Method for predicting parameters of a space-borne opportunistic communication window, electronic device, storage medium and program product

Abstract

The embodiment of the application provides a kind of spaceborne opportunistic communication window parameter prediction method, electronic equipment, storage medium and program product, related to wireless communication technical field, the method comprises: obtaining the orbital parameter information of multiple available satellites, and the spaceborne metasurface is deployed in available satellite;For each available satellite, according to the orbital parameter information, the orbital state information of available satellite in preset time range is calculated;For each available satellite, determine the available satellite that meets the preset discrimination criterion as candidate satellite by screening, and the preset discrimination criterion is that in preset time range, the subsatellite point position of available satellite is located in mirror surface reflection search area;For each candidate satellite, the reference spatial point corresponding to candidate satellite is used as the pointing target of transmitting station and receiving station, and the beam intersection region of transmitting station and receiving station is calculated;For each candidate satellite, based on the beam intersection region corresponding to candidate satellite, the communication window parameter is predicted, and the precision of passive reflection communication window prediction is improved.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a method for predicting parameters of a spaceborne opportunistic communication window, an electronic device, a storage medium, and a program product. Background Technology

[0002] With the large-scale deployment of low-Earth orbit (LEO) satellite constellations, satellite communication is gradually developing towards full-area coverage. Traditional onboard active relay communication architectures suffer from drawbacks such as hardware complexity and high power consumption. Onboard metasurfaces, with their advantages of low power consumption, ease of deployment, and beam control, have become a new technological path for passive reflection communication. This type of reflection link satisfies the three-point specular reflection geometric constraints of the "transmitter-onboard metasurface-receiving station." However, the high-speed motion of LEO satellites causes the reflection illumination area to drift rapidly, resulting in short and dynamically fluctuating communication windows that are difficult to predict accurately. Existing satellite transit prediction methods are mostly based on single-point line-of-sight visibility determination between the satellite and the ground, suitable for active relay scenarios, but lack dynamic geometric modeling and communication window prediction capabilities for passive reflection scenarios, thus restricting the practical application of onboard passive reflection communication. Summary of the Invention

[0003] This application provides a method, electronic device, storage medium, and program product for predicting parameters of spaceborne opportunistic communication windows, in order to alleviate or solve one or more technical problems existing in the prior art.

[0004] In a first aspect, embodiments of this application provide a method for predicting parameters of a spaceborne opportunistic communication window, including: Obtain orbital parameter information of multiple available satellites, which are equipped with onboard metasurfaces; For each available satellite, the orbital status information of the available satellite within a preset time range is calculated based on the orbital parameter information; The available satellites are screened to determine the available satellites that meet the preset discrimination criteria as candidate satellites. The preset discrimination criteria is that the nadir position of the available satellite is located within the specular reflection search area within the preset time range. The specular reflection search area is the Earth's spherical area with the midpoint of the great circle arc between the ground transmitting station and the receiving station as the center and the preset angular distance as the radius. For each of the candidate satellites, the beam intersection area of ​​the transmitting station and the receiving station is calculated, with the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station. For each of the candidate satellites, the communication window parameters of the candidate satellites are predicted based on the beam intersection region corresponding to the candidate satellites.

[0005] In some embodiments of this application, the method further includes, prior to performing a screening of the available satellites: Determine the symmetrical midpoint direction of the transmitting station and the receiving station below the Earth's surface; Based on the symmetrical intermediate direction, determine the midpoint of the spherical great circle arc between the transmitting station and the receiving station; The mirror reflection search area is defined on the Earth's surface with the midpoint of the great circle arc as the center and the preset angular distance as the radius.

[0006] In some embodiments of this application, the step of screening each of the available satellites to determine the available satellites that meet the preset discrimination criteria as candidate satellites includes: Determine the sub-satellite point position of each available satellite at each discrete epoch within the preset time range; For each available satellite, based on the preset discrimination criteria, if it is determined that the nadir position of the available satellite enters the specular reflection search area at any time within the preset time range, then the available satellite is determined as the candidate satellite; otherwise, if it is determined that the nadir position of the available satellite does not enter the specular reflection search area within the preset time range, then the available satellite is eliminated.

[0007] In some embodiments of this application, before calculating the beam intersection region of the transmitting station and the receiving station for each candidate satellite, using the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station, the method further includes: For each candidate satellite, the latitude and longitude of the midpoint of the great circle arc of the sphere are used as the latitude and longitude of the reference space point, and the orbital altitude of the candidate satellite is used as the spatial altitude of the reference space point, so as to obtain the spatial position coordinates of the reference space point.

[0008] In some embodiments of this application, the step of calculating the beam intersection region of the transmitting station and the receiving station for each candidate satellite, using the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station, includes: Based on the spatial coordinates of the reference space point, calculate the fixed pointing parameters of the transmitting station pointing to the reference space point and the fixed pointing parameters of the receiving station pointing to the reference space point; Using the fixed pointing parameters of the transmitting station and the fixed pointing parameters of the receiving station remaining unchanged within the preset time range as the calculation condition, the transmission beam range covered by the transmitting station in space and the reception beam range covered by the receiving station in space are calculated respectively. The intersection of the transmitted beam range and the received beam range is calculated to obtain the beam intersection region.

[0009] In some embodiments of this application, predicting the communication window parameters of the candidate satellite based on the beam intersection region corresponding to the candidate satellite includes: Predict the times when the candidate satellites enter and leave the beam intersection area to determine the effective reflection period in the communication window parameters; Based on the spatial position coordinates of the candidate satellite at each discrete epoch during the effective reflection period, the bistatic angle at the corresponding discrete epoch is calculated. The bistatic angle is a geometric parameter in the communication window parameters used to characterize the reflection communication link, including the pointing angle parameter between the transmitting station and the candidate satellite and the pointing angle parameter between the candidate satellite and the receiving station.

[0010] In some embodiments of this application, the orbital parameter information includes at least one of the following parameters from the two roots: semi-major axis, eccentricity, orbital inclination, right ascension of the ascending node, argument of perigee, and mean perigee.

[0011] Secondly, embodiments of this application provide an electronic device, including a memory, a processor, and a computer program stored in the memory, wherein the processor implements any of the methods of embodiments of this application when executing the computer program.

[0012] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method of any one of the embodiments of this application.

[0013] Fourthly, embodiments of this application provide a computer program product, including a computer program, which, when executed by a processor, implements any of the methods described in the embodiments of this application.

[0014] Based on the above technical solution, this application has at least the following beneficial effects or advantages: This application embodiment obtains the available satellite orbit parameters of a satellite equipped with an onboard metasurface, infers the satellite's orbital operation status within a preset time period, constructs a spherical mirror reflection search area between transceiver stations, completes preliminary satellite screening based on nadir point position constraints, and selects candidate satellites that meet the basic reflection geometry conditions. Then, based on a unified reference space point, it determines the pointing range of the ground transceiver stations, solves the bistatic beam intersection region, and combines beam coverage constraints to complete the prediction of communication window parameters. This application embodiment meets the three-point mirror geometric symmetry condition for passive reflection communication, conforms to the operational characteristics of high-speed motion of low-orbit satellites, breaks the applicability limitations of traditional single-point visibility determination methods, efficiently reduces the computational analysis workload of invalid satellites, accurately predicts the effective communication period in passive reflection scenarios, significantly improves the rationality and accuracy of satellite passive reflection communication window prediction, and ensures the stable and reliable construction of reflection communication links.

[0015] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0016] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments according to this application and should not be construed as limiting the scope of this application.

[0017] Figure 1 A flowchart is shown below illustrating a method for predicting parameters of a spaceborne opportunistic communication window provided in an embodiment of this application. Figure 2 Another flowchart of a method for predicting parameters of a spaceborne opportunistic communication window provided in an embodiment of this application is shown; Figure 3 This illustration shows a schematic diagram of the principle of a method for predicting parameters of a spaceborne opportunistic communication window provided in an embodiment of this application; Figure 4 This illustration shows a schematic diagram of the principle of a method for predicting parameters of a spaceborne opportunistic communication window provided in an embodiment of this application; Figure 5 A block diagram of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0018] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the concept or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0019] To facilitate understanding of the technical solutions of the embodiments of this application, the relevant technologies of the embodiments of this application are described below. The following related technologies are optional solutions and can be arbitrarily combined with the technical solutions of the embodiments of this application, all of which fall within the protection scope of the embodiments of this application. It should be noted that the application scenarios or application examples provided in this application are for ease of understanding, and the embodiments of this application do not specifically limit the application of the technical solutions.

[0020] With the increasingly dense deployment of low-Earth orbit (LEO) satellite constellations, achieving global information coverage using massive numbers of satellites has become a trend in the field of satellite communications. Traditional satellite communications mostly rely on active relay payloads for signal relay, but such systems face challenges such as high hardware complexity and high onboard power consumption. In recent years, metasurfaces, as two-dimensional engineered surfaces with phase manipulation capabilities, have been developed. They offer low cost, near-zero power consumption, and flexible beam control capabilities. When mounted on a satellite, they can form a passive reflection communication architecture based on spaceborne metasurfaces. However, unlike traditional active satellite communications, which only need to meet the single-point coverage logic of "visibility between satellite and ground," the reflection link based on spaceborne metasurfaces requires a high degree of conformity between the transmitting station, the spaceborne metasurface, and the receiving station in terms of specular reflection geometry. Due to the extremely high orbital velocity of LEO satellites, the illumination area formed on the ground by the main lobe of the spaceborne metasurface drifts rapidly as the satellite passes overhead. The communication window often exhibits extremely short and nonlinear fluctuation characteristics, making it extremely difficult to capture and predict effective communication opportunities. Most existing satellite transit prediction schemes are designed for line-of-sight visibility of active beams, which makes it difficult to support accurate link establishment and real-time antenna pointing guidance for reflection links.

[0021] To address the aforementioned challenges, this application proposes a spaceborne opportunistic communication device and a communication window prediction method. This system utilizes a spaceborne metasurface to construct a passive spaceborne communication system. Simultaneously, it constructs a three-dimensional geometric analytical model using ephemeris data and transceiver coordinates to accurately locate the critical time window that satisfies reflection phase constraints, achieving refined prediction of the communication window. This application not only solves the technical pain point of difficulty in capturing reflection timing from spaceborne metasurfaces but also provides a reliable time reference for system scheduling and burst communication, significantly improving link establishment success rate and communication reliability.

[0022] For communication scenarios involving low-Earth orbit satellites, existing technologies primarily calculate the satellite's trajectory relative to a specific ground station by analyzing ephemeris data such as TLE and combining it with orbit extrapolation models like SGP4. The core logic is "single-point visibility" determination, which involves calculating the azimuth and elevation angles of the satellite relative to the ground station. When the elevation angle exceeds the physical obstruction limit of the receiving antenna, a communication window is considered open. In active satellite relay systems, this prediction scheme only needs to satisfy the single-point visibility constraint. The system then generates a satellite transit schedule to guide the antenna in pointing and tracking. In this case, window prediction mainly focuses on the line-of-sight (LoS) relationship in spatial geometry, aiming to address the timing of relay payload access. Existing satellite visibility calculation schemes are primarily designed for relay modes, with the core criterion being "single-point visibility," meaning that a link can be established as long as the satellite's elevation angle relative to a single ground station meets the obstruction requirement. However, in passive surface reflection communication scenarios, link establishment must strictly adhere to the geometric symmetry constraint formed by the three points: the transmitting station, the onboard metasurface, and the receiving station. If the traditional solution is used, the system will be unable to capture the fleeting reflection opportunity, causing the transmitting and receiving parties to be unable to enter the link establishment state synchronously, resulting in antenna pointing deviation or link establishment failure.

[0023] In existing research involving metasurface-assisted satellite communications, the technical implementation paths mostly focus on using metasurfaces or smart surfaces as auxiliary enhancements to active systems. For example, by integrating reflective units into the satellite's solar panels or body structure, active payloads can assist in beamforming or beam steering to improve the coverage performance of the satellite-to-ground link or perform interference cancellation. The implementation of such schemes still heavily relies on the satellite's active processing unit for signal synchronization and feedback control, with the metasurface serving only as a physical layer enhancement component in the active communication chain. For communication scenarios that completely deviate from active payload processing and utilize only onboard metasurfaces as passive reflective nodes, existing technologies typically lack prior modeling of the dynamic geometric path between the "transmitter station - onboard metasurface - receiver station," making it difficult to accurately predict the communication window based on reflection geometry.

[0024] The method proposed in this application is designed for predicting communication windows in spaceborne opportunistic communication devices. Specifically, it addresses application scenarios involving high-speed movement of low-Earth orbit satellites, extremely short reflection communication windows, and a strong dependence on three-point geometric constraints. A prediction framework is constructed, comprising "initial screening with full constellation dimensionality reduction—precise determination of reflection geometry—joint verification of physical layer constraints." Unlike traditional satellite-to-ground prediction methods based solely on single-point visibility, this application uses the spatial geometric relationship between the launch station, the spaceborne metasurface, and the receiving station as the core constraint, and continuously determines reflection conditions in the time domain, thereby achieving high-precision prediction of the effective time window for reflection communication.

[0025] The technical solution of this application and how it solves the aforementioned technical problems are described in detail below with specific embodiments. The listed specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0026] See Figure 1 The flowchart shown is a method for predicting the parameters of a spaceborne opportunistic communication window. The method specifically includes steps 101 to 105.

[0027] Step 101: Obtain orbital parameter information for multiple available satellites, which are equipped with onboard metasurfaces. Step 102: For each available satellite, calculate the orbital status information of the available satellite within a preset time range based on the orbital parameter information; Step 103: Screen each available satellite and determine the available satellites that meet the preset discrimination criteria as candidate satellites. The preset discrimination criteria is that within a preset time range, the nadir position of the available satellite is located within the mirror reflection search area. The mirror reflection search area is the Earth's spherical area with the midpoint of the great circle arc between the ground transmitting station and the receiving station as the center and the preset angular distance as the radius. Step 104: For each candidate satellite, using the reference space point corresponding to the candidate satellite as the pointing target of the launch station and the receiving station, calculate the beam intersection area of ​​the launch station and the receiving station. Step 105: For each candidate satellite, predict the communication window parameters of the candidate satellite based on the beam intersection region corresponding to the candidate satellite.

[0028] In some embodiments, the aforementioned available satellites are equipped with onboard opportunistic communication equipment, which includes, but is not limited to, the following components: a ground transmitting terminal, an onboard passive reflective node, and a ground receiving terminal. The onboard passive reflective node deploys a smart reflective surface, such as a metasurface capable of specular reflection, which utilizes the high reflectivity of its physical surface to guide the beam emitted by the transmitting end to the distant receiving area. Unlike conventional active satellite-to-ground communication systems, the onboard node in this embodiment does not require complex signal down-conversion processing or active power forwarding. The link establishment satisfies the specular reflection law between the "transmitting station - onboard metasurface - receiving station." This embodiment constructs a passive reflective link by adjusting the beam direction of the ground transceiver antenna.

[0029] In some implementations, for large-scale low-Earth orbit constellation applications, orbital parameter information of multiple available satellites can be collected in batches. The orbital parameter information records the instantaneous orbital characteristics of the satellites and serves as the basis for estimating the dynamic spatial position of the satellites. Available satellites may include all on-orbit satellites with passive reflection capabilities within the constellation.

[0030] Based on the acquired orbital parameter information, orbital extrapolation logic can be introduced to continuously calculate the orbital state of a single satellite within a complete preset time range. The orbital state includes key information such as spatial coordinates, operating speed, and spatial attitude at different times, which can fully describe the dynamic operation process of a low-orbit satellite passing through the area at high speed.

[0031] Furthermore, based on the spherical geometric characteristics of the transmitting and receiving stations, a specular reflection search area can be constructed. Specifically, the spherical constraint range is defined with the midpoint of the great circle arc of the sphere as the center and a fixed angular distance. Based on the distribution of the nadir point position at different discrete times of the satellite, an initial screening of usable satellites can be completed, selecting candidate satellites that meet the basic reflection geometric conditions. An independent reference space point is configured for each candidate satellite to fix the antenna pointing of the ground transmitting and receiving stations. A stable beam intersection region is then calculated by combining the antenna beam coverage range. The reference space point can be determined based on the orbital altitude of the candidate satellites. Finally, based on the spatial constraints of the beam intersection region, the time nodes for each candidate satellite to enter and exit the effective airspace can be identified according to the changes in the candidate satellite's on-orbit position. Link geometric parameters are collected synchronously, ultimately completing the comprehensive prediction of various parameters of the satellite communication window in the passive reflection communication scenario.

[0032] The embodiments of this application meet the condition of three-point mirror geometric symmetry for passive reflection communication, conform to the operational characteristics of high-speed motion of low-orbit satellites, break the applicability limitations of traditional single-point visibility determination methods, efficiently reduce the amount of computational analysis of invalid satellites, accurately predict the effective communication period in passive reflection scenarios, significantly improve the rationality and accuracy of satellite passive reflection communication window prediction, and ensure the stable and reliable construction of reflection communication links.

[0033] In some embodiments of this application, before screening each available satellite, the specular reflection search area can be delineated by the following steps: First, determine the symmetrical midpoint between the transmitting station and the receiving station under the Earth's sphere; second, determine the midpoint of the great circle arc between the transmitting station and the receiving station based on the symmetrical midpoint; finally, delineate the specular reflection search area on the Earth's sphere with the midpoint of the great circle arc as the center and a preset angular distance as the radius.

[0034] This implementation converts the geographical coordinates of the transmitting and receiving stations into geocentric spatial vectors, and solves for the spherical symmetry midpoint direction between the two stations through vector normalization and summation. Combining the geometric characteristics of a great circle, the coordinates of the midpoint of the great circle arc between the transmitting and receiving stations can be calculated. The great circle represents the trajectory of the shortest path between two points on the Earth's surface, and the midpoint of the great circle objectively characterizes the central geometric orientation of the two points, adapting to the spatial matching requirements of three-point specular reflection. Then, using the solved great circle midpoint as the region center, a preset angular distance is selected as the spherical radiation range, uniformly delineating a closed and continuous specular reflection search area within the Earth's sphere.

[0035] The embodiments of this application can calculate the surface adaptation range corresponding to the reflection communication, unify the geometric judgment benchmark for subsequent satellite selection, and reduce the repetitive solution steps in subsequent multi-satellite batch calculations by completing the geometric model construction in advance.

[0036] In some embodiments of this application, screening is performed on each available satellite to determine available satellites that meet preset discrimination criteria as candidate satellites. This includes performing the following steps: determining the nadir position of each available satellite at each discrete epoch within a preset time range; for each available satellite, based on the preset discrimination criteria, if it is determined that the nadir position of an available satellite enters the specular reflection search area at any time within the preset time range, then the available satellite is determined as a candidate satellite; otherwise, if it is determined that the nadir position of an available satellite does not enter the specular reflection search area within the preset time range, then the available satellite is eliminated.

[0037] This implementation divides the preset prediction time range into several uniformly distributed discrete epochs, with each epoch serving as an independent time sampling node, resolving the satellite's spatial position moment by moment. Combining satellite orbit calculation data, the nadir position of each available satellite at each discrete epoch is calculated. The nadir position is the projected coordinate of the satellite's spatial position onto the Earth's surface, directly reflecting the satellite's Earth coverage azimuth. The nadir coordinates at each moment are compared with the preset specular reflection search area using spherical position comparison, and the spherical angular distance is used to determine the point's location. If the nadir point of a single satellite falls within the search area at any epoch, it is identified as a candidate satellite; satellites without a matching point throughout the entire process are directly eliminated. This implementation predicts the transit trajectories of candidate satellites and determines whether the nadir position enters the valid ground search area at each discrete moment, quickly eliminating invalid satellites with inconsistent geometry and simplifying the number of target satellites required for subsequent complex calculations.

[0038] In some embodiments of this application, before calculating the beam intersection area of ​​the launch station and the receiving station for each candidate satellite, with the reference space point corresponding to the candidate satellite as the pointing target of the launch station and the receiving station, the latitude and longitude of the midpoint of the great circle arc of the spherical surface are used as the latitude and longitude of the reference space point for each candidate satellite, and the orbital altitude of the candidate satellite is used as the spatial altitude of the reference space point to obtain the spatial position coordinates of the reference space point.

[0039] This implementation method is used to construct reference space points for each candidate satellite. These reference space points are virtual reference coordinates used to uniformly constrain the fixed pointing of the ground antenna. They do not require the deployment of physical geographic locations, nor do they require the candidate satellites to actually pass through these spatial positions. The planar latitude and longitude of the reference space points can directly reuse the midpoint parameters of the great circle arcs of the transmitting and receiving stations to meet the geometric constraints of specular reflection. The altitude parameter is determined as the orbital altitude data of the corresponding candidate satellite. For each candidate satellite, a corresponding reference space point is independently configured. Within the effective communication window of the candidate satellite, the ground pointing remains fixed due to the reference space point, not changing with the movement of the candidate satellite. The ground antenna does not require real-time angle adjustment, simplifying the calculation and control of ground communication angles, pre-locking the antenna pointing target, and providing a stable reference for subsequent antenna angle calculations and beam range calculations.

[0040] In some embodiments of this application, for each candidate satellite, the reference space point corresponding to the candidate satellite is used as the pointing target of the transmitting station and the receiving station. The beam intersection area of ​​the transmitting station and the receiving station is calculated. Specifically, the fixed pointing parameters of the transmitting station pointing to the reference space point and the fixed pointing parameters of the receiving station pointing to the reference space point are calculated based on the spatial position coordinates of the reference space point. The calculation condition is that the fixed pointing parameters of the transmitting station and the receiving station remain unchanged within a preset time range. The transmitting beam range covered by the transmitting station in space and the receiving beam range covered by the receiving station in space are calculated respectively. Finally, the intersection of the transmitting beam range and the receiving beam range is calculated to obtain the beam intersection area.

[0041] This embodiment provides an optional implementation method for calculating the beam intersection region of transceiver stations. Based on the three-dimensional coordinates of a reference spatial point and the coordinates of the ground station, a spatial pointing vector is constructed. By decomposing the azimuth component through coordinate system rotation transformation, the stable azimuth and elevation angles of the transmitting and receiving stations can be calculated. Combining the inherent structural parameters of the antenna and the operating frequency band, a fixed main lobe beamwidth is determined. Extending outward from the fixed pointing direction, three-dimensional spatial cone-shaped coverage areas of the transmitting and receiving beams can be constructed respectively. Under a unified spatial coordinate system, spatial superposition operations are performed on the coverage areas of the two independent beams to extract the overlapping spatial domain jointly covered by the bidirectional beams, forming the beam intersection region. The boundary of this region is jointly defined by the antenna pointing direction and beamwidth, and its spatial position is fixed over a long period, accurately defining the effective coverage range of the bidirectional signal and providing clear spatial constraints for determining the communication window.

[0042] In some embodiments of this application, the communication window parameters of the candidate satellite are predicted based on the beam intersection region corresponding to the candidate satellite. The effective reflection period in the communication window parameters can be determined by predicting the time when the candidate satellite enters and leaves the beam intersection region. Based on the spatial position coordinates of the candidate satellite at each discrete epoch within the effective reflection period, the bistatic angle at the corresponding discrete epoch is calculated. The bistatic angle is a geometric parameter in the communication window parameters used to characterize the reflected communication link, including the pointing angle parameter between the transmitting station and the candidate satellite and the pointing angle parameter between the candidate satellite and the receiving station.

[0043] This implementation method continuously monitors the real-time on-orbit spatial position of candidate satellites, compares the inclusion relationship between satellite coordinates and beam intersection regions epoch by epoch, captures the start time of satellite entering the intersection region and the end time of satellite leaving the region, and determines the continuous effective reflection period of candidate satellites as the timing parameters of the communication window.

[0044] Within the effective reflection period coverage, spatial pointing vectors from the transmitter to the spaceborne metasurface and from the spaceborne metasurface to the receiver are constructed using fixed discrete time intervals as sampling nodes. By calculating the angle between the spatial vectors, the bidirectional pointing angle parameters at each moment are solved one by one, and combined to form complete bi-station angle data.

[0045] This implementation quantifies the available time interval of passive reflection communication and can simultaneously determine the bistation angle parameters at each discrete moment within the effective time period, fully describing the dynamic geometric change characteristics of the reflection link within the effective time period and enriching the parameter dimensions of the communication window.

[0046] In some embodiments of this application, the orbital parameter information includes at least one of the following parameters from the two-row roots: semi-major axis, eccentricity, orbital inclination, right ascension of the ascending node, argument of perigee, and mean perigee. The satellite orbital parameters are primarily derived from the two-row roots (TLE) and are used to describe the operational status of low-Earth orbit satellites. By utilizing orbital data from different dimensions, the accuracy of orbital status extrapolation can be improved, providing accurate and stable underlying data support.

[0047] The following provides a specific implementation of the prediction method for spaceborne opportunistic communication window parameters provided in this application. (Refer to...) Figure 2 The process includes the following steps: (1) Obtain orbital parameter information of each available satellite in the low Earth orbit constellation. First, the orbital parameters of the target low-Earth orbit satellite constellation are obtained. These parameters include, but are not limited to, the semi-major axis, eccentricity, orbital inclination, right ascension of the ascending node, argument of perigee, and mean perigee angle in the two-elemental model (TLE). Based on these orbital parameters, an orbital extrapolation model is used to calculate the orbital state of the satellites within the predicted time range. The position and velocity information of each satellite at discrete epochs are uniformly mapped to the geocentric inertial coordinate system (ECI) or the geocentric geofixed coordinate system (ECEF) to construct a spatiotemporal distribution model of the entire constellation of satellites.

[0048] Through the above modeling steps, a unified description of large-scale low-Earth orbit satellite constellations in the time dimension is achieved, providing a consistent reference coordinate basis for subsequent geometric constraint determination.

[0049] (2) Initial screening of candidate satellites based on the midpoint of the great circle arc on the sphere Given the geographical coordinates of the transmitting and receiving stations, convert their latitude and longitude coordinates into unit position vectors in a geocentric coordinate system. , Where the subscript 't' represents the transmitting station and 'r' represents the receiving station. (Reference) Figure 4 Based on the principle of the shortest path on a sphere, the great circle path between the transmitting and receiving stations can be uniquely determined by the two position vectors mentioned above. Furthermore, by normalizing and summing these vectors, the direction vector at the midpoint of the great circle arc on the sphere can be obtained:

[0050] in, The symmetrical midpoint between the transmitting and receiving stations in a spherical geometric sense is represented, and its corresponding geographical coordinates serve as the central reference point for the potential reflection region. Around the midpoint of the aforementioned great circle arc, this embodiment constructs a candidate reflection search region on the sphere. This region is centered on the midpoint of the aforementioned great circle arc. Centered on, and with a preset angular distance threshold As the radius of the region, Used to describe the allowed range of reflection path deviations.

[0051] refer to Figure 4 Within the prediction timeframe, for any low-Earth orbit satellite, calculate its nadir position vector at each discrete epoch. And determine whether the spherical angular distance between it and the midpoint of the aforementioned great circle arc satisfies the following criterion:

[0052] When the satellite's nadir trajectory meets the above conditions at any time, the satellite trajectory is determined to have entered the above candidate reflection search area and is included in the candidate satellite set; otherwise, the satellite is removed from the subsequent fine calculation process.

[0053] By using the above-mentioned initial screening mechanism based on the midpoint of the great circle arc, the number of satellites requiring precise reflection determination can be significantly reduced while ensuring the geometric integrity of reflection communication, thereby significantly reducing the computational complexity of reflection communication window prediction under the conditions of the entire constellation.

[0054] (3) Calculate the antenna pointing and beam overlap area First, obtain the latitude and longitude coordinates and altitude information of the transmitting and receiving stations; second, determine the main lobe beamwidth of each station based on the structural parameters of the antennas used by the transmitting and receiving stations.

[0055] The aforementioned antenna is a high-gain antenna, and its radiation characteristics can be approximated as a directional radiation mode dominated by the main lobe. Given the effective aperture size of the antenna... Given the operating frequency, the main lobe beamwidth of the antenna can be estimated using the 3 dB half-power beamwidth determination criterion commonly used in antenna engineering. Specifically, the 3 dB main lobe beamwidth can be approximately expressed as:

[0056] in, To correspond to the electromagnetic wave wavelength in the operating frequency band, These are empirical coefficients related to antenna type and radiation pattern characteristics. Through the above engineering approximations, the main lobe beamwidths of the transmitting and receiving antennas can be determined based on the antenna's physical dimensions and operating frequency band without complex electromagnetic field derivations. The obtained beamwidths are used as fixed configuration parameters for subsequent beam coverage analysis and feasibility assessment of reflection communication.

[0057] Based on the latitude and longitude of the transmitting and receiving stations and the orbital altitude of the initial screening satellites, the spatial coordinates P pointing to the transceiver antennas are determined, including latitude, longitude, and altitude. The latitude and longitude of these spatial coordinates must satisfy the specular reflection geometry between the transmitting station, the onboard metasurface, and the receiving station; therefore, they are equal to the latitude and longitude of the midpoints of the great circles on Earth for both the transmitting and receiving stations. The altitude of the spatial coordinates is equal to the orbital altitude of the initial screening satellites.

[0058] Calculate the elevation and azimuth angles of the antennas at the transmitting and receiving stations. Use the aforementioned spatial coordinates respectively. As a pointing target, the fixed pointing parameters of the transmitting and receiving station antennas are determined, including the corresponding azimuth and elevation angles.

[0059] Let the geographical coordinates of the transmitting or receiving station be... The aforementioned spatial geometric reference phase point The geographic coordinates are The three-dimensional position vectors of the object in the geocentric coordinate system are obtained by geodetic coordinate transformation:

[0060] Based on the position vector in the aforementioned geocentric coordinate system, calculate the spatial geometric reference phase point pointed from the aforementioned transmitting or receiving station. Observation vector:

[0061] The above observation vector Through rotation transformation matrix Transform to the local tangent plane coordinate system of the site to obtain the eastward component. Northward component and celestial component :

[0062] Based on the components in the local tangent plane coordinate system of the above-mentioned site Calculate the antenna's elevation angle. With azimuth ,in:

[0063] The antenna pointing parameters remain constant within the predicted time range, ensuring that the transmitted and received beams continuously point to the same potential reflection area. This method transforms the dynamic antenna search problem inherent in reflection communication into a pre-configured fixed pointing problem, avoiding the complexity and uncertainty associated with real-time antenna pointing adjustments under high-speed low-Earth orbit satellite conditions.

[0064] refer to Figure 3 After determining the fixed antenna pointing and corresponding beamwidth parameters of the transmitting station 301 and receiving station 302 on ground 305, the intersection D of the coverage areas of the transmitting and receiving beams is calculated to obtain the effective reflection zone 304. The effective reflection zone 304 is at the same distance from the ground 305 as the satellite altitude, meaning it lies on the satellite trajectory 306. If the low-orbit satellite 303 is located within the effective reflection zone 304, its wing-shaped onboard metasurfaces can reflect the signal transmitted by the transmitting station 301 to the receiving station 302. The aforementioned coverage area intersection D is defined by the antenna main lobe direction and its beamwidth, and is used to describe the angular domain range within which the antenna can effectively radiate or receive signals in space. In a spatial geometric sense, when a spatial region is simultaneously within the coverage area of ​​both the transmitting and receiving beams, it can be considered that the region simultaneously satisfies both the transmission illumination condition and the reception reachability condition.

[0065] In this embodiment, the spatial region that simultaneously satisfies the bistatic beam coverage condition is defined as the bistatic beam overlap region. Furthermore, considering the need to simultaneously satisfy the specular reflection geometry between the transmitting station, the onboard metasurface, and the receiving station, this embodiment considers the bistatic beam overlap region as a potentially effective reflection zone that satisfies the specular reflection condition. Only when a candidate satellite enters this effective reflection zone during its operation is it spatially feasible to form a reflective communication link. Through this method, the complex reflection geometry is transformed into a spatial region determination problem based on beam coverage relationships, providing clear and executable spatial constraints for the subsequent time determination of the reflective communication window.

[0066] (4) Candidate satellite communication window prediction After constructing the reflection communication scenario and determining the effective reflection zone, this embodiment of the application performs epoch-by-epoch fine-grained calculations on the candidate satellite set obtained from the initial screening within the predicted time range. Specifically, within each discrete epoch of the simulation scenario, it is determined whether the current position of the candidate satellite has entered or left the aforementioned effective reflection zone. When the satellite trajectory first enters the effective reflection zone, the corresponding entry time is recorded; when the satellite trajectory leaves the effective reflection zone, the corresponding departure time is recorded. This determines the continuous usable time interval of the candidate satellite in the reflection communication scenario. Within the aforementioned continuous time interval, geometric parameter information related to the reflection communication link is further obtained, including the pointing angle parameters between the transmitting station and the satellite, and the pointing angle parameters between the satellite and the receiving station, to characterize the changes in the bistatic angle in the reflection link.

[0067] By performing detailed traversal calculations on all candidate satellites within the predicted time range, a set of all candidate links that could potentially form reflection communication within the target time period can be derived. Each candidate link corresponds to a defined reflection communication window, which includes the window's start time, end time, and the corresponding bistatic angle parameters.

[0068] Through the constellation calculation process based on the above-mentioned reflection scenario, the embodiments of this application realize the transformation from spatial feasibility determination to time-schedulable communication window, providing a reliable time basis for subsequent communication task scheduling, antenna preset control and sudden communication triggering.

[0069] The following is combined Figure 3 and Figure 4 To further illustrate the technical solutions of the embodiments of this application, the process of this example aims to realize beyond-line-of-sight communication using a spaceborne metasurface.

[0070] Step 1: Obtain geolocation and communication parameters The geographical locations of the transmitting station are: latitude 45.1°, longitude 126.1°, altitude 150m; the geographical locations of the receiving station are: latitude 39.25°, longitude 117.18°, altitude 45m; the antenna apertures are 16m and 13m respectively, and the frequencies are both 5.9 GHz. The calculated beam angles are 0.2634 degrees and 0.3241 degrees respectively. Step 2: Initial satellite screening like Figure 4 As shown, the midpoint 404 of the great circle arc between the transmitting station 401 and the receiving station 402 is calculated to be: latitude 42.34°, longitude 121.39°; the ephemeris of the low-Earth orbit satellite constellation 403 is obtained, and satellites whose sub-satellite point 405 is located within the effective area 406 within 24 hours on January 15, 2026 (UTC time) are selected. Figure 4 The example effective area 406 is a circle with the midpoint 404 of the great circle arc as the center and the latitude and longitude difference of one degree as the radius. It can be understood that the effective area 406 is determined based on the midpoint 404 of the great circle arc. The specific shape, size and relationship of the effective area 406 to the midpoint 404 of the great circle arc can be implemented in different designs.

[0071] Step 3: Calculate the overlap area and communication window prediction The altitudes of the initially screened satellites are analyzed, with a point at an altitude of 55 km, located at the midpoint of a great circle. Based on the locations of the transmitter and receiver points and this point, the overlap area and elevation / azimuth angles of the bistatic antennas are calculated. Furthermore, each satellite in the initially screened satellite set is traversed to determine whether it will pass through the overlap area within 24 hours on January 15, 2026 (UTC), thus obtaining the calculated communication window. This completes the entire window prediction process.

[0072] This application also provides a spaceborne passive communication system, which includes a spaceborne passive reflective payload (metasurface) and a ground-based transmitter / receiver terminal. Based on the initial screening logic of the midpoint of a large circular arc, the beam overlap area is determined, and then the communication window is predicted.

[0073] This technical solution significantly improves computational efficiency in large-scale low-Earth orbit satellite constellation environments by constructing a prediction logic of "hierarchical dimensionality reduction and physical coupling." The spherical great circle arc midpoint initial screening mechanism introduced in this application utilizes the prior characteristics of the physical distribution of reflection points to accurately eliminate satellites that cannot establish links in the initial stage, achieving compression of the spatial search dimension. This "dimensionality reduction first, then precise calculation" strategy enables the algorithm to complete the entire constellation screening in a very short time, providing extremely high timeliness for real-time window capture in sudden communication tasks, fundamentally solving the problem of excessive computational load caused by ultra-large-scale constellations.

[0074] In terms of prediction accuracy and reliability, this scheme breaks through the logical limitations of traditional single-point visibility models between satellite and ground, establishing a high-precision discrimination framework with deeply coupled "station-satellite-station" three-point reflection geometric constraints. By constructing a three-dimensional model of the bi-station beam overlap region in the reflection communication scenario, this embodiment transforms the abstract and complex specular reflection conditions into concrete spatial inclusion judgment logic, eliminating false windows that are geometrically visible but physically inaccessible from a physical perspective. Simultaneously, by combining the engineering approximation of the antenna main lobe's 3dB beamwidth with a fixed pointing strategy, it ensures that the predicted time window not only possesses strict geometric completeness but also extremely high physical link confidence, greatly reducing the risk of link establishment failure due to false or missed window reports in ultra-long-distance communication.

[0075] Furthermore, this application's embodiments greatly simplify the connection between the prediction model and actual engineering deployment by transforming the complex dynamic antenna search problem into spatial discrimination based on a preset fixed direction. This method not only ensures the robustness of the prediction process in high-speed motion environments but also provides a clear, definite, and executable judgment criterion for the preset control, task scheduling, and sudden communication triggering of ground station antennas. In summary, this scheme achieves zero-miss capture and high-precision locking of extremely short reflection windows with extremely low computational overhead, providing core algorithmic support for the practical and large-scale application of large spatiotemporal scale reflection communication systems.

[0076] Figure 5 This is a block diagram of an electronic device used to implement embodiments of this application. Figure 5 As shown, the electronic device includes a memory 501 and a processor 502. The memory 501 stores a computer program that can run on the processor 502. When the processor 502 executes the computer program, it implements the method described in the above embodiments. The number of memories 501 and processors 502 can be one or more. In a specific implementation, the electronic device may also include a communication interface 503 for communicating with external devices and exchanging data.

[0077] In practical implementation, if the memory 501, processor 502, and communication interface 503 are implemented independently, they can be interconnected via a bus to communicate with each other. This bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. This bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0078] Optionally, in a specific implementation, if the memory 501, processor 502 and communication interface 503 are integrated on a single chip, the memory 501, processor 502 and communication interface 503 can communicate with each other through an internal interface.

[0079] This application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method provided in this application.

[0080] This application provides a computer program product, including a computer program that, when executed by a processor, implements the method provided in this application.

[0081] This application also provides a chip including a processor for calling and executing instructions stored in a memory, causing a communication device with the chip installed to perform the method provided in this application.

[0082] This application also provides a chip, including: an input interface, an output interface, a processor, and a memory. The input interface, output interface, processor, and memory are connected through an internal connection path. The processor is used to execute code in the memory. When the code is executed, the processor is used to execute the method provided in the application embodiment.

[0083] It should be understood that the aforementioned processor can be a CPU (Central Processing Unit), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. General-purpose processors can be microprocessors or any conventional processor. It is worth noting that the processor can be a processor supporting Advanced Reduced Instruction Set Machines (ARM) architecture.

[0084] Further, optionally, the aforementioned memory may include read-only memory and random access memory. The memory may be volatile memory or non-volatile memory, or may include both. Non-volatile memory may include read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may include random access memory (RAM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available. Examples include Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Sync Link DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0085] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another.

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0087] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0088] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process. Furthermore, the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functionality involved.

[0089] The logic and / or steps described in the flowchart or otherwise herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0090] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. All or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware, the program being stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiments.

[0091] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. This storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0092] The above description is merely an exemplary embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope described in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for predicting parameters of a spaceborne opportunistic communication window, characterized in that, include: Obtain orbital parameter information of multiple available satellites, which are equipped with onboard metasurfaces; For each available satellite, the orbital status information of the available satellite within a preset time range is calculated based on the orbital parameter information; The available satellites are screened to determine the available satellites that meet the preset discrimination criteria as candidate satellites. The preset discrimination criteria is that the nadir position of the available satellite is located within the specular reflection search area within the preset time range. The specular reflection search area is the Earth's spherical area with the midpoint of the great circle arc between the ground transmitting station and the receiving station as the center and the preset angular distance as the radius. For each of the candidate satellites, the beam intersection area of ​​the transmitting station and the receiving station is calculated, with the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station. For each of the candidate satellites, the communication window parameters of the candidate satellites are predicted based on the beam intersection region corresponding to the candidate satellites. The prediction of the communication window parameters of the candidate satellite based on the beam intersection region corresponding to the candidate satellite includes: Predict the times when the candidate satellites enter and leave the beam intersection area to determine the effective reflection period in the communication window parameters; Based on the spatial position coordinates of the candidate satellite at each discrete epoch during the effective reflection period, the bistatic angle at the corresponding discrete epoch is calculated. The bistatic angle is a geometric parameter in the communication window parameters used to characterize the reflection communication link, including the pointing angle parameter between the transmitting station and the candidate satellite and the pointing angle parameter between the candidate satellite and the receiving station.

2. The method according to claim 1, characterized in that, Before performing a screening of each of the available satellites, the method further includes: Determine the symmetrical midpoint direction of the transmitting station and the receiving station below the Earth's surface; Based on the symmetrical intermediate direction, determine the midpoint of the spherical great circle arc between the transmitting station and the receiving station; The mirror reflection search area is defined on the Earth's surface with the midpoint of the great circle arc as the center and the preset angular distance as the radius.

3. The method according to claim 1, characterized in that, The step of filtering each available satellite to determine the available satellites that meet the preset discrimination criteria as candidate satellites includes: Determine the sub-satellite point position of each available satellite at each discrete epoch within the preset time range; For each available satellite, based on the preset discrimination criteria, if it is determined that the nadir position of the available satellite enters the specular reflection search area at any time within the preset time range, then the available satellite is determined as the candidate satellite; otherwise, if it is determined that the nadir position of the available satellite does not enter the specular reflection search area within the preset time range, then the available satellite is eliminated.

4. The method according to claim 1, characterized in that, Before calculating the beam intersection region of the transmitting station and the receiving station for each of the candidate satellites, using the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station, the method further includes: For each candidate satellite, the latitude and longitude of the midpoint of the great circle arc of the sphere are used as the latitude and longitude of the reference space point, and the orbital altitude of the candidate satellite is used as the spatial altitude of the reference space point, so as to obtain the spatial position coordinates of the reference space point.

5. The method according to claim 4, characterized in that, For each of the candidate satellites, using the reference space point corresponding to the candidate satellite as the pointing target of the transmitting station and the receiving station, the beam intersection region of the transmitting station and the receiving station is calculated, including: Based on the spatial coordinates of the reference space point, calculate the fixed pointing parameters of the transmitting station pointing to the reference space point and the fixed pointing parameters of the receiving station pointing to the reference space point; Using the fixed pointing parameters of the transmitting station and the fixed pointing parameters of the receiving station remaining unchanged within the preset time range as the calculation condition, the transmission beam range covered by the transmitting station in space and the reception beam range covered by the receiving station in space are calculated respectively. The intersection of the transmitted beam range and the received beam range is calculated to obtain the beam intersection region.

6. The method according to claim 1, characterized in that, The orbital parameter information includes at least one of the following parameters from the two roots: semi-major axis, eccentricity, orbital inclination, right ascension of the ascending node, argument of perigee, and mean perigee.

7. An electronic device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory, wherein the processor, when executing the computer program, implements the method of any one of claims 1-6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 1-6.

9. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method according to any one of claims 1-6.

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