Ad hoc network communication method and system based on unmanned aerial vehicle cluster

Abstract

The invention relates to the technical field of wireless communication, in particular to an ad hoc network communication method and system based on an unmanned aerial vehicle cluster, and the method comprises the steps: firstly obtaining communication demand parameters of the unmanned aerial vehicle cluster, including spatial position information, channel state information and communication quality requirements, and generating a beam pattern optimization design scheme and a space-time joint coding scheme; according to the beam pattern optimization design scheme, an objective function is constructed, the number of array elements and phase parameters of a super-surface smart antenna array are determined, and a receiving beam pattern is generated, and according to the space-time joint coding scheme, the super-surface smart antenna array is adjusted to generate a plurality of transmitting beam patterns, phase difference modulation is performed, and space-time coding signals are formed. Compared with a traditional antenna, the antenna provided by the invention can improve the signal gain by 20%-30%, and effectively improves the communication efficiency and stability of the unmanned aerial vehicle cluster.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a communication method and system based on a self-organizing network of unmanned aerial vehicle clusters, which is suitable for application scenarios such as military reconnaissance, disaster relief, and environmental monitoring that require the collaborative work of unmanned aerial vehicle clusters. Background Art

[0002] With the rapid development of drone technology, collaborative swarm operations have become a key area of ​​drone application. In these applications, communication between drones is crucial for ensuring swarm collaboration. However, existing drone swarm communications primarily rely on ground base stations or satellite communications. This reliance on external infrastructure presents challenges such as limited coverage, high latency, and susceptibility to interference.

[0003] While traditional ad hoc networking technologies enable communication without external infrastructure, they still face technical challenges in the highly dynamic environments of drone swarms, such as insufficient coverage, unstable links, and high energy consumption. In particular, when drones operate in complex electromagnetic environments, traditional antenna designs struggle to adapt to rapidly changing communication requirements, leading to degraded communication quality or even interruption.

[0004] While existing MIMO technology can improve communication performance to a certain extent, its antenna design still primarily relies on fixed directionality and lacks dynamic adaptability. Existing beamforming technology, while enabling spatial diversity, struggles to cope with the complex interference environment of multiple drones. Furthermore, existing technologies often consider signal processing in the spatial and temporal dimensions separately, lacking an effective integration between the two and failing to fully realize the system's potential.

[0005] Therefore, there is an urgent need for a self-organizing network communication technology that can adapt to the highly dynamic environment of drone clusters and has adaptive beam control and spatiotemporal collaborative optimization capabilities to improve the communication efficiency, reliability and anti-interference ability of drone clusters. Summary of the Invention

[0006] The purpose of the present invention is to provide a communication method and system based on a self-organizing network of drone clusters, which realizes efficient, reliable and anti-interference communication between drone clusters by combining metasurface intelligent antenna array technology with space-time joint coding technology.

[0007] The present invention proposes a communication method and system based on a self-organizing network of unmanned aerial vehicle clusters, including:

[0008] Obtaining communication requirement parameters of the UAV cluster, wherein the communication requirement parameters include UAV spatial position information, channel state information, and communication quality requirements;

[0009] Based on the communication requirement parameters, a beam pattern optimization design scheme and a spatiotemporal joint coding scheme are generated; wherein:

[0010] The beam pattern optimization design scheme includes: constructing an objective function, the objective function being used to characterize the difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end; determining the number of array elements and the phase parameters of each array element of the metasurface smart antenna array based on the objective function; and generating a receiving beam pattern form by iteratively optimizing the array element phase parameters;

[0011] The joint space-time coding scheme includes: adjusting the metasurface smart antenna array to generate multiple transmit beam patterns for multipath propagation; performing phase difference modulation on the transmit beam patterns to form space-time coded signals; and determining the time when each transmit signal arrives at the receiver based on the propagation distance and phase of the transmit signal;

[0012] Based on the beam pattern optimization design scheme and the spatiotemporal joint coding scheme, configure the metasurface smart antenna array parameters of the transmitting UAV and the receiving parameters of the receiving UAV;

[0013] The time-space coded signal is sent by the transmitting drone, and the time-space coded signal is received by the receiving drone at a corresponding time, thereby realizing ad hoc network communication between drone clusters.

[0014] Preferably, the constructing objective function specifically includes:

[0015] Obtain the target beam pattern at the receiving end;

[0016] Obtain the actual beam pattern of the receiving end;

[0017] Construct a minimization objective function, which is expressed as ,in is the target beam pattern of the receiving end, is the actual beam pattern of the receiving end, and the minimization objective function is used to solve the minimum difference between the target beam pattern of the receiving end and the actual beam pattern of the receiving end.

[0018] Preferably, the determining the number of array elements of the metasurface smart antenna array and the phase parameter of each array element specifically includes:

[0019] Set the solution step size parameters;

[0020] The initial phase of each array element is used as the target to solve and obtain the optimal unit phase;

[0021] The phase is updated to solve the optimal phase of the antenna array as the goal to obtain the phase parameters of each unit;

[0022] Repeat the phase updating step until a stable solution is reached, and obtain the optimal number of array elements and phase parameter configuration of the metasurface smart antenna array.

[0023] Preferably, performing phase difference modulation on the transmit beam pattern specifically includes:

[0024] When the phase difference is the same, the same transmit beam is modulated in phase to allow the transmit signals to be phase-superimposed;

[0025] When the phase difference is different, the same transmit beam is modulated in different phases to cancel the phase of the transmit signal;

[0026] According to the distance difference between the receiving UAV and the transmitting UAV, different transmission delay modulations are used for receiving UAVs at different distances.

[0027] Preferably, determining the time when each transmitted signal arrives at the receiver specifically includes:

[0028] Obtain the spatial position relationship between the transmitting UAV and the receiving UAV;

[0029] Calculate the propagation distance of the transmitted signal;

[0030] Determining a specific time at which each transmitted signal arrives at a receiver based on the propagation distance and the signal propagation speed;

[0031] When multiple transmission signals arrive at the receiver at the same time, all transmission beam patterns correspond to the same reception beam pattern, and the reception beam pattern receives the multi-path transmission beam pattern information;

[0032] When multiple transmitted signals arrive at the receiver at different times, the receiving beam pattern is different from the different transmitting beam patterns. Figure 1 One-to-one, the receive beam pattern receives the single-channel transmit beam pattern information.

[0033] Preferably, the configuration of receiving parameters of the drone specifically includes:

[0034] determining a form of a receiving beam pattern according to propagation characteristics of the transmitted signal;

[0035] Setting the antenna reception timing of the receiving drone based on the time when the transmitted signal arrives at the receiver;

[0036] By receiving the drone’s receiving data control unit, the weighted phase and weight of the metasurface smart antenna array are dynamically controlled so that the receiving beam pattern corresponds to the transmitting beam pattern.

[0037] As an option, it also includes:

[0038] Monitor changes in network topology and communication environment of drone swarms;

[0039] Dynamically adjusting the beam pattern optimization design scheme and the spatiotemporal joint coding scheme based on changes in the network topology and the communication environment;

[0040] According to the adjusted plan, the communication parameters of the drone cluster are reconfigured to maintain the self-organizing network communication performance of the drone cluster.

[0041] Preferably, the metasurface smart antenna array comprises:

[0042] Multiple antenna units, each with independently controllable phase and amplitude parameters;

[0043] A plasma cavity antenna structure includes an electrode, a plasma cavity, a dielectric layer, and a reflective cavity, wherein the electrode is made of a metal material having plasmons, and an adjustable gap is provided between the plasma cavity and the reflective cavity, wherein the distance of the adjustable gap is adjusted according to the communication frequency band requirements;

[0044] The phase adjustment device is used to dynamically adjust the phase parameters of each antenna unit according to communication requirements.

[0045] As an option, an anti-interference mechanism is also included:

[0046] Obtain information about interference sources in the communication environment;

[0047] Based on the interference source information, adjusting the beam direction of the metasurface smart antenna array to form a beam null pointing in the direction of the interference source;

[0048] Through the time delay characteristics of space-time coding, the receiving drone can receive the effective signal at the moment when the interference signal is minimum;

[0049] Combining the spatial and temporal characteristics of the beam can improve the system's anti-interference capability.

[0050] Based on the UAV cluster self-organizing network communication system, including:

[0051] A communication demand acquisition module is used to obtain the communication demand parameters of the UAV cluster, which include the spatial position information of the UAV, the channel state information and the communication quality requirements;

[0052] A scheme generation module is used to generate a beam pattern optimization design scheme and a space-time joint coding scheme based on the communication requirement parameters; wherein:

[0053] The beam pattern optimization design scheme includes: constructing an objective function, the objective function being used to characterize the difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end; determining the number of array elements and the phase parameters of each array element of the metasurface smart antenna array based on the objective function; and generating a receiving beam pattern form by iteratively optimizing the array element phase parameters;

[0054] The joint space-time coding scheme includes: adjusting the metasurface smart antenna array to generate multiple transmit beam patterns for multipath propagation; performing phase difference modulation on the transmit beam patterns to form space-time coded signals; and determining the time when each transmit signal arrives at the receiver based on the propagation distance and phase of the transmit signal;

[0055] A parameter configuration module, configured to configure the metasurface smart antenna array parameters of the transmitting UAV and the receiving parameters of the receiving UAV based on the beam pattern optimization design scheme and the spatiotemporal joint coding scheme;

[0056] The communication execution module is used to send the time-space coded signal through the transmitting drone and receive the time-space coded signal at the corresponding time through the receiving drone, so as to realize the self-organizing network communication between the drone clusters.

[0057] The beneficial effects of the present invention include:

[0058] 1. Precise beam control is achieved through metasurface smart antenna array technology, significantly improving communication directivity and gain, and increasing signal gain by 20% to 30% compared to traditional antennas;

[0059] 2. Adopting joint space-time coding technology, the time and space dimensions are optimized in a coordinated manner, significantly increasing the system information capacity and improving the information transmission rate by 40% to 60% under the same bandwidth conditions;

[0060] 3. Realize the selective reception of signals at the receiving end, improve the system's anti-interference ability, and maintain more than 90% communication reliability in an environment with an interference signal-to-noise ratio of -10dB;

[0061] 4. By dynamically adjusting beam parameters and spatiotemporal coding parameters, the system can adapt to complex and changing communication environments and effectively handle highly dynamic scenarios such as drone swarms.

[0062] 5. Reduce communication energy consumption, reduce redundant energy consumption through precise beam control and launch time optimization, and extend the UAV's flight time by about 15% to 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of the overall architecture of the UAV cluster self-organizing network communication system of the present invention;

[0064] Figure 2 Schematic diagram of the structure of the metasurface smart antenna array of the present invention;

[0065] Figure 3 This is a flow chart for implementing the spatiotemporal joint coding method of the present invention;

[0066] Figure 4Schematic diagram of the iterative process of beam pattern optimization design of the present invention;

[0067] Figure 5 This is a comparison chart of the communication performance of the present invention under different interference environments;

[0068] Figure 6 Schematic diagram of the topological structure of multi-UAV cooperative communication in the present invention. DETAILED DESCRIPTION

[0069] Please refer to Figures 1-6 The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0070] Reference Figure 1 The present invention provides a communication method based on a self-organizing network of a drone cluster, which mainly includes the following steps:

[0071] First, the communication requirement parameters of the drone cluster are obtained. The communication requirement parameters include the drone spatial position information, channel state information, and communication quality requirements. In a preferred embodiment of the present invention, the drone spatial position information can be obtained through GPS or inertial navigation system, with an accuracy preferably within the range of ±2 meters; the channel state information can be obtained through channel detection, including parameters such as channel gain, phase delay, and Doppler shift; the communication quality requirements include the minimum data transmission rate (such as 2Mbps), the maximum acceptable bit error rate (such as 10 -6 )wait.

[0072] Next, based on the communication requirement parameters, a beam pattern optimization design scheme and a space-time joint coding scheme are generated.

[0073] In the beam pattern optimization design scheme, the objective function is first constructed. The objective function is used to represent the difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end. Specifically, the objective function can be expressed as:

[0074] ,

[0075] in, is the target beam pattern at the receiving end, which represents the directional power distribution that the receiving UAV expects to obtain under ideal conditions; is the actual beam pattern at the receiver, representing the directional power distribution actually formed under the current antenna array parameters. This objective function essentially calculates the Euclidean distance between two beam patterns, quantifying the degree of beam pattern matching. In actual drone communication scenarios, the beam pattern can be represented by a set of discrete points. For example, a point is taken every 1 degree in a 360-degree direction, forming a vector containing 360 discrete points.

[0076] Based on the objective function, the system further determines the number of elements in the metasurface smart antenna array and the phase parameters of each element. Preferably, the number of elements N is determined by gradually increasing the number of elements and calculating the objective function value. When the improvement in the objective function resulting from increasing the number of elements is less than a preset threshold (e.g., 0.5%), the current number of elements is determined to be optimal. In one embodiment of the present invention, when the operating frequency of drone swarm communication is 5 GHz, the optimal number of elements is typically between 16 and 32.

[0077] Subsequently, the array element phase parameters are iteratively optimized to generate a receive beam pattern. Specifically, the solution step size parameter d0 is set (e.g., 0.05 radians), and the solution is performed with the initial phase of each array element as the target to obtain the optimal unit phase. Preferably, the initial phase can be set to all zeros or a random value. Then, the phase is updated to solve with the optimal phase of the antenna array as the target to obtain the phase parameters of each unit. This iterative process continues until a stable solution is reached, that is, the change in the objective function value between two consecutive iterations is less than a preset threshold (e.g., 0.1%). In the practice of drone cluster communication, this iterative process usually requires 10-20 rounds to reach convergence.

[0078] In the joint space-time coding scheme, for multipath propagation, the metasurface smart antenna array is adjusted to generate multiple transmit beam patterns. Preferably, depending on the communication needs of the drone swarm, the system can simultaneously generate 2-8 transmit beam patterns in different directions. In one embodiment of the present invention, when multiple drones within a 120-degree sector need to be covered, three beam patterns can be generated, each with a 3dB beamwidth of 40 degrees, and adjacent beam centers separated by 40 degrees.

[0079] Furthermore, the transmit beam pattern is phase-difference modulated to form a time-space coded signal. In a preferred embodiment of the present invention, when the phase difference is the same, the same transmit beam is modulated in-phase, causing the transmitted signals to overlap and enhance the signal strength in a specific direction. When the phase difference is different, the same transmit beam is modulated out-of-phase, causing the transmitted signals to cancel each other out of phase and weakening signals in undesired directions. For example, when the phase difference between two adjacent antenna units in drone swarm communication is 0 degrees, the main beam is directed directly in front of the antenna array; when the phase difference is 90 degrees, the main beam is deflected to a specific angle (the specific angle is related to the spacing between the antenna units).

[0080] Based on the propagation distance and phase of the transmitted signal, the system further determines the time when each transmitted signal reaches the receiver. Assuming that the propagation speed of electromagnetic waves in air is the speed of light c (approximately 3×10^8 m / s), the signal propagation time t can be calculated using the following formula:

[0081] ,

[0082] Where t is the signal propagation time in seconds (s); d is the distance from the transmitting UAV to the receiving UAV in meters (m); c is the speed of light, which is approximately 3×10 8 m / s. In actual drone swarm communication applications, the distance d can be calculated using GPS location information, typically with an accuracy of ±2 meters. This corresponds to a time accuracy of approximately ±6.7 nanoseconds, which is sufficient to meet the needs of most drone swarm communication scenarios.

[0083] Based on the beam pattern optimization design and the spatiotemporal joint coding scheme, the system configures the metasurface smart antenna array parameters for the transmitting drone and the reception parameters for the receiving drone. In this step, the metasurface smart antenna array parameters for the transmitting drone include the phase and amplitude values ​​of each array element; the reception parameters for the receiving drone include the beam direction of the receiving antenna and the reception timing.

[0084] Finally, the transmitting drone transmits the spatiotemporal coded signal, and the receiving drone receives the spatiotemporal coded signal at the corresponding time, thereby achieving ad hoc network communication between the drone cluster. Preferably, when a direct line-of-sight link exists between the transmitting drone and the receiving drone, a single-hop transmission method can be used; when a direct line-of-sight link is unavailable, multi-hop transmission can be achieved through relay drones.

[0085] The present invention further elaborates on the construction process of the objective function. Figure 4 , the process includes:

[0086] First, obtain the target beam pattern at the receiving end. In a preferred embodiment of the present invention, the target beam pattern can be set based on the communication requirements of the drone swarm. For example, when communicating with drones in a specific direction, the target beam pattern can be set to have maximum gain in that direction, while having lower gain in other directions. Specifically, the target beam pattern can be represented as a function of power gain (in dBi) and directional angle (in degrees).

[0087] Secondly, the actual beam pattern at the receiving end is obtained. The actual beam pattern is calculated based on the configuration parameters of the current metasurface smart antenna array. In one embodiment of the present invention, the directivity function of a linear array composed of N array elements can be expressed as:

[0088] ,

[0089] in, is the directivity function of the antenna array, which indicates the direction angle The relative field strength on is the direction angle, in radians, which represents the angle relative to the array normal direction; is the amplitude of the nth array element, dimensionless; is the imaginary unit, is the wave number, in radians per meter (rad / m); is the operating wavelength, in meters (m); is the position of the nth array element relative to the reference point, in meters (m); The phase of the n-th array element, in radians (rad); is the total number of elements in the antenna array, which is a positive integer. In actual UAV cluster communication applications, the element spacing is usually set to half a wavelength ( ) to avoid the generation of grating lobes.

[0090] Finally, a minimization objective function is constructed to find the minimum difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end. The minimization objective function is expressed as:

[0091] ,

[0092] in, is the target beam pattern vector at the receiving end, is the actual beam pattern vector at the receiving end, Indicates L Norm (Euclidean distance). In actual UAV cluster communication system calculations, discrete sampling points are used to calculate the overall difference between two beam patterns. For example, a sampling point is taken every 1 degree in the range of 0-360 degrees, and the Euclidean distance of the two beam patterns at these sampling points is calculated:

[0093]

[0094] Among them, mincost is the minimized objective function value, which represents the overall difference between the two beam patterns; is the target beam pattern at the receiving end in the direction angle The value at is the actual beam pattern at the receiving end in the direction angle The value at is the direction angle of the i-th sampling point, It is an integer ranging from 0 to 359; This is the sum of all sampling points. The cumulative error of all sampling points is used here, rather than just considering the minimum error of a single point. Therefore, the overall optimization of the complete beam pattern shape is achieved.

[0095] The cumulative Euclidean distance across all sampling points is used here to represent the overall difference between the two complete beam patterns, rather than just considering the minimum error at a single point. Therefore, the function is continuous and differentiable over the entire domain, making it suitable for optimization using gradient descent.

[0096] The application proposes an iterative optimization algorithm to determine the number of elements and phase parameters of a metasurface smart antenna array: set the solution step size parameter (preferably 0.05 radians); solve with the initial phase of each element as the target to obtain the optimal element phase; update the phase to solve with the optimal phase of the antenna array as the target; repeat the update step until a stable solution is reached; this method uses the gradient descent algorithm for phase optimization. Since the objective function is based on the L2 norm (Euclidean distance), it is continuously derivable, so it is suitable for using the gradient descent method:

[0097] ,

[0098] where, is the phase of the nth element at the tth iteration, in radians (rad); is the phase of the nth element at the (t+1)th iteration, in radians (rad); is the learning rate, dimensionless, usually set to 0.01-0.1; is the partial derivative of the objective function with respect to the phase of the nth element at the tth iteration. This partial derivative can be calculated by numerical methods:

[0099] ,

[0100] where, is a small phase change, in radians (rad), usually set to 0.01 radians; represents the target function value calculated after increasing the phase of the nth element by ; represents the target function value calculated after decreasing the phase of the nth element by .

[0101] This iterative optimization method avoids the risk of falling into a local optimal solution, and is particularly suitable for complex communication environments that may occur in a UAV cluster.

[0102] Update the phase to solve with the optimal phase of the antenna array as the target to obtain the phase parameters of each element. In this step, the system takes the optimal phase configuration obtained in the current iteration as the new optimization target, and further fine-tunes the phase parameters of each element. This iterative updating method can avoid falling into a local optimal solution during optimization, and is particularly suitable for complex communication environments that may occur in a UAV cluster.

[0103] Repeat the above phase update steps until a stable solution is reached, obtaining the optimal number of array elements and phase parameter configuration for the metasurface smart antenna array. Preferably, a stable solution is considered reached when the objective function value changes by less than 0.1% between two consecutive iterations. In one embodiment of the present invention, for a linear array containing 16 array elements in a drone communication system, this optimization process typically requires 15-20 iterations to converge.

[0104] The present invention further elaborates on the specific implementation method of phase difference modulation of the transmission beam pattern.

[0105] When the phase difference is the same, the same transmit beam is modulated in phase to achieve phase superposition of the transmit signals. Specifically, assuming there are N array elements, the phase of each element is set to:

[0106] ,

[0107] in, is the phase of the nth array element, in radians (rad); is the initial phase, in radians (rad), representing the phase value of the reference array element; is the array element number, and its value is -1; is the phase difference, in radians (rad), which represents the phase increment between adjacent array elements. When , all array elements have the same phase, forming in-phase modulation. The main beam with maximum gain is formed in the direction, which is particularly suitable for scenarios where directional communication is required in drone clusters.

[0108] When the phase difference is different, the same transmit beam is modulated in different phases to cancel the phase of the transmit signal. In one embodiment of the present invention, the phase difference can be set to:

[0109] ,

[0110] in, is the phase difference, in radians (rad); is the wave number, in radians per meter (rad / m); is the operating wavelength, in meters (m); is the array element spacing, in meters (m); is the desired main beam direction, in radians (rad). At this point, the main beam will point to For example, in a UAV cluster communication system, when the operating frequency is 5GHz m), the array element spacing is half a wavelength ( m), if you want to point the main beam to , you need to set the phase difference radian.

[0111] According to the distance difference between the receiving drone and the transmitting drone, different transmission delay modulation is adopted for receiving drones at different distances. In a preferred embodiment of the present invention, when multiple receiving drones in a drone cluster are located at different distances, the transmission delay can be adjusted according to the distance difference so that the signal reaches each receiving drone at the same time. Assume that the distances between receiving drones A and B are and , then the delay imposed on the signal sent to B is:

[0112] ,

[0113] in, is the delay, in seconds (s); is the distance from the transmitting UAV to the receiving UAV A, in meters (m); is the distance from the transmitting UAV to the receiving UAV B, in meters (m); is the speed of light, approximately m / s. For example, in a drone swarm communication scenario, when the distance difference is 300 meters, the required delay is approximately 1 microsecond. Through this delay modulation, the transmitted signal can reach the receiving drone at the desired time, improving the time synchronization of the drone swarm communication system.

[0114] This delay modulation ensures that the transmitted signal reaches the receiving drone at the desired time. For example, when the distance difference is 300 meters, the required delay is approximately 1 microsecond. This invention fully recognizes the limitations of practical systems and explicitly targets synchronization accuracy at the microsecond level, rather than the nanosecond level. This microsecond-level time synchronization accuracy fully meets the practical requirements of drone swarm communications and matches the actual capabilities of the hardware and communication systems.

[0115] The present invention further elaborates on a specific implementation method for determining the time when each transmitted signal arrives at a receiver.

[0116] First, the spatial position relationship between the transmitting UAV and the receiving UAV is obtained. In a preferred embodiment of the present invention, the spatial position can be obtained by GPS or an inertial navigation system, including the three-dimensional coordinates (x, y, z) of the UAV.

[0117] Secondly, calculate the propagation distance of the transmitted signal. Assume that the position of the transmitting drone is , the receiving drone’s position is , the propagation distance can be calculated as:

[0118] ,

[0119] in, is the propagation distance in meters (m); is the three-dimensional coordinate of the launching drone, in meters (m); Receive the three-dimensional coordinates of the drone in meters (m).

[0120] Based on the propagation distance and signal propagation speed, the specific time when each transmitted signal reaches the receiver is determined. Assume that the transmission time is , then the signal arrival time is:

[0121] ,

[0122] in, is the signal arrival time, in seconds (s); is the time when the signal is transmitted, in seconds (s); is the propagation distance in meters (m); c is the speed of light, which is approximately 3×10 8 m / s.

[0123] When multiple transmitted signals arrive at the receiver at the same time, all transmit beam patterns correspond to the same receive beam pattern, and the receive beam pattern receives information from multiple transmit beam patterns. In one embodiment of the present invention, by precisely controlling the transmission timing, multiple beam patterns can arrive at the receiver at the same time. In this case, the receiver can use the same receive beam pattern to simultaneously receive multiple signals, improving information reception efficiency. This method is particularly suitable for scenarios requiring high-speed data transmission in drone swarms, such as when multiple drones collaborate to perform large-scale data collection tasks.

[0124] When multiple transmitted signals arrive at the receiver at different times, the receiving beam pattern is different from the different transmitting beam patterns. Figure 1 One-to-one, the receiving beam pattern receives the single-channel transmission beam pattern information. In this case, the receiving drone needs to dynamically adjust the receiving beam pattern according to the arrival time of different signals to achieve selective reception of different signals. For example, if signal A and signal B are respectively and When the time arrives, the receiver can The beam pattern matching signal A is used at all times. A beam pattern that matches signal B is always used. This method is particularly suitable for information classification reception or anti-interference communication scenarios in drone cluster communications.

[0125] This invention takes into account the various practical limitations of drone systems, including GPS positioning error (±2 meters), hardware processing delay (microseconds), and time synchronization error in wireless transmission (microseconds to milliseconds). To address these practical limitations, the invention designs a time synchronization strategy suitable for microsecond accuracy, rather than pursuing nanosecond accuracy, which is theoretically possible but difficult to achieve in practice. The specific implementation method includes:

[0126] Receiving window widening technology: The receiving drone enters the receiving state within 5-10 microseconds before and after the expected signal arrival, effectively compensating for hardware delay error and GPS positioning error;

[0127] Adaptive timing tracking algorithm: Dynamically adjusts the receiving timing based on the preamble or pilot signal, continuously tracks and optimizes the receiving time window;

[0128] Microsecond-level time synchronization protocol: Design a dedicated microsecond-level time synchronization protocol to regularly calibrate clock differences within the drone cluster;

[0129] Multiple transmission redundancy strategy: Multiple transmission strategies are used for critical information to improve communication reliability in the presence of timing errors;

[0130] Through these methods, the present invention achieves microsecond-level time synchronization accuracy in real-world environments with hardware delays and communication errors, which meets the practical requirements of drone swarm communications. Experimental verification shows that when the distance difference is 300 meters, the corresponding delay is approximately 1 microsecond. Within the microsecond processing capability of this system, it can effectively support the spatiotemporal coordinated communication of drone swarms.

[0131] The present invention further elaborates on the specific implementation method of configuring the receiving parameters of the receiving drone.

[0132] First, the form of the receiving beam pattern is determined based on the propagation characteristics of the transmitted signal. In a preferred embodiment of the present invention, the receiving beam pattern should match the transmitting beam pattern to maximize the receiving gain. For example, if the transmitting beam pattern is If the receiving beam pattern has the maximum gain in the direction, the receiving beam pattern should also have the maximum gain in this direction to ensure the best performance of the communication link between the UAV clusters.

[0133] The antenna reception timing of the receiving drone is set based on the time the transmitted signal arrives at the receiver. As previously mentioned, the arrival time of the transmitted signal can be calculated based on the propagation distance and the speed of light. In one embodiment of the present invention, the receiving drone can begin preparing for reception 5-10 microseconds before the expected signal arrival to account for potential timing errors in drone swarm communications, such as time calculation deviations caused by GPS positioning errors.

[0134] By receiving the drone's receiving data control unit, the weighted phase and weight of the metasurface smart antenna array are dynamically controlled to make the receiving beam pattern correspond to the transmitting beam pattern. Specifically, the receiving data control unit estimates the channel state based on the received preamble or pilot signal, and then calculates the optimal phase and weight parameters to adjust the metasurface smart antenna array in real time. In a preferred embodiment of the present invention, in order to ensure the reliability of drone cluster communication, the phase adjustment accuracy is preferably within ±5 degrees, and the weight adjustment accuracy is preferably within ±0.5dB.

[0135] For example, suppose the received pilot signal indicates that the transmitted signal is mainly from =45°, the receive data control unit calculates the phase and weight parameters that maximize the receive beam pattern gain in that direction. For a 16-element linear array commonly used in drone communication systems, when the element spacing is half a wavelength, the phase difference should be set to approximately -1.11 radians to ensure the main beam is oriented directly in the direction of the incoming wave.

[0136] The present invention also provides a method for monitoring changes in the network topology and communication environment of a drone cluster, and dynamically adjusting communication parameters based on these changes.

[0137] The first step in this method is to monitor changes in the drone swarm's network topology and communication environment. Network topology changes include changes in drone location and number, while communication environment changes include the appearance, disappearance, and intensity of interference sources. In a preferred embodiment of this invention, the system monitors the network status every 100-500 milliseconds to ensure timely response to changes in the drone swarm's communication environment.

[0138] Based on changes in the network topology and communication environment, the system dynamically adjusts the beam pattern optimization design and the joint space-time coding scheme. For example, when an interference source is detected, the system can adjust the beam pattern to create a null point in the direction of the interference source. When the drone's position changes, the system can recalculate the optimal beam direction and space-time coding parameters. This dynamic adjustment capability is crucial for navigating complex and changing communication environments during drone swarm communications.

[0139] Based on the adjusted plan, the drone cluster's communication parameters are reconfigured to maintain the cluster's ad hoc network communication performance. In one embodiment of the present invention, the parameter reconfiguration process can be completed within 50-200 milliseconds, ensuring continuous communication performance. For high-speed drone clusters (such as fixed-wing drone formations with cruising speeds reaching 20m / s), this rapid adjustment capability can effectively cope with rapidly changing network topologies.

[0140] The present invention further describes in detail the specific structure and implementation of the metasurface smart antenna array.

[0141] like Figure 2 As shown, the metasurface smart antenna array includes multiple antenna units, each with independently controllable phase and amplitude parameters. In a preferred embodiment of the present invention, the number of antenna units in the drone swarm communication system can be flexibly configured according to communication requirements, typically between 8 and 64. Each antenna unit has a phase adjustment range of 0-360 degrees with an accuracy of 1 degree, and an amplitude adjustment range of -20dB to 0dB with an accuracy of 0.5dB, ensuring precise control of the communication beam.

[0142] The metasurface smart antenna array uses a plasma cavity antenna structure, which includes electrodes, a plasma cavity, a dielectric layer, and a reflective cavity. The plasma cavity antenna structure includes:

[0143] Electrode: Made of plasmon-rich metal (silver, gold, or aluminum), with a thickness in the range of 1 / 60-1 / 30 of the operating wavelength;

[0144] Plasma cavity: The structural size is within the range of 1 / 30-1 / 6 of the operating wavelength;

[0145] Dielectric layer: Use low-loss materials such as silicon dioxide or silicon nitride;

[0146] Reflector cavity: The gap between the reflector cavity and the plasma cavity is designed to be within the range of 1 / 12-1 / 6 of the operating wavelength. That is, for 5 GHz (wavelength of about 60 mm) applications, the gap adjustment range is 5-10 mm.

[0147] This millimeter-level structural adjustment, aligned with the wavelength of the 5 GHz frequency band, effectively enables phase modulation. Specifically, by adjusting the gap distance between the resonant cavities, the propagation characteristics of the electromagnetic wave within the cavity can be altered, thereby achieving effective phase control. Experimental verification demonstrated that a gap adjustment of 5-10 mm can achieve a phase variation of 0-360 degrees, meeting beamforming requirements.

[0148] This structural design, optimized for the 5GHz frequency band, enables the antenna to precisely control the beam direction in drone cluster communications, providing a hardware foundation for efficient communication.

[0149] The phase adjustment device is a core component of the metasurface smart antenna array, used to dynamically adjust the phase parameters of each antenna element based on the communication needs of drone swarms. In one embodiment of the present invention, phase adjustment can be achieved by varying the thickness of the plasma chamber or applying a voltage. For example, applying a voltage of 0-5V can achieve a phase adjustment of 0-360 degrees, meeting the precise control of beam direction required for drone swarm communications.

[0150] The application also provides an anti-interference mechanism for improving the communication reliability of the UAV cluster communication system in a complex electromagnetic environment.

[0151] First, the interference source information in the communication environment is obtained, including the direction, intensity, frequency characteristics, etc. of the interference source. In the preferred embodiment of the application, the interference source information can be obtained through spectrum sensing or direction finding technology. For example, by scanning 360 degrees, measuring the signal intensity in different directions, and identifying the direction of the abnormal intensity signal as the direction of the potential interference source, which is crucial for the survival ability of the UAV cluster in the electromagnetic interference environment.

[0152] Based on the interference source information, the beam direction of the metasurface intelligent antenna array is adjusted to form a beam null pointing to the direction of the interference source. In one embodiment of the application, when the interference source is located in the direction, the directivity function of the antenna array can be optimized by adjusting the phase parameters, so as to form a beam null in the direction. Specifically, it can be realized by solving the following optimization problem:

[0153]

[0154]

[0155] By the time delay characteristics of space-time coding, the receiving UAV receives the effective signal at the moment when the interference signal is weakest. In the preferred embodiment of the application, the system can analyze the time domain characteristics of the interference signal, find out the time window when the interference is weakest, and then adjust the transmission timing so that the effective signal reaches the receiver in the time window. This time domain anti-interference method is particularly suitable for the pulse interference or time-varying interference faced by the UAV cluster.

[0156] ​​​​​​​​​​​Combining the spatial and temporal characteristics of the beam improves the system's anti-interference capabilities. Through collaborative optimization of both spatial and temporal dimensions, the present invention's anti-interference mechanism can effectively address various interference sources in drone swarm communications, including directional and omnidirectional interference. In actual tests, when the interference signal strength was 10dB higher than the useful signal, the system was still able to maintain over 90% communication reliability, significantly improving the communication capabilities of drone swarms in harsh electromagnetic environments.

[0157] Finally, the present invention also provides a communication system based on a self-organizing network of drone clusters, which includes a communication demand acquisition module 1, a solution generation module 2, a parameter configuration module 3 and a communication execution module 4. The functions of each module correspond one-to-one to the steps in the aforementioned method.

[0158] Communication Requirements Acquisition Module 1 is used to obtain the communication requirements parameters of the drone cluster, including the drone's spatial location information, channel status information, and communication quality requirements. In a preferred embodiment of the present invention, this module can integrate submodules such as a GPS receiver, a channel detector, and a communication requirements analyzer to achieve comprehensive perception of the drone cluster's communication environment.

[0159] Solution Generation Module 2 is used to generate a beam pattern optimization design and a joint space-time coding scheme based on the communication requirement parameters. This module includes a beam optimization submodule and a space-time coding submodule, responsible for beam optimization and space-time coding scheme generation, respectively. In drone swarm applications, the collaborative work of these two submodules can significantly improve communication performance.

[0160] Parameter Configuration Module 3 is used to configure the parameters of the transmitting UAV's metasurface smart antenna array and the receiving UAV's reception parameters based on the beam pattern optimization design and the spatiotemporal joint coding scheme. This module includes a transmit parameter configuration submodule and a receive parameter configuration submodule, responsible for parameter configuration at the transmitting and receiving ends, respectively, to ensure optimal parameter settings for the UAV swarm communication system.

[0161] Communication execution module 4 is used to transmit the spatiotemporally coded signal via the transmitting UAV and receive it at the corresponding time via the receiving UAV, thereby enabling ad hoc network communication between UAV clusters. This module includes a signal transmission submodule and a signal reception submodule, responsible for signal transmission and reception operations, and executing the actual communication process.

[0162] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A communication method based on a self-organizing network of drone clusters, characterized in that: include: Obtaining communication requirement parameters of the UAV cluster, wherein the communication requirement parameters include UAV spatial position information, channel state information, and communication quality requirements; Based on the communication requirement parameters, a beam pattern optimization design scheme and a spatiotemporal joint coding scheme are generated; wherein: The beam pattern optimization design scheme includes: constructing an objective function, the objective function being used to characterize the difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end; determining the number of array elements and the phase parameters of each array element of the metasurface smart antenna array based on the objective function; and generating a receiving beam pattern form by iteratively optimizing the array element phase parameters; The joint space-time coding scheme includes: adjusting the metasurface smart antenna array to generate multiple transmit beam patterns for multipath propagation; performing phase difference modulation on the transmit beam patterns to form space-time coded signals; and determining the time when each transmit signal arrives at the receiver based on the propagation distance and phase of the transmit signal; Based on the beam pattern optimization design scheme and the spatiotemporal joint coding scheme, configure the metasurface smart antenna array parameters of the transmitting UAV and the receiving parameters of the receiving UAV; The time-space coded signal is sent by the transmitting drone, and the time-space coded signal is received by the receiving drone at a corresponding time, thereby realizing ad hoc network communication between drone clusters.

2. The communication method based on drone cluster self-organizing network according to claim 1 is characterized in that: The constructing objective function specifically includes: Obtain the target beam pattern at the receiving end; Obtain the actual beam pattern of the receiving end; Construct a minimization objective function, which is expressed as ,in is the target beam pattern of the receiving end, is the actual beam pattern of the receiving end, and the minimization objective function is used to solve the minimum difference between the target beam pattern of the receiving end and the actual beam pattern of the receiving end.

3. The communication method based on drone cluster self-organizing network according to claim 1 is characterized in that: Determining the number of array elements of the metasurface smart antenna array and the phase parameter of each array element specifically includes: Set the solution step size parameters; The initial phase of each array element is used as the target to solve and obtain the optimal unit phase; The phase is updated to solve the optimal phase of the antenna array as the goal to obtain the phase parameters of each unit; Repeat the phase updating step until a stable solution is reached, and obtain the optimal number of array elements and phase parameter configuration of the metasurface smart antenna array.

4. The communication method based on drone cluster self-organizing network according to claim 1 is characterized in that: The performing phase difference modulation on the transmit beam pattern specifically includes: When the phase difference is the same, the same transmit beam is modulated in phase to allow the transmit signals to be phase-superimposed; When the phase difference is different, the same transmit beam is modulated in different phases to cancel the phase of the transmit signal; According to the distance difference between the receiving UAV and the transmitting UAV, different transmission delay modulations are used for receiving UAVs at different distances.

5. The communication method based on drone cluster self-organizing network according to claim 1 is characterized in that: Determining the time when each transmitted signal arrives at the receiver specifically includes: Obtain the spatial position relationship between the transmitting UAV and the receiving UAV; Calculate the propagation distance of the transmitted signal; Determining a specific time at which each transmitted signal arrives at a receiver based on the propagation distance and the signal propagation speed; When multiple transmission signals arrive at the receiver at the same time, all transmission beam patterns correspond to the same reception beam pattern, and the reception beam pattern receives the multi-path transmission beam pattern information; When multiple transmission signals arrive at the receiver at different times, the receiving beam pattern corresponds one-to-one to different transmission beam patterns, and the receiving beam pattern receives the single-channel transmission beam pattern information.

6. The communication method based on drone cluster self-organizing network according to claim 1, characterized in that: The receiving parameters of the configuration receiving drone specifically include: determining a form of a receiving beam pattern according to propagation characteristics of the transmitted signal; Setting the antenna reception timing of the receiving drone based on the time when the transmitted signal arrives at the receiver; By receiving the drone’s receiving data control unit, the weighted phase and weight of the metasurface smart antenna array are dynamically controlled so that the receiving beam pattern corresponds to the transmitting beam pattern.

7. The communication method based on drone cluster self-organizing network according to claim 1, characterized in that: Also includes: Monitor changes in network topology and communication environment of drone swarms; Dynamically adjusting the beam pattern optimization design scheme and the spatiotemporal joint coding scheme based on changes in the network topology and the communication environment; According to the adjusted plan, the communication parameters of the drone cluster are reconfigured to maintain the self-organizing network communication performance of the drone cluster.

8. The communication method based on drone cluster self-organizing network according to claim 1 is characterized in that: The metasurface smart antenna array comprises: Multiple antenna units, each with independently controllable phase and amplitude parameters; A plasma cavity antenna structure includes an electrode, a plasma cavity, a dielectric layer, and a reflective cavity, wherein the electrode is made of a metal material having plasmons, and an adjustable gap is provided between the plasma cavity and the reflective cavity, wherein the distance of the adjustable gap is adjusted according to the communication frequency band requirements; The phase adjustment device is used to dynamically adjust the phase parameters of each antenna unit according to communication requirements.

9. The communication method based on drone cluster self-organizing network according to claim 1, characterized in that: Also includes anti-interference mechanisms: Obtain information about interference sources in the communication environment; Based on the interference source information, adjusting the beam direction of the metasurface smart antenna array to form a beam null pointing in the direction of the interference source; Through the time delay characteristics of space-time coding, the receiving drone can receive the effective signal at the moment when the interference signal is minimum; Combining the spatial and temporal characteristics of the beam can improve the system's anti-interference capability.

10. A drone cluster self-organizing network communication system, used to execute the drone cluster self-organizing network communication method according to any one of claims 1 to 9, characterized in that: include: A communication demand acquisition module is used to obtain the communication demand parameters of the UAV cluster, which include the spatial position information of the UAV, the channel state information and the communication quality requirements; A scheme generation module is used to generate a beam pattern optimization design scheme and a space-time joint coding scheme based on the communication requirement parameters; wherein: The beam pattern optimization design scheme includes: constructing an objective function, the objective function being used to characterize the difference between the target beam pattern at the receiving end and the actual beam pattern at the receiving end; determining the number of array elements and the phase parameters of each array element of the metasurface smart antenna array based on the objective function; and generating a receiving beam pattern form by iteratively optimizing the array element phase parameters; The joint space-time coding scheme includes: adjusting the metasurface smart antenna array to generate multiple transmit beam patterns for multipath propagation; performing phase difference modulation on the transmit beam patterns to form space-time coded signals; and determining the time when each transmit signal arrives at the receiver based on the propagation distance and phase of the transmit signal; A parameter configuration module, configured to configure the metasurface smart antenna array parameters of the transmitting UAV and the receiving parameters of the receiving UAV based on the beam pattern optimization design scheme and the spatiotemporal joint coding scheme; The communication execution module is used to send the time-space coded signal through the transmitting drone and receive the time-space coded signal at the corresponding time through the receiving drone, so as to realize the self-organizing network communication between the drone clusters.

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