With the rapid development of drone technology, drones are now widely used in various fields such as agriculture, inspection, security, and rescue. Currently, the most widely used method is the operation of single drones, which, due to their solitary operation, can be time-consuming and inefficient, especially when the task area is large, requiring multiple round trips and even site changes to fully cover the area. Some areas are limited by terrain factors, restricting communication between drones and ground control stations, and preventing drones from reaching the work area, thus affecting the scope of the task. Compared to these issues with single drones, drone ad-hoc networking systems offer numerous advantages in addressing these problems, such as:
Diverse drones collaborate to perceive the task environment, utilizing ad-hoc networking technology for rapid information exchange among them, enabling comprehensive monitoring of the task area. When line-of-sight communication falls into blind spots, multi-drone relay ensures full coverage. The drone swarm system is independent of individual drones; even when some leave or join, the system maintains integrity and can continue executing tasks.
Concept of Unmanned Aerial Vehicle Ad-hoc Networking
The Drone Ad-hoc Network is a dynamic self-organizing network system with arbitrary, temporary, and autonomous network topology, composed of drones acting as network nodes. Each drone, as a network node, is equipped with a mobile ad-hoc network communication module, which not only has routing functions but also message forwarding capabilities, enabling the formation of any network topology through wireless connections. Each drone in this network serves both as a task node and a relay node: as a task node, it can execute task intentions under the command of a ground control station or other drones; as a relay node, it can participate in routing maintenance and packet forwarding based on the network's routing strategy and routing table.
Unmanned Aerial Vehicle (UAV) Ad Hoc Networking System Composition
The drone ad-hoc network system includes a ground control station node and several drone nodes. The structural diagram is shown in Figure 1, where one ground control station and four drones form a drone ad-hoc network. In the drone ad-hoc network, due to wireless transmission distance limitations or terrain restrictions, routing between drones may sometimes require multiple network segments. As shown in Figure 1, drone node C and the ground control station cannot communicate directly, but they can communicate via node D and the ground control station using the C→D→ground control station routing, or via nodes A and B and the ground control station using the C→A→B→ground control station routing.
Unmanned Aerial Vehicle (UAV) Ad-hoc Network Solution Features
Drones' ad-hoc networks, in addition to featuring the technical characteristics of general ad-hoc networks such as independent networking, self-organization, dynamic topology, unconstrained mobility, and multi-hop routing, also possess the following operational characteristics:
1. Suitable for Complex Terrain and Non-Line-of-Sight Applications: Individual drones are prone to be affected by terrain or other environmental factors, preventing real-time communication between drones and the ground. However, in a drone ad-hoc network, each drone can act as a relay, enabling applications in complex terrains and non-line-of-sight scenarios.
2. Suitable for Long-Distance Operations: Due to Earth's curvature, wireless transmission over long distances is significantly affected, and combined with terrain factors around base stations, communication distances often fall short of 50km. When using drone ad-hoc network communication links, the drone closest to the base station, in addition to performing the role of a task drone, also acts as a relay. With the addition of relay functionality, the communication distance of the data link can be extended to 150-200km, eliminating the need for multiple round trips and site changes, thereby improving operational efficiency.
3. Strong Interference Resistance: The ad-hoc network structure ensures that the entire drone fleet is no longer just a simple chain, even if any link in the chain fails, the entire drone system will not fail. This means that the interference resistance of the drone system has been significantly enhanced.
4. High Intelligence Level: Drone ad-hoc networks can timely perceive network changes, automatically configure or restructure the network, ensuring real-time connectivity of the data link, and possess high autonomy and adaptability. Additionally, drone ad-hoc networks can share information, process received information, and make independent decisions, achieving intelligent task execution.
5. Diverse Functions: After forming an ad-hoc network, the drone network has all the functions of terminals, with complementary advantages and cooperative division of labor, forming an organic whole, achieving better task execution than a single drone.
6. Multi-Channel High-Definition Data Transmission: One mission can achieve multiple traditional task effects. As shown in Figures 2 and 3, this task uses drone environmental protection monitoring as an example. Due to the large area of environmental monitoring, four drones are simultaneously conducting environmental protection operations. The control distance between the ground and the drones reaches 50km, and the maximum control distance between drones reaches 150km. The four drones can simultaneously collect FHD video and transmit it back to the ground station in real-time. If environmental anomalies are detected, multiple drones can be dispatched to the scene above for multi-angle data collection, simultaneously avoiding the risk of disconnection due to complex terrain and mountain obstructions.
Industry Application
1. In the security industry, due to the large coverage area and limited surveillance range of a single drone, multiple flights and even site changes may be required to fully cover the mission area, leading to longer time consumption and lower efficiency. A drone malfunction can disrupt the mission. By utilizing a drone ad-hoc network, a large-scale surveillance task can be completed in one go, and multiple drones can monitor from different angles to identify issues. A single drone failure will not impact the mission execution.
2. In emergency search and rescue operations in mountainous areas, complex terrain and environments can pose challenges. A single drone may experience communication issues due to data link obstructions. By employing a drone ad-hoc network, each drone can act as a relay, eliminating data link obstructions.
3. In the geophysical exploration industry, aircraft need to fly at low altitudes for extended periods to achieve precise surveying results, but the Earth's curvature limits the flight radius. The ad-hoc network model effectively solves this issue by using one or more drones as relay bridges to achieve long-distance low-altitude exploration.
4. In the environmental protection industry, using a drone ad-hoc network for environmental monitoring allows for flexible adjustment of the network size based on the mission. For smaller monitoring areas, a few drones can be deployed; for larger areas, multiple drones can be used to efficiently and effectively complete tasks.
