Unmanned aerial vehicle - multi-orbit satellite uplink transmission interruption performance analysis method

Abstract

The present application relates to a kind of unmanned aerial vehicle-multiple orbit satellite uplink transmission interruption performance analysis method.The orbit parameters of multiple orbits where satellite is located are obtained;The probability density of the distance between unmanned aerial vehicle and satellite in respective orbit is determined based on the orbit parameters;The probability density function and cumulative distribution function representing the distance distribution between unmanned aerial vehicle and satellite in respective orbit are derived based on the probability density;Based on the overlapping interval between multiple orbits, the probability density function and cumulative distribution function of the distance between unmanned aerial vehicle and satellite in multiple orbits are expressed in a segmented manner, which accurately describes the distance distribution between satellite and unmanned aerial vehicle;The outage probability of satellite communication link is calculated by combining the segmented expression with the signal-to-noise ratio distribution characteristics of satellite communication link.The present application quantitatively analyzes the influence of satellite orbit parameters and signal transmission power and other system parameters on the outage probability of satellite communication link through the closed-form expression of the outage probability of unmanned aerial vehicle-multiple orbit satellite uplink transmission communication link.

Description

Technical Field

[0001] This invention relates to the technical field of satellite communication, and in particular to a method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite. Background Technology

[0002] In recent years, satellite communication has attracted significant attention from related industries due to its wide applicability in large-scale broadcasting, navigation, and disaster relief operations. With its inherent characteristics of seamless connectivity and wide-area coverage, satellite communication has become an important enhancement technology for 6G systems. However, it also faces technical challenges such as signal obstruction, significant path loss, and security threats. Particularly in urban environments or mountainous areas, building and terrain obstructions can lead to deep signal fading, affecting communication quality.

[0003] In modern satellite communication systems, the performance of the communication link between satellites and drones is one of the key factors affecting the reliability of the entire system. Due to the complexity of satellite orbit distribution, drone location, and signal propagation environment, the outage probability (OP) of the communication link is an important performance indicator.

[0004] Current methods for analyzing interruption probability have the following limitations: Existing technologies mainly focus on the downlink transmission performance of Space-Air-Ground Integrated Network (SATN) systems, while the uplink transmission performance of cooperative SATN has not been fully studied. This includes insufficient analysis of uplink security performance and inadequate exploration of the impact of spatial randomness on security performance.

[0005] Analysis of the probability of communication link interruption between satellites and drones is usually based on simplified geometric models. These models often assume that satellites are uniformly distributed and have a single orbit, ignoring the complexity of multi-orbit satellite distribution. In practical applications, such simplified models cannot accurately reflect the distance distribution between satellites and drones, especially in multi-orbit satellite systems, where the complexity of satellite distribution can lead to a significant deviation between the actual interruption probability and the theoretical calculation.

[0006] The complexity of the signal propagation environment is not fully considered. Existing technologies, when analyzing the probability of interruption, typically assume an ideal signal propagation environment, neglecting the impact of atmospheric turbulence, weather conditions, and other factors on signal propagation. In practical applications, the signal-to-noise ratio (SNR) of free-space optical communication (FSO) links is significantly affected by environmental factors such as atmospheric turbulence, fog, and rain, leading to discrepancies between the calculated interruption probability and actual conditions. For example, atmospheric turbulence causes fluctuations in the intensity of optical signals, and the Gaussian distribution model commonly used in existing technologies cannot accurately describe these fluctuations.

[0007] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0008] It should be noted that this section is intended to provide background or context for the technical solutions of the invention as set forth in the claims. The description herein does not imply acceptance as prior art simply because it is included in this section. Summary of the Invention

[0009] The purpose of this invention is to provide a method for analyzing the uplink transmission interruption performance of UAV-multi-orbit satellite, thereby at least partially solving one or more problems caused by the limitations and defects of related technologies.

[0010] This invention provides a method for analyzing uplink transmission interruption performance between UAVs and multi-orbit satellites, including: Obtain the orbital parameters of the satellite in multiple orbits; The probability density of the distance between the UAV and the satellite in their respective orbits is determined based on the orbital parameters. Based on the probability density, the probability density function and cumulative distribution function representing the distance distribution between the UAV and the satellite in their respective orbits are derived. Based on the overlapping intervals between multiple orbits, the probability density function and cumulative distribution function of each orbit are integrated, and the probability density function and cumulative distribution function of the distance between UAVs and satellites on multiple orbits are expressed in a piecewise manner. The probability of satellite communication link interruption is calculated by combining the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits, expressed in a piecewise manner, with the signal-to-noise ratio distribution characteristics of the satellite communication link.

[0011] Optionally, the step of obtaining the orbital parameters of the satellite in multiple orbits includes: Based on a spatial rectangular coordinate system with the Earth's center as the origin, the orbital parameters of the satellite in multiple orbits are determined by parameters such as orbital radius, orbital inclination, and right ascension of the ascending node.

[0012] Optionally, the step of determining the probability density of the distance between the UAV and the satellite in their respective orbits based on the orbital parameters includes: The true anomaly angle is defined by the angle between the ascending node of the orbit and the satellite, and the satellite's coordinates are determined by combining the orbital radius, orbital inclination, and right ascension of the ascending node. The probability density of the distance between the UAV and the satellite in their respective orbits is determined based on the uniform distribution of satellites in orbit.

[0013] Optionally, the step of deriving the probability density function and cumulative distribution function of the distance distribution between the UAV and the satellite representing their respective orbits based on the probability density includes: Based on the geometric relationship of the satellite in its orbit, and based on the expression for the distance between the UAV and the satellite, the cumulative distribution function of the distance between the UAV and the satellite in a single orbit is derived; The probability density function of the distance between a UAV and a satellite in a single orbit is derived by differentiating the cumulative distribution function.

[0014] Optionally, the step of integrating the probability density function and cumulative distribution function of each orbit based on the overlapping interval between multiple orbits, and expressing the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits in a piecewise manner includes: Based on the overlapping intervals between multiple orbits, the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits are divided into two categories: the case where the satellite is only in a single orbit and the case where the satellite is in multiple orbits simultaneously, and then expressed in a segmented manner.

[0015] Optionally, the step of calculating the probability of satellite communication link interruption by combining the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits expressed in a piecewise manner with the signal-to-noise ratio distribution characteristics of the satellite communication link includes: The signal-to-noise ratio distribution of the satellite communication link is described using a Gamma-Gamma distribution model.

[0016] Optionally, the step of calculating the probability of satellite communication link interruption by combining the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits expressed in a piecewise manner with the signal-to-noise ratio distribution characteristics of the satellite communication link includes: Optionally, the step of numerically integrating the calculated satellite communication link interruption probability to derive an expression representing the relationship between the interruption probability and system parameters includes: By utilizing the probability density function of the distance between the satellite and the UAV, combined with the cumulative distribution function of the instantaneous signal-to-noise ratio under the Gamma-Gamma model, the interruption probability is expressed as an integral of the square of the distance. A numerical integration method is then used to efficiently calculate this integral, yielding the numerical relationship between the interruption probability and satellite orbital parameters, UAV altitude, and signal propagation environment parameters.

[0017] The technical solution provided by this invention may include the following beneficial effects: This invention uses a closed-form expression for the probability of communication link interruption between a UAV and a multi-orbit satellite to quantitatively analyze the impact of system parameters such as satellite orbital parameters and signal transmission power on the probability of communication link interruption. Through detailed geometric analysis and probability density function derivation, it accurately describes the distance distribution between the satellite and the UAV, making it particularly suitable for systems where satellites are distributed across multiple orbits. This makes the calculation of the interruption probability more accurate and can reflect the complexities of actual communication environments. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] Figure 1 A flowchart illustrating the uplink transmission interruption performance analysis method for UAV-multi-orbit satellite in an exemplary embodiment of the present invention is shown. Figure 2 A more detailed flowchart illustrating the UAV-multi-orbit satellite uplink transmission interruption performance analysis method in an exemplary embodiment of the present invention is shown. Figure 3 This diagram illustrates the parameters required to determine the satellite orbital position in an exemplary embodiment of the present invention. Figure 4 This illustrates the true anomaly angle for determining the position of a satellite on the orbital plane in an exemplary embodiment of the present invention. A schematic diagram of the area; Figure 5 This is a schematic diagram of a model in which satellites are uniformly distributed on two orbits in an exemplary embodiment of the present invention.

[0020] Figure 6 This illustrates an exemplary embodiment of the invention where the interruption probability varies with different transmit power levels. Value and The following is a simulation diagram; Figure 7 This illustrates an exemplary embodiment of the invention where the interruption probability varies with different transmit power levels. The following is a simulation diagram. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0022] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0023] This invention provides a method for analyzing uplink transmission interruption performance between UAVs and multi-orbit satellites, with reference to... Figure 1 As shown, it includes the following steps: Step S101: Obtain the orbital parameters of the multiple orbits in which the satellite is located.

[0024] Step S102: Determine the probability density of the distance between the UAV and the satellite in their respective orbits based on the orbital parameters.

[0025] Step S103: Based on the probability density, derive the probability density function and cumulative distribution function of the distance distribution between the UAV and the satellite representing their respective orbits.

[0026] Step S104: Integrate the probability density function and cumulative distribution function of each orbit based on the overlapping interval between multiple orbits, and express the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits in a piecewise manner.

[0027] Step S105: Calculate the probability of satellite communication link interruption by combining the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits expressed in a piecewise manner with the signal-to-noise ratio distribution characteristics of the satellite communication link.

[0028] It is important to understand that, considering the distribution of satellites in two orbits and the complex signal propagation environment, the interruption performance of the uplink RD link in SATN was studied. The RD link uses FSO transmission, leveraging the inherent advantages of its highly directive laser beam, thus providing a theoretical basis for the optimized design of satellite communication systems.

[0029] It's also important to understand that in direct communication between satellites and ground terminals, signals suffer from deep fading due to terrain obstacles such as urban buildings and mountains, leading to a sharp decline in communication link quality or even interruption. Unmanned aerial vehicles (UAVs), as drones, offer a flexible and effective solution for improving satellite-to-ground communication.

[0030] It's also necessary to understand the establishment of a spatial rectangular coordinate system with the Earth's center as the origin. Let the altitude of the ground-based UAV R be... The angle between the boundary of its signal coverage area and the line connecting it to the Earth's center is... .

[0031] Define two satellite orbits that pass through the drone's coverage area: orbit AB and orbit FG. Both orbits have the same radius. It intersects the equatorial plane on the same straight line, but with a different angle of inclination. and (set up ).

[0032] Define the distribution of satellites along their orbital arcs: For orbit AB, the satellite's true anomaly angle In the interval Uniformly distributed within, corresponding to an orbital arc length of .

[0033] For orbit FG, the satellite's true anomaly angle In the interval Uniformly distributed within, corresponding to an orbital arc length of .

[0034] It's also important to understand that the probability density analysis of satellite-UAV distance provides a method for calculating the probability density function (PDF) and cumulative distribution function (CDF) of the distance between satellites and UAVs based on satellite orbital parameters. This method can accurately describe the distance distribution between satellites and UAVs and is applicable to situations where satellites are uniformly distributed on a single orbit and two orbits.

[0035] It is also necessary to understand the distance between satellite D and drone R. ,in According to the true nearest angle u Given a uniform distribution, by substitution of variables, we can deduce the distance in the case of a single track. d PDF and CDF. For scenarios where satellites are uniformly distributed across two orbits, distances are derived by interval. d CDF and PDF.

[0036] It is also necessary to understand the method for calculating the probability of communication link interruption. A method based on the distance distribution between satellites and UAVs is proposed. This method combines the SNR distribution characteristics of FSO links and utilizes a Gamma-Gamma distribution model to accurately calculate the probability of communication link interruption.

[0037] It is also necessary to understand that, assuming the RD link is an FSO link following a Gamma-Gamma distribution, the instantaneous signal-to-noise ratio of this link... ,in , C 0 is a constant related to transmit power, channel parameters, etc. (Obtained) CDF expression .

[0038] It is also necessary to understand that the interruption probability is defined as ,Will CDF and Substituting the PDF into the definition of interruption probability, the interruption probability can be expressed as a function of the squared distance. The points.

[0039] It is also necessary to understand the calculation method of the interruption probability: This paper provides an analysis method for satellite communication systems based on interruption probability analysis. Through a closed-form expression of the interruption probability of the UAV-multi-orbit satellite uplink transmission communication link, it quantitatively analyzes the impact of system parameters such as satellite orbit parameters and signal transmission power on the interruption probability of the satellite communication link.

[0040] It is also important to understand that the system adapts to complex environments: by fully considering the complexity of the signal propagation environment, the satellite communication system can maintain high communication performance under different weather conditions and atmospheric environments, thus enhancing the system's adaptability.

[0041] It is also important to understand the precise description of the distance distribution between satellites and drones: This invention, through detailed geometric analysis and probability density function derivation, accurately describes the distance distribution between satellites and drones, making it particularly suitable for systems where satellites are distributed across two orbits. This makes the calculation of the interruption probability more accurate and can reflect the complexities of real-world communication environments.

[0042] The aforementioned method for analyzing uplink transmission interruption performance between UAVs and multi-orbit satellites is employed. Through a closed-form expression for the probability of uplink transmission interruption, the impact of system parameters such as satellite orbital parameters and signal transmission power on the probability of satellite communication link interruption is quantitatively analyzed. Detailed geometric analysis and probability density function derivation accurately describe the distance distribution between the satellite and the UAV. This method is particularly suitable for systems where satellites are distributed across multiple orbits, making the calculation of the interruption probability more accurate and reflecting the complexities of real-world communication environments.

[0043] The following will provide a more detailed explanation of each step of the above-described UAV-multiorbit satellite uplink transmission interruption performance analysis method in this example embodiment.

[0044] In some embodiments, step S101 includes: Based on a spatial rectangular coordinate system with the Earth's center as the origin, the orbital parameters of the satellite in multiple orbits are determined by parameters such as orbital radius, orbital inclination, and right ascension of the ascending node.

[0045] It is important to understand that reference Figure 3 As shown, a satellite's orbital position can be determined by three parameters: orbital radius. Track inclination Right ascension of ascending node With the Earth's center as the origin, the line of intersection between the orbital plane and the equatorial plane is... x Establish a rectangular coordinate system using the axes, i.e. First, we derive the probability density of the distance between the satellite and the drone when the satellites are uniformly distributed in a single orbit.

[0046] In the orbital plane, the angle between the ascending node and the satellite is called the true anomaly angle. u For a single orbit, the coordinates of a satellite can be represented as... .

[0047] In some embodiments, reference Figure 2 As shown, step S102 includes: The true anomaly angle is defined by the angle between the ascending node of the orbit and the satellite, and the satellite's coordinates are determined by combining the orbital radius, orbital inclination, and right ascension of the ascending node.

[0048] The probability density of the distance between the UAV and the satellite in their respective orbits is determined based on the uniform distribution of satellites in orbit.

[0049] It is important to understand the distance between the satellite and the drone. d PDF and CDF can be obtained through geometric relationships and probability density transformations.

[0050] refer to Figure 4 As shown, because the satellites are uniformly distributed in orbit, the true anomaly angle is... In the interval The distribution is uniformly distributed on the upper surface, and its probability density function is: In some embodiments, reference Figure 2 As shown, step S103 includes: Based on the geometric relationship of the satellite in its orbit, and based on the expression for the distance between the UAV and the satellite, the cumulative distribution function of the distance between the UAV and the satellite in a single orbit is derived; The probability density function of the distance between a UAV and a satellite in a single orbit is derived by differentiating the cumulative distribution function.

[0051] It is important to understand that the connection between the satellite and the Earth's center is... z The included angle of the axis is According to geometric relationships, we have: .

[0052] make Then the probability density function of Y is: Furthermore, let Then the probability density function of X is: Distance between satellite and drone R d for: The distance can be calculated. d The CDF is: Taking the derivative again, we get dThe probability density function is: In some embodiments, step S104 includes: Based on the overlapping intervals between multiple orbits, the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits are divided into two categories: the case where the satellite is only in a single orbit and the case where the satellite is in multiple orbits simultaneously, and then expressed in a segmented manner.

[0053] It is important to understand the probability density of the distance between the satellite and the UAV when the satellites are uniformly distributed in two orbits. The angle between the boundary of the R-transmitted signal coverage area and the line connecting the Earth's center is... The drone's altitude is H R On the spherical cap surface within the drone's coverage area, there are orbits AB and FG, both with radii of [missing information]. The satellites are evenly distributed on these two orbits.

[0054] refer to Figure 5 As shown, assume the inclination angles of orbits AB and FG are respectively... and The satellite's true perimeter angle is uniformly distributed within the corresponding interval. By analyzing the overlapping interval of the two orbits, the distance between the satellite and the UAV can be obtained. d Piecewise expressions for CDF and PDF.

[0055] Scenario 1: When At that time, the satellite was only in orbit AB, and CDF was... Scenario 2: When At that time, the satellite was in orbits AB and FG, and CDF was... in, , .

[0056] Distance between satellites and drones evenly distributed in two orbits d The PDF is: In some embodiments, reference Figure 2 As shown, step S105 includes: The signal-to-noise ratio distribution of the satellite communication link is described using a Gamma-Gamma distribution model.

[0057] It is important to understand that the probability of communication link interruption is calculated by using the PDF and CDF of the distance between the satellite and the drone, combined with the signal-to-noise ratio distribution characteristics of the FSO link.

[0058] make The PDF representation of ω is: The signal-to-noise ratio distribution of the FSO link is described using the Gamma-Gamma distribution model.

[0059] The instantaneous SNR of an FSO link can be expressed as: in, , , .

[0060] The RD link follows a Gamma-Gamma distribution, and the instantaneous signal-to-noise ratio of the FSO link is... The PDF and CDF are as follows: in, , , , , , .

[0061] In some embodiments, reference Figure 2 As shown, step S105 includes: The probability of interruption is calculated by integration, and the integral is divided into two segments for calculation, corresponding to the distribution of satellites in different orbits.

[0062] It is necessary to understand that... PDF and Substituting CDF into the definition of interrupt probability have to The probability of interruption (OP) is calculated by integration. The integral is divided into two segments for calculation, corresponding to the distribution of satellites in different orbits.

[0063] in, In practical calculations, numerical integration methods are used to efficiently solve the above integrals. Numerical integration methods have clear physical meaning, are easy to program, and can directly utilize the CDF function of the Gamma-Gamma distribution, making them suitable for rapid performance evaluation in engineering applications.

[0064] Based on the aforementioned analysis method for uplink transmission interruption performance between UAVs and multi-orbit satellites, the following experiment provides a more detailed explanation. Using the derived interruption probability expression, the relationship between the interruption probability and satellite orbital parameters, UAV altitude, and signal propagation environment parameters is analyzed. By adjusting parameters such as satellite orbital inclination, UAV altitude, or signal transmission power, the configuration of the satellite communication system is optimized to reduce the probability of communication link interruption. Specific optimization algorithms or strategies are provided, such as using numerical optimization methods to find the optimal combination of satellite orbital parameters to minimize the system interruption probability.

[0065] Based on the above technical solutions of the embodiments of the present invention, the simulation experimental results will be described in detail below with reference to the accompanying drawings. Figure 6 and Figure 7 Simulation curves of uplink operation (OP) versus transmit power under different system parameters are presented to verify the effectiveness of the proposed analysis method for system performance evaluation. Specifically, by rationally configuring satellite orbit parameters, selecting appropriate detection methods, and controlling link pointing errors, the probability of uplink transmission interruption can be significantly reduced, thereby improving the reliability of the UAV-multi-orbit satellite communication system. Simulation results are as follows: Figure 6 and Figure 7 As shown.

[0066] Specifically, Figure 6 The relationship between the interruption probability and the transmission power is shown under different atmospheric turbulence intensities and different detection methods. When the turbulence is weakest (…), the probability of interruption varies with the transmission power. When the turbulence is at its strongest, the system interruption probability is significantly lower than when the turbulence is at its most intense. The results show that a weakly turbulent environment is beneficial for improving uplink transmission interruption performance. Meanwhile, under the same turbulent conditions, the HD detection method (…) The interruption probability of ) is consistently lower than that of using the IM / DD method ( The interruption probability is lower because HD detection achieves a higher instantaneous signal-to-noise ratio. Therefore, Figure 6 This demonstrates that the method of the present invention can quantitatively assess the impact of different turbulence intensities and receiver detection schemes on the interruption probability, providing a theoretical basis for parameter selection of practical systems in complex atmospheric environments. Figure 7 Different pointing error parameters are shown. The curve showing the change in down-interruption probability as a function of transmit power. Pointing error parameters. This reflects the alignment accuracy of the laser link between the UAV and the satellite. A larger value indicates higher precision. Figure 7 It can be seen that, under the same transmission power, the smaller The corresponding interruption probability is significantly higher than that of larger ones. This indicates that improving link pointing accuracy can effectively suppress performance loss caused by beam misalignment, thereby significantly reducing the probability of communication interruption. Figure 7 The results verify the ability of the analytical method of this invention to model pointing error factors, and provide a quantitative reference for optimizing system performance by improving tracking accuracy in practical engineering.

[0067] The table below shows the specific parameters used in the experiment.

[0068] 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 the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine different embodiments or examples described in this specification.

[0069] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the appended claims.

Claims

1. A method for analyzing the uplink transmission interruption performance of UAV-multi-orbit satellite, characterized in that, include: Obtain the orbital parameters of the satellite in multiple orbits; The probability density of the distance between the UAV and the satellite in their respective orbits is determined based on the orbital parameters. Based on the probability density, the probability density function and cumulative distribution function representing the distance distribution between the UAV and the satellite in their respective orbits are derived. Based on the overlapping intervals between multiple orbits, the probability density function and cumulative distribution function of each orbit are integrated, and the probability density function and cumulative distribution function of the distance between UAVs and satellites on multiple orbits are expressed in a piecewise manner. The probability of satellite communication link interruption is calculated by combining the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits, expressed in a piecewise manner, with the signal-to-noise ratio distribution characteristics of the satellite communication link.

2. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 1, characterized in that, The steps for obtaining the orbital parameters of the satellite in multiple orbits include: Based on a spatial rectangular coordinate system with the Earth's center as the origin, the orbital parameters of the satellite in multiple orbits are determined by parameters such as orbital radius, orbital inclination, and right ascension of the ascending node.

3. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 2, characterized in that, The step of determining the probability density of the distance between the UAV and the satellite in their respective orbits based on the orbital parameters includes: The true anomaly angle is defined by the angle between the ascending node of the orbit and the satellite, and the satellite's coordinates are determined by combining the orbital radius, orbital inclination, and right ascension of the ascending node. The probability density of the distance between the UAV and the satellite in their respective orbits is determined based on the uniform distribution of satellites in orbit.

4. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 3, characterized in that, The steps of deriving the probability density function and cumulative distribution function of the distance distribution between the UAV and the satellite representing their respective orbits based on the probability density include: Based on the geometric relationship of the satellite in its orbit, and based on the expression for the distance between the UAV and the satellite, the cumulative distribution function of the distance between the UAV and the satellite in a single orbit is derived; The probability density function of the distance between a UAV and a satellite in a single orbit is derived by differentiating the cumulative distribution function.

5. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 4, characterized in that, The step of integrating the probability density function and cumulative distribution function of each orbit based on the overlapping interval between multiple orbits, and expressing the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits in a piecewise manner includes: Based on the overlapping intervals between multiple orbits, the probability density function and cumulative distribution function of the distance between UAVs and satellites in multiple orbits are divided into two categories: the case where the satellite is only in a single orbit and the case where the satellite is in multiple orbits simultaneously, and then expressed in a segmented manner.

6. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 1, characterized in that, The step of calculating the probability of satellite communication link interruption by combining the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits expressed in a piecewise manner with the signal-to-noise ratio distribution characteristics of the satellite communication link includes: The signal-to-noise ratio distribution of the satellite communication link is described using a Gamma-Gamma distribution model.

7. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 6, characterized in that, The step of calculating the probability of satellite communication link interruption by combining the probability density function and cumulative distribution function of the distance between the UAV and the satellite in multiple orbits expressed in a piecewise manner with the signal-to-noise ratio distribution characteristics of the satellite communication link includes: The probability of interruption is calculated by integration, and the integral is divided into two segments for calculation, corresponding to the distribution of satellites in different orbits.

8. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to any one of claims 1-7, characterized in that, Also includes: By utilizing the probability density function of the distance between the satellite and the UAV, and combining it with the cumulative distribution function of the instantaneous signal-to-noise ratio under the Gamma-Gamma distribution model, an expression for the interruption probability representing the relationship between the interruption probability and system parameters is derived.

9. The method for analyzing uplink transmission interruption performance of UAV-multi-orbit satellite according to claim 8, characterized in that, The method involves numerically integrating the calculated probability of satellite communication link interruption to provide a directly calculable engineering tool for performance evaluation and optimization design of satellite communication systems.

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