A low earth orbit satellite space-ground link multi-mode efficiency optimization system and method

Abstract

The application discloses a low-orbit satellite satellite-ground link multi-mode efficiency optimization system and method, and belongs to the technical field of low-orbit satellite communication. The system takes "hardware integration + resource dynamic + decision autonomy" as the core, and comprises a hardware architecture composed of a signal processing module, a frequency conversion processing module, a phased array transmitting antenna and a wide-beam receiving antenna, and a satellite-ground resource sharing management system based on a distributed ledger. Three types of working modes, i.e. wide-beam transceiving, wide-beam receiving + point-beam staring and wide-beam receiving + point-beam jumping, are designed based on the same hardware architecture. In combination with a user network access strategy of the multi-address technology and a user network exit process of "active reporting satellite adjustment", the system realizes full-link integration of measurement control data transmission, user access and information broadcast. The application improves resource utilization and system response speed, supports satellite lightweight design, and lays a foundation for commercial application of low-orbit satellites.

Description

Technical Field

[0001] This invention relates to a multi-mode performance optimization system and method for low-Earth orbit satellite-to-ground links, belonging to the field of low-Earth orbit satellite communication systems, and is applicable to the functional integration, resource scheduling, and multi-scenario service adaptation of satellite-to-ground links in low-Earth orbit satellite internet. Background Technology

[0002] With the iteration of satellite communication technology, low-Earth orbit (LEO) satellites, due to their advantages of short transmission latency and low link loss, have become a core component of satellite internet, and their functions are evolving from single services to diversified and multifunctional applications. However, existing LEO satellite systems face significant technical bottlenecks:

[0003] 1. Functional fragmentation and service simplification: Domestic and foreign manufacturers focus on broadband coverage, but none of them have achieved functional integration. Limited satellite resources cannot support the expansion of services in multiple scenarios.

[0004] 2. Rigid resource scheduling: Traditional systems have scattered functional modules and lack service priority design, making it difficult to adapt to diverse user needs; moreover, satellite-to-ground resource management relies on ground operation and maintenance, resulting in slow response speed and low resource utilization.

[0005] 3. Insufficient adaptability to multiple scenarios: It is unable to flexibly adjust the working mode according to different scenarios (such as wide area coverage, high-speed transmission in key areas, and multi-area polling service), making it difficult to meet the differentiated user access and data transmission needs;

[0006] 4. Frequent user access conflicts: When multiple users access the network concurrently under a wide beam receiving link, frequency or code domain conflicts are prone to occur, resulting in a low network access success rate, and the terminal access process is complex and the hardware cost is high.

[0007] The aforementioned shortcomings have hindered the large-scale application of low-orbit satellites, and there is an urgent need for a satellite-to-ground link performance optimization scheme that can achieve functional integration, autonomous decision-making and scheduling, and adaptability to multiple scenarios. Summary of the Invention

[0008] To address the technical shortcomings of existing low-Earth orbit (LEO) satellite-to-ground links, this invention aims to provide a multi-mode performance optimization system and method for LEO satellite-to-ground links, achieving the following objectives:

[0009] Construct a satellite-ground autonomous collaborative resource management mechanism to improve resource utilization and system response speed; design multi-mode beam control strategies to adapt to different scenarios such as "wide coverage and low data rate" and "directional high data rate".

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A multi-mode performance optimization system for low-Earth orbit satellite-to-ground links includes a hardware coordination module and a satellite-to-ground resource sharing management system. The hardware coordination module includes: a signal processing module for parsing, encoding, scheduling, demodulating, and fusing multi-channel signals; a frequency conversion processing module connected to the signal processing module for uplink / downlink frequency conversion of satellite-to-ground signals, ensuring signal transmission compatibility; and a phased array transmitting antenna connected to the frequency conversion processing module. Its array size is dynamically configurable, supporting on-demand adjustment of beamwidth between wide beam, spot beam staring, and spot beam skipping states to meet different transmission distance and rate requirements. A beam receiving antenna connects to a frequency conversion processing module; it features a wide half-power angle for wide-area coverage and efficient acquisition of ground telemetry and control commands and random access requests from users across the entire region. The satellite-ground resource sharing management system is built on distributed ledger technology and includes: a payload control unit on the satellite side for dynamically monitoring key satellite operating parameters and pre-storing ground station geographic and equipment capability information; a comprehensive information station on the ground side for synchronously updating and uploading information on its equipment idle time periods, peak data processing capabilities, and storage capacity; and real-time information synchronization between the satellite and ground sides via a satellite-ground link to form a satellite-ground resource database, supporting autonomous decision-making and scheduling of system resources.

[0012] Furthermore, the phased array transmitting antenna is a Ka-band active phased array antenna, and the array size can be configured as 16×16, 10×10, 5×5 or 1×1. The beamwidth and equivalent omnidirectional radiation power are adjusted by channel switching; the half-power angle of the wide beam receiving antenna enables wide-area signal acquisition.

[0013] Furthermore, in the aforementioned satellite-ground resource sharing management system, the satellite end pre-sets eleven sets of physical isolation resources: one set is dedicated to telemetry and control, and the other ten sets are combinations of frequency channels and Gold spreading codes dedicated to user network access.

[0014] A method for optimizing the multi-mode performance of low-Earth orbit (LEO) satellite-to-ground links, implemented through a LEO satellite-to-ground link multi-mode performance optimization system, includes the following steps:

[0015] Step 1: System initialization, start the hardware collaboration module, the payload control unit initializes satellite parameters and writes them to the satellite-ground resource database, and the integrated information station updates resource data;

[0016] Step 2: Based on the satellite status and service model, autonomously select or switch one of the three working modes, and migrate the affected terminals via inter-satellite links before switching.

[0017] Step 3: User access is achieved based on spread spectrum combined with multiple access technology. The terminal dynamically selects the frequency channel and spreading code through UTC time and unique ID, sends a short frame access request and triggers the retransmission mechanism.

[0018] Step 4: Dynamically configure the phased array antenna array size and adapt the transmission performance by controlling the channel switch via commands according to the scenario requirements.

[0019] Step 5: Adopt the active reporting and network withdrawal mechanism, release resources and update the satellite-ground resource database after satellite verification.

[0020] Furthermore, in step 2, the three working modes are as follows:

[0021] Mode A: Enables wide-beam transmission and reception, suitable for the initial orbit insertion phase of a satellite; the functional priorities are, in order: primary telemetry and control functions, secondary user access functions, and final broadcast functions.

[0022] Mode B: Enables wide-beam reception and spot-beam staring, suitable for high-concurrency scenarios within China; the functional priorities are as follows: first-level emergency monitoring and control functions, second-level user access functions, mid-level broadcast functions, and last-level non-emergency monitoring and control functions.

[0023] Mode C: Enables wide-beam reception and spot beam skipping, suitable for protecting key overseas users. The functional priority is as follows: first-level emergency monitoring and control functions, second-level broadcast functions, mid-level user access functions, and last-level non-emergency monitoring and control functions.

[0024] Furthermore, the satellite despreads the signal through eleven parallel receiving links, verifies the terminal ID, and establishes an information link after confirming its legitimacy.

[0025] In Mode A: Determine whether the terminal is in the beam coverage area. If so, adjust the downlink rate to the rate corresponding to the minimum receiving capability of all terminals and start access.

[0026] In Mode B: If the terminal's receiving capability matches the broadcast rate, it will be connected to the network; otherwise, it will not be connected to the network. If beam adjustment is needed to cover new users, it will be determined whether the rate is maintained after beam extension. If so, the beam will be extended and the user will be connected.

[0027] In Mode C: If the receiving capability Ra of a new user is greater than or equal to the existing rate Rb, then Rb is maintained; otherwise, Rb is reduced to Ra and the dwell time of the new user position is adjusted to Ta = Tb × Rb / Ra, where Ta is the adjusted dwell time of the new user position and Tb is the dwell time of the new user position before adjustment. When a new user position needs to be added, the skip scan regression period is increased by Tm, where Tm = broadcast information size / new user link rate × redundancy coefficient.

[0028] Furthermore, in step 3, the retransmission mechanism includes: after the terminal initially sends a signal, it waits for 3 seconds. If there is no response, it performs 10 frequency traversals. If it still fails, it performs 10 spreading code traversals. If it fails again, it enters a 3-minute recovery period, calibrates the UTC, detects the RF link, increases the power, and then restarts access.

[0029] Furthermore, in step 3, the terminal uses the linear congruential method to obtain a floating-point number in the interval [0,1) as the delay time, and sends the short frame according to the delay time after it is generated.

[0030] Furthermore, in step 5, the specific process of proactively reporting the network withdrawal mechanism is as follows:

[0031] Step 501: When the terminal determines that it needs to withdraw from the network, it encrypts the withdrawal request using the exclusive spreading code pre-issued by the satellite and sends it to the satellite;

[0032] Step 502: After the satellite verifies the user's legitimacy, it releases the resources allocated to that user, adjusting according to network status.

[0033] To ensure the safety of online users, the transmission rate should be dynamically adjusted.

[0034] If resource adaptation is required, adjust the beam coverage area;

[0035] If there are no users in a wave position, the wave position will be shut down and the skip scan cycle will be shortened;

[0036] Step 503: The satellite updates the network decommissioning information and resource adjustment parameters to the ground resource database, completing the resource recovery.

[0037] Furthermore, the specific process of step 4 is as follows:

[0038] Step 401: Based on its own real-time orbital parameters and the position information and receiving capabilities reported by the terminal, the satellite calculates the carrier-to-noise ratio of the communication link using the link budget formula; the orbital parameters include at least orbital altitude and orbital inclination; the calculation process of the link budget includes:

[0039] a. Calculate the communication distance between the satellite and the user terminal based on the satellite's position vector in the Earth-fixed coordinate system and the user terminal's position vector;

[0040] b. Calculate the link transmission loss based on the communication distance and operating frequency;

[0041] c. Calculate the carrier-to-noise ratio of the link based on the beam transmit power, link transmission loss, and user terminal receiving capability.

[0042] Step 402: Compare the calculated carrier-to-noise ratio with the target carrier-to-noise ratio threshold required for the current working mode to evaluate whether the current link quality meets the transmission requirements.

[0043] Step 403: Generate antenna configuration instructions based on the evaluation results and current scenario requirements;

[0044] Step 404: Send the antenna configuration command to the phased array transmitting antenna, and adjust the effective array size by controlling the power on and off of its channel switches, thereby changing the beamwidth and EIRP; after the adjustment is completed, send the final transmission capability parameters and beam status information to the terminal or ground station through an acknowledgment message.

[0045] Compared with the prior art, the advantages of the present invention are:

[0046] 1. Deep Functional Integration: Integrates telemetry, telemetry, and data transmission, user access, and information broadcasting links, breaking through the limitations of traditional satellite functions and achieving full-link collaboration;

[0047] 2. Efficient resource utilization: Based on a distributed ledger-based satellite-to-ground resource sharing mechanism, and using UTC and unique device identifiers, combined with hop expansion and multiple access technologies, it maximizes user network access and reduces conflicts;

[0048] 3. Multi-scenario adaptation: Three working modes cover scenarios such as wide-area broadcasting and directional high-speed services. The phased array antenna can adjust the array size as needed to adapt to different transmission requirements.

[0049] 4. Autonomy and Lightweight Design: Supports autonomous satellite switching modes and management of user network access / deactivation, reducing reliance on ground operations and maintenance; integrated hardware design supports lightweight satellite design.

[0050] 5. Service continuity: Before mode switching, cross-satellite user handover is completed through inter-satellite links, the retransmission mechanism ensures the success rate of network access, and the decommissioning resources are recovered in real time. Attached Figure Description

[0051] Figure 1 This is a diagram of the satellite-to-ground link system in an embodiment of the present invention.

[0052] Figure 2 This is a logic diagram of the satellite-to-ground link performance improvement method in this embodiment of the invention.

[0053] Figure 3 This is a diagram illustrating the user network access channel selection principle in an embodiment of the present invention.

[0054] Figure 4 This is a flowchart of the access request signal synthesis process in an embodiment of the present invention.

[0055] Figure 5 This is an information adjustment decision logic diagram in an embodiment of the present invention.

[0056] Figure 6 This is a flowchart of the three working modes in this embodiment of the invention. Detailed Implementation

[0057] The following is combined with Figures 1 to 6 The present invention will be described in further detail below.

[0058] (I) Low-Earth Orbit Satellite-Ground Link Multi-Mode Performance Optimization System

[0059] 1. System Architecture Design

[0060] Specific reference Figure 1 This embodiment of a low-Earth orbit satellite-to-ground link multi-mode performance optimization system includes a hardware collaboration module and a satellite-to-ground resource sharing management system:

[0061] (1) Hardware Coordination Module: Composed of a deep collaboration of a signal processing module, a frequency conversion processing module, a phased array transmitting antenna, and a wide-beam receiving antenna.

[0062] Signal processing module: As the data processing center, it completes information parsing, encoding, scheduling, and demodulation and fusion of multi-channel signals;

[0063] Frequency conversion module: realizes frequency conversion of satellite-to-ground signals and ensures signal transmission compatibility;

[0064] Phased array transmitting antenna: Supports on-demand beamwidth adjustment (wide beam / spot beam staring / spot beam skipping), improving transmission distance and speed;

[0065] Wide-beam receiving antenna module: Enables wide-area coverage and efficiently captures ground telemetry and control commands and user access requests across the entire area.

[0066] (2) Satellite-Ground Resource Sharing Management System: Based on distributed ledger technology, the satellite payload control unit dynamically monitors key satellite parameters (orbital altitude, inclination, etc.) and pre-stores ground station geographic and equipment information. The ground station synchronously updates equipment idle time periods, data processing peaks, and storage capacity to form a real-time and reliable satellite-ground resource database to support autonomous scheduling.

[0067] 2. Multi-mode working mechanism

[0068] A multi-mode performance optimization system for low-Earth orbit satellite-to-ground links has three operating modes to adapt to different scenarios. The mode switching is based on the satellite's full lifecycle service parameter model, satellite-to-ground resource database data, and satellite health status. Essentially, it is a dynamic adaptation of function fusion priority.

[0069] (1) Mode A: Wide beam transceiver: The receiver uses a wide beam to achieve full-angle telemetry and control and wide-area user access request acquisition; the transmitter uses a wide beam to send out all-area non-discriminatory information, which is suitable for the initial orbit insertion stage of the satellite. The functional priority is "telemetry and control function > user access function > broadcast function".

[0070] (2) Mode B: Wide beam reception + spot beam staring: The receiver maintains wide-area signal acquisition, and the transmitter sends information to a specific area at high speed with a high-gain spot beam. It is suitable for high-concurrency user services during the day in China. The function priority is "emergency measurement and control function > user access function > broadcast function > non-emergency measurement and control function".

[0071] (3) Mode C: Wide beam reception + spot beam scanning: The receiver captures the signal across the entire area, and the transmitter scans multiple areas (such as key cities) according to priority. It is suitable for overseas scenarios that focus on protecting key users. The functional priority is "emergency measurement and control function > broadcast function > user access function > non-emergency measurement and control function".

[0072] Before mode switching, the system first selects the beamwidth based on the real-time traffic volume of the coverage area, and then switches the affected terminals to adjacent satellites through inter-satellite links, generating only millisecond-level signal fluctuations to ensure service continuity.

[0073] 3. User onboarding and offboarding policies

[0074] User network access strategy: Based on expansion hop combined with multiple access technology, the process is as follows:

[0075] (1) Terminal initialization: The terminal’s built-in GNSS module captures real-time UTC time and latitude and longitude information, converts it into geocentric coordinate system (WGS-84) parameters, and reads the factory-fixed unique ID identifier;

[0076] Let the latitude, longitude, and altitude of the ground station be (L, B, H), where L is longitude, B is latitude, and H is altitude. Then its position vector in the Earth-fixed coordinate system is (Xg, Yg, Zg).

[0077] ;

[0078] in, , is the elliptic radius of curvature;

[0079] a is the semi-major axis of the Earth, a = 6378137m;

[0080] Let be the square of the first eccentricity of the Earth's ellipsoid. =0.0066943799901413.

[0081] Simultaneously complete hardware self-test (RF power, clock synchronization, antenna pre-pointing).

[0082] (2) Spreading parameter configuration:

[0083] The satellite side is pre-configured with 11 frequency channel resources and 11 Gold spreading code resources. Among them, numbers 0-9 are dedicated to user network access (a combination of frequency channel and Gold spreading code), and number 10 is dedicated to telemetry and control. Physical isolation is used to avoid service encroachment.

[0084] Terminal-side frequency channels: Dynamic traffic splitting is achieved by mapping the units digit of the UTC time second value to channels 0-9;

[0085] Terminal-side spreading code: The last digit of the unique ID is mapped by the factory-fixed ID. The ID is planned by the operator to ensure a balanced distribution of numbers from 0 to 9 (each code corresponds to approximately 10% of the terminals).

[0086] Access request frame: adopts a short frame structure (preamble + data segment + checksum + tail code). The data segment contains terminal ID, latitude and longitude, and receiving capability information, which shortens the transmission time and resists interference.

[0087] (3) Response detection and retransmission: After the terminal sends the initial signal, it waits for 3 seconds. If no response is received, it triggers 10 frequency traversals (switching the frequency point once every 3 seconds). If it still fails, it starts 10 spreading code traversals (continuously increasing in a loop). If all fail, it enters a 3-minute recovery period (calibrating UTC, detecting the RF link, and increasing power), and then restarts access.

[0088] (4) User withdrawal strategy: Adopting a closed-loop mechanism of "proactive reporting - satellite adjustment - ledger update":

[0089] When a terminal determines that it has left the coverage area or does not need service, it encrypts and sends a network withdrawal request using a dedicated spreading code pre-issued by the satellite. After verifying the user's legitimacy, the satellite adjusts its network status accordingly: if online users need to be protected, the transmission rate is dynamically adjusted; if resources need to be adapted, the beam coverage is adjusted; if there are no users on a beam position, the beam position is closed and the skip scan cycle is shortened. The satellite writes the network withdrawal information and resource adjustment parameters into a distributed ledger (satellite-ground resource database) to complete resource reclamation.

[0090] 6. Phased array transmitting antenna performance optimization module

[0091] By using commands to switch channels on and off and adjust the array size, the beamwidth and EIRP (Electronic Inductively Coupled Power) can be adapted to meet the transmission distance and rate requirements in different scenarios.

[0092] (II) Multi-mode performance optimization method for low-Earth orbit satellite-to-ground links

[0093] This embodiment provides a multi-mode performance optimization method for low-Earth orbit satellite-to-ground links, which includes the following steps:

[0094] Step 1: System initialization.

[0095] The hardware architecture module is activated, the payload control unit initializes satellite parameters and writes them into the distributed ledger, and the ground-based integrated information station updates ground resource data into the distributed ledger; the phased array transmitting antenna and the wide-beam receiving antenna complete self-tests.

[0096] Step 2, Selecting and switching working modes.

[0097] When the satellite is initially placed into orbit, the operating mode control module defaults to mode A (wide beam transceiver).

[0098] During normal operation, the working mode control module autonomously switches to mode B or mode C based on the satellite health status and ground service model in the distributed ledger. Before switching, the beamwidth is adjusted according to the service volume requirements, and cross-satellite user switching is completed through inter-satellite links to ensure service continuity.

[0099] Step 3: User onboarding process.

[0100] After the terminal executes the initialization process, it selects the frequency channel and spreading code according to the spread spectrum parameter configuration rules, synthesizes the access request signal and sends it; the satellite receives the despreading signal through 11 parallel receiving links, verifies the terminal ID (by comparing it with the distributed ledger whitelist), and establishes the information link after confirming its legitimacy.

[0101] Step 4, Adjusting the size of the phased array antenna

[0102] Choose the phased array size according to the needs of the scenario: use a 1×1 or 5×5 array for wide coverage scenarios, and a 10×10 or 16×16 array for high-speed targeted services.

[0103] Based on its real-time orbital parameters (including orbital altitude, orbital inclination, beam half-power angle, etc.) and combined with terminal position data, the satellite calculates the ground distance between the terminal and the satellite beam center point using spherical geometry formulas. It then calculates the link loss and beam EIRP based on the terminal's reported G / T data, and further calculates the carrier-to-noise ratio (CNR). The information rate is then calculated based on the CNR. The specific process is as follows:

[0104] The position vector of the satellite in the Earth-fixed coordinate system obtained by the satellite platform is denoted as... Based on the latitude, longitude, and altitude (L, B, H) reported by the terminal, calculate the terminal's position vector (Xg, Yg, Zg) in the Earth-fixed coordinate system.

[0105]

[0106] in, , is the elliptic radius of curvature;

[0107] a is the semi-major axis of the Earth, a = 6378137m;

[0108] Let be the square of the first eccentricity of the Earth's ellipsoid. =0.0066943799901413.

[0109] Subtracting the coordinates of the satellite and the ground station yields the pointing vectors of the satellite and the ground station, respectively. Let this vector be expressed in Earth-fixed coordinates as... Then the calculation formula is as follows:

[0110] ;

[0111] ;

[0112] ;

[0113] ;

[0114] in: Communication distance, in km; The operating frequency is expressed in MHz. Link attenuation, measured in dB; This represents the beam transmit power, measured in dBW. The value is the antenna gain of the receiving system ( ) and noise temperature ( The value is expressed in dB / K. It is the signal power of the receiving system. With noise power spectral density The ratio, or carrier-to-noise ratio, is measured in dBHz.

[0115] After completing the downlink capability calculation for the newly added terminal, and in conjunction with the current working mode, the transmission capability, beam adjustment, and network access information confirmation are completed and transmitted.

[0116] In Mode A: Determine whether the terminal is within the beam coverage area. If so, adjust the downlink rate to the rate corresponding to the minimum receiving capability of all terminals and start access.

[0117] In Mode B: If the terminal's receiving capability matches the broadcast rate, it will be connected to the network; otherwise, it will not be connected to the network. If a new user needs to be added, it will be determined whether the rate is maintained after beam extension. If so, the beam will be extended and the user will be connected. Beam extension is achieved by reducing the array size.

[0118] In Mode C: If the receiving capability Ra of a new user is greater than or equal to the existing rate Rb, then Rb is maintained; otherwise, it is reduced to Ra and the dwell time of the new user position is adjusted to Ta = Tb × Rb / Ra. When a new user position needs to be added, the skip scan regression period is increased by Tm, where Tm = broadcast information size / new user link rate × redundancy coefficient.

[0119] Step 5: User cancellation process.

[0120] The terminal sends an encrypted request to leave the network. After verification by the satellite, resources are released, idle bandwidths are closed (if any), and the distributed ledger is updated. Specifically, if online users need to be guaranteed, the transmission rate is dynamically adjusted; if resources need to be adapted, the beam coverage is adjusted; if there are no users on a bandwidth, the bandwidth is closed and the skip scan cycle is shortened.

Claims

1. A multi-mode performance optimization system for low-Earth orbit satellite-to-ground links, characterized in that, It includes a hardware collaboration module and a satellite-to-ground resource sharing management system. The hardware collaboration module includes: a signal processing module for parsing, encoding, scheduling, demodulating, and fusing multi-channel signals; a frequency conversion processing module connected to the signal processing module for uplink / downlink frequency conversion of satellite-to-ground signals, ensuring signal transmission compatibility; a phased array transmitting antenna connected to the frequency conversion processing module; its array size is dynamically configurable, supporting on-demand adjustment of beamwidth between wide beam, spot beam staring, and spot beam skipping states to meet different transmission distance and rate requirements; and a wide beam receiving antenna connected to the frequency conversion processing module. The frequency processing module features a wide half-power angle for wide-area coverage and efficient acquisition of ground telemetry and control commands and random access requests from users across the entire region. The satellite-ground resource sharing management system is built upon distributed ledger technology and includes: a payload control unit on the satellite side for dynamically monitoring key satellite operating parameters and pre-storing ground station geographic and equipment capability information; a comprehensive information station on the ground side for synchronously updating and uploading information on its equipment idle time periods, peak data processing capabilities, and storage capacity; and real-time information synchronization between the satellite and ground sides via a satellite-ground link to form a satellite-ground resource database, supporting autonomous decision-making and scheduling of system resources. The performance optimization process is as follows: Step 1, system initialization, start the hardware collaboration module, the payload control unit initializes the satellite parameters and writes them into the satellite-ground resource database, and the integrated information station updates the resource data; Step 2: Based on the satellite status and service model, autonomously select or switch one of the three working modes, and migrate the affected terminals via inter-satellite links before switching. Step 3: User access is achieved based on spread spectrum combined with multiple access technology. The terminal dynamically selects the frequency channel and spreading code through UTC time and unique ID, sends a short frame access request and triggers the retransmission mechanism. Step 4: Dynamically configure the phased array antenna array size and adapt the transmission performance by controlling the channel switch via commands according to the scenario requirements. Step 5: Adopt the active reporting and network decommissioning mechanism, release resources and update the satellite-ground resource database after satellite verification; The specific process of step 4 is as follows: Step 401: Based on its own real-time orbital parameters and the position information and receiving capabilities reported by the terminal, the satellite calculates the carrier-to-noise ratio of the communication link using the link budget formula; the orbital parameters include at least orbital altitude and orbital inclination; the calculation process of the link budget includes: a. Calculate the communication distance between the satellite and the user terminal based on the satellite's position vector in the Earth-fixed coordinate system and the user terminal's position vector; b. Calculate the link transmission loss based on the communication distance and operating frequency; c. Calculate the carrier-to-noise ratio of the link based on the beam transmit power, link transmission loss, and user terminal receiving capability. Step 402: Compare the calculated carrier-to-noise ratio with the target carrier-to-noise ratio threshold required for the current working mode to evaluate whether the current link quality meets the transmission requirements. Step 403: Generate antenna configuration instructions based on the evaluation results and current scenario requirements; Step 404: Send the antenna configuration command to the phased array transmitting antenna, and adjust the effective array size by controlling the power on and off of its channel switches, thereby changing the beamwidth and EIRP; after the adjustment is completed, send the final transmission capability parameters and beam status information to the terminal or ground station through an acknowledgment message.

2. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, The phased array transmitting antenna is a Ka-band active phased array antenna, and the array size can be configured as 16×16, 10×10, 5×5 or 1×1. The beamwidth and equivalent omnidirectional radiation power are adjusted by channel switching. The half-power angle of the wide beam receiving antenna enables wide-area signal acquisition.

3. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, In the aforementioned satellite-ground resource sharing management system, the satellite end has eleven pre-set physical isolation resources: one set is dedicated to telemetry and control, and the other ten sets are combinations of frequency channels and Gold spreading codes for user network access.

4. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, In step 2, the three working modes are as follows: Mode A: Enables wide-beam transmission and reception, suitable for the initial orbit insertion phase of a satellite; the functional priorities are, in order: primary telemetry and control functions, secondary user access functions, and final broadcast functions. Mode B: Enables wide-beam reception and spot-beam staring, suitable for high-concurrency scenarios within China; the functional priorities are as follows: first-level emergency monitoring and control functions, second-level user access functions, mid-level broadcast functions, and last-level non-emergency monitoring and control functions. Mode C: Enables wide-beam reception and spot beam skipping, suitable for protecting key overseas users. The functional priority is as follows: first-level emergency monitoring and control functions, second-level broadcast functions, mid-level user access functions, and last-level non-emergency monitoring and control functions.

5. A low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 4, characterized in that, The satellite despreads the signal through eleven parallel receiving links, verifies the terminal ID, and establishes an information link after confirming its legitimacy. In Mode A: Determine whether the terminal is in the beam coverage area. If so, adjust the downlink rate to the rate corresponding to the minimum receiving capability of all terminals and start access. In Mode B: If the terminal's receiving capability matches the broadcast rate, it will be connected to the network; otherwise, it will not be connected to the network. If beam adjustment is needed to cover new users, it will be determined whether the rate is maintained after beam extension. If so, the beam will be extended and the user will be connected. In Mode C: If the receiving capability Ra of a new user is greater than or equal to the existing rate Rb, then Rb is maintained; otherwise, Rb is reduced to Ra and the dwell time of the new user position is adjusted to Ta = Tb × Rb / Ra, where Ta is the adjusted dwell time of the new user position and Tb is the dwell time of the new user position before adjustment. When a new user position needs to be added, the skip scan regression period is increased by Tm, where Tm = broadcast information size / new user link rate × redundancy coefficient.

6. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, In step 3, the retransmission mechanism includes: after the terminal initially sends a signal, it waits for 3 seconds. If there is no response, it performs 10 frequency traversals. If it still fails, it performs 10 spreading code traversals. If it fails again, it enters a 3-minute recovery period, calibrates the UTC, detects the RF link, increases the power, and then restarts the access.

7. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, In step 3, the terminal uses the linear congruential method to obtain a floating-point number in the interval [0,1) as the delay time, and sends the short frame according to the delay time after it is generated.

8. The low-Earth orbit satellite-to-ground link multi-mode performance optimization system according to claim 1, characterized in that, In step 5, the specific process of proactively reporting the network withdrawal mechanism is as follows: Step 501: When the terminal determines that it needs to withdraw from the network, it encrypts the withdrawal request using the exclusive spreading code pre-issued by the satellite and sends it to the satellite; Step 502: After the satellite verifies the user's legitimacy, it releases the resources allocated to that user, adjusting according to network status. To ensure the safety of online users, the transmission rate should be dynamically adjusted. If resource adaptation is required, adjust the beam coverage area; If there are no users in a wave position, the wave position will be shut down and the skip scan cycle will be shortened; Step 503: The satellite updates the network decommissioning information and resource adjustment parameters to the ground resource database, completing the resource recovery.

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