A free space optical communication link simulation analysis method and interface system

Abstract

The application relates to a free space optical communication link simulation analysis method and an interface system, and relates to the technical field of optical communication. In order to solve the problems in the prior art, the free space optical communication link simulation analysis method comprises the following steps: determining a link type, determining a transceiving terminal, configuring a transceiving terminal parameter, configuring a link parameter, calculating a transceiving terminal gain, calculating a pointing loss, calculating a channel transmission loss, calculating a link margin, and displaying a calculation result. A model covers deep space, near earth and inter-satellite link scenes, and link performance is quantitatively evaluated through a formula. The free space optical communication link simulation interface system comprises the following modules: link selection, data input, link budget, visual analysis and output, supports parameter configuration, real-time calculation and chart display, and can generate a standardized report. The scheme solves the problems of insufficient parameter coverage and poor interactivity of a traditional method, realizes the integration of "configuration-calculation-analysis", and improves link design optimization efficiency and user experience.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a free-space optical communication link simulation analysis method and interface system. Background Technology

[0002] Free-space optical communication is a communication technology that uses lasers to transmit data in free space, offering advantages such as high bandwidth, low latency, and resistance to electromagnetic interference. However, free-space optical communication is susceptible to factors such as atmospheric turbulence, weather conditions, and optical path loss, leading to unstable link performance. Existing simulation analysis methods are typically based on a single model, making it difficult to comprehensively consider the influence of multiple environmental factors, and they lack user-friendly interfaces, limiting the efficiency and accuracy of the analysis.

[0003] See the journal *Wireless Communications*, where Liu Dachang et al. published "Performance Budgeting of Space Optical Communication in Atmospheric Channels," which derived expressions for link margin and link reliability for the overall link, providing a theoretical basis for selecting the optimal beam type, system design parameters, and link budget analysis for space optical communication systems. However, this simulation method still relies on a single environmental parameter input and lacks a simulation framework coupled with multiple physics. Furthermore, the interfaceless system leads to poor algorithm interactivity and cumbersome parameter adjustments, making it difficult for engineers to efficiently conduct comparative analyses of link performance under different scenarios and limiting the rapid verification of theoretical results in system design.

[0004] Therefore, there is an urgent need for a technical solution that can integrate multiple environmental factors, provide efficient simulation analysis methods and user-friendly interactive interfaces to meet the design and optimization needs of free-space optical communication systems. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides a free-space optical communication link simulation and analysis method and interface system. Through comprehensive modeling and a user-friendly interactive interface, it enables efficient simulation and analysis of the performance of free-space optical communication links.

[0006] The technical solution of this invention to solve the technical problem is:

[0007] A free-space optical communication link simulation and analysis method, characterized by comprising the following steps:

[0008] Step 1: Determine the link type. Based on the actual needs of the application scenario, determine the link type among deep space, near-Earth, and inter-satellite links.

[0009] Step 2: Determine the transceiver terminals of the communication system. Based on the uplink and downlink technical characteristics, select the corresponding transceiver devices.

[0010] Based on the link type identification results in step 1, the system automatically matches the corresponding transceiver terminal type;

[0011] For deep space and near-Earth space-to-ground link scenarios, ground stations and satellites are selected as transceiver terminals; the ground station, as the earth-end equipment, has simulation parameters that include geographical location and equipment characteristics; the satellite, as the space-end equipment, has simulation parameters that include orbital parameters and antenna performance.

[0012] The inter-satellite link scenario selected a dual-satellite terminal, and the simulation parameters included orbital relationship, spatial geometric path and loss characteristics;

[0013] Step 3: Configure the transceiver terminal parameters, and perform differentiated configuration according to the device type;

[0014] Ground terminal parameter configuration includes altitude, optical antenna efficiency, antenna aperture, and pointing error; satellite terminal parameter configuration includes satellite altitude, optical antenna efficiency, antenna aperture, and pointing error.

[0015] Step 4: Configure the link physical parameters, and perform differentiated configuration according to the link type;

[0016] For satellite-to-ground link scenarios, the laser operating wavelength, antenna elevation angle, and tropospheric altitude are configured synchronously; for inter-satellite link scenarios, the parameter configuration includes the laser operating wavelength and the distance between the two satellites.

[0017] Step 5: Calculate the transmit and receive end gains; the transmit and receive end gains are determined based on the antenna design parameters.

[0018] Step 6: Calculate the pointing loss based on the antenna pointing error and wavelength;

[0019] Step 7: Calculate channel transmission loss; calculate free space path loss based on laser wavelength and transmission distance; superimpose geometric scattering loss and Mie scattering loss for uplink and downlink of satellite-to-ground link.

[0020] Step 8: Calculate the link margin and display the calculation results; display key performance indicators in tabular form, including transmit gain, receive gain, pointing loss, path loss, atmospheric attenuation, and link margin, and finally present the link margin calculation results in quantitative indicators.

[0021] In step 5, the gain of the transmitting and receiving ends is calculated based on the antenna aperture and wavelength, as follows:

[0022]

[0023] Among them, D t D is the aperture of the transmitting antenna, measured in meters (m). r λ is the aperture of the receiving antenna, in meters (m); λ is the wavelength, in meters (m).

[0024] In step 6, the pointing loss of the transmitter and receiver is calculated based on the pointing error and the linear gain of the transmitter and receiver. The calculation formulas are as follows:

[0025]

[0026] Among them, Pe t Pe is the pointing error of the transmitter, measured in radians; r The receiver pointing error is expressed in radians.

[0027] In step 7, the free space path loss is calculated based on the laser wavelength and transmission distance. The calculation formula is as follows:

[0028]

[0029] Wherein, for inter-satellite links, d is the distance between two satellites; for satellite-to-ground links, d is the distance from the satellite to the ground station.

[0030] Based on the distance the beam travels in the troposphere, the attenuation coefficient due to geometric scattering, and the extinction ratio of Mie scattering, the geometric scattering loss and Mie scattering loss are calculated, from which the total scattering loss can be calculated; specifically including:

[0031]

[0032] L sca =L geo +L mie

[0033] Among them, L geo The attenuation due to geometric scattering is measured in dB; L mie The attenuation due to Mie scattering is expressed in dB; d T σ is the distance the light beam travels in the troposphere; mie It is the extinction ratio of Mie scattering; A geo It is the attenuation coefficient caused by geometric scattering;

[0034] The attenuation coefficient caused by geometric scattering can be calculated based on the visibility V and the grain size coefficient δ, using the following formula:

[0035]

[0036] Where V is visibility, measured in km; δ is the particle size coefficient.

[0037] The Mie extinction ratio is calculated based on empirical coefficients; specifically, it includes:

[0038]

[0039] a = 0.000487λ 3 -0.002237λ 2 +0.003864λ-0.004442

[0040] b = -0.00573λ 3 +0.02639λ 2 -0.04552λ+0.05164

[0041] c = 0.02565λ 3 -0.1191λ 2 +0.20385λ-0.216

[0042] d = -0.0638λ 3 +0.3034λ 2 -0.5083λ+0.425

[0043] Among them, h GS This represents the height of the ground station above mean sea level, in km; a, b, c, and d are empirical coefficients related to wavelength λ.

[0044] In step 8, the link margin is calculated by the difference between the received power and the required signal power, using the following formula:

[0045] L M =P r -P req

[0046] Among them, P r Received power, in dBm, P req This is the required signal power, measured in dBm.

[0047] Furthermore, the received power is calculated based on the transmit power, the optical efficiency of the transceiver antenna, the gain of the transceiver antenna, the pointing loss, the free space path loss, the atmospheric absorption loss, and the atmospheric scattering loss, as shown in the following formula:

[0048] P r =P t +μ t +μ r +G t +G r -LP t -LP r -L P -L abs -L sca

[0049] Among them, the transmission power P t This refers to the output power of the transmitter, measured in dB; the antenna optical efficiency is μ. tand μ r These represent the efficiency of the antenna optical system at the transmitting and receiving ends, respectively; antenna gain G t and G r These represent the gains of the transmitting and receiving antennas, respectively, in dB; the pointing loss LP t and LP r These represent the losses caused by antenna pointing errors at the transmitting and receiving ends, respectively, in dB; free space path loss L P Free-space path loss between the ground station and the satellite, measured in dB; atmospheric absorption loss L. abs Attenuation loss caused by atmospheric absorption, measured in dB; atmospheric scattering loss L sca This is the attenuation loss caused by atmospheric scattering, measured in dB.

[0050] A free-space optical communication link simulation interface system, characterized in that it includes:

[0051] The link selection module, located in the upper left pane of the operation page, includes three options: "Satellite-Ground", "Satellite-Satellite", and "Deep Space-Ground", representing three communication link modes: near-Earth laser communication, inter-satellite laser communication, and deep space laser communication, respectively. By selecting different laser communication channels, a free-space optical communication simulation channel can be constructed. Within this module, users can access and modify the attribute parameters of a target entity by selecting that entity.

[0052] The data input module features a parameter input pane that includes options for ground station, uplink / downlink, and satellite. These tabs allow users to configure link properties, precisely input satellite orbit parameters, adjust antenna size, and manage parameters for multiple objects. This module provides the system with a precise input parameter system, ensuring the accuracy and reliability of subsequent simulation calculations.

[0053] The link budget module, located at the top of the central pane of the application, allows you to select to perform uplink, downlink, or inter-satellite link calculations; based on the established model, it calculates the link margin performance metrics of the communication links.

[0054] In the link budget module, clicking the calculate button will execute the link budget calculation process; after the calculation is completed, the detailed calculation results will be displayed in the lower area; in the link parameter calculation display unit, users can view various parameters and calculated values, such as transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin; there is a calculation result output option, which allows users to quickly save the calculation data in a standardized format for easy subsequent analysis and verification;

[0055] The visualization analysis and output module, located on the right side of the interface, uses visualization technology to present simulation results intuitively. Users can directly perform editing operations, adjust the relevant settings of the X and Y axes, and customize the value range and step size of the X axis. Users can select appropriate axis coordinates and their value ranges according to the required data information to accurately display specific parts of the data or charts.

[0056] After selecting the X-axis coordinate, users can select contour information again to draw contour images and compare them with the X-axis data. At the same time, it supports generating standardized reports from simulation results, integrating data tables, chart analysis, and key parameter descriptions to provide a complete link performance evaluation document.

[0057] Users first input parameters into the link selection module and data input module, including altitude, optical antenna efficiency, antenna aperture, pointing error, laser operating wavelength, tropospheric altitude, elevation angle, inter-satellite distance, and transmit power; as well as climate characteristic parameters, including channel attenuation parameters and tropospheric altitude. The system provides five configurable options: near-ground uplink / downlink, inter-satellite link, and deep-space uplink / downlink. After selecting the link type, the link budget module performs link attenuation calculations based on the input parameters, specifically analyzing gas absorption attenuation and scattering attenuation. Then, it calculates the transceiver gain, pointing loss, free-space path loss, and link margin. The calculation results are then transmitted to the link. The parameter calculation and display unit outputs transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin indicators, fully realizing comprehensive budget analysis and reliability assessment of free space optical communication links. Finally, by selecting the type of horizontal and vertical axis parameters, adjusting the parameter value range, and setting the isolines and step size in the visualization analysis and output module, the system will automatically generate multi-dimensional images, displaying the link budget analysis results in a real-time graphical format. The plotting results can be saved using the "Save Image" or "Save Image As" buttons.

[0058] The beneficial effects of this invention are:

[0059] 1. This invention constructs a simulation analysis method for free-space optical communication links, covering the entire process from link scenario modeling and parameter input to link margin calculation. It matches corresponding parameter configurations and loss calculation models according to different application scenarios in deep space, near-Earth, and inter-satellite environments, automatically selects suitable transceiver terminals, and comprehensively considers multiple influencing factors such as antenna design, atmospheric environment, and geographical location. Through refined calculations of transceiver gain, pointing loss, channel transmission loss, and atmospheric loss, it achieves accurate quantitative evaluation of link performance. Combined with multi-dimensional visualization analysis, it supports multi-parameter correlation display. It solves the problem of insufficient parameter coverage in traditional algorithms, improving the adaptability of simulation analysis to diverse scenarios. It intuitively presents key performance indicators, transforming complex calculation results into visual decision-making basis. The entire method is highly systematic and logically rigorous, providing an efficient, accurate, and comprehensive solution for free-space optical communication link simulation analysis.

[0060] 2. At the interface system level, this invention integrates parameter input, calculation and analysis, visualization, and data management functions through a structured interface design, constructing a full-process simulation platform. This provides an efficient, accurate, and intuitive operation solution for free-space optical communication link budget analysis, significantly improving link design and optimization efficiency. The link canvas supports dynamic construction of communication links, and focused operations directly modify entity parameters; category tabs integrate parameter input and real-time verification. Calculation results and custom charts are presented on the same screen, supporting multi-dimensional parameter self-configuration, isolinear image drawing, and standardized report generation, achieving integrated "configuration-calculation-analysis" operation. Compared with traditional interfaces, this reduces interaction steps, enhances the intuitiveness of result interpretation, and significantly improves simulation efficiency and user experience in engineering applications. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the simulation and analysis method for a free-space optical communication link according to the present invention;

[0062] Figure 2 This is a schematic diagram of the overall interface of the free space optical communication link simulation and analysis interface system of the present invention.

[0063] Figure 3 This is a schematic diagram of the link selection module in a free-space optical communication link simulation and analysis interface system of the present invention;

[0064] Figure 4 This is a schematic diagram of the data input module in a free-space optical communication link simulation and analysis interface system of the present invention;

[0065] Figure 5 This is a schematic diagram of the link budget module in a free-space optical communication link simulation and analysis interface system of the present invention;

[0066] Figure 6This is a schematic diagram of the drawing and display unit in the visualization analysis and output module of the free space optical communication link simulation analysis interface system of the present invention;

[0067] Figure 7 This is a schematic diagram of the coordinate axis setting and image export unit in the visualization analysis and output module of the free space optical communication link simulation analysis interface system of the present invention;

[0068] Figure 8 for Figure 5 The diagram shows the actual output data results after inputting parameters into a free-space optical communication link simulation and analysis interface system.

[0069] Figure 9 for Figure 6 The diagram shows the actual output image after inputting parameters into a free-space optical communication link simulation analysis interface system. Detailed Implementation

[0070] The present invention will now be described in further detail with reference to the accompanying drawings.

[0071] like Figure 1 As shown, a free-space optical communication link simulation and analysis method includes the following steps:

[0072] A simulation and analysis method for free-space optical communication links includes the following steps:

[0073] Step 1: Determine the link type. Based on the actual needs of the application scenario, determine the link type among deep space, near-Earth, and inter-satellite links.

[0074] Step 2: Determine the transceiver terminals of the communication system. Based on the uplink and downlink technical characteristics, select the corresponding transceiver devices.

[0075] Based on the link type identification results in step 1, the system automatically matches the corresponding transceiver terminal type.

[0076] For deep space and near-Earth space-to-ground link scenarios, ground stations and satellites are selected as transceiver terminals. The ground station, as the Earth-based device, has simulation parameters including geographical location and equipment characteristics; the satellite, as the space-based device, has simulation parameters including orbital parameters and antenna performance.

[0077] The inter-satellite link scenario selected a dual-satellite terminal, and the simulation parameters included orbital relationship, spatial geometric path and loss characteristics.

[0078] Step 3: Configure the transceiver terminal parameters, and perform differentiated configuration according to the device type.

[0079] Ground terminal parameter configuration includes altitude, optical antenna efficiency, antenna aperture, and pointing error. Satellite terminal parameter configuration includes satellite altitude, optical antenna efficiency, antenna aperture, and pointing error.

[0080] Step 4: Configure the link physical parameters, and perform differentiated configuration according to the link type.

[0081] For satellite-to-ground link scenarios, the laser operating wavelength, antenna elevation angle, and tropospheric altitude are configured synchronously; for inter-satellite link scenarios, the parameter configuration includes the laser operating wavelength and the distance between the two satellites.

[0082] Step 5: Calculate the transmit and receive end gains. The transmit and receive end gains are determined based on the antenna design parameters.

[0083] In step 5, the gain of the transmitter and receiver is calculated based on the antenna aperture and wavelength, as follows:

[0084]

[0085] Among them, D t D is the aperture of the transmitting antenna, measured in meters (m). r λ is the aperture of the receiving antenna, in meters (m). λ is the wavelength, in meters (m).

[0086] Step 6: Calculate the pointing loss. The pointing loss is calculated based on the antenna pointing error and wavelength.

[0087] In step 6, the pointing loss of the transmitter and receiver is calculated based on the pointing error and the linear gain of the transmitter and receiver. The calculation formulas are as follows:

[0088]

[0089] Among them, Pe t This is the transmitter pointing error measured in radians. Pe r The receiver pointing error is expressed in radians.

[0090] Step 7: Calculate channel transmission loss. Based on the laser wavelength and transmission distance, calculate the free space path loss; for both uplink and downlink of the satellite-to-ground link, superimpose geometric scattering loss and Mie scattering loss.

[0091] The free space path loss is calculated based on the laser wavelength and transmission distance using the following formula:

[0092]

[0093] For inter-satellite links, d represents the distance between two satellites. For satellite-to-ground links, d represents the distance from the satellite to the ground station.

[0094] Based on the distance the beam travels in the troposphere, the attenuation coefficient due to geometric scattering, and the extinction ratio of Mie scattering, the geometric scattering loss and Mie scattering loss are calculated, from which the total scattering loss can be determined. Specifically, this includes:

[0095]

[0096] L sca =L geo +L mie

[0097] Among them, L geo The attenuation is measured in dB due to geometric scattering. L mie This is the attenuation due to Mie scattering, expressed in dB. T σ is the distance the light beam travels in the troposphere. mie It is the extinction ratio of Mie scattering. A geo It is the attenuation coefficient caused by geometric scattering.

[0098] The attenuation coefficient caused by geometric scattering can be calculated based on the visibility V and the grain size coefficient δ, using the following formula:

[0099]

[0100] Where V is visibility, measured in km, and δ is the particle size coefficient.

[0101] The Mie extinction ratio is calculated based on empirical coefficients. Specifically, this includes:

[0102]

[0103] a = 0.000487λ 3 -0.002237λ 2 +0.003864λ-0.004442

[0104] b = -0.00573λ 3 +0.02639λ 2 -0.04552λ+0.05164

[0105] c = 0.02565λ 3 -0.1191λ 2 +0.20385λ-0.216

[0106] d = -0.0638λ 3 +0.3034λ 2 -0.5083λ+0.425

[0107] Among them, h GSThis represents the height of the ground station above mean sea level, in kilometers. a, b, c, and d are empirical coefficients related to wavelength λ.

[0108] Step 8: Calculate link margin and display the calculation results. Key performance indicators, including transmit gain, receive gain, pointing loss, path loss, atmospheric attenuation, and link margin, are presented in tabular form. Finally, the link margin calculation results are presented as quantitative indicators.

[0109] The link margin mentioned in step 8 is calculated by the difference between the received power and the required signal power, and the specific formula is as follows:

[0110] L M =P r -P req

[0111] Among them, P r Received power, in dBm, P req This is the required signal power, measured in dBm.

[0112] Furthermore, the received power is calculated based on the transmit power, the optical efficiency of the transceiver antenna, the gain of the transceiver antenna, the pointing loss, the free space path loss, the atmospheric absorption loss, and the atmospheric scattering loss, as shown in the following formula:

[0113] P r =P t +μ t +μ r +G t +G r -LP t -LP r -L P -L abs -L sca

[0114] Among them, the transmission power P t This refers to the output power of the transmitter, measured in dB; the antenna optical efficiency is μ. t and μ r These represent the efficiency of the antenna optical system at the transmitting and receiving ends, respectively; antenna gain G t and G r These represent the gains of the transmitting and receiving antennas, respectively, in dB; the pointing loss LP t and LP r These represent the losses caused by antenna pointing errors at the transmitting and receiving ends, respectively, in dB; free space path loss L P Free-space path loss between the ground station and the satellite, measured in dB; atmospheric absorption loss L. abs Attenuation loss caused by atmospheric absorption, measured in dB; atmospheric scattering loss Lsca This is the attenuation loss caused by atmospheric scattering, measured in dB.

[0115] like Figure 2 As shown, a free-space optical communication link simulation and analysis interface system is provided. The system includes: a link selection module, a data input module, a link budget calculation module, and a visualization analysis and output module.

[0116] Link Selection Module. Located in the upper left pane of the operation page. It includes three options: "Satellite-Ground," "Satellite-Satellite," and "Deep Space-Ground," representing near-Earth laser communication, inter-satellite laser communication, and deep space laser communication link modes, respectively. Users can construct a free-space optical communication simulation channel by selecting different laser communication channels. Within this module, users can access and modify the attribute parameters of a target entity by selecting that entity.

[0117] Data Input Module. This module includes a parameter input pane with options for ground station, uplink / downlink, and satellite. These tabs allow users to configure link properties, precisely input satellite orbit parameters, adjust antenna size, and manage parameters for multiple objects. This module provides the system with a precise input parameter system, ensuring the accuracy and reliability of subsequent simulation calculations.

[0118] Link Budget Module. In the top area of ​​the application's central pane, select to perform uplink / downlink or inter-satellite link calculations. Based on the established model, calculate the link margin performance metrics for the communication links.

[0119] In the link budget module, clicking the calculate button will execute the link budget calculation process. After the calculation is complete, detailed calculation results will be displayed in the lower area. In the link parameter calculation display unit, users can view various parameters and calculated values, such as transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin. An output option for calculation results is provided, allowing users to quickly save the calculated data in a standardized format for easy subsequent analysis and verification.

[0120] The visualization analysis and output module, located on the right side of the interface, uses visualization technology to present simulation results intuitively. Users can directly edit the settings of the X and Y axes, and customize the range and step size of the X-axis. Users can select appropriate axis coordinates and their value ranges based on the required data to accurately display specific parts of the data or charts.

[0121] After selecting the X-axis coordinate, users can select contour information again to draw contour images and compare them with the X-axis data. Simultaneously, the system supports generating standardized reports from simulation results, integrating data tables, chart analysis, and key parameter descriptions to provide a complete link performance evaluation document.

[0122] like Figure 3 As shown, the link selection module includes three link types: satellite-to-ground, satellite-to-satellite, and deep space-to-ground. Users can select the corresponding link for simulation analysis based on their space communication scenario requirements. Typical parameters are preset for each type.

[0123] The link selection module provides a synchronous link diagram. Taking the "satellite-ground" link architecture as an example, the system presents the link relationship between the ground station and satellite A and supports parameter settings. Users can select the target entity in this module to switch between the visualization scene and the parameter configuration area, and can input core parameters such as satellite altitude, optical antenna efficiency, antenna aperture, and pointing error in real time.

[0124] like Figure 4 As shown, the data input module is where users customize input parameters. In the lower left corner, there is a parameter input area with a split-column layout. This pane presents switchable options for three types: ground station, link, and satellite, via a collapsible panel. Users configure parameters within each option, customizing parameters in the numerical input boxes according to their actual needs.

[0125] Under the satellite options, user-configurable parameters include satellite altitude, optical antenna efficiency, antenna aperture, and pointing error. In the link options settings, for satellite-to-ground link types, configurable parameters include laser operating wavelength, antenna elevation angle, and tropospheric altitude; for inter-satellite link scenarios, parameter configuration includes laser operating wavelength and the orbital distance between the two satellites. Under the ground station options, user-configurable parameters include altitude, optical antenna efficiency, antenna aperture, and pointing error.

[0126] In the data input module, all parameter input fields are equipped with a data validation mechanism. When the input value exceeds the preset range, a red-bordered warning and explanation will be triggered. These operations will be directly synchronized to the system's calculation model, and the link budget module will perform relevant link budget analysis.

[0127] like Figure 5 As shown, the link budget module is located in the center of the application's main interface. This module adopts a layered layout design, with an operation toolbar at the top and a link parameter calculation display unit at the bottom.

[0128] The core components of the operation toolbar are the "Link Type" drop-down menu, the power input area, the dual operation button group, and the operation control area.

[0129] The "Link Type" dropdown menu expands the options list when clicked, containing five standard link type options, categorized by scenario: "Space-to-Ground Uplink," "Space-to-Ground Downlink," "Inter-Satellite Link," "Deep Space Uplink," and "Deep Space Downlink." Users select the appropriate link type based on their actual computational needs.

[0130] In the power input area, below the "Link Type" drop-down menu, there are two parameter input boxes: "Transmit Power (dB)" and "Required Signal Power (dB)". In the system default configuration, the "Transmit Power (dB)" input box is preset to 17.5dB, corresponding to a typical satellite communication scenario; the "Required Signal Power (dB)" input box is set to a default value of -35.5dB. Users can input and adjust the "Transmit Power" value.

[0131] The toolbar features a dual-button group on the right, including "Save Output Data" and "Save Output Data As". Clicking "Save Output Data" automatically generates a timestamped CSV file in the installation directory folder, while the status bar displays "Data saved to default path". Selecting "Save Output Data As" triggers a system file dialog box, supporting custom storage paths and filenames, and supporting export in .xlsx, .txt, and .dat formats. Upon completion, a success notification window displaying file path details will appear, ensuring the user is fully aware of the data storage location.

[0132] The operation control area includes a "Run" button component. Clicking the "Run" button will initiate calculations based on user-defined data parameters: first, the input parameters are parsed; then, calculations are performed; and finally, the data is displayed. The calculation process generates a link budget analysis report in real time, containing core indicators such as transceiver gain, transceiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin.

[0133] In the link parameter calculation and display unit, all parameter values ​​are displayed as "0" before clicking "Run". After clicking the "Run" button, the calculation results are recorded in the information panel area at the bottom of the interface, including transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin. The calculation results can be exported in tabular form.

[0134] like Figure 6 As shown, the drawing display unit in the visualization analysis and output module is located in the right area of ​​the interface, and this area adopts an interactive visualization design.

[0135] The plot display area employs an intelligent legend layout mechanism, with a fixed floating legend box displayed in the upper right corner of the chart. It uses a dual identifier system of color coding and line style annotations to clearly indicate the specific parameters corresponding to different line styles. Multi-touch zoom and drag-and-drop panning functions are supported, allowing users to adjust the viewing angle.

[0136] like Figure 7 As shown, this is the coordinate axis setting and image export unit in the visualization analysis and output module, which is located below the plotting display area mentioned above.

[0137] In the coordinate axis settings area, users can select parameter variables for the X-axis, Y-axis, and isotropic lines via drop-down menus. After selecting a parameter, the information bar on the right will simultaneously display the parameter's unit of measurement, typical value range, and calculation step size. Taking the X-axis as the ground station's altitude as an example, the default value range is 1.0-3.0km, with a step size of 0.1. Users can adjust the range and step size by directly inputting values. The system has a built-in range validity check function, which will trigger a border warning when the input value exceeds the reasonable range. A typical application scenario is analyzing the characteristics of sudden changes in link performance within the 2-5km altitude range, where precise limitation of the X-axis range can achieve data focusing.

[0138] The image export unit has three control buttons below the coordinate axis setting area: the "Draw" button enables one-click drawing; the "Save Image" button saves the image as a 600dpi vector graphic to the preset project directory by default; and the "Save Image As" button provides PNG, SVG, and PDF format options.

[0139] Example:

[0140] Figure 8 for Figure 5 The diagram shows the actual output data results after inputting parameters into a free-space optical communication link simulation analysis interface system.

[0141] like Figure 8 As shown, combined with Figure 5 The interactive configuration interface for the data input module. Figure 8 The calculation results are when the input parameters are those in Table 1.

[0142] Table 1

[0143]

[0144] The calculation results are displayed in a visual format, such as... Figure 8 The panel area in the center of the overall interface, as shown, allows users to adjust the display ratio using the zoom controls. The system also provides multi-format export functionality, supporting saving the current data as an SVG file. The default storage path is the project workspace, but users can also customize the local directory.

[0145] Figure 9 As shown Figure 6 The diagram shows the actual output image after inputting parameters into a free-space optical communication link simulation analysis interface system.

[0146] like Figure 9 As shown, based on the parameters input in Table 1 above, Figure 9 The plotting results are shown in Table 2 when the parameters shown in Table 2 are entered in the coordinate axis setting unit.

[0147] Table 2

[0148] Parameter categories Specific parameters Range of values Step length unit Independent variable (x-axis) Ground station - altitude 0-5 0.1 km Grouping variables (isolines) Angle of elevation 50-80 5 degrees Dependent variable (vertical axis) Link margin - - dB

[0149] The drawing results are displayed in a visual format, such as... Figure 9 In the panel area on the right side of the interface shown, users can adjust the display ratio in real time using the zoom controls. When the displayed content exceeds the visible range, users can also scroll horizontally using the pan slider on the right, or click the reset button to restore the default display state.

[0150] Figure 9 The plotted results are an analysis of the impact of ground station altitude on link margin. The horizontal axis represents the ground station altitude, with a range of 0-5 km and a step size of 0.1, reflecting continuous changes in altitude. The vertical axis corresponds to the link margin index, expressed in dB, used to quantify link performance. The lines in the plot represent the link margin variation curves under different elevation angles (range 50-80°, step size 5). The curve clusters use a color gradient to distinguish the elevation angle parameter; different colored curves represent different link elevation angles. A curve is set every 5° from the blue curve (elevation angle = 50°) to the red curve (elevation angle = 80°). When analyzing the impact of ground station altitude on link margin, the range of link elevation angles from 50° to 80° is considered simultaneously. For example, when analyzing the link margin at an altitude of 2km, the specific values ​​of the link margin will be examined for seven cases with link elevation angles of 50°, 55°, 60°, 65°, 70°, 75°, and 80°.

[0151] like Figure 9 The analysis diagram of the impact of ground station altitude on link margin is shown. By dynamically changing the altitude on the horizontal axis, the trend of link margin with increasing altitude can be intuitively analyzed. Combined with the curve clusters corresponding to different elevation angles, the influence of ground station altitude on link margin under different elevation angle conditions can be explored, providing a visual data reference for link design optimization and performance evaluation, and facilitating the rapid acquisition of link margin characteristics under the combined effect of altitude and elevation angle.

Claims

1. A simulation and analysis method for free-space optical communication links, characterized in that, It includes the following steps: Step 1: Determine the link type. Based on the actual needs of the application scenario, determine the link type among deep space, near-Earth, and inter-satellite links. Step 2: Determine the transceiver terminals of the communication system. Based on the uplink and downlink technical characteristics, select the corresponding transceiver devices. Based on the link type identification results in step 1, the system automatically matches the corresponding transceiver terminal type; For deep space and near-Earth space-to-ground link scenarios, ground stations and satellites are selected as transceiver terminals; As an earth-based device, the simulation parameter system for ground stations includes geographical location and equipment characteristics; As a space-based device, the simulation parameters for satellites include orbital parameters and antenna performance; The inter-satellite link scenario selected a dual-satellite terminal, and the simulation parameters included orbital relationship, spatial geometric path and loss characteristics; Step 3: Configure the transceiver terminal parameters, and perform differentiated configuration according to the device type; Ground terminal parameter configuration includes altitude, optical antenna efficiency, antenna aperture, and pointing error; satellite terminal parameter configuration includes satellite altitude, optical antenna efficiency, antenna aperture, and pointing error. Step 4: Configure the link physical parameters, and perform differentiated configuration according to the link type; For satellite-to-ground link scenarios, the laser operating wavelength, antenna elevation angle, and tropospheric altitude are configured synchronously; for inter-satellite link scenarios, the parameter configuration includes the laser operating wavelength and the distance between the two satellites. Step 5: Calculate the transmit and receive end gains; the transmit and receive end gains are determined based on the antenna design parameters. Step 6: Calculate the pointing loss based on the antenna pointing error and wavelength; Step 7: Calculate channel transmission loss; calculate free space path loss based on laser wavelength and transmission distance; superimpose geometric scattering loss and Mie scattering loss for uplink and downlink of satellite-to-ground link. Based on the laser wavelength and transmission distance, the free space path loss is calculated using the following formula: ； Wherein, for inter-satellite links, d is the distance between two satellites; for satellite-to-ground links, d is the distance from the satellite to the ground station. Based on the distance the beam travels in the troposphere, the attenuation coefficient caused by geometric scattering, and the extinction ratio of Mie scattering, the geometric scattering loss and Mie scattering loss are calculated, from which the atmospheric scattering loss can be calculated; specifically including: ， ， ； in, The attenuation is measured in dB due to geometric scattering. The attenuation due to Mie scattering is measured in dB. It is the distance the light beam travels in the atmospheric troposphere; It is the extinction ratio of Mie scattering; It is the attenuation coefficient caused by geometric scattering; The attenuation coefficient caused by geometric scattering can be calculated based on the visibility V and the grain size coefficient δ, using the following formula: ； Where V is visibility, measured in km; δ is the particle size coefficient. The Mie extinction ratio is calculated based on empirical coefficients; specifically, it includes: ， ； in, This indicates the height of the ground station above mean sea level, in km; a, b, c, and d are empirical coefficients related to wavelength λ. Step 8: Calculate link margin and display the calculation results; present key performance indicators in tabular form, including transmit gain, receive gain, pointing loss, path loss, atmospheric attenuation, and link margin. Finally, present the link margin calculation results as quantitative indicators. The link margin is calculated by the difference between the received power and the required signal power, and the specific formula is as follows: ； in, Received power, in dBm. This is the required signal power, measured in dBm. The received power is calculated based on the transmit power, the optical efficiency of the transceiver antenna, the gain of the transceiver antenna, the pointing loss, the free space path loss, the atmospheric absorption loss, and the atmospheric scattering loss. The specific formula is as follows: ； Among them, transmission power This refers to the output power of the transmitter, measured in dB; antenna optical efficiency. and These represent the antenna optical system efficiency at the transmitting end and the receiving end, respectively; antenna gain. and These represent the gain of the transmitting and receiving antennas, respectively, in dB; pointing loss. and These represent the losses caused by antenna pointing errors at the transmitting and receiving ends, respectively, in dB; free space path loss. Free-space path loss between the ground station and the satellite, measured in dB; atmospheric absorption loss. Attenuation loss caused by atmospheric absorption, measured in dB; atmospheric scattering loss. This is the attenuation loss caused by atmospheric scattering, measured in dB.

2. The free-space optical communication link simulation and analysis method according to claim 1, characterized in that, In step 5, the gain of the transmitting and receiving ends is calculated based on the antenna aperture and wavelength, as follows: ， ； in, It is the aperture of the transmitting antenna, in meters (m). λ is the aperture of the receiving antenna, in meters (m); λ is the wavelength, in meters (m).

3. The free-space optical communication link simulation and analysis method according to claim 1, characterized in that, In step 6, the pointing loss of the transmitter and receiver is calculated based on the pointing error and the linear gain of the transmitter and receiver. The calculation formulas are as follows: ， ； in, The pointing error of the transmitter is measured in radians. The receiver pointing error is expressed in radians. For the linear gain of the transmitter, This represents the linear gain at the receiving end.

4. A free-space optical communication link simulation interface system, characterized in that its... include: The link selection module, located in the upper left pane of the operation page, includes three options: "Satellite-Ground," "Satellite-Satellite," and "Deep Space-Ground," representing three communication link modes: near-Earth laser communication, inter-satellite laser communication, and deep space laser communication, respectively. By selecting different laser communication channels, a free-space optical communication simulation channel can be constructed. Within this module, users can access and modify the attribute parameters of a target entity by selecting that entity. The data input module includes a parameter input pane, which includes options for ground station, uplink / downlink, and satellite. These tabs allow users to configure link properties, precisely input satellite orbital parameters, adjust antenna size, and manage parameters for multiple objects. This module provides the system with a precise input parameter system, ensuring the accuracy and reliability of subsequent simulation calculations. The link budget module, located at the top of the central pane of the application, allows you to select to perform uplink, downlink, or inter-satellite link calculations; based on the established model, it calculates the link margin performance metrics of the communication links. In the link budget module, clicking the calculate button will execute the link budget calculation process; Once the calculation is complete, the detailed results will be displayed in the area below. In the link parameter calculation and display unit, users can view the parameter calculation results, including transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin; it is configured with calculation result output options, allowing users to quickly save the calculation data in a standardized format for easy subsequent analysis and verification. The visualization analysis and output module, located on the right side of the interface, uses visualization technology to present simulation results intuitively. Users can directly perform editing operations, adjust the relevant settings of the X and Y axes, and customize the value range and step size of the X axis. Users can select appropriate axis coordinates and their value ranges according to the required data information to accurately display specific parts of the data or charts. After selecting the X-axis coordinate, users can select contour information again to draw contour images and compare them with the X-axis data. At the same time, it supports generating standardized reports from simulation results, integrating data tables, chart analysis, and key parameter descriptions to provide a complete link performance evaluation document. Users first input parameters in the link selection module and data input module, including altitude, optical antenna efficiency, antenna aperture, pointing error, laser operating wavelength, tropospheric altitude, elevation angle, inter-satellite distance, and transmit power; as well as climate characteristic parameters, including channel attenuation parameters and tropospheric altitude; the system provides five configurable options: near-ground uplink / downlink, inter-satellite link, and deep-space uplink / downlink; after the user selects the link type, the link budget module performs link attenuation calculation based on the input parameters, specifically analyzing gas absorption attenuation and scattering attenuation; Then, the transceiver gain, pointing loss, free space path loss, and link margin are calculated. The calculation results are transmitted to the link parameter calculation and display unit, and the output includes transmitter gain, receiver gain, transmitter linear gain, receiver linear gain, transmitter pointing loss, receiver pointing loss, free space path loss, geometric scattering loss, Mie scattering loss, and link margin indicators, thus fully realizing the multi-dimensional budget analysis and reliability assessment of the free space optical communication link. Finally, by selecting the type of horizontal and vertical coordinate parameters, adjusting the parameter value range, and setting the isolines and step size in the visualization analysis and output module, the system will automatically generate a multi-dimensional image and display the link budget analysis results in a real-time graphical form. The plotting results can be saved by using the "Save Image" or "Save Image As" buttons.

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