sends test data packets to the low-orbit satellite; After the low-Earth orbit satellite receives the test data packet, it calculates the received bit error rate and the received signal-to-noise ratio of the test data packet. When the received bit error rate is lower than the preset verification bit error rate threshold and the received signal-to-noise ratio is higher than the preset verification signal-to-noise ratio threshold, the link availability verification is deemed successful.

[0038] Specifically, the test packets are 512-byte pseudo-random binary sequences (PRBS) to pre-allocate bandwidth. Send at 80% rate ( Preset verification bit error rate threshold. Preset verification signal-to-noise ratio threshold Received bit error rate Calculate by comparing the bit differences between the sent and received data packets ( ), Received signal-to-noise ratio By receiving signal power With noise power Ratio calculation ( (Unit: dB)

[0039] Based on the above, the verification process is executed specifically within an independent time window (completely decoupled from resource pre-allocation) to ensure that the verification results truly reflect the instantaneous state of the link; it avoids compressing the switching time window due to coupled operations, thereby improving the reliability and timeliness of switching decisions.

[0040] Single link verification may fail due to transient strong interference or other accidental factors, requiring alternative solutions to address verification failures and improve the robustness and ultimate success rate of the entire coverage blind spot compensation process. Therefore, in one embodiment, the coverage blind spot compensation process further includes: When the link availability verification fails, the candidate high-orbit satellite that failed the verification is removed from multiple candidate high-orbit satellites. The remaining candidate high-orbit satellites with the highest orbit phase matching condition satisfaction are re-selected as the new candidate high-orbit satellites. The pre-allocated bandwidth resources, transmission time slots and link availability verification steps are repeated until the link availability verification passes or the candidate high-orbit satellites are exhausted.

[0041] Specifically, the degree of satisfaction of orbit phase matching conditions Calculated using the following formula: in: This represents the absolute value of the orbital phase difference between the candidate high-orbit satellite and the low-orbit satellite at the moment of separation (unit: degrees). Preset phase tolerance threshold (unit: degrees); The minimum spherical distance (in kilometers) between the nadir trajectory of the high-orbit satellite and the predicted position of the low-orbit satellite within 30 seconds after the separation time. The coverage radius of the high-orbit satellite beam (unit: kilometers); , (Weighting coefficients determined through orthogonal experiments, balancing phase matching and coverage capability); The value ranges from [0,1], with larger values ​​indicating a higher degree of matching. The re-screening process iterates a maximum of 3 times, updating the candidate set and re-performing pre-assignment and validation in each iteration.

[0042] Based on the above, this re-screening mechanism forms a closed loop of verification-rejection-re-screening (using a scoring function to quantify the screening criteria), improving the system's fault tolerance and switching success rate in scenarios with link fluctuations, and avoiding business interruption caused by a single verification failure.

[0043] Accurate orbit prediction and high-precision time synchronization are prerequisites for accurate prediction and compensation of coverage blind spots. Relative motion, clock drift, and different perturbation forces exist between high- and low-Earth orbit satellites; therefore, in one embodiment, the method further includes a pre-network time synchronization step. High-orbit satellite broadcasting includes a time synchronization signal with a transmission timestamp; After receiving the signal, the low-Earth orbit satellite returns a response signal containing the reception timestamp. High-orbit satellites calculate clock deviation values ​​based on the transmission timestamp, the reception timestamp in the response signal, their own secondary reception timestamp, and the inter-satellite distance calculated based on orbital elements; Low-Earth orbit satellites correct their local clocks based on clock offset values; In the calculation of inter-satellite distances, only the orbital elements of low-Earth orbit satellites are corrected by the J2 term perturbation, while the orbital elements of high-Earth orbit satellites are calculated based on the two-body problem model.

[0044] Specifically, the time synchronization signal adopts the IEEE 1588v2 precision time protocol frame format. Inter-satellite distance. Through formula calculate, The position vector of the high-orbit satellite is calculated from the orbital elements using a two-body model. (the moment at the midpoint of signal propagation). The low-Earth orbit satellite position vector is calculated from the orbital elements using the J2 perturbation correction model, and the J2 perturbation acceleration is... ,in The second-order band harmonic coefficient of Earth's gravitational field. The radius of the Earth's equator. The Z-axis component of the position vector in the geocentric inertial frame.

[0045] Clock deviation value According to the formula Calculate, where, Send timestamps to high-orbit satellites (local time of the high-orbit satellite, in seconds). This is the timestamp received by the low-Earth orbit satellite (local time of the low-Earth orbit satellite, in seconds). This is the second reception timestamp for the high-orbit satellite (local time of the high-orbit satellite, unit: seconds). For the speed of light ( The reason for only applying J2 correction to low-Earth orbit satellites is that low-Earth orbit satellites have low orbital altitudes (typically 500–1200 km), and the J2 perturbation effect is significant (position error can reach the level of hundreds of meters); high-Earth orbit satellites (such as geostationary orbit, altitude 35,786 km) have weak J2 perturbation effects (position error less than 10 meters), and the two-body model is sufficient to meet the synchronization accuracy requirements.

[0046] Based on the above, this synchronization step improves the accuracy of inter-satellite distance calculation through targeted perturbation correction (reducing the low-orbit position error from hundreds of meters to within 10 meters), thereby improving the accuracy of clock deviation calculation (synchronization accuracy reaches the microsecond level), providing a high-precision time reference for orbit phase sequence prediction, and reducing the cumulative prediction error.

[0047] To avoid the problem of blind zone determination deviation caused by the disconnect between time synchronization and orbit prediction, in one embodiment, the time synchronization step before network deployment is performed before each triggering of the coverage blind zone compensation process, and the calculation result of the clock deviation value is used to correct the prediction accuracy of the orbit phase sequence.

[0048] Specifically, clock skew value The integral start time used to correct the orbital dynamics model: the original start time... Correction to ,by Reintegrate from the starting point to generate the orbital phase sequence The corrected sequence is used to update the link quality prediction curve and the exit time prediction. The correction process is implemented in the onboard computer by calling the orbit integration library function (input the corrected start time, output the new sequence).

[0049] Based on the above, this application method feeds back the time synchronization results to the track prediction stage, forming a closed loop of synchronization-correction-prediction; effectively suppressing the track phase prediction deviation caused by clock drift, and improving the timeliness and accuracy of coverage blind spot determination.

[0050] To avoid the risk of data loss during business migration, in one embodiment, the low-Earth orbit satellite caches the business data to be migrated in the onboard storage during the business migration process. After the backup inter-satellite link is established, the low-Earth orbit satellite reads the cached data from its onboard memory and transmits it to the high-Earth orbit satellite through the backup inter-satellite link. After receiving the data, the high-Earth orbit satellite sends an acknowledgment command to the low-Earth orbit satellite. Upon receiving the acknowledgment command, the low-Earth orbit satellite clears the cached data from its onboard memory.

[0051] Specifically, the onboard storage uses dual-port static random access memory (SRAM) with a capacity no less than the amount of service data to be migrated. The cached data is 1.2 times larger than the data packet sequence number (with a 20% redundancy reserve); the cached data is stored in sequence according to the data packet sequence number. The acknowledgment command includes the sequence number range and checksum of the successfully received data packets (using the CRC-32 algorithm); after receiving the acknowledgment command, the low-Earth orbit satellite verifies the sequence number range and checksum, and clears the corresponding cached data after successful verification. The clearing operation is completed within 100 milliseconds. The onboard memory is connected to the satellite communication processing unit via a PCIe 3.0 bus, with a data read / write bandwidth of no less than 1Gbps.

[0052] Based on the above, this mechanism ensures that data is not lost during the migration process through onboard caching (even if the original link is suddenly interrupted, the data can still be recovered from the cache for transmission), and avoids duplicate data transmission by combining confirmation and clearing processes; ensuring the integrity and reliability of business migration and achieving zero-interruption business switching.

[0053] On the other hand, this embodiment provides a high-low orbit satellite cooperative networking system, applied to the high-low orbit satellite cooperative networking method described above, such as... Figure 2 As shown, the system includes: The data acquisition module is configured to acquire the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites. The orbit prediction module is configured to calculate the orbital phase sequence of low-Earth orbit satellites within a preset time window based on orbital elements and the current orbital phase using an orbital dynamics model. The link quality prediction module is configured to generate a link quality prediction curve for inter-satellite links based on the orbit phase sequence and the preset orbit phase-link quality mapping relationship. The orbit phase-link quality mapping relationship characterizes the link quality attenuation law caused by relative motion of low-Earth orbit satellites under different orbit phases. The coverage blind spot determination module is configured to determine that a low-orbit satellite is about to enter the coverage blind spot of a high-orbit satellite when the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, and to trigger the coverage blind spot compensation process. The coverage blind spot compensation module is configured to, after triggering the coverage blind spot compensation process, predict the departure time of the low-Earth orbit satellite from the current high-Earth orbit satellite coverage area based on the orbital phase sequence. Within a first preset time window before the departure time, it selects multiple candidate high-Earth orbit satellites that meet the orbital phase matching conditions from the high-Earth orbit satellite constellation and pre-allocates bandwidth resources and transmission time slots for the backup inter-satellite links between the candidate high-Earth orbit satellites and the low-Earth orbit satellites. After the first preset time window ends and within a second preset time window before the departure time, it performs link availability verification on the backup inter-satellite links. When the link availability verification passes, it migrates the service to the backup inter-satellite links before the departure time. After the service migration is completed, it releases the resources of the inter-satellite links.

[0054] The data acquisition module connects to the satellite's onboard system via the CCSDS standard interface to acquire orbital elements in real time; it outputs the current orbital phase through the built-in orbital calculation unit (based on the Kepler equation solver). The orbit prediction module incorporates a built-in orbit dynamics calculation engine (integrating a fourth-order Runge-Kutta integrator and the J2 perturbation correction algorithm), taking the orbital elements as input. Output orbital phase sequence The link quality prediction module loads the phase interval and link quality parameter mapping table constructed as described above, and generates the link quality prediction curve using a linear interpolation algorithm. The coverage blind spot determination module configures the service assurance threshold register (which can be configured in software). , The prediction curve is compared with the threshold in real time. The coverage blind spot compensation module integrates a candidate satellite screening unit (executes the orbit phase matching condition in the aforementioned method), a resource allocation unit (executes the bandwidth resource and transmission time slot process in the aforementioned method), a link verification unit (executes the link availability verification process in the aforementioned method), and a migration control unit (executes the confirmation and clearing mechanism in the service migration process in the aforementioned method). The units are interconnected through the AXI4 bus to achieve data interaction. All modules are deployed on the low-Earth orbit satellite's onboard radiation-hardened computer, and the modules communicate with each other through shared memory and message queues (using the VxWorks real-time operating system message mechanism). In practical applications, the deployment location of the modules can be adjusted according to the system architecture (e.g., the coverage blind spot determination module is deployed in the ground control center), and this embodiment does not limit this.

[0055] The system solidifies the methodology into functional modules, with each module working collaboratively to achieve automatic prediction and compensation for coverage blind spots (data acquisition → prediction → judgment → compensation closed-loop process); through hardware acceleration and modular design, it ensures efficient and reliable networking, providing stable system support for high and low orbit satellite collaborative communication.

[0056] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for collaborative networking of high and low orbit satellites, characterized in that, Includes the following steps: Obtain the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites; Based on the orbital elements and the current orbital phase, the orbital phase sequence of the low-Earth orbit satellite within a future preset time window is calculated using an orbital dynamics model; Based on the orbital phase sequence and the preset orbital phase-link quality mapping relationship, an inter-satellite link quality prediction curve is generated. The orbital phase-link quality mapping relationship characterizes the link quality attenuation law caused by relative motion of low-Earth orbit satellites under different orbital phases. When the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, it is determined that the low-orbit satellite is about to enter the coverage blind zone of the high-orbit satellite and the coverage blind zone compensation process is triggered. The coverage blind spot compensation process includes: predicting the departure time of a low-orbit satellite from the current high-orbit satellite coverage area based on the orbital phase sequence; within a first preset time window before the departure time, selecting multiple candidate high-orbit satellites that meet the orbital phase matching conditions from the high-orbit satellite constellation; and pre-allocating bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-orbit satellites and the low-orbit satellites; and performing link availability verification on the backup inter-satellite link after the first preset time window ends and within a second preset time window before the departure time. Once the link availability verification is successful, services will be migrated to the backup inter-satellite link before the decommissioning time. After the service migration is completed, the resources of the inter-satellite link are released.

2. The high-low orbit satellite collaborative networking method according to claim 1, characterized in that, The process of constructing the orbital phase-link quality mapping relationship includes: The measured bit error rate and signal-to-noise ratio of the inter-satellite link were collected for different orbital phases of low-Earth orbit satellites during their complete orbital period. The orbital period is divided into multiple phase intervals. The measured bit error rate and signal-to-noise ratio in each phase interval are statistically aggregated to generate a table corresponding to the phase interval and link quality parameters. The correspondence table between the phase interval and the link quality parameters is used as the mapping relationship between the track phase and the link quality.

3. The high- and low-orbit satellite collaborative networking method according to claim 1, characterized in that, In the coverage blind spot compensation process, the orbit phase matching conditions include: the absolute value of the orbit phase difference between the candidate high-orbit satellite and the low-orbit satellite at the time of separation is less than a preset phase tolerance threshold, and the nadir point trajectory of the candidate high-orbit satellite covers the predicted position of the low-orbit satellite after the time of separation.

4. The high- and low-orbit satellite collaborative networking method according to claim 3, characterized in that, The process of pre-allocating bandwidth resources and transmission time slots for the backup inter-satellite links between the candidate high-orbit and low-orbit satellites includes: The basic bandwidth requirement is calculated based on the data volume of the service to be migrated and the predicted duration of the backup inter-satellite link. The retransmission redundancy coefficient is calculated based on the predicted bit error rate in the link quality prediction curve of the backup inter-satellite link. The retransmission redundancy coefficient increases as the predicted bit error rate increases. Multiply the basic bandwidth requirement by the retransmission redundancy coefficient to obtain the pre-allocated bandwidth; The predicted duration of the backup inter-satellite link is divided into multiple transmission time slots, and the number of transmission time slots is determined based on the pre-allocated bandwidth and the amount of data of the service to be migrated.

5. The high-low orbit satellite cooperative networking method according to claim 4, characterized in that, The process of performing link availability verification on the backup inter-satellite link includes: Within the second preset time window, the high-orbit satellite sends test data packets to the low-orbit satellite; After receiving the test data packet, the low-orbit satellite calculates the received bit error rate and received signal-to-noise ratio of the test data packet. When the received bit error rate is lower than the preset verification bit error rate threshold and the received signal-to-noise ratio is higher than the preset verification signal-to-noise ratio threshold, the link availability verification is deemed successful.

6. The high-low orbit satellite collaborative networking method according to claim 1, characterized in that, The coverage blind spot compensation process also includes: When the link availability verification fails, the candidate high-orbit satellite that failed the verification is removed from the multiple candidate high-orbit satellites. The remaining candidate high-orbit satellites with the highest orbit phase matching condition satisfaction are re-selected as the new candidate high-orbit satellites. The pre-allocated bandwidth resources, transmission time slots and link availability verification steps are repeated until the link availability verification passes or the candidate high-orbit satellites are exhausted.

7. The high- and low-orbit satellite collaborative networking method according to claim 1, characterized in that, This method also includes a time synchronization step before network deployment: High-orbit satellite broadcasting includes a time synchronization signal with a transmission timestamp; After receiving the signal, the low-Earth orbit satellite returns a response signal containing the reception timestamp. The high-orbit satellite calculates the clock deviation value based on the transmission timestamp, the reception timestamp in the response signal, its own secondary reception timestamp, and the inter-satellite distance calculated based on the orbital elements; Low-Earth orbit satellites correct their local clocks based on the aforementioned clock deviation value; In the calculation of the inter-satellite distance, only the orbital elements of low-Earth orbit satellites are subject to J2 perturbation correction, while the orbital elements of high-Earth orbit satellites are calculated based on the two-body problem model.

8. The high-low orbit satellite cooperative networking method according to claim 7, characterized in that, The pre-network time synchronization step is executed before each triggering of the coverage blind spot compensation process, and the calculation result of the clock deviation value is used to correct the prediction accuracy of the orbit phase sequence.

9. The high- and low-orbit satellite collaborative networking method according to claim 1, characterized in that, During the service migration process, the low-Earth orbit satellite caches the service data to be migrated in its onboard storage. After the backup inter-satellite link is established, the low-Earth orbit satellite reads cached data from the onboard memory and transmits it to the high-Earth orbit satellite through the backup inter-satellite link. After receiving the data, the high-Earth orbit satellite sends an acknowledgment command to the low-Earth orbit satellite. Upon receiving the acknowledgment command, the low-Earth orbit satellite clears the cached data in the onboard memory.

10. A high-low orbit satellite collaborative networking system, characterized in that, include: The data acquisition module is configured to acquire the orbital elements of high-orbit satellites, the orbital elements of low-orbit satellites, and the current orbital phase of low-orbit satellites. The orbit prediction module is configured to calculate the orbital phase sequence of the low-Earth orbit satellite within a future preset time window based on the orbital elements and the current orbital phase using an orbital dynamics model. The link quality prediction module is configured to generate a link quality prediction curve for inter-satellite links based on the orbit phase sequence and a preset orbit phase-link quality mapping relationship. The orbit phase-link quality mapping relationship characterizes the link quality attenuation law caused by relative motion of low-Earth orbit satellites under different orbit phases. The coverage blind spot determination module is configured to determine that a low-orbit satellite is about to enter the coverage blind spot of a high-orbit satellite when the link quality prediction curve indicates that the inter-satellite link quality will be lower than the service guarantee threshold, and to trigger the coverage blind spot compensation process. The coverage blind spot compensation module is configured to, after triggering the coverage blind spot compensation process, predict the departure time of the low-Earth orbit satellite from the current high-Earth orbit satellite coverage area based on the orbital phase sequence; within a first preset time window before the departure time, select multiple candidate high-Earth orbit satellites that meet the orbital phase matching conditions from the high-Earth orbit satellite constellation, and pre-allocate bandwidth resources and transmission time slots for the backup inter-satellite link between the candidate high-Earth orbit satellites and the low-Earth orbit satellites; after the first preset time window ends and within a second preset time window before the departure time, perform link availability verification on the backup inter-satellite link; when the link availability verification passes, migrate services to the backup inter-satellite link before the departure time; and release the resources of the inter-satellite link after the service migration is completed.

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