Cross-domain air-water communication method and system based on unmanned surface vehicle

Abstract

The application provides a cross-domain air-water communication method and system based on an unmanned surface vehicle, comprising the following steps: taking the unmanned surface vehicle as a cross-domain relay, establishing an underwater acoustic link between the bottom of the vehicle and an underwater vehicle through an angle-adjustable underwater acoustic transducer; configuring the unmanned vehicle with a self-organizing network and a satellite dual-backup water communication link; constructing a dynamic routing algorithm by fusing a sea state index and a node distance weighted cost, and adaptively optimizing a transmission path; and designing an enhanced reliable transmission protocol based on UDP, supporting data fragmentation caching, selective retransmission and breakpoint resuming. According to the application, the cross-domain data interaction between air and water can be completed without the underwater vehicle surfacing, the exposure risk is avoided, and the energy consumption is reduced; the double-link ensures uninterrupted communication in the open sea, the dynamic routing and the reliable protocol are adapted to the complex marine environment, an air-sea-underwater integrated collaborative communication network can be built, and the application is suitable for marine exploration and underwater covert operation scenes.

Description

Technical Field

[0001] This invention relates to the field of cross-domain communication technology, specifically to a cross-domain air-water communication method and system based on unmanned surface vessels, applicable to communication scenarios between the air and underwater. Background Technology

[0002] With the increasing demands for marine resource development, environmental monitoring, and underwater mission execution, mobile platforms such as underwater vehicles (UVs) need to frequently exchange information with shore-based command centers and drones above the sea. Currently, information exchange between surface and underwater platforms mainly relies on UVs surfacing to transmit data. To transmit information collected by various underwater sensors back to shore, the UVs need to repeatedly surface to transmit data and report information. This method has two major drawbacks: first, the repeated surfacing and diving of the UVs consumes a lot of energy, significantly shortening its endurance; second, the surfacing process easily exposes the UV's location, failing to meet the requirements of stealth missions.

[0003] To address this issue, studies have explored various methods for cross-domain information transmission between underwater and surface platforms, including underwater repeaters, wired fiber optic cables, and laser wave communication. Underwater repeaters, which deploy numerous fixed communication relays in specific waterways to ensure communication between the surface and underwater, are inherently unsuitable for unmanned underwater platforms. Since underwater vehicles often need to move underwater to perform missions, static relays cannot guarantee real-time information transmission. Laying wired fiber optic cables underwater is costly and only suitable for localized areas, making it difficult to cover large areas of the open ocean. Laser wave communication meets the mobility requirements of underwater platforms, but because light waves require precise alignment for effective data transmission, they are easily blocked, and the communication distance is shortened in turbid water.

[0004] Therefore, how to build a cross-domain air-sea communication system that is compatible with underwater mobile platforms, takes into account both stealth and reliability, and can adapt to complex marine environments is a key issue that urgently needs to be addressed in the field of marine communication.

[0005] Patent document CN113037395B discloses a method for collaborative operation of cross-domain unmanned equipment on and under water. By building a collaborative operation system for cross-domain unmanned equipment on and under water, including unmanned surface vessels (USVs), unmanned underwater vehicles (UUVs), unmanned aerial vehicles (UAVs), and command and control stations, and by connecting the UUV sub-network with the surface USV and UAV sub-network, the interoperability of underwater acoustic communication and surface radio communication is realized. This enables the cross-domain unmanned equipment to form a collaborative network, which can realize the collaborative operation of multiple cross-domain heterogeneous unmanned equipment systems such as USVs, UAVs, and UUVs. It overcomes the differences in the mobility of cross-domain platforms, and enables cross-domain unmanned systems to collaboratively execute tasks according to given mission requirements, under the condition of real-time interaction with the ground command and control center.

[0006] However, this patent document uses a fixed-function unmanned surface vessel master node as the core to establish communication between surface and underwater sub-networks and solve the basic problem of dispersed operation and lack of coordination of cross-domain equipment. It does not consider the stealth of the submersible and only achieves cross-domain coordination. The submersible may still need to surface or rely on fixed relays. Furthermore, since the patent document uses a fixed-function unmanned surface vessel master node as the core, the route is fixed and cannot adapt to changes in the marine environment.

[0007] Therefore, there is an urgent need in the market for a communication method applicable to both air and underwater, so that submersibles can transmit information without having to surface. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the purpose of this invention is to provide a cross-domain air-water communication method and system based on unmanned surface vessels, so as to overcome the shortcomings of the prior art that underwater vehicles need to surface to transmit data and the poor adaptability of existing cross-domain communication schemes.

[0009] A cross-domain air-water communication method based on an unmanned surface vessel, provided by the present invention, includes: Step S1: Deploy at least one unmanned surface vessel as a cross-domain communication relay node, and mount a dynamically adjustable underwater acoustic transducer on the bottom of the unmanned surface vessel. Step S2: Construct a unified unmanned surface vessel communication system inside the unmanned surface vessel for heterogeneous communication protocol parsing and data forwarding; the unmanned surface vessel communication system includes a main communication control module, an underwater acoustic communication module, an ad hoc network communication module, and a satellite communication module; Step S3: Based on one or more unmanned surface vessels that have been configured, construct a marine cross-domain communication system; the marine cross-domain communication system uses multiple unmanned surface vessels that support cross-domain air-water communication as key routing nodes in the network composition, and the unmanned vessels form a sea surface network system through self-organizing networks to open up cross-domain communication links on the water and underwater. Step S4: Employ a dynamic routing algorithm for the marine environment, combine sea state perception information and inter-node link distance information to calculate the comprehensive link cost, select the transmission path with the lowest total cost, and use an enhanced UDP communication protocol to complete reliable data transmission.

[0010] Preferably, the specific method for dynamically adjusting the orientation of the underwater acoustic transducer in step S1 is as follows: The main communication control module combines the detection results from the underwater acoustic communication module with the real-time underwater acoustic communication quality to calculate the optimal beam pointing angle and drive the two-dimensional / three-dimensional adjustment mechanism to adjust the transducer attitude and avoid acoustic transmission obstruction.

[0011] Preferably, the cross-domain communication link in step S3 includes: Underwater users communicate with unmanned surface vessels via underwater acoustic links. The unmanned surface vessels use a dual-link strategy, with self-organizing networks as the primary method and satellite communication as a backup, to transmit data back to the shore and issue commands.

[0012] Preferably, the automatic switching between dual links is as follows: when the self-organizing network link is normal, the high-speed transmission of the self-organizing network is used first; When the self-organizing network exceeds its coverage area or is interrupted by electromagnetic interference, the main communication control module seamlessly switches to the satellite communication link to complete data transmission.

[0013] Preferably, the formula for calculating the link integration cost in step S4 is:

[0014] in, From this node To the next hop node The overall cost of the link, It is a node Reported or by nodes A quantitative sea state index inferred from historical information. It is a node and Estimated distance or distance-related link quality metric between them and These are preset weighting coefficients.

[0015] Preferably, the transmission mechanism of the enhanced UDP communication protocol includes data fragment persistent caching, selective acknowledgment retransmission, timeout exponential backoff retransmission, and communication interruption breakpoint resumption.

[0016] According to the present invention, a cross-domain air-water communication system based on an unmanned surface vessel is provided for executing the communication method, comprising: a plurality of underwater users, at least one unmanned surface vessel, a sea surface / air platform, a shore-based information processing system, and a communication satellite; The underwater user is equipped with underwater acoustic communication equipment; The unmanned surface vessel serves as the core relay node, and is equipped with a built-in main communication control module, underwater acoustic communication module, surface communication components, and motion sensing devices. The waterborne communication component includes a self-organizing network communication module and a satellite communication module; The main communication control module is connected to the underwater acoustic communication module, the waterborne communication component, and the motion sensing device, respectively, to realize cross-domain data relay, dynamic route calculation, and reliable protocol scheduling.

[0017] Preferably, the underwater acoustic communication module is equipped with an electrically controlled two-dimensional / three-dimensional angle adjustment mechanism, which is controlled by the main communication control module and is used to adjust the beam direction of the underwater acoustic transducer on the bottom of the boat in real time.

[0018] Preferably, the self-organizing network communication module is used for short-range high-speed wireless networking between boats, between boat engines, and between boats and shore. The satellite communication module serves as a long-distance emergency backup link, and the two together constitute a primary and backup dual-redundant maritime communication link.

[0019] Preferably, the communication main control module has a built-in software program that integrates a marine environment dynamic routing algorithm stack and an enhanced UDP reliable transmission protocol stack to achieve path optimization, data fragmentation caching, selective retransmission, and breakpoint resumption.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses an unmanned surface vessel as a cross-domain communication relay, allowing underwater vehicles to complete data transmission without surfacing, completely avoiding the risk of location exposure, while also saving energy consumption for surfacing and diving, thus extending the endurance of the underwater vehicle. 2. The unmanned surface vessel of this invention adopts a self-organizing network and satellite dual backup links with the shore base to ensure uninterrupted communication in the open sea and complex electromagnetic environments; the underwater acoustic communication equipment has an adjustable angle design to adapt to the movement trajectory of underwater users and ensure the stability of the communication link.

[0021] 3. The dynamic routing mechanism of this invention combines sea conditions and node distance decisions to avoid link interruptions caused by sea conditions; the efficient communication protocol reduces data packet loss and retransmission overhead through selective retransmission, thereby improving data transmission efficiency under complex sea conditions.

[0022] 4. This invention constructs a cross-domain communication system that integrates UAV reconnaissance, underwater detection, and shore-based control capabilities, thereby enhancing the coordination and intelligence of marine mission execution. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the marine cross-domain communication network architecture of the present invention; Figure 2 This is a schematic diagram of the dynamic routing algorithm suitable for marine environments according to the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0025] This invention designs an air-water cross-domain communication scheme based on unmanned surface vessels; constructs a marine cross-domain communication system from above sea level to below sea level; and establishes a dynamic routing mechanism and efficient communication protocol suitable for marine communication.

[0026] Example 1 According to the present invention, a cross-domain air-water communication method based on an unmanned surface vessel is provided, such as... Figure 1 As shown, it includes: Step S1: Configure at least one unmanned surface vessel (USV) as a relay node for cross-domain communication. In one embodiment of the invention, the USV is specially designed in terms of physical structure, with its hull divided into an instrument compartment, an equipment compartment, and an engine compartment. Core communication equipment is installed in the equipment compartment, specifically including a main communication control module, an underwater acoustic communication module, an ad hoc network communication module, and a satellite communication module. To ensure effective signal transmission and reception, an antenna mounting platform is installed on the USV's deck mast. This platform integrates the antennas for the ad hoc network communication module, the satellite communication antenna for the satellite communication module, and a BeiDou positioning antenna for positioning. These antennas are electrically connected to the corresponding modules in the equipment compartment via specialized waterproof connectors.

[0027] It should be noted that the transducer portion of the underwater acoustic communication module, used for communication with underwater users, is mounted on the bottom of the unmanned surface vessel (USV). In this embodiment, the underwater acoustic communication module adopts an embedded semi-fixed design. This design not only ensures the structural stability and hydrodynamic performance of the transducer during navigation, but more importantly, it allows for dynamic adjustment of the transducer's orientation. For example, the module can integrate sonar detection functionality or be linked with an independent obstacle avoidance sonar on the vessel. When an obstacle is detected in the acoustic path between the USV and the target underwater user, or when the communication signal quality deteriorates due to multipath effects, the main communication control module can calculate the optimal obstacle avoidance or beam pointing angle based on sonar data or real-time communication quality feedback, and drive a two-dimensional or three-dimensional adjustment mechanism (not shown) to precisely adjust the transducer orientation of the underwater acoustic communication module. In this way, signal obstruction can be actively avoided, the communication link optimized, and the stability and reliability of underwater communication ensured.

[0028] Step S2: Construct a unified unmanned surface vessel (USV) communication system inside the USV. This system includes a main communication control module, an underwater acoustic communication module, an ad hoc network communication module, and a satellite communication module. The main communication control module is the core of this system. This module can be a high-performance industrial-grade embedded computer running specialized control and routing software. It connects and communicates with the underwater acoustic communication module, ad hoc network communication module, and satellite communication module through standardized physical interfaces (e.g., Ethernet network interface, RS-232 / RS-485 serial port, etc.). The core responsibility of the main communication control module is to establish seamless links between the various heterogeneous communication modules, enabling seamless data routing and forwarding. When a data packet is received from any communication module (e.g., the underwater acoustic communication module), the main communication control module parses its data format and protocol, and based on the destination address and current routing strategy, encapsulates it into a format and protocol suitable for another communication module (e.g., the ad hoc network communication module) before forwarding it. In other words, this module can, for example, convert data carried by underwater acoustic modulation and demodulation protocols into radio signal data based on Internet protocols, and vice versa, thereby realizing the parsing and conversion of heterogeneous communication protocols and the unified scheduling and forwarding of cross-link data. The satellite communication module is mainly used for transmitting instructions from shore-based command centers and data feedback in emergency situations. The ad hoc network communication module is used for communication between boats, between boats and engines, and between boats and shore, as well as other platforms above the sea surface. The underwater acoustic communication module is responsible for issuing instructions and transmitting information back to underwater users. Step S3: Based on one or more configured unmanned surface vessels (USVs), construct a marine cross-domain communication system. This system includes underwater users, USVs, low-altitude unmanned aerial vehicles (UAVs), shore-based information processing systems, and satellites. The system uses multiple USVs supporting cross-domain air-sea communication as key routing nodes. The USVs form a self-organizing network on the sea surface, establishing cross-domain communication links between the surface and underwater domains. The communication link establishment process is as follows: Establishment of underwater communication links: Underwater users (such as an underwater vehicle performing a reconnaissance mission) establish point-to-point underwater acoustic communication links with the nearest or strongest-signal unmanned surface vessel (USV) via their onboard underwater acoustic communication equipment. Data collected by the underwater user (such as sonar images and hydrological data) can then be transmitted to the USV through this link. As an optional implementation, multiple underwater users can also form an underwater local network through underwater acoustic communication. Information undergoes multiple hops underwater relay, eventually converging at the underwater user closest to the USV, where it is then uploaded.

[0029] Establishment of the maritime communication link: After receiving data from underwater users, the unmanned surface vessel (USV) is processed and forwarded by the main communication control module. In this embodiment, a reliable communication strategy with a primary and backup dual-link architecture is adopted. The primary link is an ad hoc network communication link established through an ad hoc network communication module. This module can form a mobile ad hoc network with other USVs, low-altitude UAVs, or near-shore base stations. This type of network has the advantages of being decentralized, self-healing, and having high bandwidth, making it suitable for high-speed data exchange between surface platforms within a certain area. When the USV is within the coverage area of ​​a near-shore or low-altitude UAV, data will be preferentially sent to the near-shore base station via the primary link, and then delivered to the remote shore-based command center via the land network. The backup link is a satellite communication link established through a satellite communication module. When the USV sails to the open sea and exceeds the ad hoc network communication range, or when the ad hoc network link is interrupted due to strong electromagnetic interference, the main communication control module will automatically detect the link failure and seamlessly switch the communication task to the satellite communication module. At this time, the data will be directly sent to the remote shore-based command center via satellite. This combination of primary and backup methods ensures that the unmanned surface vessel can maintain a reliable communication connection with the shore base regardless of its location.

[0030] Correspondingly, the command transmission link is the reverse of the above process. Commands from the remote shore-based command center can be sent to unmanned surface vessels via near-shore base stations and ad hoc networks, or directly via satellite. After receiving the command, the main communication control module selects the appropriate link for forwarding based on the target of the command. For example, it may send collaborative operation commands to low-altitude UAVs via the ad hoc network communication module, or issue new mission commands to underwater users via the underwater acoustic communication module.

[0031] It is understandable that the complex and ever-changing marine environment has a significant impact on wireless communication. Therefore, this invention proposes a dynamic routing algorithm for the marine environment to optimize data transmission paths in ad hoc maritime networks. Specifically, a dynamic routing algorithm based on a dynamic source routing protocol is employed, combining a minimum hop count routing mechanism and a sea state distance adaptive mechanism to make comprehensive routing decisions and optimize data transmission paths. It should be noted that this algorithm is activated when any node in the network (e.g., an unmanned surface vessel) needs to send data or receives a routing request. Figure 2 As shown, the marine environment dynamic routing algorithm includes: Step S4.1: The node first collects two types of key information. The first type is the local sea state information perceived by the node, i.e., sensing information, which is obtained by reading real-time data from the motion sensing equipment on board the vessel, such as the vessel's pitch, roll, heave, and other motion attitude parameters. Severe rolling and heave usually indicate severe sea conditions. The second type is the link quality information with neighboring nodes, i.e., distance information, which can be estimated through physical layer signal parameters. For example, by measuring the received signal strength of radio signals from other nodes and combining it with a known path loss model, the approximate distance between nodes can be estimated. The stronger the signal, the closer the distance and the more stable the link.

[0032] Step S4.2: The main communication control module processes the acquired sensing and distance information. By analyzing the amplitude and frequency of the motion sensing data, it quantifies and rates the sea state at the current node's location. For example, a sea state index can be set from level 1 (calm seas) to level 5 (very rough seas). Simultaneously, the received signal strength indication is converted into a measure of distance or link quality.

[0033] Step S4.3: Combine the sea state information and distance information to calculate the comprehensive cost of each possible link. This comprehensive cost is a weighted sum, and its calculation formula can be defined as:

[0034] in, From this node To the next hop node The overall cost of the link; It is a node Reported or by nodes Quantitative sea state index inferred from historical information; It is a node and Estimated distance or distance-related link quality metric between them; and These are preset weighting coefficients that can be adjusted according to task requirements. For example, in tasks that prioritize stability, the weight of sea state can be increased. This step calculates the total link cost for all reachable neighbor nodes.

[0035] Step S4.4: In a complete route discovery process (e.g., a route request broadcast and response process based on a dynamic source routing protocol), the combined cost of all links on a path is accumulated to obtain the total cost of multiple candidate paths from the source to the destination. Finally, the path with the minimum total combined cost is selected as the current optimal route.

[0036] Step S4.5: Based on the result of path selection step S4.4, the node forwards the data packet along the next hop of the optimal path, or, during route discovery, sends a route reply packet containing the optimal path information back to the source node. In this way, data flows can intelligently avoid areas with rough seas and unstable communication, thereby significantly improving the success rate of data transmission and the overall robustness of the network.

[0037] Furthermore, considering the inherent instability and susceptibility to interruption of marine communication links (especially underwater acoustic and satellite links), this invention also provides a highly efficient and robust communication protocol to ensure the integrity and efficiency of data transmission. This protocol is a deep enhancement based on connectionless transmission methods (such as User Datagram Protocol), employing a connectionless UDP communication protocol and utilizing transmission-retransmission mechanisms including flow buffering, timeout retransmission, acknowledgment, selective retransmission, and breakpoint resumption. A detailed description of each mechanism is as follows: Traffic Buffering and Persistence: Before sending data, the sender segments the data to be sent (especially large files) into smaller data blocks with unique sequence numbers. After transmission, these data blocks enter a traffic buffer pool located at the sender (e.g., the communication main control module 24 of the unmanned surface vessel 20). Considering the extremely low bandwidth of underwater acoustic communication, data may need to remain in the buffer for a long time. Therefore, this buffer pool is designed for persistent storage, meaning the data is written to non-volatile storage media (such as solid-state drives) to prevent the loss of sent but unacknowledged data due to unexpected device restarts or program crashes. Selective retransmission: After receiving a data packet, the receiving end checks its sequence number. If the expected packet is received and subsequent consecutive packets exist in the buffer, it processes them together and sends an ACK acknowledgment, indicating the sequence number of the next expected packet. If the received packet's sequence number is ahead of the expected value, it indicates packet loss. The receiving end stores the lost packet in its receive buffer and sends a SACK acknowledgment. This SACK contains the sequence numbers of all out-of-order packets that have been correctly received. Upon receiving this message, the sending end does not need to retransmit the entire window of data; it only needs to accurately retransmit the indicated lost packets, thus greatly reducing unnecessary retransmission overhead. Timeout Retransmission and Exponential Backoff: The sender starts a timer for each data packet it sends. If no acknowledgment message is received within the specified time, the packet is considered lost, and a timeout retransmission is triggered. To avoid cascading network congestion caused by frequent retransmissions during periods of persistently poor network conditions, the retransmission mechanism employs an exponential backoff algorithm. That is, if a timeout retransmission fails, the waiting time for the next retransmission will double, and so on, thus giving the network time to recover.

[0038] Resume Transmission: To handle prolonged communication interruptions, the protocol also includes a resume transmission mechanism. The sender saves its current transmission status, including the sequence numbers of sent and acknowledged packets, the state of the sliding window, and the contents of the traffic buffer pool, to a file in real time or periodically. When the communication link (e.g., a satellite link interrupted for several minutes due to obstruction) is restored, the sender program can read this status file, restore to the state before the interruption, and continue sending data from the last successfully acknowledged position without starting from scratch. This is crucial for transmitting large files in marine environments, significantly improving transmission efficiency and user experience.

[0039] This invention, based on the system network, considers a flexible dynamic routing mechanism and a stable communication link protocol. It employs a dynamic routing algorithm more suitable for the marine environment, combining a minimum hop count routing mechanism and a sea state distance adaptive mechanism with a traditional dynamic source routing protocol to make comprehensive routing decisions, optimizing data transmission paths and improving data transmission stability. Addressing the issues of instability and frequent disconnections in marine environments and satellite communications, it designs an efficient and robust communication link protocol to enhance communication performance in marine environments.

[0040] Example 2 The present invention also provides a cross-domain air-water communication system based on unmanned surface vessels. The cross-domain air-water communication system based on unmanned surface vessels can be implemented by executing the process steps of the cross-domain air-water communication method based on unmanned surface vessels. That is, those skilled in the art can understand the cross-domain air-water communication method based on unmanned surface vessels as a preferred embodiment of the cross-domain air-water communication system based on unmanned surface vessels.

[0041] A cross-domain air-water communication system based on an unmanned surface vessel, provided by the present invention, includes: One or more underwater users. Underwater users, acting as sources of underwater information and executors of tasks, can be autonomous underwater vehicles, tethered remotely operated underwater vehicles, underwater gliders, or fixed sensor arrays deployed on the seabed. Each underwater user is equipped with an underwater acoustic communication module for transmitting and receiving acoustic signals underwater.

[0042] At least one unmanned surface vessel (USV) serves as a core relay node. The USV acts as a bridge between the underwater and surface worlds, integrating a highly integrated communication and control system, specifically including: The main communication control module. This module, as the core control unit of the unmanned surface vessel communication system, typically consists of a ruggedized embedded computer or server with powerful computing capabilities and multiple communication interfaces. It runs the core software designed in this embodiment of the invention, including a gateway program for forwarding data between different links, the dynamic routing algorithm for the marine environment described in Embodiment 1, and an efficient and robust communication protocol stack. Underwater acoustic communication module. This module is responsible for two-way communication with underwater users and includes an underwater acoustic modem and a matching transducer. The transducer is mounted under the hull and can convert electrical signals into sound waves for transmission, or convert received sound waves back into electrical signals. As a preferred embodiment, the transducer is mounted on an electrically controlled mechanism with azimuth and pitch adjustment, controlled by the main communication control module to achieve dynamic beam pointing, thereby optimizing the communication link quality.

[0043] A maritime communication component. This component preferably includes two different types of communication modules to provide redundancy and flexibility. The first is an ad hoc network communication module, which is a radio communication device operating in a suitable frequency band and supporting mobile ad hoc network protocols. It is used for short-range, high-speed communication with other surface / air platforms (such as other unmanned surface vessels, low-altitude drones) or near-shore base stations within a certain geographical range, forming a localized, dynamic communication network. The second is a satellite communication module, which is a satellite phone or data terminal that provides beyond-line-of-sight (BLS) and even global coverage communication capabilities by connecting to space-based communication satellites. It typically serves as a supplement and backup to the ad hoc network communication, ensuring that unmanned surface vessels can maintain connectivity with remote shore-based command centers even in distant maritime areas. Motion sensing equipment. This equipment is typically an inertial measurement unit (IMU) capable of measuring the six degrees of freedom (6 degrees of freedom) motion attitude and acceleration of the unmanned surface vessel (USV), including roll, pitch, bow, heave, sway, and pitch. The sensor's output data is continuously sent to the main communication control module, serving as the direct basis for the latter to determine sea state when executing the dynamic routing algorithm for the marine environment.

[0044] One or more surface / air platforms. These platforms act as extension nodes for the ad hoc network, enhancing its coverage and resilience. For example, a low-altitude unmanned surface vessel (USV) can be deployed to fly between USVs and near-shore base stations, acting as an air relay to address communication disruptions caused by the Earth's curvature or obstructions. Multiple USVs can also form a convoy and communicate with each other via the ad hoc network, expanding coverage for underwater users.

[0045] Shore-based information processing system. This system is typically deployed in a remote shore-based command center and consists of a server cluster, data storage array, network equipment, and operator consoles. The shore-based information processing system is responsible for receiving various data transmitted from unmanned surface vessels at the front, and for storing, processing, analyzing, and visualizing this data. Simultaneously, operators also use this system to issue instructions and plan missions to various task units.

[0046] Satellite communication network. This network includes space-based communication satellites and corresponding ground stations, providing a wide-area, reliable communication link between unmanned surface vessels and remote shore-based command centers.

[0047] During system operation, the main communication control module is configured to execute the method described in Example 1. This main communication control module connects the underwater acoustic communication module and the surface communication components (i.e., the ad hoc network communication module and the satellite communication module), and is configured to perform data relay forwarding between the underwater communication link established by the underwater acoustic communication module and the surface communication link established by the surface communication components. Furthermore, the main communication control module is also configured to: calculate and select the optimal forwarding path for data in the ad hoc network using a dynamic routing algorithm, based on sea state information represented by the output of motion sensors and inter-node distance information estimated by analyzing wireless signal strength, etc.

[0048] Example 3 To better understand the technical solution of the present invention, this embodiment will combine a specific application scenario to further illustrate the working process of the communication method and system provided by the present invention, especially the synergistic effect of dynamic routing and reliable transmission protocol.

[0049] Scenario Setting: An autonomous underwater vehicle (AUV), acting as the underwater user, is performing seabed topographic mapping in a certain sea area, continuously generating a large amount of sonar image data. An unmanned surface vessel (USV) provides communication support as a relay node on the surface. A low-altitude UAV is located in the nearby airspace as a backup relay. A remote shore-based command center needs to receive the mapping data from the AUV in real time. The mission flow is as follows: Data Generation and Underwater Transmission: An autonomous underwater vehicle (AUV) (underwater user) transmits a 20MB high-resolution sonar image file to an unmanned surface vessel (USV) via its underwater acoustic communication equipment. Due to the narrow bandwidth (e.g., only 32kbps), high latency, and instability of the underwater acoustic channel, directly transmitting the entire large file is very risky. At this point, a reliable transmission protocol client running on the AUV begins to divide the 20MB file into, for example, 10,000 2KB data packets with sequence numbers from 1 to 10,000.

[0050] Application of breakpoint resume: The vehicle begins sending data packets to the unmanned surface vessel (USV) via its underwater acoustic communication module. Suppose that when sending the 3000th packet (approximately 6MB of data), the vehicle performs a deep dive to avoid an obstacle, causing a 10-minute interruption of the acoustic link with the USV. During this period, its protocol stack records that the last acknowledged packet is number 2950. After 10 minutes, the link is restored, and the vehicle's protocol stack loads the breakpoint information from its non-volatile storage. Without user intervention, it automatically resumes sending from packet number 2951, rather than retransmitting from the beginning. Correspondingly, the USV's receiver also resumes receiving from the point of interruption, ensuring the continuity of data transmission.

[0051] Application of selective retransmission: During subsequent transmission, due to multipath effects in the marine environment, the unmanned surface vessel (USV) received data packets with sequence numbers 5001, 5002, 5004, and 5005, but missed packet 5003. At this point, the USV's protocol stack replies with a selective acknowledgment message, explicitly stating: "All packets up to 5005 have been received, but packet 5003 is missing." Upon receiving this message, the USV only retransmits packet 5003, instead of retransmitting all subsequent packets starting from 5003, thereby improving channel utilization.

[0052] Surface Relay and Dynamic Routing Decision: After the unmanned surface vessel's (USV) main communication control module fully receives and reassembles the 20MB sonar image file, it needs to forward it to the remote shore-based command center. At this point, the dynamic routing algorithm is activated, and the main communication control module first evaluates available surface communication links. Two neighboring nodes are detected through the ad hoc network communication module: a near-shore base station and a low-altitude UAV. Data read from its own motion sensors is analyzed to determine that the current sea state is relatively severe, with a quantified sea state index of 4 (out of 5). The signal strength to the near-shore base station is weak, the estimated distance is long, and the link quality score is 60 (out of 100); while the signal to the low-altitude UAV is strong, the estimated distance is short, and the link quality score is 95.

[0053] Meanwhile, the routing information broadcast by the low-altitude drone indicates that the weather at the drone's location is clear, the sea state index is 1, and the link quality score from the drone to the near-shore base station 40 is 98.

[0054] The routing algorithm begins by calculating the total cost of the two paths (assuming sea state weights). Link quality weight (Link quality cost is 100 - score) Route 1 (direct to base station): Assuming the sea state of the base station is 1, the cost is... .

[0055] Route 2 (via drone): .

[0056] .

[0057] .

[0058] The total cost is .

[0059] Comparing the two paths, the total cost of path 2 (4) is much smaller than that of path 1 (16.6). Therefore, the main communication control module chooses to relay the data via a low-altitude UAV.

[0060] High-speed data forwarding: The unmanned surface vessel (USV) uses its ad hoc network communication module to quickly send a 20MB file to a low-altitude UAV via a high-bandwidth link. The UAV then forwards the file to the shore-based unit via a high-quality link between itself and a near-shore base station. Although the process adds an extra hop, the overall transmission time is shorter and the success rate is higher because it avoids the low-quality direct links affected by rough sea conditions. Alternatively, in another embodiment, if the low-altitude UAV flies away or the USV sails to the open sea, causing all ad hoc network links to be interrupted, the main communication control module will automatically switch the file transmission task to the satellite communication module, ensuring that critical data is ultimately delivered.

[0061] Through the above specific process, this embodiment demonstrates how the proposed method and system can effectively overcome the challenges of the marine environment and achieve efficient and robust cross-domain air-water communication by combining intelligent routing and reliable protocols.

[0062] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0063] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features of the present invention can be arbitrarily combined with each other.

Claims

1. A cross-domain air-water communication method based on unmanned surface vessels, characterized in that, include: Step S1: Deploy at least one unmanned surface vessel as a cross-domain communication relay node, and mount a dynamically adjustable underwater acoustic transducer on the bottom of the unmanned surface vessel. Step S2: Construct a unified unmanned surface vessel communication system inside the unmanned surface vessel for heterogeneous communication protocol parsing and data forwarding; the unmanned surface vessel communication system includes a main communication control module, an underwater acoustic communication module, an ad hoc network communication module, and a satellite communication module; Step S3: Based on one or more unmanned surface vessels that have been configured, construct a marine cross-domain communication system; the marine cross-domain communication system uses multiple unmanned surface vessels that support cross-domain air-water communication as key routing nodes in the network composition, and the unmanned vessels form a sea surface network system through self-organizing networks to open up cross-domain communication links on the water and underwater. Step S4: Using a dynamic routing algorithm for the marine environment, the comprehensive cost of the link is calculated by combining sea state perception information and inter-node link distance information, and the transmission path with the lowest total cost is selected. It employs an enhanced UDP communication protocol to ensure reliable data transmission.

2. The cross-domain air-water communication method based on unmanned surface vessels according to claim 1, characterized in that, The specific method for dynamically adjusting the orientation of the underwater acoustic transducer in step S1 is as follows: The main communication control module combines the detection results from the underwater acoustic communication module with the real-time underwater acoustic communication quality to calculate the optimal beam pointing angle and drive the two-dimensional / three-dimensional adjustment mechanism to adjust the transducer attitude and avoid acoustic transmission obstruction.

3. The cross-domain air-water communication method based on unmanned surface vessels according to claim 1, characterized in that, The cross-domain communication links in step S3 include: Underwater users communicate with unmanned surface vessels via underwater acoustic links. The unmanned surface vessels use a dual-link strategy, with self-organizing networks as the primary method and satellite communication as a backup, to transmit data back to the shore and issue commands.

4. The cross-domain air-water communication method based on unmanned surface vessels according to claim 3, characterized in that, Dual-link automatic switching is as follows: when the self-organizing network link is normal, priority is given to using the high-speed transmission of the self-organizing network. When the self-organizing network exceeds its coverage area or is interrupted by electromagnetic interference, the main communication control module seamlessly switches to the satellite communication link to complete data transmission.

5. The cross-domain air-water communication method based on unmanned surface vessels according to claim 1, characterized in that, The formula for calculating the link integration cost in step S4 is as follows: in, From this node To the next hop node The overall cost of the link, It is a node Reported or by nodes A quantitative sea state index inferred from historical information. It is a node and Estimated distance or distance-related link quality metric between them and These are preset weighting coefficients.

6. The cross-domain air-water communication method based on unmanned surface vessels according to claim 1, characterized in that, The transmission mechanism of the enhanced UDP communication protocol includes persistent data fragmentation caching, selective acknowledgment retransmission, timeout exponential backoff retransmission, and communication interruption resume.

7. A cross-domain air-water communication system based on an unmanned surface vessel, characterized in that, The method for performing the communication method according to any one of claims 1 to 6 includes: a plurality of underwater users, at least one unmanned surface vessel, a surface / air platform, a shore-based information processing system, and a communication satellite; The underwater user is equipped with underwater acoustic communication equipment; The unmanned surface vessel serves as the core relay node, and is equipped with a built-in main communication control module, underwater acoustic communication module, surface communication components, and motion sensing devices. The waterborne communication component includes a self-organizing network communication module and a satellite communication module; The main communication control module is connected to the underwater acoustic communication module, the waterborne communication component, and the motion sensing device, respectively, to realize cross-domain data relay, dynamic route calculation, and reliable protocol scheduling.

8. The cross-domain air-water communication system based on unmanned surface vessels according to claim 7, characterized in that, The underwater acoustic communication module is equipped with an electrically controlled two-dimensional / three-dimensional angle adjustment mechanism. The adjustment mechanism is controlled by the main communication control module and is used to adjust the beam direction of the underwater acoustic transducer on the bottom of the boat in real time.

9. The cross-domain air-water communication system based on unmanned surface vessels according to claim 7, characterized in that, The self-organizing network communication module is used for short-range high-speed wireless networking between boats, between boat engines, and between boats and shore. The satellite communication module serves as a long-distance emergency backup link, and the two together constitute a primary and backup dual-redundant maritime communication link.

10. The cross-domain air-water communication system based on unmanned surface vessels according to claim 7, characterized in that, The communication main control module has built-in software programs that integrate a marine environment dynamic routing algorithm stack and an enhanced UDP reliable transmission protocol stack to achieve path optimization, data fragmentation caching, selective retransmission, and breakpoint resumption.

Images