A data link communication system and method for beyond-line-of-sight swarm telemetry and control of unmanned aerial vehicles (UAVs).

Abstract

This invention provides a data link communication system and method for beyond-line-of-sight (BLOS) swarm telemetry and control of unmanned aerial vehicles (UAVs), including a ground command and control station, a platform UAV, and a mission UAV. The ground command and control station and the platform UAV transmit data via a satellite communication link; the platform UAV and the mission UAV transmit data via a network communication link; and the mission UAV and the ground command and control station transmit data via both a satellite communication link and a network communication link. The advantages of this invention are: it combines Ka-band high-throughput satellite communication with TD-LTE regional network communication, and through technologies such as combined platform hardware design, heterogeneous network communication, data encryption and decryption, efficient encoding and transmission, universal protocol framing, multi-channel backup mechanisms, and differentiated network distribution, it achieves rapid transmission and distribution of service data in the link system, meeting the needs of large-scale, high-bandwidth, and highly mobile UAV swarm operations in beyond-line-of-sight situations.

Description

Technical Field

[0001] This invention belongs to the field of transmission technology, and in particular relates to a data link communication system and method for beyond-line-of-sight cluster telemetry and control of unmanned aerial vehicles. Background Technology

[0002] In beyond-line-of-sight (BLOS) communication, due to the Earth's curvature affecting line-of-sight signal transmission, systems often employ satellite relay communication to achieve BLOS data communication. Traditional high-speed satellite communication primarily uses the Ku band, but it suffers from numerous problems in terms of resource consumption, coverage, signal interference, terminal size, and application costs. Newer high-speed satellite communication technologies often utilize the Ka band, based on a multi-beam, space-division multiplexing architecture. This offers advantages in channel bandwidth, beam coverage, anti-interference capabilities, terminal size, IP-based design, and data traffic costs. While ensuring transmission efficiency, it effectively reduces the load requirements of satellite communication terminal equipment on UAVs, reserving more space for UAVs to carry mission equipment.

[0003] In terms of regional coverage operations, the single-machine mission mode has shortcomings in terms of range coverage, operation timeliness, mission cycle, and battlefield survivability. Therefore, the system mostly adopts a multi-machine collaborative cluster operation mode, while taking into account application cost and system complexity. The selection of mission drones is mostly based on light and small drones, thereby realizing clustered regional network coverage operations.

[0004] When facing beyond-line-of-sight cluster operations, considering factors such as aircraft load, mission timeliness, mobility expansion, system operation and application costs, a single satellite communication link or network link cannot meet the current mission requirements. Therefore, it is necessary to design a new link communication system that integrates the characteristics of both link technologies. Summary of the Invention

[0005] In view of this, the present invention aims to propose a data link communication system and method for beyond-line-of-sight cluster telemetry and control of unmanned aerial vehicles (UAVs), so as to solve at least one of the problems in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A data link communication system for beyond-line-of-sight cluster telemetry and control of unmanned aerial vehicles (UAVs) includes a ground command and control station, a platform UAV, and a mission UAV.

[0008] The ground command and control station and the platform drone communicate via a satellite communication link.

[0009] The platform's drone terminal and the mission drone terminal communicate via a network communication link;

[0010] The mission drone and the ground command and control station also communicate via satellite communication links and network communication links.

[0011] A data link communication system for beyond-line-of-sight cluster telemetry and control of unmanned aerial vehicles (UAVs) includes a ground command and control station, a platform UAV, and a mission UAV.

[0012] The ground command and control station includes a satellite communication module, a public network access module, and a service processing module;

[0013] The platform's UAV terminal includes an airborne satellite communication module, a bus interface unit, a master node networking communication module, and a payload service module;

[0014] The mission drone terminal includes a node networking communication module and a payload service module.

[0015] A data link communication method for beyond-line-of-sight swarm telemetry and control of unmanned aerial vehicles (UAVs), including a forward communication method:

[0016] The remote control data undergoes channel selection and protocol encryption in the service processing module, and is then forwarded to the satellite via a single-hop or double-hop satellite communication link.

[0017] The platform's UAV receives forward remote control data from satellite communication, which is then processed and routed through the bus interface unit protocol frame synchronization and forwarding, and transmitted to the local payload service module, or transmitted to the mission UAV payload service module via the network link.

[0018] Each platform's payload service module synchronizes, decrypts, and parses remote control commands to complete the control response to the corresponding terminal commands.

[0019] Furthermore, in forward communication:

[0020] The ground control station's service processing module receives the same remote control command from the link monitoring software simultaneously via serial port and network port / service network. Based on the interface mode, default configuration, and timeout judgment logic, it confirms the effective channel of the remote control command.

[0021] The ground command and control station's business processing module has an embedded encryption and decryption unit that encrypts the input remote control commands into protocol frame data and converts them into encrypted remote control data frames.

[0022] The ground command and control station's business processing module sends remote control data frames into the network protocol stack, converting them into network data packets containing remote control data.

[0023] Based on the routing configuration and default gateway information, the ground control station service processing module can choose a dual-hop method: the network remote control data packets are sent to the satellite via the local satellite communication module, or a single-hop method: the packets are sent to the satellite via the public network access VPN service channel and then sent to the satellite by the gateway station satellite communication unit.

[0024] Furthermore, in forward communication:

[0025] The network layer remote control data packets are routed and forwarded via the satellite communication link, received by the platform's UAV satellite communication module, and then transferred to the platform's UAV bus interface unit.

[0026] The platform UAV bus interface unit determines the execution routing information based on the target address of the network layer remote control data packet: if the target address is the platform UAV, the data packet is forwarded to the local payload service module; if the target address is the mission UAV, the data packet is pushed to the network communication module, and after routing and forwarding by the network module, it is finally transmitted to the mission UAV payload service module.

[0027] The payload service modules of mission-oriented UAVs and platform UAVs perform protocol stack parsing on network layer remote control data packets to reconstruct encrypted remote control data frames.

[0028] Perform protocol decryption and frame deframe operations to obtain the original remote control commands;

[0029] The remote control commands are parsed to confirm the final responding device terminal and command parameters, thus completing the command control. A data link communication method for beyond-line-of-sight (BLOS) cluster telemetry and control of unmanned aerial vehicles (UAVs) includes a return communication method:

[0030] The mission UAV and platform UAV payload service modules initiate business data collection, perform data encoding, protocol framing and encrypted transmission processes, and encapsulate the data into network data packets through the network protocol stack.

[0031] The mission-return composite data from the UAV is transmitted to the platform's UAV bus interface unit via a network link;

[0032] The platform's UAV return composite data is transmitted to the local bus interface unit via the internal communication interface;

[0033] The composite data frames of the mission UAV and the platform UAV are queued and routed for forwarding, and then sent to the satellite by the satellite communication module of the platform UAV.

[0034] Ground control stations transmit satellite communication data via single-hop or double-hop methods to obtain return composite service data, perform protocol data decryption and parsing, and complete status information monitoring and service data processing.

[0035] Furthermore, in the return communication:

[0036] The payload service modules of mission UAVs and platform UAVs detect and capture raw video data through the video input interface, perform image processing and video compression encoding, transmit the encoded video stream through the buffer code, and push the encoded video stream into the corresponding buffer channel before composite data framing.

[0037] The payload service modules of mission UAVs and platform UAVs acquire various types of aircraft data, including flight path attitude, payload information, telemetry data and system status, through internal and external data interfaces, and push them into the corresponding cache channel before composite data framing.

[0038] The payload service modules of mission drones and platform drones queue and frame multiple sets of cached service data according to data type, transmission rate, priority, caching status and waiting time variables, and perform data encryption processing on composite data frames.

[0039] The payload service modules of mission-oriented UAVs and platform UAVs send dense composite data frames into the network protocol stack, which converts them into network data packets containing composite data.

[0040] The mission UAV composite data packet is transmitted to the platform UAV bus interface unit through the network link, and the platform UAV composite data packet is transmitted to the local bus interface unit through the internal data interface.

[0041] The platform's UAV bus interface unit queues composite data frames and transmits them to the local satellite communication module for uploading, based on the routing configuration and default gateway information.

[0042] Network layer composite data is routed and forwarded via satellite communication link, received by the ground command and control station's satellite communication module or public network access module based on gateway station VPN service, and then transferred to the ground command and control station's business processing module.

[0043] The ground control station's service processing module performs protocol stack parsing on network layer composite data packets to obtain composite service frames; after processing by the embedded encryption / decryption unit, it completes the decryption of composite service frame data; and pushes the plain-state composite service frames into the service network and core network parsing and forwarding processes respectively.

[0044] Furthermore, the ground command and control station's business processing module adopts a dual-network mutual backup mode to forward business data. According to the interface protocol, it forwards the original and parsed business data to the backend link monitoring and task processing unit to complete status monitoring and business data processing.

[0045] Furthermore, TCP protocol is used to complete data transmission for raw composite and multi-channel synchronous data; UDP multicast protocol is used to complete data forwarding for telemetry data; and RTSP transport protocol is used to complete data streaming for video image data.

[0046] Compared with existing technologies, the UAV data link communication system and method for beyond-line-of-sight cluster telemetry and control described in this invention has the following advantages:

[0047] This invention combines Ka-band high-throughput satellite communication with TD-LTE regional network communication. Through a combined platform hardware design, heterogeneous network communication, data encryption and decryption, efficient encoding and transmission, universal protocol framing, multi-channel backup mechanisms, and differentiated network distribution technologies, it achieves rapid transmission and distribution of service data within the link system. This meets the needs of large-scale, high-bandwidth, and highly mobile UAV swarm operations beyond visual line of sight. Using a long-range large UAV as a support platform, multiple lightweight and portable UAVs are deployed in the target area, leveraging the network convergence advantages of satellite communication links and regional network links. Satellite communication extends the swarm operation radius, and task allocation and multi-UAV collaboration compensate for the deficiencies of single-UAV operations, enhancing the system's on-site mobility and wartime collaborative application survivability. This provides a feasible solution for UAV systems to achieve beyond visual line of sight, high efficiency, and synchronous coverage operations. Attached Figure Description

[0048] The accompanying drawings, which form part of this invention, 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:

[0049] Figure 1 This is a schematic diagram of the application framework structure of the communication system according to an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the functional modules of the communication system terminal according to an embodiment of the present invention;

[0051] Figures 3.1-3.4 This is a schematic diagram of the ground command and control station terminal communication system according to an embodiment of the present invention;

[0052] Figures 4.1-4.5 This is a schematic diagram of the platform unmanned aerial vehicle terminal communication system according to an embodiment of the present invention;

[0053] Figure 5 This is a schematic diagram of the mission-oriented UAV terminal communication system according to an embodiment of the present invention;

[0054] Figure 6-1 This is a block diagram of the forward data transmission process according to an embodiment of the present invention;

[0055] Figure 6-2 This is a block diagram of the forward data transmission logic according to an embodiment of the present invention;

[0056] Figure 7 This refers to the ground remote control channel selection processing logic described in the embodiments of the present invention;

[0057] Figure 8 This refers to the protocol frame data encryption and decryption process described in the embodiments of the present invention;

[0058] Figure 9The diagrams are of the single-link network and dual-link heterogeneous network described in the embodiments of the present invention.

[0059] Figure 10-1 This is a block diagram of the return data transmission process according to an embodiment of the present invention;

[0060] Figure 10-2 This is a block diagram of the return data transmission logic according to an embodiment of the present invention;

[0061] Figure 11 This is a logic block diagram of video acquisition, encoding, and transmission as described in an embodiment of the present invention;

[0062] Figure 12 This is a schematic diagram of the general frame protocol for forward and backward service transmission as described in an embodiment of the present invention;

[0063] Figure 13 This is a schematic diagram of the composite service data parsing and forwarding processing logic according to an embodiment of the present invention. Detailed Implementation

[0064] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0065] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0066] like Figure 1As shown, this embodiment relates to a UAV data link communication system for beyond-line-of-sight cluster telemetry and control, comprising three types of terminal communication systems: a ground command and control station, a platform UAV, and a mission UAV. The ground command and control station can be a mobile container vehicle or a fixed ground station, and includes a ground satellite communication module, a public network access module, and a service processing module, interfacing with the user-end link monitoring and task processing unit. The platform UAV can be a large fixed-wing UAV or unmanned helicopter with long endurance, high payload, and high-altitude operation capabilities. The platform UAV includes an airborne satellite communication module, a bus interface unit, a network communication module (master node), and a payload service module. The mission UAV is a lightweight, portable, autonomous transceiver rotorcraft UAV, mounted or mounted on the platform UAV. When the platform UAV flies over the target area, it controls the mission UAV to autonomously launch and land via forward remote control commands from the ground, performing cluster telemetry and control and collaborative operations within the target area. The mission UAV includes a network communication module (slave node) and a payload service module. The ground command and control station and the platform UAV use a satellite communication link to achieve two-way data communication. Currently, UAV beyond-line-of-sight communication mostly uses Ku-band communication satellites, which generally suffer from problems such as limited available bandwidth, numerous interference sources, large size of airborne terminal equipment, technical complexity, and high application costs. Therefore, the system's satellite communication link selects the Ka-band high-throughput communication satellite - ChinaSat 16, which is designed based on a multi-beam and spatial division multiplexing architecture, to leverage the advantages of the satellite communication main chain in terms of channel bandwidth, beam coverage, handover, anti-interference capability, terminal size, IP-based design, and traffic costs.

[0067] The platform's UAV and ground command and control station establish a satellite communication link through an airborne / ground satellite communication module, a high-throughput satellite (Zhongxing-16), a gateway station, and a data processing center, enabling "double-hop" data communication between the platform's UAV and the ground command and control station. At the same time, a VPN transmission service can be established between the data processing center and the ground command and control station according to business transmission needs, reducing the latency overhead of secondary data uploading to satellites and enabling "single-hop" data communication between the platform's UAV and the ground command and control station.

[0068] The platform's UAVs and mission UAVs utilize a regional network link to achieve multi-task collaborative cluster telemetry and control. In selecting the network topology and communication protocol, key considerations include channel capacity, transmission latency, dynamic expansion, anti-interference capabilities, and system maintenance and management. Taking all factors into account, the system's network communication adopts a star network topology architecture based on the TD-LTE mobile communication protocol. This protocol employs Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output (MIMO) technologies, featuring a flat system design and exhibiting excellent performance in terms of transmission latency, data throughput, and anti-interference capabilities. Furthermore, the star topology is simple, enabling synchronous task allocation and multi-point service aggregation, reducing multi-hop routing latency, and meeting the application requirements of dynamic access, collaborative telemetry and control, and management and maintenance.

[0069] Considering the risk of communication failure across the entire network link when a master node malfunctions in a star network topology, the system incorporates a hot backup design for the master node communication module. This involves deploying multiple (≥2) network communication modules on the platform's drones, each with the same master node parameter configuration, operating simultaneously in a 1:1 ratio. The backend monitoring system decides which module to enable / switch. While the working master node module is communicating normally, the backup module shares real-time data through an internal interface, mirroring and maintaining a hot backup standby state. When the system detects a master node link malfunction, it actively migrates the network link to the hot backup master node, simultaneously switching the backup master node from standby to working mode, while the original working master node is silenced, maintaining effective data communication across the network link.

[0070] The functional modules of a communication system terminal are as follows: Figure 2 As shown.

[0071] The satellite communication module is used in the communication system between the platform's UAV and the ground command and control station terminal. It mainly consists of four parts: a data interface unit, a modem, a power amplifier unit, and an antenna system. The data interface unit has functions such as multi-type interface communication, data synchronization buffering, protocol frame conversion, and data forwarding. The modem can realize data encoding and modulation and signal demodulation and decoding. The power amplifier unit can meet the functions of transmitting and receiving signal amplification, noise suppression, and signal filtering. The antenna system is divided into an airborne antenna system and a ground antenna system. The airborne antenna system consists of a mobile antenna and a servo control system, which has the ability to track and align the satellite in real time and transmit and receive signals. The ground antenna system consists of a stationary antenna and an antenna control unit, which has the ability to extend and retract the antenna, point to the satellite, and transmit and receive signals.

[0072] Based on forward speeds of 4Mb / s and backward speeds of 8Mb / s, the platform UAV uses an equivalent aperture of a 0.6m mobile antenna and a 20W power amplifier unit, while the ground command and control station is equipped with a 1.2m stationary antenna and a 10W power amplifier unit, which can ensure effective transmission of bidirectional service data.

[0073] The public network access module is used in the ground command and control station terminal communication system. It connects to the data processing center externally and to the business processing module internally. The business processing module accesses the VPN service of the data processing center through the public network, establishing a two-way network channel between the ground command and control station and the data processing center and gateway station, and establishing a "single-hop" satellite communication process for forward remote control data and return composite business transmission.

[0074] The service processing module is used in the ground command and control station terminal communication system. Externally, it connects to the ground satellite communication module and the public network access module, while internally maintaining data communication with the link monitoring and task processing unit. It has an embedded data encryption / decryption unit capable of using an initialization vector of 128 bits and a key length of 256 bits, employing AES encryption / decryption algorithms based on Complex Cipher Feedback (CFB) or Output Feedback (OFB) stream processing modes. It simultaneously receives forward remote control commands from the command encoding module in the link monitoring software via serial and Ethernet ports, selecting specific channel commands to enable based on parameter configuration, command control, and timeout judgment logic. It supports dual network channels with mutual backup between the service network and the core network, operating on different IP segments. Return service data types are identical, with only the service network possessing forward network remote control soft command forwarding capabilities. Furthermore, the service processing module also features multi-task system management, data interface communication, composite service parsing, remote control command forwarding, data caching, and multi-protocol network communication services.

[0075] The bus interface unit is used in the platform's UAV terminal communication system. It interfaces with the airborne satellite communication module to realize satellite communication link data transmission; it interfaces with the network communication module (master node) to realize regional network communication transmission and link maintenance management; and it interfaces with the payload service module to realize local command control and local service data transmission. At the same time, the bus interface unit, based on default parameter configuration and real-time command control, uses virtual network technology to switch channel gateway information and routing address configuration to realize link data packet routing and forwarding. This enables network integration of local service data, network link data, and satellite communication link data, establishing a heterogeneous communication network for cross-link system transmission and providing service platform and communication interface support for the communication system.

[0076] The network communication module is used in the communication system between the platform UAV (master node) and the mission UAV (slave node). It mainly includes a wireless communication unit, a power amplifier unit, and an omnidirectional antenna. The wireless communication module can establish a mobile communication network based on the TD-LTE protocol. The power amplifier unit performs functions such as signal amplification, noise suppression, and signal filtering. The omnidirectional antenna handles signal reception and transmission; to ensure stable and reliable signal transmission, the system adopts a master-slave dual omnidirectional antenna design. Simultaneously, during network link communication, the link system can adjust the forward and backward link bandwidth to a shared rate mode or a specified rate mode according to the service data transmission requirements to meet differentiated transmission needs.

[0077] The payload service module is used in the communication system between the platform UAV and the mission UAV terminal. It mainly interfaces with terminal equipment modules such as flight control unit, mission pod, service payload, link measurement and control, and system management. It has functions such as data interface communication, video acquisition and encoding, protocol splitting and framing, data encryption and decryption, logical data processing, and system control reporting. It can meet the application requirements of communication terminal systems for multi-task collaborative management, link system management, terminal status monitoring, real-time command control, effective service backhaul, scheduling strategy and priority configuration switching, and source encryption and decryption.

[0078] The principle block diagrams of the communication systems of each terminal are as follows: Figures 3.1-3.4 , Figures 4.1-4.5 , Figure 5 As shown.

[0079] A data link communication system for beyond-line-of-sight (BLOS) cluster telemetry and control of unmanned aerial vehicles (UAVs) comprises three types of terminal communication systems: ground command and control stations, platform UAVs, and mission UAVs. In terms of hardware design, it fully considers the adaptability requirements of multiple application scenarios, adopting a freely combinable board design that supports flexible function selection and plug-and-play functionality. The entire terminal communication system adopts a standard VNX hardware architecture design, conforming to the VITA74 bus protocol, and includes various hardware boards such as interface modules, power modules, bus interface units, satellite communication modules, networking communication modules, service payload modules, motherboards, and Ethernet switching modules. Some boards adopt a consistent hardware schematic design. When applied to airborne or ground terminal systems, differentiated functional applications can be achieved through software configuration, thereby effectively reducing production and management costs and improving the performance of rapid equipment replacement and maintenance.

[0080] Considering hardware design costs and management and maintenance, the system uses the same chip selection and the same hardware architecture for multiple boards. The core circuit of the boards includes an FPGA processor, an ARM processor, an intermediate frequency transceiver unit, a wireless communication unit, a power management unit, a clock management unit, and a data interface unit. The FPGA processor is an XC7A200T series, using QSPI serial configuration, with SPI clock-driven fast startup capability, enabling system control and management, logic data processing, and external interface communication. The ARM processor is a Hisilicon Hi35xx series processor, featuring a dual-core ARM architecture, multi-level cache, and Neon acceleration, enabling video capture and encoding, data encryption and decryption, protocol frame data processing, network protocol communication, and routing configuration management. The intermediate frequency (IF) transceiver circuit is mainly used at both ends of the satellite communication link, employing the AD9361 RF chip, which integrates the RF front-end and flexible mixed-signal baseband section, integrates a frequency synthesizer, provides a configurable digital interface, and has multi-channel digital signal transceiver processing capabilities. To increase board-level output power, a gain amplifier is added at the rear end of the IF transceiver circuit. Under ideal conditions, it can achieve a 1dB compression point ≥16.3dBm@900MHz and an output third-order intermodulation ≥34dBm. @900MHz; The network communication circuit is mainly used at both ends of the network communication link. It selects the LC66xx series network communication module with the Datang Telecom 1860 processor as the core, which can realize TD-LTE protocol star network communication, embed AT command set, and has multiple communication interfaces such as HSIC, USB, and UART. It can be configured with master and slave nodes by software to realize "one master and multiple slaves" regional network communication; The power management circuit is mainly responsible for isolating and filtering the input power of the board, and then pushes it to the DC / DC module to convert the 28V input power into the low ripple 12V DC power required for the internal operation of the board, supporting the power supply of the system, and has EMC filtering and surge protection functions; The clock management circuit is mainly responsible for the system clock management within the board. It provides the clock signal required for the normal operation of each module unit through an independent crystal oscillator or clock management chip; The data interface unit circuit adopts a multi-hardware peripheral interface design, which effectively reduces the system design cost while meeting the free configuration and use in different scenarios.

[0081] The forward data transmission process and transmission logic block diagram of the communication system are as follows: Figure 6-1 , 6-2 As shown.

[0082] Ground remote control command channel selection processing logic as follows Figure 7 As shown.

[0083] Remote control commands, as crucial data for UAV systems, must be continuously transmitted throughout the flight to ensure the UAV can be controlled from the ground at any time. If forward remote control commands are interrupted and timeouts occur, UAVs, which are often equipped with automatic return-to-home and automatic take-off and landing procedures for flight safety, will fail, leading to mission failure. To ensure that forward remote control commands from the link monitoring software can effectively enter the link transmission system, the link monitoring and task processing unit embeds a command encoder, employing simultaneous transmission of the same remote control command via both serial and Ethernet ports to achieve dual-channel data backup. The ground control station's service processing module receives remote control commands from both interfaces and can dynamically switch interface enablement based on default system configuration, command control, and timeout judgment logic. The specific processing logic is as follows:

[0084] The business processing module simultaneously monitors remote control data via serial port and network port. The serial port uses the RS422 interface protocol with a baud rate of 230400, and the network port uses the UDP multicast transmission protocol.

[0085] When the remote control channel mode is "manual serial port", the selection logic always keeps the serial port remote control interface enabled, regardless of whether a valid remote control command is received or a reception timeout occurs in the serial port or network port.

[0086] When the remote control channel mode is "manual network port", the selection logic always keeps the network port remote control interface enabled, regardless of whether the serial port or network port data receives a valid remote control command or a reception timeout occurs.

[0087] When the remote control channel mode is "auto-select", the system defaults to high priority for the serial port, with a timeout judgment duration of 200ms interval (40ms remote control interval, 5-frame timeout). It executes the processing logic of "default serial port enable for dual-interface data reception", "automatic timeout jump for single-interface data reception", and "default serial port enable for dual-interface timeout". At the same time, in order to prevent interface back-and-forth jumps due to data transmission jitter or hardware and software failures, which may cause out-of-order or garbled frames of forward remote control commands, the selection logic adds a 2-second silence mechanism after interface switching to ensure that command transmission skips the jitter period.

[0088] The protocol frame data encryption and decryption process is as follows: Figure 8 As shown.

[0089] Wireless signals are easily captured and deciphered, especially satellite communications and public network transmissions, posing a risk of flight data leakage. Adding source encryption before signal encoding and modulation, and transmitting business data in encrypted form, can effectively improve the security of the link communication system. Both the ground command and control station's business processing module and the UAV payload's business module are embedded with data encryption / decryption units to perform encryption / decryption processing of the protocol frame data area. The specific operation process is as follows:

[0090] STEP 1: Before the first use of the embedded encryption / decryption module in the system, the key information library must be injected into the business processing system through the key injector, and it must be ensured that the same key information library is injected at both ends of the link system. The key information library consists of an initialization vector (IV) library and a key library. The length of a single initialization vector (IV) is 128 bits, and the length of a single key library is 256 bits. Each set of initialization vector library or key library stores 1 to 65535 sets of data. The size of the key information library is determined by the actual storage space of the device.

[0091] STEP2: When encrypting data in the protocol frame, the system will obtain two sets of random data through the built-in random number generation unit, and use them as the initial vector required for encryption of the protocol frame and the matching address in the key information database where the key data is located; the system loads the data corresponding to the address, and according to the encryption working mode configured by the system, performs data area encryption processing on the protocol frame by randomly combining the initial vector and key data;

[0092] STEP3: To ensure that the receiving end can perform effective protocol frame synchronization and data area decryption operations, the synchronization word and key area are retained during the protocol frame encryption process, and the initial vector and key data address used for encryption are filled into the key area within the frame and transmitted to the encryption / decryption processing module of the other end along with the encrypted protocol frame.

[0093] STEP4: After wireless link transmission and data interface communication, the peer encryption / decryption processing module receives the key protocol frame transmitted through the link. Based on the key area address information after the frame is picked according to the protocol, the corresponding initial vector and key data are loaded. According to the system configuration decryption working mode (same as the encryption end), the data area of ​​the encrypted protocol frame is decrypted and the key area information is cleared to obtain the plain protocol frame and enter the parsing and transmission stage.

[0094] The schematic diagrams of single-link and dual-link heterogeneous network architectures are as follows: Figure 9 As shown.

[0095] The mission UAV and the platform UAV communicate via a network link, while the platform UAV and the ground command and control station communicate via a satellite communication link. Both of these processes are single-network transmission modes. Through the routing configuration of this link, bidirectional fast data communication can be achieved.

[0096] The mission-deployed UAV and the ground command and control station employ a combined network link and satellite communication link transmission mode to achieve bidirectional data communication. Considering factors such as transmission timeliness, dynamic adjustment, and mobility changes, the system adopts a network configuration and routing fusion approach to establish a heterogeneous communication network between the two links, enabling rapid transmission and forwarding of network data between the two levels of links and reducing intermediate processing overhead.

[0097] The heterogeneous network communication process between the mission UAV and the ground command and control station is as follows, taking the return transmission as an example: First, the platform UAV's network communication module (master node) is configured with a default gateway. Through node scanning and terminal network access, a regional network link transmission channel is established between the mission UAV and the platform UAV. The platform UAV's satellite communication module applies for a satellite communication gateway to obtain satellite path routing information and address translation services from the gateway station, establishing a satellite communication network between the platform UAV and the ground command and control station. Second, the mission UAV initiates the return transmission. The business data is encapsulated using the network protocol stack. According to the network routing plan and interface communication configuration, the network data packet is transmitted through the network link and enters the platform UAV's bus interface unit. Third, the platform UAV's bus interface unit pushes the data packet to the airborne satellite communication module based on the satellite communication gateway and routing address information for forwarding to satellite. Finally, the ground command and control station obtains the return network data packet through a "single-hop" or "double-hop" satellite communication transmission link. After the business processing module performs protocol stack parsing and processing, the original business data is obtained, completing the return data transmission. Forward data transmission is the reverse process of backward data transmission. The only difference is that the satellite path addressing of the platform's UAV bus interface unit is changed to network routing addressing, while the rest of the processing remains the same.

[0098] In communication between single-link and dual-link heterogeneous networks, the application layer adopts the Real-Time Publish Subscribe Protocol (RTPS) to improve the system's performance in terms of fault tolerance, scalability, dynamic management, and module design. The transport layer uses TCP acceleration and the standard UDP protocol to enhance the system's concurrent connection capabilities, reduce transmission latency, and improve bandwidth utilization. The network layer uses the IP protocol with compressed packet headers to improve transmission efficiency and meet the network's dynamic addressing and routing forwarding functions.

[0099] The communication system's return service data transmission process and transmission logic block diagram are as follows: Figure 10-1 , 10-2 As shown.

[0100] The logic block diagram of the payload service module for video acquisition, encoding, transmission, and processing is as follows: Figure 11 As shown.

[0101] The link communication system is mainly used for beyond-line-of-sight (BLOS) swarm telemetry and control of UAVs to achieve real-time coverage of target areas and multi-UAV collaborative operations. Video encoding is one of the main processing tasks in UAV system applications. Under limited link bandwidth, efficient video encoding and transmission technology can effectively improve task execution efficiency and collaborative operation quality. Therefore, the payload service module in the system solution adopts the H.265 compression algorithm with variable encoding units. Compared with the fixed macroblock size of H.264, it is better suited to changes in mobile scenarios, using scene information to drive dynamic encoding, effectively reducing the encoding rate while efficiently restoring image quality. However, the actual operation scenario is uncertain, and a single video compression encoding method is prone to the "instantaneous rate overshoot" problem of encoded I-frames when encountering highly complex and dynamic image scenarios, resulting in buffer overflow or latency accumulation, and image display distortion or stuttering. To solve this problem, the system uses the P-frame intra-frame refresh I-slice method to re-encode high-bitrate I-frames into low-bitrate P-frames. While ensuring image quality, this effectively reduces the size difference between encoded I-frames and encoded P-frames, improving transmission smoothness. Meanwhile, the system adopts a ring queue storage and uniform bitrate transmission mechanism, matching the ring storage size with the interface buffer capacity and the video encoding gap, and achieving uniform bitrate transmission with high-priority real-time scheduling. This effectively solves the problem of instantaneous rate surges, avoids interface buffer overflow, and ensures a low bitrate, high image quality, and high smoothness video transmission process.

[0102] General frame protocol for forward and backward service data transmission, such as Figure 12 As shown.

[0103] In terms of return traffic transmission, the communication system needs to transmit low-speed services such as flight data, mission feedback, payload reports, link telemetry and system status, as well as high-speed services such as video streams, job data and payload synchronization. The length of a single packet of low-speed service data varies due to differences in type.

[0104] To ensure timely transmission and smooth data flow, and to prevent large-scale jitter in inter-frame time slots, the system first groups low-speed services into unified telemetry data frames. Each frame consists of 32 bytes, including a synchronization word, aircraft number, equipment code, telemetry identification code, valid data area, frame count, and checksum. The data area is filled with the actual low-speed service data, and its length is determined by the data type. Insufficient areas are padded with zeros. Each telemetry frame transmits only one type of data. Second, the system pushes telemetry frames into the interface buffer FIFO according to the telemetry data transmission priority. High-speed service data is synchronously entered into the corresponding buffer FIFO, waiting to be combined into composite data frames. Next, based on data type, transmission rate, priority, buffer status, and waiting time, a composite data frame containing low-speed telemetry and high-speed services is constructed. Each frame contains 1024 bytes, including a synchronization word, key area, aircraft number, device number, telemetry frame information (number of frames), payload type, payload data length, frame count, checksum, and data area. The data area contains telemetry data packets, single-type payload data, and zero padding. Finally, the composite service frame containing high-speed and low-speed data undergoes data area encryption and encrypted state information update before entering the network protocol stack routing and forwarding stage to complete the return transmission process.

[0105] In terms of forward service transmission, the communication system also needs to handle multiple types of remote control data frames. To facilitate data transmission and logical processing, the remote control data frames adopt a unified framing transmission protocol. Each frame consists of 256 bytes, including a synchronization word, key area, link identification code, aircraft number, equipment number, remote control identification code, remote control data length, frame count, checksum, and valid data area. The data area is padded differently according to the various remote control data lengths, with zeros used to fill the remaining space to ensure that the protocol length of each frame is the same. After completing logical channel selection and data encryption processing, the forward remote control data frame enters the network protocol stack routing and forwarding stage to complete the forward transmission process.

[0106] The logic for parsing and forwarding composite business data in the ground command and control station's business processing module is as follows:

[0107] After transmission through the link system, network data packets containing return composite services are transmitted to the ground command and control station's service processing module. Only the network protocol stack within the module performs parsing and data decryption to restore the return composite service data frame, which then enters the protocol frame parsing and forwarding stage.

[0108] During the business data parsing and forwarding process, the system adopts a data forwarding method with mutual backup between the business network and the core network. The protocol parsing and forwarding processing logic is the same in each network, with only differences in the network access address range. The specific parsing and transmission processing process is as follows:

[0109] STEP1: The plaintext composite service data frame is transmitted to the composite data parsing and forwarding unit of the service network and core network via internal interface communication, and the protocol is executed to synchronize frame picking;

[0110] STEP 2: To preserve the original business data for monitoring, a TCP network protocol server is set up for frame forwarding logic to transmit the unparsed and unprocessed original composite data to the link monitoring and task processing unit. The specific process is as follows: A composite data TCP protocol server is created to listen for external access connection requests; when a TCP client initiates an access connection request, a TCP network communication connection is established with it, and a linked list mechanism is used to dynamically manage the connection terminal Socket; after the composite data synchronization frame picking ends, the process moves to the original composite data forwarding stage, where the linked list information of the managed connection terminal Socket is checked. If a valid connection exists, the forwarding process is executed; if the connection has expired or there is no valid connection, the linked list information is updated, and the forwarding stage is skipped.

[0111] STEP3: Perform frame count detection on composite protocol frames and mark whether the frame count is continuous or discontinuous; perform checksum calculation on the frame header information area to confirm the accuracy of the data transmitted in the link. Composite frames that fail the checksum are discarded directly; otherwise, continue the protocol frame data parsing process.

[0112] STEP4: Based on the "telemetry frame information" identifier in the composite service frame, obtain the number of telemetry frames transmitted in the current composite frame. At the start address of the telemetry data in the composite frame protocol, extract and forward the telemetry data packet by packet. The telemetry data transmission adopts the UDP multicast protocol to facilitate simultaneous reception and processing by backend multi-link monitoring devices. If the identifier information is 0x00, it means that the current composite frame does not carry return telemetry data.

[0113] STEP 5: Based on the "payload type" and "payload data length" information in the composite service frame, confirm the specific type of payload data being transmitted in the current composite frame. If it is synchronous data, then according to the transmission protocol agreement, use the same TCP service protocol as the original composite data transmission method to execute access monitoring, linked list management, and data transmission logic. STEP 6: If the "payload type" is marked as video data, then the frame de-forwarding logic checks whether the RTSP creation identifier is valid. If valid, dynamically create the video RTSP service and monitor the service operation status through the signal monitoring mechanism. If invalid, it means that the RTSP service has already been created, and directly enter the video forwarding stage. The frame de-forwarding logic and the video RTSP service use a FIFO mechanism to achieve video data transmission. Before the video data is written to the interface FIFO, the cache monitoring logic checks the FIFO cache status. If the cached data has not reached the warning depth, the video data is written directly. If the cached data reaches the warning depth and multiple consecutive checks are valid, the system confirms that the RTSP service is abnormal and performs a service termination operation. At this time, the signal monitoring mechanism captures the RTSP service exit status and updates the RTSP creation identifier, and the system enters the next service creation and transmission process.

[0114] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0115] In the several embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of units described above is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The aforementioned units may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A data link communication system for beyond-line-of-sight cluster telemetry and control of unmanned aerial vehicles (UAVs), characterized in that: This includes ground command and control stations, platform drone terminals, and mission drone terminals; The ground command and control station and the platform drone communicate via a satellite communication link. The platform's drone terminal and the mission drone terminal communicate via a network communication link; The mission drone and the ground command and control station communicate via satellite communication links and network communication links. The ground command and control station includes a satellite communication module, a public network access module, and a service processing module; The platform's UAV terminal includes an airborne satellite communication module, a bus interface unit, a master node networking communication module, and a payload service module; The mission drone terminal includes a node networking communication module and a payload service module; in: The remote control data undergoes channel selection and protocol encryption in the service processing module, and is then forwarded to the satellite via a single-hop or double-hop satellite communication link. During forward communication in a communication system: The platform's UAV receives forward remote control data from satellite communication, which is then processed and routed through the bus interface unit protocol frame synchronization and forwarding, and transmitted to the local payload service module, or transmitted to the mission UAV payload service module via the network link. Each platform's payload service module synchronizes, decrypts, and parses remote control commands to complete the control response to the corresponding terminal commands; The ground control station's service processing module receives the same remote control command from the link monitoring software simultaneously via serial port and network port / service network. Based on the interface mode, default configuration, and timeout judgment logic, it confirms the effective channel of the remote control command. The ground command and control station's business processing module has an embedded encryption and decryption unit that encrypts the input remote control commands into protocol frame data and converts them into encrypted remote control data frames. The ground command and control station's business processing module sends remote control data frames into the network protocol stack, converting them into network data packets containing remote control data. Based on the routing configuration and default gateway information, the ground control station's service processing module selects a dual-hop mode: network remote control data packets are sent to satellite via the local satellite communication module or a single-hop mode is selected; or the data packets are sent to satellite via the gateway station's satellite communication unit through a VPN service channel accessed via the public network.

2. The UAV data link communication system for beyond-line-of-sight cluster telemetry and control according to claim 1, characterized in that, In forward communication: The network layer remote control data packets are routed and forwarded via the satellite communication link, received by the platform's UAV satellite communication module, and then transferred to the platform's UAV bus interface unit. The platform UAV bus interface unit determines the execution routing information based on the target address of the network layer remote control data packet: if the target address is the platform UAV, the data packet is forwarded to the local payload service module; if the target address is the mission UAV, the data packet is pushed to the network communication module, and after routing and forwarding by the network module, it is finally transmitted to the mission UAV payload service module. The payload service modules of mission-oriented UAVs and platform UAVs perform protocol stack parsing on network layer remote control data packets to reconstruct encrypted remote control data frames. Perform protocol decryption and frame deframe operations to obtain the original remote control commands; The remote control command is parsed to confirm the final responding device terminal and command parameters, thus completing the command control.

3. The UAV data link communication system for beyond-line-of-sight cluster telemetry and control according to claim 1, characterized in that, Including the return communication method: The mission UAV and platform UAV payload service modules initiate business data collection, perform data encoding, protocol framing and encrypted transmission processes, and encapsulate the data into network data packets through the network protocol stack. The mission-return composite data from the UAV is transmitted to the platform's UAV bus interface unit via a network link; The platform's UAV return composite data is transmitted to the local bus interface unit via the internal communication interface; The composite data frames of the mission UAV and the platform UAV are queued and routed for forwarding, and then sent to the satellite by the satellite communication module of the platform UAV. Ground control stations transmit satellite communication data via single-hop or double-hop methods to obtain return composite service data, perform protocol data decryption and parsing, and complete status information monitoring and service data processing.

4. The UAV data link communication system for beyond-line-of-sight cluster telemetry and control according to claim 3, characterized in that, In return communication: The payload service modules of mission UAVs and platform UAVs detect and capture raw video data through the video input interface, perform image processing and video compression encoding, transmit the encoded video stream through the buffer code, and push the encoded video stream into the corresponding buffer channel before composite data framing. The payload service modules of mission UAVs and platform UAVs acquire various types of aircraft data, such as flight path attitude, payload information, telemetry data and system status, through internal and external data interfaces, and push them into the corresponding cache channel before composite data framing. The payload service modules of mission drones and platform drones queue and frame multiple sets of cached service data according to data type, transmission rate, priority, caching status and waiting time variables, and perform data encryption processing on composite data frames. The payload service modules of mission-oriented UAVs and platform UAVs send dense composite data frames into the network protocol stack, which converts them into network data packets containing composite data. The mission UAV composite data packet is transmitted to the platform UAV bus interface unit through the network link, and the platform UAV composite data packet is transmitted to the local bus interface unit through the internal data interface. The platform's UAV bus interface unit queues composite data frames and transmits them to the local satellite communication module for uploading, based on the routing configuration and default gateway information. Network layer composite data is routed and forwarded via satellite communication link, received by the ground command and control station's satellite communication module or public network access module based on gateway station VPN service, and then transferred to the ground command and control station's business processing module. The ground command and control station's service processing module performs protocol stack parsing on network layer composite data packets to obtain composite service frames. After processing by the embedded encryption / decryption unit, the composite service frame data is decrypted; the plaintext composite service frame is then pushed into the service network and core network for parsing and forwarding processes.

5. A UAV data link communication system for beyond-line-of-sight cluster telemetry and control according to any one of claims 3 or 4, characterized in that: The ground command and control station's business processing module adopts a dual-network mutual backup mode to forward business data. According to the interface protocol, it forwards the original and parsed business data to the backend link monitoring and task processing unit to complete status monitoring and business data processing.

6. The UAV data link communication system for beyond-line-of-sight cluster telemetry and control according to claim 5, characterized in that: The TCP protocol is used to complete the data transmission for both raw composite and multi-channel synchronous data. For telemetry data, UDP multicast protocol is used to complete data forwarding; For video image data, the data is pushed through the RTSP transmission protocol.

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