An unmanned aerial vehicle multi-source signal intelligent response method and system

Abstract

The application discloses a kind of unmanned aerial vehicle multi-source signal intelligent response method and system.The method is applied to the intelligent terminal carried on unmanned aerial vehicle, comprising: based on the ephemeris data of low-orbit satellite constellation, the first jump visible window of each low-orbit satellite passing above native and the second jump feeding window flying above ground gateway are calculated;The end-to-end arrival time when the response data is sent through each candidate window is calculated, the end-to-end arrival time is the later one of the time when sending is completed in window and the starting time of the next second jump feeding window of the satellite, and the forwarding processing delay is added;The earliest window that the end-to-end arrival time meets regulatory time limit is selected as target sending window, and the current window is abandoned when the end-to-end arrival time of subsequent window is earlier;Response data is sent in target sending window.The application solves the problem of response data sending time and arrival time mismatch under the storage and forwarding type low-orbit satellite link, and shortens the end-to-end arrival delay of regulatory response data.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically, to a method and system for intelligent response to multi-source signals from unmanned aerial vehicles. Background Technology

[0002] With the development of the low-altitude economy, unmanned aerial vehicles (UAVs) are increasingly widely used in logistics transportation, agricultural plant protection, power line inspection, surveying and mapping, and other fields. To ensure low-altitude flight safety and compliance supervision, relevant standards clearly require UAVs to have remote identification capabilities. UAVs are typically equipped with external intelligent terminals that integrate cellular communication modules, low-Earth orbit (LEO) satellite communication modules, satellite positioning modules, and remote identification broadcasting modules. In areas with good cellular network coverage, they upload regulatory response data via cellular links. In areas beyond visual line of sight, remote areas, or complex terrain where cellular links are interrupted, they maintain communication with the operation and management platform via LEO satellite links.

[0003] Existing cellular and low-Earth orbit satellite link coordination schemes mainly include: dual-link passive threshold switching, which has a lag and does not distinguish whether the satellite is visible or not, and the satellite module is started outside the window, wasting power; window prediction and timed transmission and reception based on ephemeris, which only considers the first hop from the terminal to the satellite and does not consider the second hop delivery time from the satellite to the gateway station; and network-side store-and-forward enhancement, which does not involve the terminal-side transmission timing selection.

[0004] Low-Earth orbit (LEO) narrowband IoT constellations generally employ a store-and-forward (SOT) system. After receiving data, the satellite stores it onboard and then forwards it to the ground when it passes over a ground gateway station, resulting in uncontrollable onboard latency. This approach still suffers from the following drawbacks: a mismatch between transmission timing and delivery time (the regulatory side focuses on delivery time rather than transmission time); a single-point dependence on ephemeris validity in the scheduling system (window prediction gradually drifts when ephemeris becomes invalid and cannot be updated, leading to power wastage or missed windows); and a mismatch between window capacity and cached data volume (low-Earth orbit narrowband link speeds easily exceed the single-window capacity), and the reliance on bidirectional confirmation for breakpoint resumption, which is prone to loop breakage on intermittent links. Therefore, these problems need to be addressed from the terminal-side response and scheduling perspective. Summary of the Invention

[0005] This invention provides a method and system for intelligent response to multi-source signals from unmanned aerial vehicles, which at least solves the technical problem of mismatch between the timing of response data transmission and the end-to-end delivery time under store-and-forward type low-Earth orbit satellite links in related technologies.

[0006] According to a first aspect of the present invention, a multi-source signal intelligent response method for unmanned aerial vehicles (UAVs) is provided, applied to an intelligent terminal mounted on an UAV. The intelligent terminal integrates a cellular communication module, a low-Earth orbit (LEO) satellite communication module, and a satellite positioning module. The LEO satellite communication module communicates with a LEO satellite constellation using a store-and-forward system. When a LEO satellite passes over a ground gateway station, it forwards data stored on-board to the ground gateway station. The ground gateway station is communicatively connected to an operation and management platform. The method includes: acquiring ephemeris data of the LEO satellite constellation and combining it with the UAV's own position output by the satellite positioning module; calculating the first visible window during a preset time period when each LEO satellite passes over the UAV and satisfies a minimum elevation angle constraint; and calculating the timeframe during which each LEO satellite passes over the ground gateway station. The second hop feed window above the station is defined; the end-to-end delivery time of the response data when it is sent through each candidate first hop visible window is calculated, wherein the end-to-end delivery time is the later of the time when the response data is completed within the first hop visible window and the start time of the next second hop feed window of the low-Earth orbit satellite that sent the response data, plus the forwarding processing delay; the candidate first hop visible window with the earliest end-to-end delivery time that meets the regulatory time limit of the response data is selected as the target transmission window; when there is a subsequent candidate first hop visible window with an earlier end-to-end delivery time, the current first hop visible window is abandoned and the response data is scheduled to the subsequent candidate first hop visible window; the low-Earth orbit satellite communication module is controlled to send the response data within the target transmission window.

[0007] Optionally, the response data includes response data of multiple priority types; when multiple first-hop visible windows can be used as candidate sending windows, the method further includes: scheduling the response data with the highest priority to the first-hop visible window with the earliest end-to-end delivery time, and scheduling the response data of other priority types to the first-hop visible window with an earlier sending start time or a larger bandwidth margin.

[0008] Optionally, the method further includes: periodically collecting link quality parameters of the cellular link and determining the cellular link status as available, abnormal, or interrupted; scheduling the response behavior to one of the following modes based on the waiting time from the target transmission window and the cellular link status: when the cellular link status is available, transmitting the response data in real time via the cellular link and controlling the low-Earth orbit satellite communication module to sleep; when the cellular link status is abnormal or interrupted and the waiting time is less than a first preset time threshold, controlling the low-Earth orbit satellite communication module to warm up so that the low-Earth orbit satellite communication module enters a ready state before the target transmission window arrives; when the cellular link status is interrupted and the target transmission window arrives, arranging the cached response data according to a preset priority and then burst transmitting it within the target transmission window; when the cellular link status is interrupted and the waiting time is greater than the first preset time threshold, compressing the response data and caching it in local storage, and controlling the low-Earth orbit satellite communication module to remain in sleep mode.

[0009] Optionally, the method further includes: when the cellular link status changes to interruption during the target transmission window, directly entering burst transmission, and burst transmission of cached response data within the remaining duration of the target transmission window; when the cellular link status is abnormal and not interrupted, sending the response data via the cellular link and caching a copy locally, and deduplicating response data repeatedly delivered via multiple links by the operation management platform according to the message sequence number and timestamp.

[0010] Optionally, the method further includes: during the dormant period of the transmission channel of the low-Earth orbit satellite communication module, configuring the receiving channel of the low-Earth orbit satellite communication module to be normally open or open according to a preset duty cycle, and listening to the broadcast frames periodically transmitted by the low-Earth orbit satellite; when the broadcast frame is detected, extracting the Doppler frequency shift characteristics of the broadcast frame carrier, determining the zero-crossing time of the Doppler frequency shift from positive to negative as the most recent passing time of the low-Earth orbit satellite relative to the local unit, and comparing the measured most recent passing time with the predicted window time; if the deviation exceeds a preset deviation threshold, correcting the first hop visible window with the measured most recent passing time.

[0011] Optionally, the method further includes: when the ephemeris data exceeds its validity period and the cellular link is interrupted and the ephemeris data cannot be updated, entering a fallback response mode: abandoning window prediction, when the broadcast frame is detected and the signal characteristics of the broadcast frame meet preset conditions, determining that the low-orbit satellite is in a visible state, and sending the highest priority response data in the cache in the form of a short frame.

[0012] Optionally, arranging the cached response data according to a preset priority includes: dividing the response data into first-priority data with a regulatory time limit, second-priority data with a maximum tolerable delay, and third-priority data that allows large delays, and allocating a corresponding quota of the available bandwidth of the target transmission window to each priority data, wherein the first-priority data has absolute priority in queuing within the target transmission window; when the amount of data to be transmitted exceeds the predicted data capacity of the target transmission window, dead reckoning compression is performed on the location data, single-reference compression is performed on the identity information, and incremental reporting compression is performed on the device status data.

[0013] Optionally, the method further includes: for data blocks that cannot be fully transmitted in a single first-hop visible window, using rateless erasure coding to encode the data blocks into encoded fragment streams; before the arrival of each first-hop visible window, determining the number of encoded fragments generated in this window according to the predicted data volume that the first-hop visible window can carry and sending them, wherein the encoded fragments sent by different first-hop visible windows are independent of each other, and the unsent encoded fragments are invalidated; the operation management platform restores the data block when the cumulative number of received encoded fragments reaches the decoding threshold.

[0014] According to a second aspect of the present invention, a multi-source signal intelligent response system for unmanned aerial vehicles (UAVs) is provided, comprising an intelligent terminal mounted on the UAV, a low-Earth orbit (LEO) satellite constellation, a ground gateway station, and an operation and management platform. The LEO satellite constellation employs a store-and-forward system, wherein the LEO satellites in the constellation receive and store uplink data from the intelligent terminal, and forward the stored data to the ground gateway station when passing over it. The ground gateway station is communicatively connected to the operation and management platform and transmits received data to the platform. The intelligent terminal includes a cellular communication module, a LEO satellite communication module, a satellite positioning module, a remote identification broadcast module, a local memory, and a main control unit. The main control unit is connected to the cellular communication module, the LEO satellite communication module, the satellite positioning module, the remote identification broadcast module, and the local memory, respectively. The main control unit is configured to execute the multi-source signal intelligent response method for UAVs described in the first aspect.

[0015] Optionally, the smart terminal further includes a power management unit, which is connected to the main control unit and the local memory respectively. The power management unit is used to tighten the warm-up time threshold and cancel the transmission task of low-priority data when the power supply voltage is lower than a preset voltage threshold.

[0016] In this embodiment of the invention, the terminal jointly predicts the first-hop visibility window from the terminal to the satellite and the second-hop power supply window from the satellite to the gateway station. The end-to-end delivery time, rather than the transmission time, is used as the basis for selecting the timing of response data transmission. Response data with regulatory time limits is no longer blindly transmitted via the nearest overhead satellite, but instead is sent through the earliest landing window, thus shortening and making the delivery delay of response data more predictable. Simultaneously, during the dormant period of the satellite communication module's transmission channel, the receiving channel listens to satellite broadcast frames, calibrating the prediction window with the measured nearest transit time. In the event of ephemeris failure, this degenerates into a fallback response triggered by listening, ensuring that the scheduling system can maintain a minimum level of response capability even under ephemeris failure conditions. Therefore, this invention can at least solve the technical problem of mismatch between the transmission timing and end-to-end delivery time of response data in store-and-forward low-Earth orbit satellite links in related technologies, achieving the technical effects of shortening the end-to-end delivery delay of regulatory response data, reducing satellite communication power consumption, and improving response reliability under extreme conditions. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 This is a schematic diagram of the overall architecture of the multi-source signal intelligent response system for unmanned aerial vehicles according to an embodiment of the present invention;

[0019] Figure 2 This is a hardware structure block diagram of a smart terminal according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the circuit connection between the low-orbit satellite communication module and the main control unit according to an embodiment of the present invention;

[0021] Figure 4 This is a flowchart of a multi-source signal intelligent response method for unmanned aerial vehicles according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram illustrating the principle of double-hop window and end-to-end delivery time calculation according to an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of a response mode scheduling state machine according to an embodiment of the present invention;

[0024] Figure 7 This is a flowchart of broadcast frame monitoring calibration and failure fallback according to an embodiment of the present invention;

[0025] Figure 8 This is a schematic diagram illustrating the priority bandwidth quota and data compression principle according to an embodiment of the present invention;

[0026] Figure 9 This is a schematic diagram of cross-window rateless coding fragmentation relay according to an embodiment of the present invention.

[0027] The above figures include the following reference numerals:

[0028] 10. Smart terminal; 11. Main control unit; 12. Cellular communication module; 13. Low Earth orbit satellite communication module; 14. Satellite positioning module; 15. Remote identification and broadcasting module; 16. Local memory; 17. Power management unit; 20. Low Earth orbit satellite constellation; 30. Ground gateway station; 40. Operation management platform; 50. Business system. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Figure 1 This is a schematic diagram of the overall architecture of an unmanned aerial vehicle multi-source signal intelligent response system according to an embodiment of the present invention. Figure 1 As shown, the system includes a smart terminal 10 mounted on the unmanned aerial vehicle (UAV), a low-Earth orbit (LEO) satellite constellation 20, a ground gateway station 30, an operation and management platform 40, and a business system 50. The smart terminal 10 is an external communication and monitoring device added to the UAV, which can be quickly adapted without relying on the UAV's native system. Product forms include independent external devices and flight control connection devices. The LEO satellite constellation 20 is a narrowband IoT constellation using a store-and-forward system. In this embodiment, the Tianqi constellation is used as an example, with an orbital altitude of approximately 900 km and operating in the UHF band. Other LEO narrowband IoT constellations using a store-and-forward system with similar orbital altitudes and frequency bands can also be used. The ground coordinates of the ground gateway station 30 are fixed and pre-stored locally on the smart terminal 10 or distributed via the operation and management platform 40. The operation and management platform 40 is deployed in the cloud. The business system 50 is the business system for regulatory or industry clients, serving as the final consumer of response data; the regulatory time limit originates from the business requirements of this stage.

[0031] like Figure 1As shown, the system's data link comprises four data streams in terms of flow direction. Data stream one is the user link between the smart terminal 10 and the low-Earth orbit satellite constellation 20, referred to as the first hop in this invention: the low-Earth orbit satellite periodically sends broadcast frames to the coverage area, and the terminal only needs to activate its receiving channel to obtain these broadcast frames; the smart terminal 10 sends service frames to the low-Earth orbit satellite within the first hop's visible window. Data stream two is the feeder link between the low-Earth orbit satellite constellation 20 and the ground gateway station 30, referred to as the second hop in this invention: when the low-Earth orbit satellite passes over the smart terminal 10, it receives and stores the terminal's uplink data, and when it flies over the ground gateway station 30, it forwards the data stored on the satellite to the ground; the reverse direction is the telemetry and control channel between the ground gateway station 30 and the satellite. Data flow three is the ground segment between ground gateway station 30 and operation management platform 40: terminal service frames received by the gateway station are transmitted to operation management platform 40 via the 5G terrestrial network. Telemetry and control commands issued by operation management platform 40 are forwarded to smart terminal 10 via the gateway station and satellite. The transmission and processing time of this ground segment is the physical source of the forwarding and processing latency. Data flow four is the service interface between operation management platform 40 and business system 50: operation management platform 40 pushes processed service frames to business system 50 and receives service requests transmitted by business system 50. Figure 1 The right side also shows a multi-satellite, multi-terminal scenario: another smart terminal under the coverage of another low-orbit satellite, multiple unmanned aerial vehicles sharing the same constellation, possibly sharing the same first-hop visibility window, and different satellites passing over different terminals, and different satellites waiting for second-hop power supply, with delivery time scheduling calculated on a case-by-case basis according to the granularity of satellites and windows.

[0032] Figure 2 This is a hardware structure block diagram of a smart terminal according to an embodiment of the present invention. Figure 2As shown, the smart terminal 10 includes a main control unit 11, a cellular communication module 12, a low-orbit satellite communication module 13, a satellite positioning module 14, a remote identification and broadcasting module 15, a local memory 16, and a power management unit 17. The main control unit 11 is connected to the cellular communication module 12, the low-orbit satellite communication module 13, the satellite positioning module 14, the remote identification and broadcasting module 15, the local memory 16, and the power management unit 17, respectively. The main control unit 11, for example, uses a single-core ARM processor with a main frequency of not less than 200MHz, or it can use other embedded processors with equivalent computing power; the cellular communication module 12, for example, uses a 4G LTE Cat 1 module, or it can use a 5G compatible cellular communication module, supporting standard API interfaces and data protocols for interfacing with low-altitude traffic management systems, UAV integrated monitoring platforms, and industry operation systems; the low-orbit satellite communication module 13 operates in the UHF band, with a watt-level transmit power, and can use a low-orbit satellite IoT communication module compatible with the Tianqi constellation, such as the 400-GM20 communication module, or other low-orbit satellite communication modules with equivalent communication rates and receiving sensitivity. The main control unit 11 uses the serial port AT command set to configure parameters, trigger transmission, read reception, and control the entry and exit of low-power states for this module; the satellite positioning module 14 is a multi-mode satellite positioning module, supporting GPS, BeiDou, and GLONASS joint calculation, with optional SBAS or RTK enhancement, outputting the local position and velocity vectors at an update frequency of 1Hz to 10Hz; the remote identification broadcast module 15 uses Remote The ID broadcast method continuously broadcasts standardized identification messages at millisecond intervals via Bluetooth or Wi-Fi Beacon links, covering a radius of 100 meters from the UAV's ground projection point. The local storage 16, for example, uses an encrypted storage with a capacity of no less than 128GB to cyclically record copies of response data, flight data records, and communication logs. When an impact or abnormal state is detected, the storage area is immediately locked and writing is prohibited to ensure the integrity and traceability of flight data. The power management unit 17 sends the power supply voltage to the analog-to-digital conversion channel via a voltage divider resistor network. The main control unit 11 collects the power supply voltage in real time to realize power sensing. When the power supply voltage is lower than the preset voltage threshold, the warm-up time threshold is tightened and the transmission task of low-priority data is canceled, so that power is prioritized for response data with regulatory time limits.

[0033] Figure 3 This is a schematic diagram of the circuit connection between the low-Earth orbit satellite communication module and the main control unit according to an embodiment of the present invention. Figure 3As shown, the battery power supply pin of the low-Earth orbit satellite communication module 13 is connected to the power supply voltage, which is filtered by a filter capacitor to power the module. The RF antenna pin is connected to the satellite antenna via an antenna mount, and the low-Earth orbit satellite communication module 13 transmits and receives UHF band RF signals via the RF antenna pin. The serial port transmit pin and serial port receive pin of the low-Earth orbit satellite communication module 13 are respectively connected to the serial port receiver and serial port transmitter of the main control unit 11. The main control unit 11 sends AT commands and reads the downlink data received by the module through this serial port link. The reset pin, power-saving mode external interrupt pin, and ringing indicator pin of the low-Earth orbit satellite communication module 13 are respectively connected to the general-purpose input / output pins of the main control unit 11. The main control unit 11 controls the module to reset via the reset pin and the power-saving mode external interrupt pin. The pin-gated module enters and wakes up in low-power mode. When the module receives a downlink signal, it outputs an event indication to the main control unit 11 via the ringing indicator pin. After being woken up, the main control unit 11 reads the broadcast frame. The network status indicator pin of the low-orbit satellite communication module 13 drives an LED via a current-limiting resistor to indicate the network registration status of the module. The external power supply pin outputs a stable voltage to power the external indicator circuit. A voltage divider resistor network is connected between the power supply voltage and ground. The midpoint of the voltage divider resistor network is connected to the analog-to-digital conversion pin of the low-orbit satellite communication module 13. The power supply voltage is divided and sent to the analog-to-digital conversion channel. The main control unit 11 collects the power supply voltage in real time based on this. The debug serial port pin of the low-orbit satellite communication module 13 is connected to the program download interface for firmware burning and debugging of the module.

[0034] It should be noted that the low-Earth orbit satellite communication module 13 operates in three states: deep sleep, receiver monitoring, and transmitter operation. In deep sleep, it maintains only a microampere-level current while the transmitter channel is closed. In receiver monitoring, the receiver channel is open, and the current is in the milliampere level. In transmitter operation, the current is in the hundreds of milliamperes level. The current in the receiver state is much lower than that in the transmitter state, and the low-power scheduling method of deep sleep and monitor operation can be implemented in hardware.

[0035] Figure 4 This is a flowchart of a multi-source signal intelligent response method for unmanned aerial vehicles according to an embodiment of the present invention. This method is applied to the main control unit 11 of the aforementioned intelligent terminal 10. Figure 4 As shown, the method includes the following steps:

[0036] Step S202: Obtain the ephemeris data of the low-orbit satellite constellation 20, and combine it with the local position output by the satellite positioning module 14 to calculate the first visible window in which each low-orbit satellite passes over the local area and meets the minimum elevation angle constraint within a preset time period, and the second feed window in which each low-orbit satellite flies over the ground gateway station 30 and meets the minimum elevation angle constraint.

[0037] Specifically, ephemeris data is pre-stored in local memory 16 and updated periodically by the operation and management platform every 40 cycles when the cellular link is available. The ephemeris data includes the six orbital elements and the validity period. When the cellular link is unavailable, the local ephemeris is used and its remaining validity period is marked. The main control unit 11 reads the local ephemeris to simplify the orbit propagation model and calculate the nadir trajectory of each satellite for the next 24 hours. The simplified orbit propagation model can be, for example, the SGP4 / SDP4 model, or a Kepler recursive model based on the six orbital elements. For the longitude (Lon), latitude (Lat), and altitude (Alt) of the local unit, the geocentric angle of the satellite relative to the local unit at each moment is calculated. With elevation angle :

[0038]

[0039]

[0040] in, , The latitude and longitude of the point beneath the star. For the Earth's radius, This represents the satellite's orbital altitude; all angles in the above two formulas are in radians. and Use the same unit of length. When Greater than the minimum elevation angle threshold Visibility is determined by timing; consecutive visible moments constitute the first visible window, and the start time of visibility is recorded. The end time is visible. Window duration And the maximum elevation angle. For example, taking 5°, at an orbital altitude of approximately 900km, the equivalent upper limit of the geocentric angle for the elevation angle constraint is approximately 24°. The longest window for direct transit is approximately 14 minutes, while typical windows are in the range of 3 to 5 minutes. The window duration monotonically varies with the maximum elevation angle, therefore the maximum elevation angle is used as the basis for classifying window quality. The calculation of the second hop feed window shares all computational resources and ephemeris data with the first hop, only replacing the observation point coordinates with the ground coordinates of ground gateway station 30 to obtain the feed window sequence for each satellite and record the feed start time. The terminal computing power overhead is approximately twice that of a simple first-hop calculation. The minute-by-minute recursive calculation for 38 satellites over 24 hours involves tens of thousands of orbital point calculations, which a 200MHz-level main control unit can complete in seconds, recalculating only when the ephemeris is updated or the aircraft's position changes significantly. As the aircraft continuously moves during flight, the main control unit 11 corrects the position of each window based on the incremental motion vector output by the satellite positioning module 14. and When the positioning signal is lost for a short time, the machine position is extrapolated based on the most recent valid positioning and the window quality level is reduced. After the positioning is restored, it is corrected again based on the measured position.

[0041] Step S204: Periodically collect the link quality parameters of the cellular link and determine the status of the cellular link as available, abnormal, or interrupted.

[0042] Specifically, the link quality parameters include reference signal received power, number of visible base stations, and handover frequency. The main control unit 11 collects these parameters and performs a moving average according to a preset collection period, for example, 1 second. When the reference signal received power after the moving average is not lower than the first signal threshold and there are no consecutive heartbeat packet losses, the cellular link is determined to be available. When the reference signal received power is lower than the first signal threshold but not lower than the second signal threshold, or when there are consecutive heartbeat packet losses but not exceeding the preset number of losses, it is determined to be abnormal. When the reference signal received power is lower than the second signal threshold, or when the consecutive heartbeat packet losses exceed the preset number of losses, or when network registration fails, it is determined to be interrupted. When the UAV is at an altitude of 100 to 500 meters, it is in the sidelobe or even null area of ​​the ground base station antenna. The cellular link has ping-pong handover and blind spots. Moving average and state hysteresis avoid state jitter caused by single-point reading fluctuations.

[0043] Step S206: Calculate the end-to-end delivery time of the response data when it is sent through the first hop visible window of each candidate.

[0044] Specifically, for each type of response data in the buffer queue, categorized by priority, and combined with the two types of windows obtained in step S202, the end-to-end delivery time under each candidate sending opportunity is calculated. Data transmitted through a satellite's first visible window is delivered at the later of the time the transmission was completed within that window and the start time of the satellite's next feeding window, with the forwarding processing delay added in between.

[0045]

[0046] in, The time when the response data is sent within the first visible window is obtained by superimposing the queuing time and the sending time on the window start time. The sending time is estimated based on the amount of data to be sent and the predicted available rate of the window. This is the start time of the second-hop feed window following the first-hop visibility window for the satellite; The forwarding and processing delay from ground gateway station 30 to operation management platform 40 is on the order of seconds to tens of seconds, and can be calibrated by actual measurement at the platform interface; all the above times and delays use the same time unit. As can be seen from the above formula, when the satellite passes overhead and quickly sees the gateway station, Plays a decisive role; early launch leads to early arrival. When a satellite passes overhead and then orbits for a considerable time before signal is received at the station, The second hop plays a decisive role, locking the delivery time. At this point, any advance sent via the satellite cannot be converted into a delivery advance.

[0047] Step S208: Select the earliest end-to-end delivery time that meets the regulatory time limit for response data from each candidate first-hop visible window as the target sending window; when the end-to-end delivery time corresponding to the subsequent first-hop visible window is earlier than the end-to-end delivery time corresponding to the current first-hop visible window, abandon the current first-hop visible window and schedule the response data to the subsequent first-hop visible window.

[0048] Specifically, for those with regulatory time limits The main control unit 11 filters out responses from the candidate window set, such as identity verification messages, no-fly zone or electronic fence alarm responses, and tamper alarms. Later In the window, select from the remaining windows. The smallest one is the target transmission window; if currently within the first visible window of a satellite, but that window's... Inferior to a subsequent window If the second-hop power-on waiting time for the current satellite is too long, the current window is abandoned, and the response data is kept in the buffer and scheduled for transmission in a subsequent window. For response data without regulatory time limits, it is prioritized for scheduling to the window with the shortest second-hop power-on waiting time, provided that its maximum tolerable delay is met, in order to release the buffer as soon as possible. When there are candidate windows for multiple satellites in the same time period, response data of different priorities are split and scheduled: the highest priority data is scheduled to... The smallest window is used, and other priority data is scheduled to be sent to windows with earlier start times or larger bandwidth margins, so as to achieve parallel processing of timely data landing first and batch data releasing the cache as early as possible.

[0049] The following is a numerical example. Assume an orbital altitude of approximately 900 km and an orbital period of approximately 103 minutes. At a certain moment, satellite A is within the first visible window of the terminal, and its next feed window is 42 minutes later; satellite B's first visible window begins 10 minutes later, and satellite B enters its feed window 6 minutes after passing overhead. Ignore... Transmitted immediately via satellite A Approximately 42 minutes later; abandon the current window and wait for transmission via satellite B. Approximately 10 minutes plus 6 minutes, or 16 minutes later. The delivery times of the two scheduling methods differ by about 26 minutes, and the response data with regulatory time limits is delivered approximately 26 minutes earlier with the latter scheduling method.

[0050] Figure 5 This is a schematic diagram illustrating the principle of double-hop window and end-to-end delivery time calculation according to an embodiment of the present invention. Figure 5As shown, the upper timeline represents the first hop visible window, and the lower timeline represents the second hop power supply window; the figure shows the completion time of transmission. Start time of the next power supply window With end-to-end delivery time The temporal relationship between them, among which .

[0051] Step S210: Based on the waiting time from the target transmission window and the cellular link status, schedule the response behavior to the corresponding working mode.

[0052] Figure 6 This is a schematic diagram of a response mode scheduling state machine according to an embodiment of the present invention. Figure 6 As shown, the main control unit 11 maintains a four-mode state machine: Mode A is the normal cellular mode, where the cellular link is available, response data is transmitted in real time via the cellular link, and the low-Earth orbit satellite communication module 13 is in sleep mode; Mode B is the satellite warm-up mode, where the cellular link is abnormal or interrupted and the waiting time before the target transmission window is reached. Less than the first preset time threshold The low-Earth orbit satellite communication module 13 is preheated to ensure it is ready before the target transmission window arrives; Mode C is the window burst mode, where the cellular link is interrupted and the target transmission window arrives, and the buffered response data is arranged according to a preset priority and then burst transmitted at the maximum rate within the window; Mode D is the buffer waiting mode, where the cellular link is interrupted and... Greater than The response data is compressed and cached in local memory 16, while the low-orbit satellite communication module 13 remains dormant. For example, take 10 minutes.

[0053] like Figure 6 As shown, the state transition conditions are as follows: upon power-on, the system initially enters mode A; the cellular link transitions to an abnormal or interrupted state, and... Less than When, the migration occurs from mode A to mode B; the cellular link becomes abnormal or interrupted and Greater than At that time, the migration proceeds from pattern A to pattern D; shortened to When the target transmission window is reached but the cellular link is still interrupted, the system migrates from mode D to mode B; when the target transmission window is reached but the cellular link is still interrupted, the system migrates from mode B to mode C; when the cellular link is restored to availability and remains stable for more than the preset stable duration. At that time, the migration will proceed from pattern B back to pattern A. For example, a 30-second interval is used to prevent ping-pong switching; when the window ends and the cellular link is still interrupted, the mode is migrated from mode C to mode D; when the window ends and the cellular link has been restored, the mode is migrated back to mode A.

[0054] The state machine also covers three boundary scenarios. First, the cellular link is interrupted during the target transmission window: when the window arrives, the link is still available, and data travels via the cellular link. If the link transitions to interruption during the window, it directly switches from mode A to mode C, immediately bursting the buffered response data within the remaining window duration, avoiding wasting the entire window due to missing the start time. Second, the cellular link is abnormal but not interrupted: the response data is still attempted to be transmitted via the cellular link and a copy is buffered locally, without entering mode C. The burst channel is only switched when an interruption is detected. Third, double-transmission deduplication: if the same response data is repeatedly delivered via two links due to the recovery of the cellular link within the window, the operation management platform 40 deduplicates the data according to the message sequence number and timestamp. The terminal does not pause satellite frames already being transmitted, avoiding frame loss caused by transmission stoppage. Additionally, in A preset end-of-frame period is reserved beforehand to stop initiating new data frames. For example, the end-of-frame period is 5 seconds to ensure that the last frame is sent completely and to avoid truncating the data frame at the end of the window.

[0055] Step S212: During the hibernation period of the transmission channel, listen to the broadcast frames periodically sent by the low-orbit satellite, perform actual measurement calibration of the prediction window, and enter the fallback response mode when the ephemeris fails.

[0056] Figure 7 This is a flowchart illustrating broadcast frame monitoring calibration and failure fallback according to an embodiment of the present invention. Figure 7 As shown, in modes A and D, the transmitting channel of the low-Earth orbit satellite communication module 13 is in deep sleep, and the main control unit 11 configures its receiving channel to be either always on or open according to a preset duty cycle: when open according to the preset duty cycle, for example, it is on for 0.3 seconds every 30 seconds. Based on the receiving current being in the milliampere range and the duty cycle being approximately 1%, the average current is in the microampere to hundreds of microampere range; it can also be combined with preheating and opened before or after the predicted window time. The monitoring power consumption of the receiving channel is more than two orders of magnitude lower than the operating power consumption of the transmitting channel, and does not affect the overall battery life.

[0057] Upon detecting a broadcast frame during reception monitoring, the main control unit 11 records the frame arrival time sequence and extracts the Doppler frequency shift characteristics of the broadcast frame carrier: for an orbit of approximately 900 km and a carrier speed of 400 MHz, the maximum Doppler frequency shift is approximately ±8.6 kHz, and the receiver's frequency resolution capability can cover this order of magnitude; the Doppler frequency shift changes from a positive maximum monotonic change through zero to a negative maximum, and the zero-crossing moment is the closest transit time (TCA) of the satellite relative to the receiver. The measured TCA is compared with the midpoint time of the prediction window. If the deviation exceeds a preset deviation threshold, the measured value is used to correct the first hop visible window table, and the ephemeris error is used to infer the overall translation correction for subsequent windows. The preset deviation threshold is, for example, 5 seconds. Through broadcast frame monitoring, the prediction window can be calibrated using the measured closest transit time, and the correction amount for the ephemeris error can be determined based on the deviation between the prediction and the measurement.

[0058] When the local ephemeris expires and the cellular link is interrupted, preventing ephemeris updates, the smart terminal 10 enters a fallback response mode: abandoning window prediction and pre-schedule planning, it only responds based on the monitoring results. If a broadcast frame is detected and its signal strength exceeds a preset strength threshold, and the Doppler shift is in the zero-crossing interval (from positive to negative), it determines that the satellite is visible and immediately sends the highest-priority response data in the cache in the shortest frame format. After successful transmission, monitoring resumes. Thus, the terminal can maintain a minimum level of regulatory data uplink capability even when the ephemeris expires and the cellular link is interrupted. In other embodiments, if the constellation broadcast frame carries constellation-side information, such as power supply plans, access time slot allocations, and constellation health status, the smart terminal 10 parses it and uses it to correct the second-hop power supply window table and multi-machine time slot parameters, forming a system-level downlink information channel from the satellite to the terminal.

[0059] Step S214: Arrange the response data according to a preset priority, compress the data when the amount of data to be transmitted exceeds the window's carrying capacity, and perform rateless encoding fragmentation on data blocks that cannot be transmitted in a single first-hop visible window.

[0060] Figure 8 This is a schematic diagram illustrating the priority bandwidth quota and data compression principle according to an embodiment of the present invention. Figure 8 As shown, in Mode C, the response data to be transmitted is arranged according to a three-level priority: the first priority data is data with regulatory time limits, including identity verification messages, no-fly zone or electronic fence alarm responses, and tamper alarms, allocated to the first 30% of the available bandwidth in the window; the second priority data is location status periodic reporting data with the maximum tolerable delay, allocated to 50% of the available bandwidth in the window; the third priority data is device status, communication logs, and flight data records that allow for large delays, allocated to the remaining 20%. The first priority data has absolute priority in queuing within the window, and any first priority data waiting to be sent within the window will be preempted for transmission.

[0061] When the amount of data to be transmitted exceeds the predicted data capacity of the target transmission window, three compression strategies are implemented: dead reckoning compression of position data, transmitting the starting coordinates, motion vector, time range, and residual correction points inserted at preset intervals; residual correction points are used to suppress integral drift in dead reckoning; single-use compression of identity information, with the complete identity identifier transmitted only once within a window, and subsequent uses of a shorter identifier; and incremental reporting of device status, transmitting only changed fields. The predicted data capacity of the window is estimated based on the window duration, maximum elevation angle, and historical measured rates. Since the actual available bandwidth is uncertain due to fluctuations in elevation angle, the predicted value is estimated at a lower level than the historical measured rates, leaving a margin.

[0062] Below is a numerical example, with consistent parameters across the entire scenario: First visible window. The window time is 180 seconds; the uplink rate is divided into two levels: a low-end level of 1200bps and a high-end level of 7031bps; based on the conversion of 1 byte = 8 bits, each location message is 300 bytes and generated at 1Hz; the complete identity information is 50 bytes; each device status message is 100 bytes. Regarding window capacity, the low-end level of 1200bps is approximately 150 bytes per second, multiplied by 180 seconds to get 27,000 bytes; the high-end level of 7031bps is approximately 879 bytes per second, multiplied by 180 seconds to get approximately 158,200 bytes. Assuming a 10-minute cellular link interruption, the buffered location messages are 600 messages (180,000 bytes total), the identity information carried in each message is 600 messages (30,000 bytes total), and the device status information is 600 messages (60,000 bytes total), totaling 270,000 bytes, which is 10 times the single window capacity of the low-end level, and even the high-end level is overloaded. After compression: Location data, calculated by dead reckoning, is compressed to 536 bytes, including 24 bytes for the starting coordinates, 24 bytes for the motion vector, 8 bytes for the time range, and 24 bytes each for 20 residual correction points, totaling 480 bytes. A correction point is inserted every 30 seconds. Identification information, used once, is 50 bytes plus a 2-byte short identifier, multiplied by 599 entries, totaling 1248 bytes. Device status is reported incrementally at 10% field changes, totaling 6000 bytes. The first priority alarm is added, totaling approximately 200 bytes, for a total of approximately 7984 bytes. The overall compression is reduced to approximately 3.0% of the original amount, with location data compressed to approximately 0.3%. In terms of transmission time, 7984 bytes multiplied by 8 bits per byte and divided by 1200bps is approximately 53.2 seconds in the low-configuration setting and approximately 9.1 seconds in the high-configuration setting. Both settings are far less than the 180-second window duration, with the remaining time used for retransmission verification or continuation of third-priority data transmission.

[0063] Figure 9 This is a schematic diagram of cross-window rateless coding fragmentation relay according to an embodiment of the present invention. Figure 9As shown, for large data blocks such as flight data records that cannot be transmitted in a single window, the main control unit 11 uses rateless erasure coding, such as LT codes. The LT codes randomly select the XOR combination of the original packets according to the robust soliton degree distribution to generate coded fragments, encoding the data block into an arbitrarily expandable coded fragment stream. The coded fragments have their own block identifiers and sequence numbers, and do not contain breakpoint semantics such as which fragment is which or how many fragments there are. Before each first-hop visible window arrives, the main control unit 11 determines the number of coded fragments generated in this window according to the predicted data volume that the window can carry and sends them. The number of fragments in the window is dynamically increased or decreased according to the actual transmission progress: if the prediction is conservative, the window is completed in advance and then transferred to other queues; if the prediction is optimistic, the fragments that are not completed are discarded and regenerated in the next window. The discarding of coded fragments does not produce a breakpoint state. The operation management platform receives coded fragments across 40 windows. When the number of coded fragments in any block reaches the decoding threshold, which is the number of original packets multiplied by one plus a decoding overhead on the order of a few percent, confidence propagation decoding is performed to restore the data block. Fragments that arrive repeatedly are directly discarded. Different redundancy strategies are employed for data of different priorities: first-priority data is not encoded and is repeatedly transmitted, with the same frame being transmitted once in the current window and once in the next window; second-priority data is retransmitted in batches for verification within each window; only third-priority large-capacity data is fragmented without rate coding. Therefore, on store-and-forward links where both uplink and downlink transmissions are intermittent, cross-window data restoration can be completed without maintaining breakpoint resume status.

[0064] In scenarios where multiple unmanned aerial vehicles share the same first-hop visibility window, the operation and management platform 40 allocates time slot offsets to the terminals during network registration. :

[0065]

[0066] in, This serves as a unique identifier for the i-th unmanned aerial vehicle. This refers to the total number of time slots within the window, for example, 6. The time slot length is obtained by dividing the window duration by the total number of time slots. and Using the same time unit. Each terminal enters mode C after... add Transmission begins at a specific time, achieving staggered timing across multiple machines. First-priority urgent data can be transmitted immediately, bypassing time slot limitations; non-urgent data is transmitted by adding 0 to 1000 bytes to its own time slot before transmission. Random backoff is implemented, and failed transmissions are retried using a binary exponential backoff mechanism to avoid collisions between multiple emergency frames. Time slot parameters can be uniformly adjusted by the operations management platform via cellular link or satellite downlink.

[0067] Step S216: After the satellite visibility period ends or the data to be transmitted is completed, switch the low-orbit satellite communication module to sleep mode and record the transmission log for subsequent window prediction.

[0068] Specifically, the main control unit 11 records the start and end times of this transmission, the satellite number corresponding to the transmission window, the second hop power-on time, the amount of data transmitted, the measured elevation angle, and the speed in the communication log of the local memory 16. The parameters for estimating the amount of data that can be carried in subsequent windows and calculating the delivery time are corrected according to the measured values ​​in the communication log. Then, the main control unit 11 switches the low-Earth orbit satellite communication module 13 to a deep sleep state, waiting for the next scheduling.

[0069] This embodiment also provides a multi-source signal intelligent response system for unmanned aerial vehicles, such as Figure 1 As shown, the system includes a smart terminal 10, a low-Earth orbit satellite constellation 20, a ground gateway station 30, and an operation and management platform 40. The main control unit 11 of the smart terminal 10 is configured to execute the unmanned aerial vehicle multi-source signal intelligent response method described in steps S202 to S216 above. The low-Earth orbit satellites in the low-Earth orbit satellite constellation 20 receive and store uplink data from the smart terminal 10 and forward it to the ground when passing over the ground gateway station 30. The ground gateway station 30 transmits the received data to the operation and management platform 40 and forwards the telemetry and control commands issued by the platform. The operation and management platform 40 receives and processes the response data, deduplicates the response data repeatedly delivered through multiple links according to the message sequence number and timestamp, issues telemetry and control commands, and pushes service frames to the business system 50. The working process and technical effects of each entity in this embodiment can be referred to the relevant descriptions in the above method embodiments, and will not be repeated here.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-source signal intelligent response method for unmanned aerial vehicles, characterized in that, An intelligent terminal is used in unmanned aerial vehicles. The intelligent terminal integrates a cellular communication module, a low-orbit satellite communication module, and a satellite positioning module. The low-orbit satellite communication module communicates with a low-orbit satellite constellation with a store-and-forward system. When the low-orbit satellite flies over a ground gateway station, it forwards the data stored on the satellite to the ground gateway station. The ground gateway station is connected to the operation and management platform. The method includes: acquiring the ephemeris data of the low-orbit satellite constellation and combining it with the local position output by the satellite positioning module, calculating the first visible window in which each low-orbit satellite passes over the local area within a preset time period and meets the minimum elevation angle constraint, and the second power supply window in which each low-orbit satellite flies over the ground gateway station. Calculate the end-to-end delivery time of the response data when it is sent through each candidate first-hop visibility window; the end-to-end delivery time is the later of the time when the response data is completed within the first-hop visibility window and the start time of the next second-hop feed window of the low-Earth orbit satellite that sent the response data, plus the forwarding processing delay; select the earliest candidate first-hop visibility window whose end-to-end delivery time satisfies the regulatory time limit of the response data as the target transmission window; when there is a subsequent candidate first-hop visibility window with an earlier end-to-end delivery time, abandon the current first-hop visibility window and schedule the response data to the subsequent candidate first-hop visibility window; control the low-Earth orbit satellite communication module to send the response data within the target transmission window.

2. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 1, characterized in that, The response data includes response data of various priority types; When multiple first-hop visible windows can be used as candidate sending windows, the method further includes: scheduling the highest priority response data to the first-hop visible window with the earliest end-to-end delivery time, and scheduling response data of other priority types to the first-hop visible window with an earlier sending start time or a larger bandwidth margin.

3. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 1, characterized in that, It also includes: periodically collecting link quality parameters of the cellular link and determining the cellular link status as available, abnormal, or interrupted; scheduling the response behavior into one of the following modes based on the waiting time from the target transmission window and the cellular link status: when the cellular link status is available, transmitting the response data in real time via the cellular link and controlling the low-Earth orbit satellite communication module to sleep; when the cellular link status is abnormal or interrupted and the waiting time is less than a first preset time threshold, controlling the low-Earth orbit satellite communication module to warm up so that the low-Earth orbit satellite communication module enters a ready state before the target transmission window arrives; when the cellular link status is interrupted and the target transmission window arrives, arranging the cached response data according to a preset priority and then burst transmitting it within the target transmission window; when the cellular link status is interrupted and the waiting time is greater than the first preset time threshold, compressing the response data and caching it in local storage, and controlling the low-Earth orbit satellite communication module to remain in sleep mode.

4. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 3, characterized in that, Also includes: When the cellular link status changes to interruption during the target transmission window, burst transmission is directly initiated, and the response data buffered in the burst transmission is transmitted during the remaining duration of the target transmission window. When the cellular link status is abnormal but not interrupted, the response data is sent via the cellular link and a copy is cached locally. Response data that is repeatedly delivered via multiple links is deduplicated by the operation management platform according to the message sequence number and timestamp.

5. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 1, characterized in that, Also includes: During the dormant period of the transmission channel of the low-orbit satellite communication module, the receiving channel of the low-orbit satellite communication module is configured to be normally open or open according to a preset duty cycle to listen to the broadcast frames periodically sent by the low-orbit satellite. When the broadcast frame is detected, the Doppler frequency shift feature of the broadcast frame carrier is extracted, and the zero-crossing time when the Doppler frequency shift changes from positive to negative is determined as the most recent passing time of the low-orbit satellite relative to the local unit. The measured most recent passing time is compared with the predicted window time. If the deviation exceeds a preset deviation threshold, the first hop visible window is corrected with the measured most recent passing time.

6. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 5, characterized in that, Also includes: When the ephemeris data expires and the cellular link is interrupted and the ephemeris data cannot be updated, the fallback response mode is entered: window prediction is abandoned, and when the broadcast frame is detected and the signal characteristics of the broadcast frame meet the preset conditions, it is determined that the low-orbit satellite is in a visible state, and the highest priority response data in the cache is sent in the form of a short frame.

7. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 3, characterized in that, The step of arranging the cached response data according to a preset priority includes: dividing the response data into first-priority data with a regulatory time limit, second-priority data with a maximum tolerable delay, and third-priority data that allows large delays, and allocating a corresponding quota of the available bandwidth of the target transmission window to each priority data, wherein the first-priority data has absolute priority in queuing within the target transmission window; when the amount of data to be transmitted exceeds the predicted data capacity of the target transmission window, dead reckoning compression is performed on the location data, single-reference compression is performed on the identity information, and incremental reporting compression is performed on the device status data.

8. The intelligent response method for multi-source signals of unmanned aerial vehicles according to claim 1, characterized in that, Also includes: For data blocks that cannot be fully transmitted in a single first-hop visible window, rateless erasure coding is used to encode the data blocks into encoded fragment streams. Before each first-hop visible window arrives, the number of encoded fragments generated in this window is determined according to the predicted data volume that the first-hop visible window can carry, and then sent. The encoded fragments sent in different first-hop visible windows are independent of each other, and the unsent encoded fragments are discarded. The operation management platform restores the data block when the cumulative number of received encoded fragments reaches the decoding threshold.

9. A multi-source signal intelligent response system for unmanned aerial vehicles, characterized in that, The system includes a smart terminal (10) mounted on an unmanned aerial vehicle, a low-Earth orbit (LEO) satellite constellation (20), a ground gateway station (30), and an operation and management platform (40). The LEO satellite constellation (20) adopts a store-and-forward system. The LEO satellites in the LEO satellite constellation (20) are used to receive and store the data uplinked by the smart terminal (10), and forward the data stored on the satellites to the ground gateway station (30) when flying over the ground gateway station (30). The ground gateway station (30) is communicatively connected to the operation and management platform (40) and is used to transmit the received data to the operation and management platform (40). The intelligent terminal (10) includes a cellular communication module (12), a low-orbit satellite communication module (13), a satellite positioning module (14), a remote identification broadcast module (15), a local memory (16), and a main control unit (11). The main control unit (11) is connected to the cellular communication module (12), the low-orbit satellite communication module (13), the satellite positioning module (14), the remote identification broadcast module (15), and the local memory (16), respectively. The main control unit (11) is configured to execute the unmanned aerial vehicle multi-source signal intelligent response method according to any one of claims 1 to 8.

10. The unmanned aerial vehicle multi-source signal intelligent response system according to claim 9, characterized in that, The smart terminal (10) also includes a power management unit (17), which is connected to the main control unit (11) and the local memory (16) respectively. The power management unit (17) is used to tighten the preheating time threshold and cancel the transmission task of low priority data when the power supply voltage is lower than the preset voltage threshold.

Images