Anti-interference secure communication and cooperative aided positioning method and system in low-altitude air traffic control intelligent networking link denial environment

Abstract

The application relates to a low-altitude air communication and navigation anti-interference safety communication and cooperative auxiliary positioning method and system in a low-altitude air communication and navigation anti-interference safety communication and cooperative auxiliary positioning method and system, and belongs to the technical field of low-altitude flight communication and navigation. When a traditional air communication and navigation link is interfered, an airborne node and at least three ground nodes with calibrated synchronization establish a ground-air two-way link, data is simultaneously transmitted through a communication and navigation integrated symbiotic waveform, and ranging is completed. A data processing server fuses distance, calibration and air pressure data, solves the position, attitude and height of the aircraft, and distributes the data to a display terminal to present on a map. The system constructs a regional coordinate system with the aid of a self-organizing network ground node, realizes reliable communication and auxiliary positioning in a denial environment, and solves the problems that existing low-altitude aircrafts cannot transmit communication data, cannot obtain effective positioning information and cause device redundancy when the traditional communication link and satellite navigation link are interfered or in a denial state.

Description

Technical Field

[0001] This invention belongs to the field of low-altitude flight communication and navigation technology, and relates to an anti-interference secure communication and collaborative assisted positioning method and system in the environment of low-altitude communication and navigation intelligent network link denial. Background Technology

[0002] The low-altitude economy encompasses various application scenarios, including general aviation, drone logistics, low-altitude inspection, and urban air traffic. As the number of low-altitude aircraft and the complexity of low-altitude flight missions continue to increase, higher demands are being placed on the continuity, reliability, and safety of communication, navigation, surveillance, and data services for these aircraft.

[0003] Existing low-altitude communication and navigation intelligent networks typically include fourth-generation (4G) mobile communication networks, fifth-generation (5G) mobile communication networks, enhanced fifth-generation (5G) mobile communication networks, sixth-generation (6G) mobile communication networks, high-orbit satellite communication systems, low-orbit satellite communication systems, flight control links, service data links, global navigation satellite systems, real-time dynamic differential positioning systems, and automatic dependent surveillance broadcast (ADS-B) systems. These communication and navigation systems can provide low-altitude aircraft with services such as flight control, data transmission, navigation and positioning, and operational monitoring under normal operating conditions.

[0004] However, the low-altitude flight environment presents challenges such as dense buildings and obstacles, variable weather conditions, complex electromagnetic environments, and uncertain distribution of interference sources. The communication and navigation links used by low-altitude aircraft may be affected by malicious detection, suppression interference, deception interference, blocking interference, or equipment malfunction. When a communication link is interfered with or denied, flight control data, operational data, and status data may not be transmitted normally, potentially causing the low-altitude aircraft to lose control. When a satellite navigation link is interfered with, deceived, or denied, the low-altitude aircraft may be unable to obtain accurate position and time information, increasing the risk of collisions, veergency, unauthorized entry into no-fly zones, or unsafe takeoff and landing.

[0005] Existing low-altitude aircraft typically have separate communication and navigation equipment, which operate independently. This not only occupies different frequencies, antennas, radio frequency channels, and processing resources, but also easily leads to a large number of airborne devices, large weight, high power consumption, and hardware redundancy. Given the strict limitations on payload weight, installation space, and power supply capacity of low-altitude aircraft, the traditional system architecture of separating communication and navigation cannot simultaneously meet the application requirements of miniaturization, high integration, and interference resistance.

[0006] Furthermore, existing low-altitude flight support systems typically rely on wide-area mobile communication networks or satellite navigation systems. When these traditional low-altitude communication and navigation networks are interfered with or blocked, there is a lack of a backup system that can be quickly deployed and independently provide safe communication and assisted positioning services within a designated area.

[0007] Therefore, it is necessary to provide a secure communication and assisted positioning method for low-altitude communication and navigation network links under the condition of link denial, so as to provide continuous and reliable air-to-ground communication and regional assisted positioning services for low-altitude aircraft without relying on traditional low-altitude communication and navigation network links. Summary of the Invention

[0008] The purpose of this invention is to provide a safe communication and assisted positioning method for low-altitude communication and navigation intelligent network links under the condition of link denial, so as to solve the problems of communication data transmission interruption, inability to obtain effective positioning information, and equipment redundancy caused by the independence of communication equipment and navigation equipment when existing low-altitude aircraft are interfered with or in a state of denial of traditional communication links and satellite navigation links.

[0009] This invention constructs a regional coordinate system by deploying at least three ground nodes, sets up airborne nodes on low-altitude aircraft, and utilizes an integrated communication and navigation symbiotic waveform to simultaneously conduct data communication and ranging interaction between airborne nodes and ground nodes. This enables safe communication and assisted positioning of low-altitude aircraft even when traditional low-altitude communication and navigation intelligent network links are interfered with or denied.

[0010] To achieve the above objectives, the present invention provides the following technical solution: A secure communication and assisted positioning method for low-altitude communication and navigation intelligent network link denial conditions, applied to a secure communication and assisted positioning system including an airborne node, at least three ground nodes, a data processing server, and an interface display terminal, the method comprising the following steps: S1. The location of each ground node is calibrated, north is determined, air pressure is calibrated, and parameters are loaded. This enables each ground node to establish a communication link between ground nodes through self-organizing network line-of-sight transmission. Based on the communication link between ground nodes, time synchronization and frequency synchronization between each ground node are achieved, so as to construct a regional coordinate system according to the calibration parameters of each ground node.

[0011] Among them, location calibration is used to determine the position of each ground node under a unified coordinate reference; north homing is used to determine the direction reference of the regional coordinate system; barometric calibration is used to obtain barometric reference data of the area where the ground node is located; parameter binding is used to write the configuration parameters such as the calibration position, direction reference, communication parameters, distance measurement parameters and node identification of the ground node into the corresponding device.

[0012] The ground nodes exchange synchronization information and node status information through line-of-sight transmission via an ad hoc network, enabling each ground node to have a unified time and frequency reference, thus providing the foundation for subsequent ground-to-ground communication, ranging timing control, and joint positioning of multiple ground nodes.

[0013] S2, when the traditional low-altitude communication and navigation intelligent network link used by the low-altitude aircraft is interfered with or is in a denial state, determines at least three ground nodes to participate in communication and ranging through the airborne node installed on the low-altitude aircraft, and establishes a two-way airborne-ground wireless transmission link between the airborne node and the determined ground nodes.

[0014] In flight path scenarios, airborne nodes use adaptive decision-making to select three or more ground nodes that are relatively close to the low-altitude aircraft from among multiple ground nodes deployed along the flight path. As the low-altitude aircraft's position changes, the airborne nodes can autonomously select ground nodes to participate in communication and ranging, ensuring that the low-altitude aircraft is within the effective coverage area of ​​the corresponding ground nodes.

[0015] In airport or take-off and landing scenarios, the airborne node establishes a two-way wireless transmission link with three ground nodes deployed near the airport runway to provide communication and auxiliary positioning services for low-altitude aircraft during approach, landing, departure or take-off.

[0016] S3 transmits and receives integrated communication and navigation symbiotic waveforms via a two-way wireless transmission link between the aircraft and the ground. It uses the integrated communication and navigation symbiotic waveforms to transmit flight control data, configuration data, and service data. During the communication process, it completes the distance measurement interaction between the airborne node and the ground nodes in various locations to obtain the distance measurement data between the low-altitude aircraft and the ground nodes in various locations.

[0017] The integrated communication and navigation waveform is transmitted and received via a shared wireless transceiver link between airborne and ground nodes, enabling the multiplexing of communication and ranging / positioning information in the spatial, temporal, frequency, and code domains. This allows data communication and ranging / positioning to be performed simultaneously within the same set of airborne and ground hardware, reducing hardware redundancy, increased weight, and increased power consumption caused by separating communication and navigation equipment.

[0018] The flight control data includes one or more of the following: flight status, flight speed, flight altitude, heading, attitude, and flight control commands of the low-altitude aircraft; the configuration data includes one or more of the following: node identifier, operating frequency, transmission parameters, ranging parameters, and mission configuration parameters; and the service data includes one or more of the following: voice data, image data, and video data.

[0019] During the transmission and reception of data frames, the airborne node and the ground node complete the exchange of ranging information. Based on the transmission and reception of communication signals, the distance measurement data between the airborne node and the corresponding ground node is obtained, so that the communication process and the ranging process are carried out in a coordinated manner.

[0020] S4 transmits distance measurement data, flight control data, calibration parameters of various ground nodes, and air pressure calibration and inversion data to the data processing server. The data processing server then analyzes and fuses the received data to determine the low-altitude aircraft's position, attitude, and altitude data in the regional coordinate system.

[0021] The data processing server determines the position of the low-altitude aircraft in the regional coordinate system using a multi-ground node distance constraint method, based on the calibration positions of at least three ground nodes and the distance measurement data between the low-altitude aircraft and each ground node.

[0022] The attitude data of the low-altitude aircraft is provided by flight control data collected from the airborne node, and the data processing server performs unified processing of the attitude data and the position data in the regional coordinate system. The data processing server also performs barometric pressure inversion based on barometric pressure calibration data and barometric pressure data collected from the airborne node to obtain the altitude data of the low-altitude aircraft. By fusing distance measurement data, barometric altitude data, and flight control data, the position, attitude, and altitude information of the low-altitude aircraft in the regional coordinate system are obtained.

[0023] S5 stores and distributes flight control data, configuration data, business data, as well as position data, attitude data, and altitude data through a data processing server, and displays the communication data and auxiliary positioning data of the low-altitude aircraft based on map software through an interface display terminal.

[0024] The interface display terminal can display the location, flight trajectory, flight altitude, heading and attitude of the low-altitude aircraft on the map interface, and can also display flight control information, configuration information, voice information, image information and video information, so that ground operators can grasp the operating status of the low-altitude aircraft.

[0025] To improve the anti-interference capability and information security of the two-way wireless transmission link between the aircraft and the ground, this invention employs one or more of the following methods when establishing and maintaining the two-way wireless transmission link: physical layer frequency hopping, directional antenna transmission, spatial filtering, time-domain and frequency-domain interference suppression, and multi-frequency point backup. These methods enhance the anti-interference performance of the two-way wireless transmission link by avoiding interference, adapting to interference, and suppressing interference.

[0026] Physical layer frequency hopping is used to enable airborne nodes and ground nodes to switch between multiple operating frequencies according to the configured frequency hopping parameters, so as to reduce the impact on communication and ranging when a single frequency is subjected to continuous interference.

[0027] Directional antenna transmission is used to improve signal gain in the target direction and reduce the impact of interference signals from non-target directions on the receiver.

[0028] Spatial filtering is used to perform spatial selection processing on the received signal based on the spatial directional difference between the target signal and the interference signal.

[0029] Time-domain and frequency-domain interference suppression is used to identify and suppress the interfered signal based on the distribution characteristics of the interference signal in the time and frequency dimensions.

[0030] Multi-frequency backup is used to switch to a backup operating frequency to continue data communication and ranging interaction when the current operating frequency is interfered with or cannot meet the communication quality requirements.

[0031] In addition, the information stream transmitted in the two-way wireless transmission link between the aircraft and the ground is encrypted and authenticated to prevent unauthorized nodes from accessing the system and to reduce the risk of flight control data, configuration data and business data being stolen, tampered with or forged.

[0032] The beneficial effects of this invention are as follows: (1) By constructing a regional coordinate system through at least three ground nodes, it can still provide air-to-ground communication and auxiliary positioning services for low-altitude aircraft when traditional mobile communication links, satellite communication links, flight control links, service links or satellite navigation links are interfered with or denied, thereby improving the safety assurance capability of low-altitude flight.

[0033] (2) By using the integrated communication and navigation symbiotic waveform, communication data and ranging and positioning information share the same wireless transceiver link and are reused in the spatial, time, frequency and code domains, reducing hardware redundancy caused by separate settings of communication and navigation equipment, and improving spectrum utilization and airborne equipment integration.

[0034] (3) The distance between the airborne node and multiple ground nodes is measured by using the communication process, and the position, attitude and altitude of the low-altitude aircraft are determined by combining the ground node calibration parameters and air pressure calibration and inversion data. The auxiliary positioning service can be provided in the designated area without relying on the satellite navigation system.

[0035] (4) Employ technologies such as physical layer frequency hopping, directional antenna transmission, spatial filtering, time and frequency domain interference suppression, multi-frequency point backup, information flow encryption and identity authentication to improve the anti-interference capability, confidentiality and reliability of the ground communication and ranging link.

[0036] (5) The ground nodes of the present invention can achieve time synchronization and frequency synchronization between nodes through self-organizing network line-of-sight transmission, and can be deployed using the power supply and dedicated line resources of existing iron towers, reducing the cost of new infrastructure construction, and are suitable for forming continuous coverage along important flight routes.

[0037] (6) This invention enables the use of three ground nodes in a triangular layout at airports or take-off and landing sites to provide low-altitude aircraft with distance, orientation, and altitude information relative to the landing point, thereby improving the safety of low-altitude aircraft during approach, landing, take-off, and departure. It consists of airborne nodes, ground nodes, a data processing server, and an interface display terminal. After position calibration, north-finding, barometric calibration, and parameter setting, it can be put into use, featuring flexible deployment, convenient configuration, high integration, and wide applicability.

[0038] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a system architecture diagram of the secure communication and assisted positioning system of the present invention; Figure 2 This is a schematic diagram illustrating the working principle of the invention when applied to flight route scenarios; Figure 3 This is a schematic diagram illustrating the working principle of the present invention when applied to airport or take-off and landing site scenarios; Figure 4 This is a flight test scenario diagram for the present invention. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0041] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0042] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0043] Example 1: System Overall Architecture like Figure 1 As shown, the secure communication and assisted positioning system in this embodiment includes an airborne layer, a transmission layer, a ground layer, a data processing layer, and an interface display layer.

[0044] The airborne layer is located on the low-altitude aircraft and includes airborne nodes and flight control and operational data equipment that are communicatively connected to the airborne nodes. The airborne nodes are used to collect, process, and transmit flight control data, configuration data, ranging and positioning data, and operational data.

[0045] Flight control data may include flight speed, altitude, heading, pitch angle, roll angle, yaw angle, flight mode, and flight control status. Configuration data may include airborne node identifiers, ground node identifiers, operating frequencies, spare frequencies, communication parameters, ranging parameters, and mission parameters. Service data may include voice data, image data, and video data.

[0046] The transport layer is used to establish a two-way wireless transmission link between airborne nodes and ground nodes when the traditional low-altitude communication and navigation network link is interfered with or denied, and to complete data communication and ranging interaction between airborne nodes and ground nodes through spatial line-of-sight transmission.

[0047] The ground layer comprises at least three ground nodes. Each ground node is equipped with a wireless transceiver unit, a ranging processing unit, a synchronization processing unit, a north-finding unit, and a barometric pressure acquisition unit. The wireless transceiver unit is used for wireless communication with airborne nodes or other ground nodes; the ranging processing unit is used to cooperate with airborne nodes to complete distance measurements; the synchronization processing unit is used to achieve time and frequency synchronization between ground nodes; the north-finding unit is used to provide a direction reference for the regional coordinate system; and the barometric pressure acquisition unit is used to acquire ground reference barometric pressure data.

[0048] The data processing layer includes a data processing server. The data processing server receives data uploaded from airborne and ground nodes, parses, stores, and fuses flight control data, configuration data, distance measurement data, barometric pressure data, and operational data, and distributes the processing results to the interface display terminal.

[0049] The interface display layer includes the interface display terminal. The interface display terminal is equipped with map software and is used to display the low-altitude aircraft's position, flight trajectory, flight altitude, attitude, heading, flight status, configuration information, and business information such as voice, images, and video.

[0050] Example 2: Construction of a Regional Coordinate System Before being put into use, the locations of various ground nodes were marked, north was determined, air pressure was calibrated, and parameters were compiled.

[0051] During location calibration, the positions of each ground node under a unified coordinate reference are determined, and the corresponding location parameters are written to the ground node or data processing server.

[0052] When searching for north, the direction reference of the regional coordinate system is determined by the north-finding instrument configured on the ground node, so that all ground nodes and data processing servers can represent the position, heading and bearing of the low-altitude aircraft under a unified direction reference.

[0053] During barometric calibration, a reference barometric pressure is collected for the area where the ground node is located, and a correspondence is established between the barometric pressure data and the regional altitude reference. During flight, the airborne node collects barometric pressure data at the location of the low-altitude aircraft, and the data processing server performs barometric pressure inversion based on the ground reference barometric pressure to obtain the altitude data of the low-altitude aircraft.

[0054] During parameter binding, the ground node position parameters, direction reference parameters, node identifiers, communication parameters, ranging parameters, and synchronization parameters are written into the corresponding nodes.

[0055] After completing the above configuration, each ground node establishes a communication link between ground nodes through self-organizing network line-of-sight transmission, and exchanges synchronization information through the communication link between ground nodes, so that multiple ground nodes maintain a unified time reference and frequency reference.

[0056] Based on the calibration positions, orientation references, and altitude references of each ground node, a regional coordinate system covering the target flight area is constructed.

[0057] Example 3: Integrated Communication and Navigation Process When a low-altitude aircraft is performing a mission, the airborne node establishes a two-way wireless transmission link with at least three ground nodes covering the current flight area.

[0058] Airborne nodes and ground nodes in various locations share a wireless transceiver link to transmit and receive integrated communication and navigation waveforms. Communication data and ranging / positioning information are carried through one or more multiplexing methods in the spatial, temporal, frequency, and code domains.

[0059] The airborne node sends flight control data, configuration data, and service data to the ground node through the air-to-ground two-way wireless transmission link, and the ground node sends control information, configuration update information, and ranging interaction information to the airborne node through the air-to-ground two-way wireless transmission link.

[0060] During communication, the airborne node interacts with at least three ground nodes to measure distances between itself and each ground node. Each ground node then sends the distance measurement data and its corresponding node identifier to the data processing server.

[0061] The data processing server determines the position of the low-altitude aircraft in the regional coordinate system by means of distance constraints between multiple ground nodes, based on the calibration positions of various ground nodes and the distance measurement data between the low-altitude aircraft and various ground nodes.

[0062] Meanwhile, the data processing server receives flight control data and air pressure data sent by the airborne node, obtains the attitude and heading of the low-altitude aircraft based on the flight control data, and obtains the altitude of the low-altitude aircraft based on the air pressure calibration data and the airborne air pressure data.

[0063] The data processing server fuses and stores position, attitude, altitude, flight status, and operational data, and sends the fusion results to the interface display terminal. The interface display terminal displays the low-altitude aircraft's current position, flight trajectory, attitude, flight altitude, and operational data in real time within the map software.

[0064] Example 4: Flight Route Scenario like Figure 2 As shown, for important flight routes, multiple ground nodes are deployed at intervals along the flight route.

[0065] Ground nodes can be deployed on existing towers and share the tower's power supply and dedicated transmission resources. Ground nodes establish a network through ad-hoc line-of-sight transmission, maintaining time and frequency synchronization among them.

[0066] When a low-altitude aircraft flies along its flight path, the airborne node uses an adaptive decision-making method to select three or more ground nodes that are relatively close to each other from the ground node network to participate in the current communication and ranging, based on the distance between the airborne node and the ground nodes in each location.

[0067] The airborne node establishes a two-way wireless transmission link with the selected ground node, and uses the integrated communication and navigation symbiotic waveform to transmit flight control data, configuration data and service data, and measures the distance between the low-altitude aircraft and the selected ground nodes.

[0068] As the low-altitude aircraft moves along its flight path, the airborne nodes re-identify the nearest ground nodes, so that the ground nodes involved in communication and ranging are adapted to the current position of the low-altitude aircraft.

[0069] In this way, a regional security communication and auxiliary positioning coverage network consisting of multiple ground nodes can be formed along the flight path. When the traditional low-altitude communication and navigation network link is interfered with or denied, communication between the low-altitude aircraft and the ground system can be maintained, and the position of the low-altitude aircraft in the regional coordinate system can be obtained.

[0070] Example 5: Airport or take-off and landing site scenario like Figure 3 As shown, three ground nodes are deployed near the runway at the airport or take-off and landing site, forming a triangular layout.

[0071] The first ground node is deployed at the end of the runway centerline, and the north-finding scale of the first ground node is parallel to the runway centerline.

[0072] The second and third ground nodes are symmetrically deployed on both sides of the runway entrance. The vertical distance between the second and third ground nodes and the runway is 50 meters to 100 meters.

[0073] The three ground nodes establish a communication link through ad hoc line-of-sight transmission, and maintain time and frequency synchronization through this communication link. An airport area coordinate system is constructed based on the calibrated positions of the three ground nodes, runway orientation, and landing point positions.

[0074] When a low-altitude aircraft approaches, takes off, or lands, the airborne node establishes a two-way wireless transmission link with three ground nodes. It uses the integrated communication and navigation symbiotic waveform to transmit flight control data and operational data, and measures the distance between the low-altitude aircraft and the three ground nodes.

[0075] The data processing server calculates the position of the low-altitude aircraft in the airport area coordinate system based on the calibrated positions of the three ground nodes and three sets of distance measurement data, and further determines the distance and orientation of the low-altitude aircraft relative to the preset landing point.

[0076] The data processing server also performs air pressure inversion based on the air pressure data collected by the airborne nodes and the reference air pressure data provided by the ground nodes to obtain the altitude information of the low-altitude aircraft relative to the airport area altitude reference.

[0077] The interface display terminal shows the positional relationship of the low-altitude aircraft relative to the runway, landing point, and three ground nodes on the airport map or runway map, providing auxiliary information for the low-altitude aircraft's approach, landing, takeoff, and departure.

[0078] Example 6: Link Interference Resistance and Secure Transmission To improve the availability of the two-way wireless transmission link between the machine and the ground in complex electromagnetic environments, this embodiment employs one or more of the following methods: physical layer frequency hopping, directional antenna transmission, spatial filtering, time-domain and frequency-domain interference suppression, and multi-frequency point backup.

[0079] Airborne and ground nodes switch frequencies according to pre-set frequency hopping parameters. When the current frequency is interfered with, the airborne and ground nodes switch to the backup frequency to continue transmitting communication data and ranging information.

[0080] Ground nodes employ directional antennas to improve signal gain in the target flight area and reduce the impact of interference signals from other directions. The receiver suppresses interference components in the received signal through spatial filtering, time-domain interference suppression, or frequency-domain interference suppression.

[0081] When an airborne node establishes a communication connection with a ground node, it undergoes authentication. After successful authentication, both the airborne and ground nodes encrypt the transmitted information stream to protect flight control data, configuration data, location data, and operational data.

[0082] Through the above anti-interference and secure transmission measures, the normal operation of the two-way wireless transmission link between the equipment and the ground can be maintained even when some operating frequencies are interfered with or there is a risk of unauthorized access.

[0083] Example 7: Flight Test like Figure 4 As shown, three sets of ground nodes are deployed at a general aviation airport, forming a triangular network configuration, and airborne nodes are installed on low-altitude aircraft.

[0084] During the test, fourth-generation mobile communication networks, fifth-generation mobile communication networks, fifth-generation enhanced mobile communication networks, sixth-generation mobile communication networks, high-orbit satellite communication systems, low-orbit satellite communication systems, existing flight control links, existing service links, global satellite navigation systems, real-time dynamic differential positioning systems, and automatic dependent surveillance broadcast systems did not participate in communication and positioning.

[0085] Centered on the airport, three take-off and landing points are selected within a range of no more than 5 kilometers from the airport. Three drones take off from the three take-off and landing points respectively and fly to the airport in an orderly manner according to the predetermined route and the predetermined flight altitude of 900 meters.

[0086] During flight, the three drones transmit flight control data, image data, video data, and other business data solely through a two-way wireless transmission link between the onboard node and the ground node, and measure the distance between the drones and the three ground nodes through the communication process.

[0087] Test results show that, under the test conditions, the effective range of this invention reached 5 kilometers, the data transmission rate reached 10 megabits per second, the communication latency was less than 25 milliseconds, and video data, image data, and flight control data could all be transmitted normally. No data packets were lost during the test.

[0088] The positioning test results show that when the airborne node is in a static state, the horizontal positioning accuracy reaches ±4 meters and the vertical positioning accuracy reaches ±2 meters; when the airborne node is in a dynamic state, the horizontal positioning accuracy reaches ±7 meters and the vertical positioning accuracy reaches ±3 meters.

[0089] The test results above demonstrate that the present invention can provide air-to-ground communication and regional assisted positioning services for low-altitude aircraft without relying on traditional low-altitude navigation and intelligent network links, meeting the application needs of low-altitude flight routes, airports, and take-off and landing sites.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A secure communication and assisted positioning method for low-altitude intelligent network link denial conditions, applied to a secure communication and assisted positioning system including an airborne node, at least three ground nodes, a data processing server, and an interface display terminal, characterized in that, Includes the following steps: S1, perform position calibration, north orientation, barometric pressure calibration and parameter loading for each of the ground nodes, so that each of the ground nodes can establish a communication link between the ground nodes through self-organizing network line-of-sight transmission, and realize time synchronization and frequency synchronization between the ground nodes based on the communication link between the ground nodes, so as to construct a regional coordinate system according to the calibration parameters of each of the ground nodes. S2, when the traditional low-altitude communication and navigation intelligent network link used by the low-altitude aircraft is interfered with or is in a denial state, at least three ground nodes participating in communication and ranging are determined by the airborne node installed on the low-altitude aircraft, and a two-way air-to-ground wireless transmission link is established between the airborne node and each of the determined ground nodes. S3, transmit and receive integrated communication and navigation symbiotic waveforms through the air-to-ground two-way wireless transmission link, use the integrated communication and navigation symbiotic waveforms to transmit flight control data, configuration data and service data, and complete the distance measurement interaction between the airborne node and each of the ground nodes during the communication process to obtain the distance measurement data between the low-altitude aircraft and each of the ground nodes; S4, the distance measurement data, the flight control data, the calibration parameters of each ground node, and the air pressure calibration and inversion data are transmitted to the data processing server. The data processing server parses and fuses the received data to determine the position data, attitude data, and altitude data of the low-altitude aircraft in the regional coordinate system. S5, the flight control data, configuration data, business data, position data, attitude data and altitude data are stored and distributed through the data processing server, and the communication data and auxiliary positioning data of the low-altitude aircraft are displayed through the interface display terminal based on map software.

2. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, The integrated communication and navigation waveform is transmitted and received by the airborne node and the ground node using the same wireless transceiver link. Communication information and ranging and positioning information are multiplexed in the spatial domain, time domain, frequency domain, and code domain, so that the communication data transmission process and the ranging and positioning process are carried out in coordination.

3. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, When establishing and maintaining the two-way wireless transmission link between the aircraft and the ground, one or more of the following methods are used to avoid or suppress interference: physical layer frequency hopping, directional antenna transmission, spatial filtering, time-domain and frequency-domain interference suppression, and multi-frequency point backup. The information stream transmitted in the two-way wireless transmission link between the aircraft and the ground is encrypted and authenticated.

4. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, The secure communication and assisted positioning system is functionally divided into an airborne layer, a transmission layer, a ground layer, a data processing layer, and an interface display layer. The airborne layer is used to collect, process, and transmit flight control data, configuration data, ranging and positioning data, and service data from the airborne terminal. The transmission layer is used to establish the air-to-ground two-way wireless transmission link and perform line-of-sight transmission. The ground layer is used for north-finding, barometric calibration and inversion, ranging and positioning, and ground-end data processing. The data processing layer is used to parse, store, fuse, and distribute the received data. The interface display layer is used to display the communication data and assisted positioning data.

5. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, In the flight path scenario, multiple ground nodes are deployed on towers set up along the flight path, and the ground nodes use the power supply resources and dedicated line transmission resources of the towers. The multiple ground nodes form a ground node network distributed along the flight path through the self-organizing network line-of-sight transmission.

6. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 5, characterized in that, The airborne node selects three or more ground nodes that are close to the low-altitude aircraft from the ground node network through an adaptive decision-making method based on the distance between the low-altitude aircraft and each of the ground nodes. As the low-altitude aircraft moves along the flight path, it autonomously selects the ground nodes that participate in communication and ranging.

7. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, In an airport or take-off and landing site scenario, the three ground nodes are arranged near the runway in a triangular layout. The first ground node is located at the end of the runway's central axis, and the direction of the north-finding instrument scale of the first ground node is parallel to the runway's central axis. The second and third ground nodes are symmetrically arranged on both sides of the runway entrance, and the vertical distance between the second and third ground nodes and the runway is 50 meters to 100 meters.

8. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 7, characterized in that, Through data transmission and ranging interaction between the airborne node and the three ground nodes, distance measurement data between the low-altitude aircraft and the three ground nodes are obtained. Based on the calibration parameters of the three ground nodes in the regional coordinate system and the distance measurement data, the distance information and orientation information of the low-altitude aircraft relative to the preset landing point are calculated.

9. The secure communication and assisted positioning method for low-altitude intelligent network links under link rejection conditions according to claim 1, characterized in that, The business data includes one or more of voice data, image data, and video data. The interface display terminal is used to display in real time the flight status information, configuration information, voice information, image information, video information, and the position, attitude, and altitude of the low-altitude aircraft in the regional coordinate system.

10. A secure communication and assisted positioning system for low-altitude intelligent network link denial conditions, characterized in that, It includes an airborne node, at least three ground nodes, a data processing server, and an interface display terminal; Each of the ground nodes is used to establish a communication link between ground nodes through self-organizing network line-of-sight transmission after completing position calibration, north-pointing, barometric calibration and parameter setting, so as to realize time synchronization and frequency synchronization between the ground nodes and construct a regional coordinate system based on the calibration parameters of each ground node. The airborne node is installed on a low-altitude aircraft and is used to identify at least three ground nodes participating in communication and ranging when the traditional low-altitude communication and navigation network link is interfered with or denied. It also establishes a two-way wireless transmission link between the airborne node and each of the identified ground nodes. The airborne node and each of the ground nodes are also used to transmit and receive integrated communication and navigation waveforms through the air-to-ground two-way wireless transmission link to transmit flight control data, configuration data and service data, and to measure the distance between the low-altitude aircraft and each of the ground nodes during the communication process; The data processing server is used to receive the flight control data, configuration data, business data, distance measurement data, and calibration parameters of each ground node, and to parse, store, and fuse the received data to determine the position data, attitude data, and altitude data of the low-altitude aircraft in the regional coordinate system, and to distribute the communication data and auxiliary positioning data. The interface display terminal is communicatively connected to the data processing server and is used to display the flight control information, configuration information, business information, position, attitude, and altitude of the low-altitude aircraft based on map software.

Images