Non-terrestrial network based space-based space-based TT&C method and related equipment

Abstract

This invention discloses a spaceborne telemetry, tracking, and command (TT&C) method and related equipment based on a non-terrestrial network. The method is used in a spaceborne TT&C device, which is installed on a low-Earth orbit (LEO) satellite platform. The method includes: acquiring the real-time orbital parameters, GNSS positioning information, and a pre-stored table of high-Earth orbit (HEO) satellite coverage information for the assigned LEO satellite; calculating the spatiotemporal relationship between the assigned LEO satellite and the cell coverage area based on the current orbital parameters, GNSS positioning information, and the pre-stored or periodically updated HEO satellite coverage information table; and, based on the calculated spatiotemporal relationship, predicting and determining the cell coverage area of ​​the target HEO satellite, proactively waking up and initiating a cell search and on-demand access control process. This method can solve the problems of high construction costs, limited multiple access capabilities, and poor dynamic adaptability of existing spaceborne TT&C technologies.

Description

Technical Field

[0001] The embodiments of this application relate to the aerospace field, and more specifically, the present invention relates to a spaceborne telemetry and control method and related equipment based on a non-terrestrial network. Background Technology

[0002] With the booming development of commercial spaceflight, the construction of low-Earth orbit (LEO) satellite constellations has entered a fast track, and the number of spacecraft in orbit is growing exponentially. This trend poses unprecedented challenges to spacecraft telemetry, tracking, and command (TT&C) systems, requiring them to have characteristics such as managing a large number of targets, high real-time performance, strong global coverage, and flexible resource scheduling. The traditional method of relying on ground stations around the world for TT&C is no longer sufficient to meet the large-scale, routine TT&C needs of the massive number of LEO satellites in the future due to its high construction and maintenance costs, blind spots in coverage, limited number of targets supported simultaneously, and rigid resource scheduling.

[0003] Space-based telemetry, tracking, and command (TT&C), utilizing medium- and high-orbit communication satellites as relay nodes to provide TT&C and data relay services to low-orbit satellites, is considered a fundamental solution to the aforementioned problems. It effectively overcomes the coverage limitations of ground-based TT&C, achieving true global seamless connectivity. In recent years, related technologies have been actively exploring space-based TT&C technology routes. The existing Tracking and Data Relay Satellite System (TDRSS) is a classic high-orbit relay solution, but as a dedicated system, its construction and operation costs are extremely high. To explore commercialization paths, the industry subsequently proposed the Communication Service Project (CSP), aiming to provide services using commercial communication satellite resources. Furthermore, related technologies have verified the near-real-time data transmission capabilities of low-orbit constellations based on the L-band, demonstrating the potential of mobile communication satellites for space-based TT&C. In addition, existing high-orbit relay satellite systems have been built and provide reliable services, but primarily serve major space missions; while the short message communication function based on BeiDou navigation satellites has also been verified in missions such as remote sensing satellites, providing valuable emergency communication means for low-orbit satellites. However, none of the above solutions can meet the demand for low-cost, high-reliability TT&C from the massive number of low-orbit commercial satellites. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] To address the problems of high construction costs, limited multiple access capabilities, and poor dynamic adaptability of existing space-based telemetry and control technologies, this invention proposes, in a first aspect, a spaceborne telemetry and control method based on a non-terrestrial network, using a spaceborne telemetry and control device located on a low-Earth orbit satellite platform. The method includes:

[0006] The system acquires the real-time orbital parameters, GNSS positioning information, and pre-stored high-orbit satellite coverage information tables of the respective low-orbit satellites.

[0007] The spatiotemporal relationship between the low-orbit satellite and the cell coverage area is calculated based on the current orbital parameters, GNSS positioning information, and the high-orbit satellite coverage information table of the high-orbit satellites that are pre-stored or periodically updated from the satellite computer.

[0008] If the cell coverage area of ​​the target high-orbit satellite is determined based on the spatiotemporal relationship prediction obtained from the calculation, the cell search and access control process is initiated in advance.

[0009] Optional, also includes:

[0010] Based on the calculated spatiotemporal relationship, predict the current serving cell signal attenuation trend and the timing of the target cell's appearance;

[0011] When the signal quality of the current serving cell is detected to drop to a predetermined threshold and the signal strength of the target cell continues to rise, a cell handover trigger command is generated to wake up the cell handover process in advance.

[0012] Optionally, the spaceborne telemetry, tracking, and command (TT&C) device includes at least two non-terrestrial network modules, and the cell handover process includes:

[0013] The first non-terrestrial network module will continue to maintain existing service transmission within the current serving cell to ensure the continuity of data flow;

[0014] The second non-terrestrial network module is woken up and instructed to complete downlink synchronization, system message decoding, random access procedure and service channel establishment on the frequency point of the target cell.

[0015] Optional, also includes:

[0016] If the second non-terrestrial network module successfully establishes a service channel in the target cell, a data stream handover operation is performed:

[0017] Switch the uplink data routing and downlink data receiving source from the first non-terrestrial network module to the second non-terrestrial network module;

[0018] After confirming that the new link service transmission is stable, the control system instructs the first non-terrestrial network module to initiate a connection release process, normally disconnect from the network and enter an idle listening state, completing the entire soft handover process.

[0019] Optional, also includes:

[0020] Based on the real-time acquired orbital parameters and three-axis velocity vectors of the low-orbit satellite, the accurate ephemeris data of the high-orbit relay satellite, the relative geometric position and radial velocity components of the two satellites, and the carrier frequency and sampling clock characteristics, the theoretical frequency offset prediction value is calculated in real time using the Doppler frequency shift calculation method. The theoretical frequency offset prediction value includes the magnitude and the trend of change.

[0021] Frequency offset pre-compensation is performed based on the calculated theoretical frequency offset prediction value;

[0022] The compensation effect is evaluated by real-time monitoring of key physical layer indicators, and feedback adjustments are made based on the compensation effect.

[0023] Optionally, the frequency offset pre-compensation based on the calculated theoretical frequency offset prediction value includes:

[0024] In the transmission link, the pre-compensation value is superimposed on the baseband digital up-conversion module to correct the transmission frequency in advance;

[0025] In the receiving link, the local oscillator of the downlink demodulator is controlled to perform frequency pre-correction;

[0026] Fine-tuning the sampling clock frequency compensates for the effects of timing deviations;

[0027] The method of evaluating the compensation effect by real-time monitoring of key physical layer indicators, and then adjusting based on the compensation effect, includes:

[0028] When abnormal link quality indicators are detected, the frequency offset estimation error is automatically calculated.

[0029] The parameter weights of the prediction algorithm are dynamically adjusted based on the magnitude and direction of the error.

[0030] Update the compensation value lookup table to optimize subsequent prediction accuracy.

[0031] Secondly, the present invention also proposes a spaceborne telemetry and control device based on a non-terrestrial network, employing the method described in any one of the first aspects above, comprising:

[0032] Main control unit;

[0033] The main power supply and backup power supply are used to power the main control unit.

[0034] Three non-terrestrial network communication modules are connected to the main control unit, and each of the three non-terrestrial network communication modules includes a low-noise amplifier (LNA) and a power amplifier (PA) component.

[0035] The sky-based telemetry and control antenna and the ground-based telemetry and control antenna are connected to the communication module;

[0036] The three non-terrestrial network communication modules include: a first non-terrestrial network module, a second non-terrestrial network module, and a third non-terrestrial network module. The first and second non-terrestrial network modules are used as primary service channels, responsible for alternating transmission of service data during cell handover to ensure the continuity and stability of the data flow. The third non-terrestrial network module is used as a cold standby module, which automatically intervenes and replaces the faulty module when the main control unit detects a hardware failure in the first or second non-terrestrial network module.

[0037] Thirdly, an electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program stored in the memory to implement the steps of the spaceborne telemetry and control method based on a non-terrestrial network as described in any of the first aspects above.

[0038] Fourthly, the present invention also proposes a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the spaceborne telemetry and control method based on a non-terrestrial network as described in any of the preceding claims of the first aspect.

[0039] In summary, the spaceborne telemetry, tracking, and command (TT&C) method based on a non-terrestrial network proposed in this application is used in a spaceborne spaceborne TT&C device. This device is located on a low-Earth orbit (LEO) satellite platform. It acquires the real-time orbital parameters, GNSS positioning information, and a pre-stored high-Earth orbit (HEO) satellite coverage information table of its assigned LEO satellite. Based on the current orbital parameters, GNSS positioning information, and the pre-stored or periodically updated HEO satellite coverage information table from the satellite's operational computer, it calculates the spatiotemporal relationship between the assigned LEO satellite and the cell coverage area. When the calculated spatiotemporal relationship predicts the cell coverage area of ​​the target HEO satellite, it proactively wakes up and initiates cell search and on-demand access control procedures. By fully utilizing the characteristic that the trajectory of LEO spacecraft can be accurately predicted, the terminal internally stores or periodically updates the HEO satellite coverage area model from the operational computer. By comparing its real-time location with the coverage information table, the terminal can wake up in advance and initiate cell search and random access procedures before physically entering the satellite coverage area. Compared with the traditional terminal's passive access method that relies entirely on measuring the received signal strength, this proactive predictive access mechanism can significantly shorten the invalid waiting time and avoid access hesitation or instability caused by signal fluctuations. Thus, within a limited overpass time window, it can strive for the longest effective service transmission time and significantly improve the system's measurement and control efficiency.

[0040] The present invention provides a spaceborne telemetry, tracking, and command method based on a non-terrestrial network. Other advantages, objectives, and features of the present invention will be partly apparent from the following description and partly understood by those skilled in the art through study and practice of the invention. Attached Figure Description

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0042] Figure 1 A schematic diagram of a spaceborne telemetry and control method based on a non-terrestrial network is provided for an embodiment of this application;

[0043] Figure 2 A schematic diagram of a spaceborne telemetry, tracking, and command network based on a non-terrestrial network is provided as an embodiment of this application.

[0044] Figure 3 A schematic diagram of a spaceborne telemetry and control device based on a non-terrestrial network is provided for an embodiment of this application;

[0045] Figure 4 This is a schematic diagram of a spaceborne telemetry and control electronic device based on a non-terrestrial network, provided as an embodiment of this application. Detailed Implementation

[0046] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The technical solutions of the embodiments of this application will now be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0047] To address the issues of high construction costs, limited multiple access capabilities, and poor dynamic adaptability of existing space-based telemetry and control technologies, please refer to [link / reference needed]. Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of a spaceborne telemetry and control method based on a non-terrestrial network, provided as an embodiment of this application. Figure 2This is a schematic diagram of a spaceborne telemetry, tracking, and command (TT&C) network process on a non-terrestrial network. The system consists of a spaceborne TT&C terminal on a low-Earth orbit (LEO) satellite, a high-Earth orbit (HEO) communication satellite for relay, and a ground-based TT&C application system. The ground-based TT&C application system handles the reception and forwarding of TT&C application data, user authentication and identity verification, terminal status management, and resource allocation, and interconnects with the application system through an application server. The application system mainly consists of a spaceborne TT&C terminal and a dedicated data network. The spaceborne TT&C terminal is installed on the LEO satellite platform and is responsible for establishing the TT&C link between the LEO satellite and the Tiantong system, and for receiving and forwarding TT&C application data. The dedicated data network provides a data transmission channel for users to receive spaceborne telemetry data. Considering the limited coverage of a single cell of a HEO mobile communication satellite and the extremely short visibility time of a LEO spacecraft traversing a single cell, a spaceborne TT&C method based on a non-terrestrial network is proposed for a spaceborne TT&C device. The spaceborne TT&C device is set up on a LEO satellite platform and specifically includes steps S110 to S130.

[0048] S110 acquires the real-time orbital parameters, GNSS positioning information, and pre-stored high-orbit satellite coverage information tables of its respective low-orbit satellites.

[0049] S120, calculate the spatiotemporal relationship between the low-orbit satellite and the cell coverage area based on the current orbital parameters, GNSS positioning information, and the high-orbit satellite coverage information table of the high-orbit satellites that are pre-stored or periodically updated from the satellite service computer.

[0050] S130: If the cell coverage area of ​​the target high-orbit satellite is predicted and determined based on the calculated spatiotemporal relationship, the cell search and access control process is initiated in advance.

[0051] Understandably, for a low-Earth orbit satellite, whether it is within the coverage area of ​​a certain cell beam of a high-Earth orbit relay satellite is essentially a geometric relationship problem: at a certain moment, whether the position of the low-Earth orbit satellite in the Earth coordinate system overlaps with the position of the high-Earth orbit satellite's beam coverage area mapped on the Earth's surface.

[0052] For example, the spaceborne telemetry, tracking, and command (TT&C) system can share data from the attitude and orbit control subsystem with the low-Earth orbit (LEO) satellite platform. On one hand, the attitude and orbit control subsystem uses star sensors, gyroscopes, and ground-injected ephemeris data to estimate the LEO satellite's orbit in real time, forming a real-time orbital parameter set. This set includes six root numbers or equivalent orbital description parameters: semi-major axis, eccentricity, inclination, right ascension of the ascending node, argument of perigee, and mean perigee angle. It may also include epoch time stamps used for simulation. On the other hand, the satellite's onboard GNSS receiver, with the support of visible navigation satellites, acquires current position, velocity, and time information. The GNSS positioning results are provided in the form of three-dimensional position coordinates and three-dimensional velocity vectors, used to supplement and correct the orbital parameters calculated by the attitude and orbit control system. The attitude and orbit fusion module within the spaceborne TT&C system can fuse and estimate orbital parameters and GNSS positioning. In the event of ephemeris errors or short-term orbital maneuvers, a more accurate current state vector is obtained through filtering algorithms. During satellite manufacturing or in orbit, the satellite's computer loads coverage information tables from high-Earth orbit (HEO) communication satellites into the LEO satellite via ground injection. This coverage information table can be organized by high-orbit satellite number and cell number. Each cell entry includes at least the center latitude and longitude of the cell beam on the ground, the coverage radius or boundary polygon corresponding to the beam's half-power point, frequency and polarization configuration, service priority, and effective time interval. When a high-orbit relay satellite undergoes payload reconfiguration, beam replanning, or frequency reallocation, the ground control center can send a new version of the coverage information table to the satellite computer via Tianlian relay, BeiDou short message service, or existing telemetry and control links. The satellite computer then periodically broadcasts or distributes the new version to the onboard telemetry and control device via the onboard bus, ensuring that the coverage information table remains consistent with the actual non-terrestrial network configuration. Thus, low-orbit satellites no longer rely on real-time ground scheduling but possess the basic data for on-orbit autonomous decision-making. Through the fusion of real-time orbit and GNSS information, low-orbit satellites can maintain a high degree of reliability in understanding their own orbital status even under orbital maneuvers, minor disturbances, or even navigation satellite obstruction. Through a pre-stored and updatable coverage information table, satellites can quickly adapt to adjustments in the high-orbit relay network topology. In an environment with a massive number of low-Earth orbit commercial satellites, this onboard autonomous sensing capability can significantly reduce the frequency of ground scheduling and lower the complexity and cost of ground systems.

[0053] Understandably, given the trajectory of a low-Earth orbit (LEO) satellite in the Earth's reference frame and the coverage areas of each high-Earth orbit (HEO) satellite's cell beams on the Earth's surface, the problem can be abstracted into whether there is an intersection between the LEO satellite's trajectory projected onto the ground and the coverage areas of each coverage cell within a predicted future timeframe, and further, determining the time interval within which this intersection occurs. Specifically, the LEO satellite's orbit in an inertial or Earth-fixed coordinate system can be extrapolated in the short term using orbital mechanics models, while the HEO cell coverage can be considered as an approximately static or slowly changing region in the Earth-fixed system. By comparing the LEO satellite's ground point trajectory with the coverage area boundary, the start time of entering the cell's coverage area, the end time of leaving the cell's coverage area, and key link parameters such as elevation angle, propagation path length, and Doppler shift within the corresponding time intervals can be determined. This process essentially transforms spatial geometric relationships into bounded time intervals, thus providing precise timing information for subsequent early wake-up and access procedures.

[0054] For example, in implementation, a unified state vector is first established based on the current orbital parameters and GNSS status. The position and velocity of the low-Earth orbit (LEO) satellite in the inertial coordinate system are then transformed to the Earth-fixed coordinate system using the Earth's rotation model. Subsequently, starting from the current moment, the module numerically extrapolates the LEO satellite's orbit within a preset prediction time window at certain time steps, obtaining the LEO satellite's three-dimensional position for multiple future moments. For each future moment, the latitude and longitude of its projection point on the Earth's surface can be calculated, and the line-of-sight direction, elevation angle, and propagation distance relative to each high-Earth orbit (HEO) satellite can be determined. For each cell entry in the coverage information table, the geometric determination module can call a pre-stored beam coverage boundary model. By determining whether the LEO satellite's projection point falls within the cell's coverage boundary polygon, and considering factors such as whether the elevation angle of the LEO satellite pointing to the HEO satellite is higher than a preset threshold and whether the propagation path is blocked by the Earth, the module determines whether the current moment falls within the cell's effective coverage area. By performing continuous analysis on the determination results within the prediction time window, coverage markers from multiple discrete time points can be integrated into a set of continuous time periods. Each period includes entry and exit times, corresponding cell identifiers, and parameters such as predicted average elevation angle and Doppler frequency offset range. To improve computational efficiency and accuracy, the module can employ linear or higher-order interpolation methods for short-term orbital changes within the prediction time window, and use a fast point determination algorithm within a polygon using latitude and longitude coordinates for coverage boundaries. Simultaneously, for maneuver plans of low-Earth orbit (LEO) satellites, the satellite computer can inform the module of the orbital adjustment plan in advance, allowing it to consider future orbital changes during prediction and avoid coverage prediction deviations caused by orbital maneuvers. Through this method of orbit extrapolation and spatiotemporal relationship calculation, LEO satellites no longer need to perform frequent, blind frequency scanning and random access attempts at any given time; instead, they can perform targeted access within the accurately predicted coverage time period. Significantly reducing the number of scanning and access attempts by onboard telemetry, tracking, and command (TT&C) devices and minimizing the energy consumption of the radio frequency front-end during prolonged operation helps extend satellite lifespan and reduce thermal design stress. Furthermore, by using high elevation angle thresholds and obstruction conditions, inferior link segments with low elevation angles or those obstructed by Earth can be filtered out, concentrating the access process within time periods with relatively ideal link conditions, thereby improving the reliability and throughput of the TT&C link. In addition, in non-terrestrial network deployment scenarios with multiple high-orbit relay satellites and multiple cells, this unified spatiotemporal relationship calculation can provide a basis for subsequent high-orbit satellite selection and cell handover strategies, enabling the satellite to achieve more flexible resource scheduling based on predicted coverage overlap, service priorities, and estimated load.

[0055] Understandably, after obtaining the entry and exit times of each cell's coverage over a future period, the key is to wake up the space-based telemetry, tracking, and command (TT&C) equipment and execute the access procedure within a suitable lead time. This requires allowing sufficient time margin from when the equipment switches from energy-saving standby mode to operating mode and completes necessary frequency calibration, time synchronization, and cell search, to when access establishment is complete. If the wake-up is too late, the low-Earth orbit satellite may have already flown out of the cell's coverage area before completing the access procedure, resulting in access failure; if the wake-up is too early, valuable power and processing resources will be wasted. Therefore, based on the calculated coverage entry time, combined with the equipment's own access procedure latency statistics and current service requirements, an appropriate lead time is set to accurately translate the prediction-driven approach into the access procedure's start time, thereby completing the TT&C and data relay tasks within the limited cell dwell time.

[0056] For example, the spaceborne telemetry, tracking, and command (TT&C) device can be equipped with an access scheduling and power management module. This module periodically reads the list of future coverage time periods provided by the aforementioned orbit extrapolation module. For each upcoming effective coverage time period, the access scheduling module can select one or more coverage time periods as the target access window based on the current onboard task queue, the amount of downlink telemetry data to be accessed, the uplink command window requirements, and the service priority of the high-orbit satellite cell. The access scheduling module pre-estimates the time required to complete one cell search, broadcast channel interpretation, random access initiation, connection establishment, and initial TT&C data transmission based on the device's historical access statistics, and adds a certain safety margin to this time as the early wake-up time. When the early wake-up time is reached, the power management module controls the RF front-end, baseband processor, and related control logic to switch from a low-power standby state to an operating state. At the same time, the carrier frequency and local oscillator system begin to stabilize, and the onboard clock and the high-orbit satellite system time are initially aligned using previous synchronization information. When the access process officially begins, the cell search module searches for pilot signals or synchronization signals in the target frequency band based on the frequency and cell identifier in the coverage information table, quickly locks the target cell, and completes synchronization. Subsequently, the device reads the system information block sent by the high-orbit satellite, confirms the service configuration and access restrictions of the current cell, and then initiates a random access request according to the access procedures of the non-terrestrial network. This completes steps such as identity recognition and resource allocation, establishing a stable inter-satellite telemetry, tracking, and command (TT&C) and data relay link. Throughout the entire dwell time, the spaceborne TT&C device can dynamically adjust the transmission strategy of TT&C data based on real-time link quality, task queue length, and estimated remaining dwell time. For example, it can prioritize sending telemetry data with longer dwell times, prioritize receiving emergency commands, or perform large-scale payload scientific data transmission when link quality is good. When it detects that the coverage period is about to end, or the link quality drops below a preset threshold, the device can orderly release link resources, complete cached data organization, gradually shut down radio frequency and high-power modules, and re-enter standby mode, waiting for the next predicted coverage window. For areas with overlapping coverage from multiple high-orbit satellites, the scheduling module can also prepare for cell handover in advance, based on the overlap of coverage periods and the service priorities of each cell, in scenarios where the current cell's dwell time is about to end and another target cell is about to enter coverage, to maintain the continuity of the TT&C link. Through this prediction-driven early wake-up and access process control, in terms of power consumption, the spaceborne space-based telemetry and control device no longer needs to keep the radio frequency and baseband modules in a full-time operating state for extended periods. Instead, it only needs to be activated for short periods when effective coverage is expected, thus significantly reducing average power consumption. Regarding access reliability, multiple orbit simulations and historical statistics can continuously correct the early wake-up time and access process delay model.In terms of resource scheduling and multi-objective management, when there are hundreds or even thousands of low-Earth orbit (LEO) satellites in a constellation, the ground system can provide only the service priority strategy for each satellite and the overall configuration of the high-Earth orbit (HEO) relay network, without needing to generate precise orbit-by-orbit ground telemetry and control plans for each LEO satellite. Each LEO satellite autonomously determines onboard when and in which coverage cell to initiate access through this scheme, thus forming a distributed, autonomous non-terrestrial network telemetry and control system, reducing ground scheduling pressure and improving the overall system scalability. Overall, it can fully utilize the real-time position and orbit information provided by LEO satellite attitude and orbit control and GNSS to perform high-precision prediction of its own orbital motion onboard; moreover, through a pre-stored and updatable HEO satellite coverage information table, the topology and cell configuration of the space-based non-terrestrial network can be explicitly modeled onboard; in addition, by using orbit extrapolation and geometric determination methods, spatial coverage relationships are transformed into a series of specific time windows, and the wake-up and access process of the onboard space-based telemetry and control devices can be precisely controlled according to the equipment access latency and service requirements. Compared to traditional telemetry, tracking, and command (TT&C) modes that rely solely on ground stations or simple onboard timed wake-up methods, this solution eliminates the need for a large-scale global ground station network and complex orbit-by-orbit planning for each satellite. Instead, it enables each LEO satellite to achieve autonomous TT&C access within a known high-orbit relay network structure. This approach significantly reduces the construction and maintenance costs of ground infrastructure for the TT&C system. Furthermore, its prediction-driven wake-up mechanism improves energy efficiency and link utilization, and it can quickly adapt to dynamic changes in the high-orbit satellite network topology. This makes it highly suitable for the space-based TT&C needs of future large-scale commercial LEO constellations.

[0057] In some examples, it also includes:

[0058] Based on the calculated spatiotemporal relationship, predict the current serving cell signal attenuation trend and the timing of the target cell's appearance;

[0059] When the signal quality of the current serving cell is detected to drop to a predetermined threshold and the signal strength of the target cell continues to rise, a cell handover trigger command is generated to wake up the cell handover process in advance.

[0060] For example, predicting the signal attenuation trend of the current serving cell and the timing of the target cell's appearance based on the calculated spatiotemporal relationship can be understood as superimposing channel quality trend prediction on geometric prediction. Specifically, after obtaining the coverage time interval, elevation angle change curve, and relative motion relationship corresponding to the current serving cell and the candidate target cell, the spaceborne telemetry and control device uses geometric quantities such as propagation path length, elevation angle descent rate, and Doppler frequency shift change rate, combined with historically measured downlink signal quality indicators of the serving cell, such as received signal strength, signal-to-noise ratio, and bit error rate statistics, to predict the signal attenuation trend of the current serving cell over the next few days by fitting a model or empirical curve, and simultaneously calculates the approximate time when the target cell beam center sweeps across the line of sight of the current low-orbit satellite. In implementation, a statistical model can be maintained on-board to show how the serving cell's signal quality changes with elevation angle and path length. For example, during multiple orbits, the probability and time required for the signal quality to drop to a threshold when the elevation angle is below a certain range can be recorded. The orbit extrapolation module can predict that the serving cell's signal will enter a rapid attenuation phase when it calculates that the elevation angle will remain below this range at a certain future moment. Similarly, for the target cell, the approximate time interval for the target cell's pilot or synchronization signal to go from undetectable to detectable and finally stable and usable can be estimated based on the change in the angle between its beam center direction and the low-Earth orbit satellite position over time. Through this prediction method combining geometry and statistics, the system no longer relies solely on a single instantaneous measurement of signal strength but instead understands the temporal relationship between the weakening of the serving cell and the strengthening of the target cell in advance. This allows sufficient decision-making and preparation time for subsequent smooth cell handover, thereby reducing the risk of link interruption caused by sudden signal drops.

[0061] For example, the step of generating a cell handover trigger command and prematurely waking up the cell handover process when the signal quality of the current serving cell drops to a predetermined threshold and the signal strength of the target cell continues to rise is an intelligent decision based on conditional triggering, superimposed on the aforementioned trend prediction. In specific implementation, the spaceborne telemetry and control device can continuously monitor the signal quality of the current serving cell during operation and compare it with pre-set thresholds and trend prediction results: when the received signal strength or signal-to-noise ratio of the serving cell approaches and falls below the threshold for several consecutive sampling periods, and based on orbital extrapolation and coverage information tables it is determined that the target cell has entered or is about to enter the visible area, and pilot detection or synchronization signal measurement confirms that the target cell signal shows a stable upward trend in the recent period, the system generates a cell handover trigger command, prematurely waking up the cell handover process before the existing link is completely lost. The cell handover process includes waking up the target cell access module, pre-loading the system information configuration of the target cell, pre-allocating buffer space during the handover period, and calling the security and authentication module to prepare for rapid identity verification in the new cell. This allows the low-orbit satellite to complete some necessary preparatory work while the serving cell link quality can still maintain basic communication. In this way, when the serving cell signal further weakens to the point where it is no longer suitable for carrying high-reliability telemetry and control communication, the system can quickly complete the handover from the serving cell to the target cell, avoiding the interruption of dropping the connection first and then reconnecting. Through this condition-triggered and early-wake-up cell handover strategy, on the one hand, it can effectively suppress handover caused by instantaneous signal fluctuations, and on the other hand, it can complete the connection migration before the serving cell inevitably fails, significantly reducing the probability of link interruption. In scenarios where a large number of low-Earth orbit constellations are operating simultaneously and high-Earth orbit relay resources are scarce, the overall stability and resource utilization efficiency of the space-based telemetry and control network are improved.

[0062] In some examples, the spaceborne telemetry, tracking, and command (TT&C) device includes at least two non-terrestrial network modules, and the cell handover process includes:

[0063] The first non-terrestrial network module will continue to maintain existing service transmission within the current serving cell to ensure the continuity of data flow;

[0064] The second non-terrestrial network module is woken up and instructed to complete downlink synchronization, system message decoding, random access procedure and service channel establishment on the frequency point of the target cell.

[0065] In some examples, it also includes:

[0066] If the second non-terrestrial network module successfully establishes a service channel in the target cell, a data stream handover operation is performed:

[0067] Switch the uplink data routing and downlink data receiving source from the first non-terrestrial network module to the second non-terrestrial network module;

[0068] After confirming that the new link service transmission is stable, the control system instructs the first non-terrestrial network module to initiate a connection release process, normally disconnect from the network and enter an idle listening state, completing the entire soft handover process.

[0069] For example, the first non-terrestrial network module and the second non-terrestrial network module are configured as independent radio frequency and baseband processing channels, respectively. They are uniformly scheduled on the satellite through the satellite service computer or payload management unit to achieve continuous telemetry and control, similar to establishing a new link and then releasing the old link. When executing the cell handover process, the scheduling strategy first keeps the first non-terrestrial network module in the current serving cell to maintain existing service transmission. It uses the already stably established inter-satellite link as the anchor link. While the signal quality of the serving cell is still within an acceptable range, it continues to carry service data such as telemetry downlink, command uplink, and payload data transmission, thereby ensuring that the data flow will not be interrupted during the handover preparation phase because the new link has not yet been established. In practice, after detecting that the handover triggering conditions are met, the onboard scheduling software marks the service queue currently carried by the first non-terrestrial network module as in hold mode, prohibiting new cell searches or handover actions on this module. It only continues to send buffered data packets and receive telemetry and control commands according to the established scheduling strategy. At the same time, it performs fine-grained monitoring of the link quality of this module. When short-term channel fluctuations are detected, it buffers link degradation through retransmission, coding adjustment, or service priority adjustment, so that the serving cell link remains available as much as possible before the handover is completed. While maintaining the stable operation of the first non-terrestrial network module, the onboard scheduling module wakes up the second non-terrestrial network module, which was previously in a low-power or idle state, and instructs the second non-terrestrial network module to complete downlink synchronization, system message decoding, random access procedures, and service channel establishment on the frequency point of the target cell. Through the onboard dual-module architecture, a true uninterrupted handover is achieved. In practice, when the orbit and coverage prediction module provides the expected availability time window for the target cell and the handover triggering conditions are met, the power management unit first supplies power to the second non-terrestrial network module and starts its local oscillator and RF front-end, enabling it to reach frequency stability and power amplifier readiness in a short time. Subsequently, the baseband processing unit configures the receiver according to the parameters such as frequency point, bandwidth, and frame structure recorded in the target cell coverage information table, performs pilot or synchronization sequence acquisition and tracking on the target cell frequency point, completes downlink timing and frequency offset correction, and then decodes the system message broadcast by the high-orbit relay satellite to obtain the random access configuration, resource allocation rules, and access restrictions of the cell. After obtaining the system information, the second non-terrestrial network module initiates a random access procedure according to the non-terrestrial network access protocol, completes the preamble transmission, response reception, identity verification, and initial resource allocation processes, and establishes an initial service bearer connection on the allocated uplink and downlink service channels.At this point, even if the first non-terrestrial network module continues to transmit data in the old cell, the second non-terrestrial network module has already established a backup service channel in the target cell. Before the scheduling module confirms that the target cell link is stable and the signal quality of the serving cell deteriorates to the point where it cannot meet service requirements, the data queue can be redirected internally on the satellite, gradually migrating the new telemetry and data transmission services to the target cell link carried by the second non-terrestrial network module. Finally, after the service migration is completely completed, the old cell connection of the first non-terrestrial network module is released in an orderly manner and enters standby mode. This switching process through parallel operation of dual modules makes the entire cell switching process almost transparent to upper-layer services. In commercial low-Earth orbit constellation scenarios with multi-task concurrency and high real-time requirements, it can significantly reduce the probability of telemetry and control interruptions and data packet loss caused by cell switching. At the same time, by waking up the second module on demand, it avoids the power consumption burden caused by full-time dual-mode operation, ensuring link continuity while taking into account energy utilization efficiency.

[0070] To address the significant Doppler effect caused by the high-speed relative motion between low-Earth orbit and high-Earth orbit satellites, some examples also include:

[0071] Based on the real-time acquired orbital parameters and three-axis velocity vectors of the low-orbit satellite, the accurate ephemeris data of the high-orbit relay satellite, the relative geometric position and radial velocity components of the two satellites, and the carrier frequency and sampling clock characteristics, the theoretical frequency offset prediction value is calculated in real time using the Doppler frequency shift calculation method. The theoretical frequency offset prediction value includes the magnitude and the trend of change.

[0072] Frequency offset pre-compensation is performed based on the calculated theoretical frequency offset prediction value;

[0073] The compensation effect is evaluated by real-time monitoring of key physical layer indicators, and feedback adjustments are made based on the compensation effect.

[0074] The theoretical frequency offset prediction can be calculated in real time using the Doppler frequency shift calculation formula: Δf = (v·cosθ / c)·f0, where v is the relative radial velocity, θ is the angle between the velocity vector and the connecting line, c is the speed of light, and f0 is the carrier center frequency. The compensation effect can be evaluated by real-time monitoring of key physical layer indicators, including the stability of the reference signal received power (RSRP); signal-to-noise ratio (SNR) and carrier interference-to-noise ratio (CINR); bit error rate (BER) and block error rate (BLER) statistics; and the trend of timing advance (TA). The built-in autonomous Doppler frequency shift prediction and compensation algorithm based on accurate ephemeris can estimate and compensate for the huge and rapidly changing frequency offset caused by the high-speed relative motion between low-Earth orbit (LEO) and high-Earth orbit (HEO) satellites in real time. This solves the key technical challenges of cell search, synchronization, and signal demodulation in high-dynamic environments, ensuring link stability and communication success rate.

[0075] In some examples, the frequency offset pre-compensation based on the calculated theoretical frequency offset prediction value includes:

[0076] In the transmission link, the pre-compensation value is superimposed on the baseband digital up-conversion module to correct the transmission frequency in advance;

[0077] In the receiving link, the local oscillator of the downlink demodulator is controlled to perform frequency pre-correction;

[0078] Fine-tuning the sampling clock frequency compensates for the effects of timing deviations;

[0079] The method of evaluating the compensation effect by real-time monitoring of key physical layer indicators, and then adjusting based on the compensation effect, includes:

[0080] When abnormal link quality indicators are detected, the frequency offset estimation error is automatically calculated.

[0081] The parameter weights of the prediction algorithm are dynamically adjusted based on the magnitude and direction of the error.

[0082] Update the compensation value lookup table to optimize subsequent prediction accuracy.

[0083] Understandably, in scenarios where low-Earth orbit (LEO) satellites use high-Earth orbit (HEO) relay satellites for space-based telemetry, tracking, and command (TT&C) and data transmission, the high-speed relative motion between the LEO and HEO satellites, with its rapidly changing direction and speed, causes a significant and rapidly varying Doppler frequency shift in the frequency observed by the receiver. Without precise prediction and pre-compensation, the receiver must scan and track over an extremely wide frequency offset range during cell search, downlink synchronization, carrier recovery, and signal demodulation. This not only significantly extends the acquisition time but also makes synchronization easily lost at the edge of link conditions, severely impacting the stability of the TT&C link and its service carrying capacity. Therefore, by introducing an autonomous Doppler prediction calculation module based on accurate ephemeris and three-axis velocity into the spaceborne telemetry and control device, the theoretical frequency offset prediction value can be calculated in real time using information such as orbital parameters, high-orbit ephemeris, relative geometry of the two satellites, and carrier frequency. At the same time, the prediction value can be corrected and adaptively adjusted by combining physical layer feedback indicators. Frequency offset pre-compensation can be applied in advance on the transmit and receive channels, so that the receiver can complete cell search and signal demodulation within a narrow residual frequency offset range. This fundamentally solves the access difficulties and increased bit error rate caused by rapid frequency offset changes in high dynamic environments.

[0084] For example, the spaceborne telemetry, tracking, and command (TT&C) device is equipped with a set of high-precision orbit and relative motion calculation units. These units periodically read the orbital elements, position coordinates, and three-axis velocity vectors of the current low-Earth orbit (LEO) satellite from the attitude and orbit control subsystem, and simultaneously retrieve precise ephemeris data of the high-Earth orbit (HEO) relay satellite stored on the onboard computer. Within each calculation cycle, the calculation unit first calculates the difference between the position vectors of the LEO and HEO satellites in a unified reference coordinate system to obtain the vector connecting the HEO satellite to the LEO satellite. It then calculates the projection of the LEO satellite's velocity vector onto this connecting line, thus obtaining the relative radial velocity component v. Subsequently, it calculates the angle θ between the velocity vector and the connecting line vector, and uses the Doppler frequency shift formula Δf = (v·cosθ / c)·f0 to calculate the theoretical frequency offset prediction for the current moment, where c is the speed of light and f0 is the carrier center frequency of the uplink or downlink used. Considering that the onboard sampling clock is not ideally drift-free, the calculation unit can also superimpose a term for the local oscillator and sampling clock frequency errors estimated by the clock characteristic model when calculating the theoretical frequency offset. This ensures that the predicted value simultaneously reflects the geometric Doppler component and the frequency offset introduced by the clock. Within a short prediction window, the calculation unit can use low-Earth orbit satellite orbit and high-Earth orbit satellite ephemeris data to perform multi-time extrapolation, generating a sequence of frequency offset changes over time. This provides not only an instantaneous frequency offset value but also its trend and rate of change, which can guide subsequent pre-compensation stepping strategies and receiver tracking bandwidth design.

[0085] For example, the spaceborne telemetry and control device sets up programmable frequency control units in both the radio frequency (RF) and baseband links. On the transmission path, by adjusting the local oscillator frequency or the digital up-conversion parameters before digital-to-analog conversion, the center frequency of the transmitted signal is offset according to the theoretical frequency offset prediction value. This makes the actual carrier frequency observed at the high-orbit relay satellite receiver closer to its nominal value, thereby reducing the locking pressure on the receiving receiver. On the receiving path, the digitally controlled oscillator in the digital down-conversion module pre-offsets the frequency of the locally sampled signal, ensuring that after pre-compensation, the residual frequency offset falls within a preset narrowband range. The receiver's acquisition and tracking loop only needs to operate within this residual range. In implementation, the spaceborne device can send the calculated theoretical frequency offset prediction value to the local oscillator control module and the baseband digitally controlled oscillator control module within each Doppler calculation cycle. The control modules calculate the target setpoint value of the local oscillator frequency or digital mixing frequency for the next period based on the magnitude and trend of the prediction value, and smoothly adjust it according to a predetermined step size or interpolation rule to avoid phase abrupt changes or loop instability caused by excessively rapid frequency jumps. For spaceborne devices that employ multi-carrier or multi-band parallel operation, separate predicted frequency offset values ​​and compensation parameters can be maintained for different frequency bands to ensure that each signal can receive targeted pre-compensation under multi-frequency link conditions, thereby improving the overall robustness of the inter-satellite link.

[0086] For example, the spaceborne telemetry, tracking, and command (TT&C) device continuously collects and statistically analyzes multiple physical layer performance indicators in the receiver baseband and demodulation modules, including the stability of the reference signal received power, the instantaneous and average values ​​of the signal-to-noise ratio (SNR) and carrier-to-interference-plus-noise ratio (CNR), the sliding statistics of the bit error rate (BER) and block error rate (BOR), and the changing trend of the timing advance. Within each compensation cycle, the system compares the current physical layer indicators with those under uncompensated or historical compensation configurations to determine whether the current theoretical frequency offset prediction and pre-compensation strategy are sufficiently accurate and whether there are still significant residual frequency offsets or offset errors. For instance, if, after pre-compensation using a set of predicted frequency offset values, the reference signal received power and carrier-to-interference-plus-noise ratio are observed to be stable, but the BER and BOR are still significantly high, and the timing advance estimation shows periodic oscillations, it indicates that the residual frequency offset is still large or the frequency offset change trend estimation is biased. The system can infer the frequency offset correction direction based on the BER gradient and the changing direction of the timing advance, and apply fine-tuning to the current theoretical frequency offset prediction value, forming a process similar to a small-step search or adaptive correction. To suppress the interference of short-term fading and random noise on the judgment, the feedback adjustment module can apply moving average or weighted filtering to physical layer indicators. The theoretical frequency offset is only adjusted when a certain indicator continuously deteriorates or improves over multiple observation periods, thus avoiding frequent changes in compensation parameters under fast channel fading conditions that could lead to system instability. In practical scenarios, a comprehensive scoring curve for the compensation effect can be set, summarizing the reference signal received power, signal-to-noise ratio, carrier interference-to-noise ratio, and block error rate into a single performance score with different weights. When the score is better than a preset threshold for a continuous period, it indicates that the current prediction and compensation strategy is reasonable, and the system maintains the existing parameters. When the score falls below a certain threshold and shows a deterioration trend, the system corrects the offset of the frequency offset prediction model or adjusts the parameters based on the residual frequency offset estimation and the direction of performance indicator changes. This achieves a closed-loop adaptive optimization process based on physical layer feedback, thus maintaining high accuracy and robustness of frequency offset compensation under different orbital positions, different high-orbit relay satellites, and different temperatures and aging conditions.

[0087] It should be noted that a complete Doppler frequency shift processing strategy is constituted by accurate theoretical prediction, pre-frequency offset compensation, and feedback correction based on physical layer indicators. This strategy significantly improves the success rate of cell search, synchronization, and signal demodulation in non-terrestrial networks under highly dynamic low-Earth orbit to high-Earth orbit inter-satellite link environments. Compared with the traditional method of simply using wideband acquisition and high-bandwidth phase-locked loops to hard-count the frequency offset within the receiver, this scheme reduces the dominant part of the Doppler frequency offset before frequency offset compensation. This allows the receiver to track within a narrow range, thereby reducing acquisition time and tracking error, and minimizing the impact of loop noise on phase and frequency estimation.

[0088] In real-world commercial scenarios, the beam planning and ephemeris of high-orbit relay satellites are not static. Commercial operators reconfigure the beam layout based on service hotspots, and high-orbit satellites may undergo slight drift control or orbit maintenance maneuvers. The process of updating the coverage information table to the satellite may be delayed or partially lost. In this case, low-orbit satellites, based on older versions of coverage information tables and ephemeris, calculate a time window for entering a target cell that is geometrically inaccurate. Waking up the cell search module according to the predicted time fails to find the expected pilot signal, and by the time a usable cell becomes available, the optimal access opportunity has already been missed. The system then attributes the failure to a deviation in a specific coverage window. Based on this, some examples also include:

[0089] In the process of waking up in advance and initiating cell search and access control according to the spatiotemporal relationship, if no target cell pilot signal or synchronization signal corresponding to the pre-stored high-orbit satellite coverage information table is detected within the predicted target high-orbit satellite cell coverage time window, the occurrence time of the prediction failure event, the orbital position and attitude state of the low-orbit satellite to which it belongs, and the actual detected other cell signals are recorded as abnormal samples.

[0090] When the number of abnormal samples reaches a preset number, based on the difference between the predicted target cell and the actual detected cell in each abnormal sample, the pre-stored high-orbit satellite coverage information table is statistically analyzed to estimate the systematic azimuth offset, coverage boundary shrinkage or expansion of the current high-orbit satellite or corresponding cell, and coverage correction parameters are generated.

[0091] When calculating the spatiotemporal relationship between the low-orbit satellite and the cell coverage area, the coverage correction parameters are superimposed on the cell geometric model corresponding to the pre-stored high-orbit satellite coverage information table to form on-board corrected cell coverage information, thereby improving the accuracy of cell coverage prediction and access success rate without relying on real-time ground updates.

[0092] Understandably, this means that even if the high-orbit relay network planning drifts slowly and the ground does not issue new tables in a timely manner, low-orbit satellites can still learn to adjust the prediction window back to the actual visible area; and in commercial constellation scenarios lacking continuous ground intervention, it can significantly improve the long-term robustness and self-repair capability of the entire space-based telemetry and control system.

[0093] In large-scale low-Earth orbit (LEO) constellations, satellites on multiple orbital planes may simultaneously cross the edge region of the same high-Earth orbit (HEO) cell. Because they use similar coverage prediction algorithms, many satellites initiate cell search and random access procedures at almost the same time. This results in an access storm on the HEO cell's random access channel, with a large number of LEO satellites simultaneously launching, causing severe collisions in the access preamble. From a single satellite's perspective, only a slightly higher number of random access failures is observed, making it difficult to recognize that this is a systemic problem caused by constellation-level multi-satellite synchronization. Therefore, in some examples, after predicting the coverage area of ​​the target HEO satellite based on the aforementioned spatiotemporal relationship and waking up the onboard space-based telemetry and control device in advance, the process also includes:

[0094] Obtain the constellation structure identification information of the low-Earth orbit satellite, wherein the constellation structure identification information includes one or more of the following: orbital plane number, right ascension of the ascending node, or satellite number;

[0095] Based on the constellation structure identification information and the predicted target cell available time window, the access start time offset of this satellite for the target cell is calculated according to the preset mapping function, so that the random access start time of low-Earth orbit satellites with different orbit planes or different numbers within the same target cell coverage window is distributed on the time axis.

[0096] Taking into account the time offset, the spaceborne telemetry, tracking and command (TT&C) device initiates cell search, random access, and service channel establishment at the access start time after the offset, thereby reducing the collision probability of random access preambles in the same high-orbit cell at the constellation scale and mitigating the impact of access storms on non-terrestrial network relay resources.

[0097] Understandably, this can fundamentally reduce the high incidence of collisions caused by large-scale synchronous random access within the same cell, without requiring centralized ground scheduling. It can fully utilize orbital parameters and constellation structure information to achieve prediction-driven decorrelation, rather than simple random backoff.

[0098] Many commercial low-Earth orbit satellites simultaneously carry high-power payloads, such as synthetic aperture radar, imaging radar, high-power broadband downlink transmitters, and certain pulsed excitation sources. These payloads generate their own radio frequency leakage during operation, contaminating the front-end of the space-based telemetry, tracking, and command (TT&C) module and impacting the onboard power bus and electromagnetic environment, causing significant fluctuations in the front-end noise and gain of the TT&C receiver. If only the external space environment and Doppler dynamics are considered, ignoring the systematic disturbances to TT&C performance caused by the operating schedules of other onboard payloads, abnormal instability in the TT&C link may occur within certain mission windows, yet the cause may be difficult to discern through external link analysis. Therefore, in some examples, this also includes:

[0099] Obtain payload schedules associated with high-power payloads on the respective low-Earth orbit satellite platform from the satellite computer. These payload schedules at least describe the start-up time, stop time, and corresponding power level of each high-power payload.

[0100] The coverage time slices of each target high-orbit satellite cell calculated based on the orbital parameters, GNSS positioning information and high-orbit satellite coverage information table are cross-compared with the payload working time table. Cell coverage time slices that highly overlap with the working time of high-power payloads are marked as telemetry and control silent risk time slices, and cell coverage time slices that are in silent or low-power state with high-power payloads are marked as priority telemetry and control time slices.

[0101] When scheduling telemetry and control missions, priority is given to arranging critical instruction injection and large-volume data transmission within the priority telemetry and control time slot. For telemetry and control services that need to maintain the link within the telemetry and control silent risk time slot, the coding redundancy, transmission power margin, and buffer capacity of the spaceborne space-based telemetry and control device are increased in advance, provided that the risks are known in advance, in order to reduce the impact of electromagnetic interference and power fluctuations generated by high-power loads on the stability of the space-based telemetry and control link.

[0102] Understandably, this explicitly introduces the onboard electromagnetic compatibility issues into the space-based telemetry, tracking, and command (TT&C) scheduling process, ensuring that the TT&C link still has controllable performance expectations during the high-power payload operation period. For typical high-interference payloads such as synthetic aperture radar, this can significantly reduce abnormal disconnections and sudden increases in bit error rate of the TT&C link.

[0103] Under certain orbital configurations and high-orbit beamouts, some low-orbit satellite trajectories may exhibit telemetry and control (TT&C) gaps that do not overlap with the cells of any high-orbit relay satellites. Alternatively, while geometrically visible, these gaps may be too low in elevation or have extremely poor link quality, making them unsuitable for critical TT&C operations. Even if mission planning aims to avoid scheduling critical operations in these areas, such gaps may still inevitably appear in certain orbital segments after unforeseen missions or orbital adjustments. Therefore, in some examples, this also includes:

[0104] Based on the orbital parameters of the low-orbit satellites and the coverage information table of high-orbit satellites, the visibility of high-orbit cells within the preset prediction time range is analyzed to identify the control and measurement gaps within the prediction time range where there is no coverage of any high-orbit satellite cells or only cell coverage with an elevation angle lower than the preset threshold.

[0105] Before the detection of entering the telemetry and control window period, the system obtains the identity information and available telemetry and control capacity information of at least one proxy satellite with continuous high-orbit cell coverage capability during the telemetry and control window period through the inter-satellite link between the satellite and other low-orbit satellites in the same constellation, and establishes an inter-satellite telemetry and control forwarding session with the proxy satellite.

[0106] Before entering the telemetry and control window period, the planned telemetry and control instructions and necessary task configurations for the low-Earth orbit satellites are pre-sent to the proxy satellites through the high-Earth orbit satellite cells, and the proxy satellites forward them to the low-Earth orbit satellites through inter-satellite links during the telemetry and control window period.

[0107] When the low-orbit satellite generates telemetry data or health status information and is within the telemetry and control window period, the telemetry data is sent to the proxy satellite via the inter-satellite link. The proxy satellite then forwards the data to the ground telemetry and control center within its own high-orbit cell coverage time slot. This ensures that effective telemetry and control capabilities for the low-orbit satellite are maintained even when there are natural blind spots in the coverage of high-orbit relay satellites.

[0108] Understandably, in a space-based telemetry, tracking, and command (TT&C) system composed of low-Earth orbit (LEO) satellites and high-Earth orbit (HEO) relay satellites, due to limitations in orbital configuration and HEO beam layout, certain orbital segments inevitably have time intervals with no HEO cell coverage, or where, although geometrically visible, the elevation angle is too low and the link quality is extremely poor. If TT&C is still forcibly relied upon for these time intervals, it often results in access failures, frequent link interruptions, or even the inability to issue critical commands. Therefore, the usual approach is to avoid these segments during mission planning or to fill the gaps by expanding ground stations. This solution, however, utilizes the inter-satellite links within the constellation to identify the upcoming TT&C gaps for the LEO satellites in advance. Before entering these gaps, an inter-satellite TT&C relay relationship is established with proxy satellites within the constellation that have continuous HEO coverage capabilities. Planned commands and mission configurations are pre-issued to the proxy satellites. During the gaps, commands and telemetry data are relayed between the LEO satellites and the proxy satellites via inter-satellite links. The proxy satellites then handle the interaction with the ground and HEO relays, thus maintaining effective TT&C capabilities for the LEO satellites even when there are natural blind spots in relay coverage.

[0109] For example, the spaceborne telemetry, tracking, and command (TT&C) device first obtains the orbital elements, three-dimensional position, and three-dimensional velocity information of the current low-Earth orbit (LEO) satellite from the attitude and orbit control subsystem and the GNSS receiver. Combined with the coverage information table of high-Earth orbit (HEO) relay satellites pre-stored or updated by the spaceborne computer, it numerically extrapolates the satellite positions for a predetermined prediction time window within a unified Earth-fixed coordinate system. For each time sampling point within the prediction window, the device calculates the line-of-sight direction, elevation angle, and propagation path length of the LEO satellite relative to each HEO relay satellite. Then, it calls upon parameters such as the beam center, boundary polygon, and service elevation angle threshold of each HEO cell in the coverage information table to determine whether the time point falls within the effective coverage area of ​​any HEO cell. By continuously analyzing the determination results throughout the entire time window, time intervals without any effective cell coverage can be marked as absolute TT&C gap periods. Simultaneously, time intervals where geometric coverage exists but the elevation angle remains below the predetermined threshold and the link budget margin is negative or extremely low are marked as low-elevation-angle TT&C risk periods. Furthermore, the system can categorize the two types of time periods mentioned above into a unified "telemetry and control gap" period based on the mission's requirements for link quality, and record the corresponding start and end times and associated orbital positions. In this way, this solution proactively reveals telemetry and control blind spots—which traditional solutions often only discover after the fact through post-mission statistics—from the perspectives of orbital geometry and link budget. This lays a temporal and spatial foundation for subsequent satellite relay scheduling, enabling early detection of unavailable telemetry and control segments and avoiding blindly relying on high-orbit relay links during these periods, thus improving the predictability of mission planning.

[0110] For example, when the spaceborne telemetry, tracking, and command (TT&C) device identifies a future time period as a TT&C window, it will initiate a proxy selection process while there is still a certain time margin before the start of the window. This process first obtains a list of other currently reachable low-Earth orbit (LEO) satellites within the constellation through the inter-satellite link management module. This list includes each satellite's orbital plane number, current orbital position, and a description of its future high-Earth orbit (HEO) coverage capabilities broadcast in the inter-satellite control plane, such as the visible time periods of each HEO cell and the TT&C capacity reserved for relay services. Subsequently, the LEO satellite broadcasts its own TT&C window information to reachable neighboring satellites, requesting candidate proxy satellites to report their HEO relay coverage status and available TT&C resources within that time period. Each candidate proxy satellite then calculates the available cell coverage window within that time period based on its own orbital parameters and HEO coverage information table, and reports the amount of TT&C commands and telemetry data it can carry. Based on feedback from candidate proxy satellites, the primary satellite prioritizes selecting a satellite with available high-orbit coverage and sufficient available telemetry and control capacity throughout the entire telemetry and control (TT&C) gap as the first proxy satellite. If no single satellite meets the criteria, two or more proxy satellites can be selected to collaboratively handle the task through time-sharing or load-sharing methods. After proxy selection, the primary satellite establishes a dedicated TT&C relay session with the proxy satellite via inter-satellite links, agreeing on session identifiers, encryption and authentication parameters, and buffering strategies for secure and stable relay of TT&C data during subsequent gaps. This process creates a distributed resource coordination mechanism within the constellation, mitigating the TT&C blind spots of individual satellites at the constellation level. Even if a satellite lacks high-orbit relay coverage in a local orbital arc, as long as other satellites with relay capabilities exist in the constellation during that period, proxy TT&C support can be provided via inter-satellite links, thus improving the overall robustness of the system.

[0111] For example, after the selection of the proxy satellite and the establishment of the inter-satellite telemetry and control relay session, the ground control center, while the affiliated low-Earth orbit satellite is still within the period covered by high-Earth orbit relays, uses the existing high-Earth orbit cell link to batch-distribute mission plans, orbital maneuvering commands, payload configuration parameters, and safety control strategies for the affiliated satellite for a period afterward to the proxy satellite, instead of immediately distributing them all to the affiliated satellite itself. Upon receiving these planned telemetry and control commands and mission configurations, the proxy satellite categorizes and stores them according to mission effective time and priority, and maintains a proxy distribution queue list in its satellite operation logic. This queue indicates when to forward which commands to the affiliated satellite via the inter-satellite link during the telemetry and control window period. When the affiliated low-Earth orbit satellite enters the telemetry and control window period and cannot establish a reliable telemetry and control link with any high-Earth orbit cell, the proxy satellite, according to a preset schedule and the real-time execution status feedback from the affiliated satellite, forwards these pre-stored commands and configurations one by one or in batches via the inter-satellite link. This allows the affiliated satellite to still complete critical operations such as attitude adjustment, payload switching, and observation mode switching as planned, even without direct ground and high-Earth orbit relay communication. Because commands are buffered in advance at the proxy satellite, the ground has already completed the deployment of critical tasks before the telemetry and control window occurs, thus significantly reducing the risk of mission interruption due to the inability to issue commands in a timely manner during the window. This transforms the telemetry and control mode, which must rely on the ground in real time, into a flexible mode that can be injected in advance and forwarded mid-course through a proxy, providing a temporal buffer layer to address insufficient high-orbit coverage or shortages of relay resources.

[0112] For example, during the telemetry and control (TT&C) gap period, the satellite's operational and payload systems continue to generate a large amount of telemetry data and health status reports, such as power supply voltage, battery state of charge, attitude controller output, temperature sensor readings, and payload operating parameters. Traditionally, this data cannot be directly transmitted during the gap period and must be temporarily stored in the satellite's limited buffer space. If the gap is too long, it may lead to buffer overflow and overwriting of historical data. In this solution, after entering the TT&C gap period, the satellite, according to a pre-agreed forwarding strategy with the proxy satellite, packages the real-time telemetry and health information into multiple frames of inter-satellite link data and sends them to the proxy satellite through the established inter-satellite TT&C forwarding session. After receiving and verifying these data packets, the proxy satellite stores them in its proxy buffer and adds necessary timestamps and source satellite identifiers to each batch of forwarded data. After the proxy satellite enters its high-orbit coverage time slot and successfully establishes links with the high-orbit relay satellite and the ground control center, it forwards the cached telemetry data to the ground via the space-based telemetry link. This allows the ground control center to obtain information on the status evolution of its satellites during the hiatus within a reasonable time delay. On the one hand, this enables ground operators to adjust subsequent tasks and risk response strategies in a timely manner based on status changes during the hiatus. On the other hand, if an abnormal event occurs during the hiatus, such as attitude instability or power failure, the proxy forwarding mechanism can report the anomaly to the ground as early as possible, without waiting for the satellite to re-enter the high-orbit coverage area before reporting it all at once. Therefore, by fully utilizing inter-satellite links to relieve the pressure on the satellite's local storage and maintaining near real-time awareness of the satellite's health status in coverage blind spots, the security and reliability of the entire non-terrestrial network telemetry and control system are significantly improved.

[0113] Please see Figure 3 One embodiment of the spaceborne telemetry, tracking, and command (TT&C) device based on a non-terrestrial network in this application may include:

[0114] Main control unit (MCU);

[0115] The main power supply and backup power supply are used to power the main control unit.

[0116] Three non-terrestrial network communication modules are connected to the main control unit, and each of the three non-terrestrial network communication modules includes a low-noise amplifier (LNA) and a power amplifier (PA) component.

[0117] The telemetry and control antenna, including an air telemetry and control antenna and a ground telemetry and control antenna, is connected to the communication module;

[0118] The three non-terrestrial network communication modules include: a first non-terrestrial network module with a first NTN module chip, a second non-terrestrial network module with a second NTN module chip, and a third non-terrestrial network module with a third NTN module chip. The first and second non-terrestrial network modules serve as primary service channels, responsible for alternating transmission of service data during cell handover to ensure the continuity and stability of the data flow. The third non-terrestrial network module serves as a cold backup module, automatically intervening and replacing the faulty module when the main control unit detects a hardware failure in either the first or second non-terrestrial network module. This redundant architecture employs multiple non-terrestrial network communication modules, with two modules used for alternating soft handover of service channels to ensure uninterrupted data flow during cell handover; the third module, as a cold backup, can immediately take over in the event of a failure in any service module, greatly improving the reliability and mission success rate of the system during long-term on-orbit operation.

[0119] like Figure 4 As shown, this application embodiment also provides an electronic device 300, including a memory 310, a processor 320, and a computer program 311 stored in the memory 310 and executable on the processor. When the processor 320 executes the computer program 311, it implements the steps of any of the above-described methods for spaceborne telemetry and control based on non-terrestrial networks.

[0120] Since the electronic device described in this embodiment is the device used to implement a spaceborne telemetry and control device based on a non-terrestrial network in this application embodiment, those skilled in the art can understand the specific implementation method and various variations of the electronic device in this embodiment based on the method described in this application embodiment. Therefore, how the electronic device implements the method in this application embodiment will not be described in detail here. Any device used by those skilled in the art to implement the method in this application embodiment is within the scope of protection of this application.

[0121] In practical implementation, when the computer program 311 is executed by the processor, it can achieve the following: Figure 1 Any of the corresponding implementation methods in the embodiments.

[0122] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

Claims

1. A spaceborne telemetry and control method based on a non-terrestrial network, characterized in that, For a space-based telemetry and control device, wherein the space-based telemetry and control device is installed on a low-Earth orbit satellite platform, the method includes: The system acquires the real-time orbital parameters, GNSS positioning information, and pre-stored high-orbit satellite coverage information tables of the respective low-orbit satellites. Based on the real-time orbit parameters, GNSS positioning information, and the high-orbit satellite coverage information table of the high-orbit satellites that are pre-stored or periodically updated from the satellite service computer, the spatiotemporal relationship between the low-orbit satellites and the cell coverage area is calculated. The high-orbit satellite coverage information table is organized by high-orbit satellite number and cell number. Each cell entry includes at least one of the following parameters: the center latitude and longitude of the cell beam on the ground, the coverage radius or boundary polygon corresponding to the half-power point of the beam, frequency and polarization configuration, service priority, and effective time interval. A unified state vector is established based on the current orbital parameters and GNSS status. The position and velocity of the low-orbit satellite in the inertial coordinate system are transformed into the Earth-fixed coordinate system through the Earth rotation model. The orbit of the low-orbit satellite is numerically extrapolated within a preset prediction time window to obtain the three-dimensional position of the low-orbit satellite at multiple future times, and the latitude and longitude of the projection point on the Earth's surface at each future time are calculated. Based on the calculated spatiotemporal relationship prediction, the cell coverage area of ​​the target high-orbit satellite is determined, and the cell search and on-demand access control process is initiated in advance, including: For each cell entry in the coverage information table, by determining whether the projection point of the low-orbit satellite falls within the cell coverage boundary polygon, and combining whether the elevation angle of the low-orbit satellite pointing to the high-orbit satellite is higher than the preset threshold and whether the propagation path is blocked by the Earth, it is determined whether the current time is within the effective coverage range of the cell, and the coverage markers of multiple discrete time points are integrated into a continuous time period including the entry time and the exit time. Based on the determination of the coverage entry time according to the continuous time period, and combined with the device's own access process latency statistics and current business needs, the early wake-up time is set. When the early wake-up time is reached, the control radio frequency front-end, baseband processor and related control logic switch from low power standby state to working state, perform cell search in the target frequency band according to the frequency and cell identifier in the coverage information table, read system information blocks and initiate random access requests to establish inter-satellite telemetry and data relay links.

2. The method as described in claim 1, characterized in that, Also includes: Based on the calculated spatiotemporal relationship, predict the current serving cell signal attenuation trend and the timing of the target cell's appearance; When the signal quality of the current serving cell is detected to drop to a predetermined threshold and the signal strength of the target cell continues to rise, a cell handover trigger command is generated to wake up the cell handover process in advance.

3. The method as described in claim 2, characterized in that, The spaceborne telemetry and control device includes at least two non-terrestrial network modules, and the cell handover process includes: The first non-terrestrial network module will continue to maintain existing service transmission within the current serving cell to ensure the continuity of data flow; The second non-terrestrial network module is woken up and instructed to complete downlink synchronization, system message decoding, random access procedure and service channel establishment on the frequency point of the target cell.

4. The method as described in claim 3, characterized in that, Also includes: If the second non-terrestrial network module successfully establishes a service channel in the target cell, a data stream handover operation is performed: Switch the uplink data routing and downlink data receiving source from the first non-terrestrial network module to the second non-terrestrial network module; After confirming that the new link service transmission is stable, the control system instructs the first non-terrestrial network module to initiate a connection release process, normally disconnect from the network and enter an idle listening state, completing the entire soft handover process.

5. The method according to any one of claims 1 to 4, characterized in that, Also includes: Based on the real-time acquired orbital parameters and three-axis velocity vectors of the low-orbit satellite, the accurate ephemeris data of the high-orbit relay satellite, the relative geometric position and radial velocity components of the two satellites, and the carrier frequency and sampling clock characteristics, the theoretical frequency offset prediction value is calculated in real time using the Doppler frequency shift calculation method. The theoretical frequency offset prediction value includes the magnitude and the trend of change. Frequency offset pre-compensation is performed based on the calculated theoretical frequency offset prediction value; The compensation effect is evaluated by real-time monitoring of key physical layer indicators, and feedback adjustments are made based on the compensation effect.

6. The method as described in claim 5, characterized in that, The frequency offset pre-compensation based on the calculated theoretical frequency offset prediction value includes: In the transmission link, the pre-compensation value is superimposed on the baseband digital up-conversion module to correct the transmission frequency in advance; In the receiving link, the local oscillator of the downlink demodulator is controlled to perform frequency pre-correction; Fine-tuning the sampling clock frequency compensates for the effects of timing deviations; The method of evaluating the compensation effect by real-time monitoring of key physical layer indicators, and then adjusting based on the compensation effect, includes: When abnormal link quality indicators are detected, the frequency offset estimation error is automatically calculated. The parameter weights of the prediction algorithm are dynamically adjusted based on the magnitude and direction of the error. Update the compensation value lookup table to optimize subsequent prediction accuracy.

7. The method as described in claim 1, characterized in that, Also includes: Based on the orbital parameters of the low-orbit satellites and the coverage information table of high-orbit satellites, the visibility of high-orbit cells within the preset prediction time range is analyzed to identify the control and measurement gaps within the prediction time range where there is no coverage of any high-orbit satellite cells or only coverage of cells with elevation angles below the preset threshold. Before the detection of entering the telemetry and control window period, the system obtains the identity information and available telemetry and control capacity information of at least one proxy satellite with continuous high-orbit cell coverage capability during the telemetry and control window period through the inter-satellite link between the satellite and other low-orbit satellites in the same constellation, and establishes an inter-satellite telemetry and control forwarding session with the proxy satellite. Before entering the telemetry and control window period, the planned telemetry and control instructions and necessary task configurations for the low-Earth orbit satellites are pre-sent to the proxy satellites through the high-Earth orbit satellite cells, and the proxy satellites forward them to the low-Earth orbit satellites through inter-satellite links during the telemetry and control window period. When the low-orbit satellite generates telemetry data or health status information and is within the telemetry and control window period, the telemetry data is sent to the proxy satellite via the inter-satellite link. The proxy satellite then forwards the data to the ground telemetry and control center within its own high-orbit cell coverage time slot. This ensures that effective telemetry and control capabilities for the low-orbit satellite are maintained even when there are natural blind spots in the coverage of high-orbit relay satellites.

8. A spaceborne telemetry and control device based on a non-terrestrial network, characterized in that, The apparatus comprising, using the method as described in any one of claims 1 to 7, includes: Main control unit; The main power supply and backup power supply are used to power the main control unit. Three non-terrestrial network communication modules are connected to the main control unit, and each of the three non-terrestrial network communication modules includes a low-noise amplifier (LNA) and a power amplifier (PA) component. The sky-based telemetry and control antenna and the ground-based telemetry and control antenna are connected to the communication module; The three non-terrestrial network communication modules include: a first non-terrestrial network module, a second non-terrestrial network module, and a third non-terrestrial network module. The first and second non-terrestrial network modules are used as primary service channels, responsible for alternating transmission of service data during cell handover to ensure the continuity and stability of the data flow. The third non-terrestrial network module is used as a cold standby module, which automatically intervenes and replaces the faulty module when the main control unit detects a hardware failure in the first or second non-terrestrial network module.

9. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program stored in the memory to implement the steps of the spaceborne telemetry and control method based on a non-terrestrial network as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the spaceborne telemetry and control method based on a non-terrestrial network as described in any one of claims 1-7.

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