Channel construction method based on wireless communication of UAV IRS array

Abstract

The present invention discloses a channel construction method based on wireless communication of an unmanned aerial vehicle (UAV) IRS array, including calculating the three-dimensional rotation matrix of the UAV, calculating the function expression of the transmission distance between the transmitting end and the receiving end and the aerial IRS array; calculating the channel complex impulse response function expression of the transmission path of the signal reaching the receiving end through the UAV IRS array; calculating the function expression of the transmission distance between the transmitting end and the receiving end and the scattering cluster; calculating the channel complex impulse response function expression of the transmission path of the signal reaching the receiving end through reflection of the scatterer; calculating the propagation characteristic correlation function, and analyzing the non-stationary characteristics of the transmission path in the time domain, space domain and frequency domain. The channel of aerial IRS wireless communication is constructed, and the wireless signal propagation mechanism of aerial IRS auxiliary communication is revealed. The proposed channel model can accurately capture the channel characteristics and dynamically adapt to the changes in the channel state.

Description

Technical Field

[0001] The invention relates to a channel construction method based on wireless communication of an IRS array of an unmanned aerial vehicle, and belongs to the technical field of wireless communication. Background Art

[0002] In recent years, with the gradual commercialization of the fifth-generation (5G) mobile communication technology, researchers in the global communications field have conducted theoretical research on the sixth-generation (6G) mobile communication technology.

[0003] At present, one of the hot topics in 6G research is to build an integrated network in three dimensions: sea, land and air, and drones are considered to be a promising example for establishing air-to-ground communication networks. At the same time, the use of intelligent reflective surfaces to assist in improving wireless transmission performance has received widespread attention from academia and industry. IRS has the advantages of low cost, low power consumption, and easy deployment. It can programmatically control the phase of electromagnetic waves and significantly improve communication performance.

[0004] The Internet of Vehicles is currently a hot spot for global innovation, which can realize ubiquitous interconnection between vehicles, roads and people, thereby alleviating traffic pressure and ensuring traffic safety. Among them, vehicle-to-vehicle communication is the most typical application scenario in the Internet of Vehicles, which requires reliability and high speed of information transmission. The 6G network has the ability to improve communication reliability and data rate, so it will also become an indispensable part of V2V communication.

[0005] As small aircraft, drones play a key role in the airspace coverage of 6G networks. Deploying IRS (Intelligent Reflecting Surface) on high-altitude platforms or drones themselves forms an aerial intelligent reflective surface, also known as aerial IRS. This concept provides a new paradigm for land and air-to-ground communications. The high maneuverability of drones can flexibly adjust or expand the coverage area of ​​IRS. However, the current research on aerial IRS is still in its early stages, so it is necessary to have a deep understanding of the corresponding channel model and propagation characteristics, which is extremely critical for the analysis and design of aerial IRS-assisted communication systems. At present, although a large number of studies have been devoted to exploring IRS-assisted low-altitude drone cooperative communication systems, and significant progress has been made in improving communication efficiency and expanding coverage, these works often focus on system architecture, algorithm optimization or performance evaluation, while there is a lack of in-depth and systematic research on the signal transmission mechanism behind IRS-assisted communication, that is, how signals can be efficiently and reliably transmitted under the control of IRS. Specifically, most of these studies have failed to fully reveal how the IRS array's control of the signal's phase and amplitude accurately affects the signal's propagation path, how to effectively bypass obstacles and directly guide the user, and the key role played by the drone's three-dimensional rotation and scattering effects in this process. Therefore, a deep understanding of the signal transmission mechanism of IRS-assisted communication is still an important gap in current research and the key to promoting the further development of IRS-assisted air-to-ground communication technology. Summary of the invention

[0006] The present invention provides a channel construction method based on wireless communication of an IRS array of a UAV, which solves the problems disclosed in the background technology. The IRS array is deployed on a UAV, revealing the wireless signal propagation mechanism of IRS-assisted communication in the air and the nonlinear relationship between the physical characteristics of the IRS and the channel model.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The channel construction method based on wireless communication of UAV IRS array includes:

[0009] Establish a three-dimensional space containing transmitters, receivers and drone IRS arrays Cartesian coordinate system and define channel model parameters;

[0010] When the signal from the transmitter reaches the receiver through the UAV IRS array, the three-dimensional rotation matrix of the UAV is calculated, and the transmission distance between the transmitter and the receiver and the UAV IRS array is calculated;

[0011] The channel complex impulse response of the transmission path from the UAV IRS array to the receiver is calculated based on the UAV's three-dimensional rotation matrix and the transmission distance between the transmitter and the receiver and the UAV IRS array;

[0012] When the signal from the transmitter is reflected by the scattering cluster and reaches the receiver, the transmission distance between the transmitter and the receiver and the scattering cluster is calculated;

[0013] The channel complex impulse response of the transmission path of the signal from the scattering cluster to the receiver is calculated according to the transmission distance between the transmitter and the receiver and the scattering cluster;

[0014] According to the channel complex impulse response of the transmission path of the signal reaching the receiver after the action of the UAV IRS array and the channel complex impulse response of the transmission path of the signal reaching the receiver after the reflection of the scattering cluster, the correlation of the transmission path between the transmitter and the receiver in the time domain, space and frequency domain is calculated when the signal sent by the transmitter reaches the receiver after the action of the UAV IRS array and the reflection of the scattering cluster;

[0015] The channel for wireless communication based on the UAV IRS array is constructed according to the correlation of the transmission path between the transmitter and the receiver in the time domain, space and frequency domain.

[0016] Furthermore, a three-dimensional space is constructed including a transmitter, a receiver, and an IRS array of a UAV. The method of defining the channel model parameters in a rectangular coordinate system includes:

[0017] Define the line connecting the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array as Axis; defines the axis passing through the midpoint of the transmitter antenna array and perpendicular to The axis line is Axis; defines the axis passing through the midpoint of the transmitter antenna array and perpendicular to The line of the plane is axis; the initial distance between the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array is expressed as , the initial height of the UAV IRS array is expressed as .

[0018] Furthermore, the method for calculating the three-dimensional rotation matrix of the drone includes:

[0019] Assume the transmitter is set up with Uniform linear antenna array, the receiver is equipped with Uniform linear antenna array;

[0020] use , and To represent the pitch angle, yaw angle and roll angle of the UAV IRS array, the direction cosine matrix of the UAV is calculated as:

[0021] ;

[0022] Among them, the rotation matrices are described as:

[0023] ;

[0024] ;

[0025] ;

[0026] Assume that there are units, then from the center of the IRS array to the Line The distance vector of the column reflection unit is expressed as:

[0027] ;

[0028] Assumptions represents the movement speed of the drone IRS array, and the distance vector from the center of the drone IRS array to the origin is expressed as:

[0029] ;

[0030] in, and They represent the coordinates of the UAV IRS array at the initial moment, , and Respectively The coordinates of the UAV IRS array at the moment; the motion direction of the UAV IRS array is determined by the azimuth and elevation To express.

[0031] Further, the method of calculating the transmission distance between the transmitter and the receiver and the UAV IRS array includes:

[0032] When the signal from the transmitter reaches the receiver through the IRS, Moment No. The distance vector of the geometric coordinates of each unit relative to the origin is expressed as ; , ;

[0033] When the signal from the transmitter is reflected by the drone IRS array and reaches the receiver, the transmitter’s The time-varying transmission distance between the root antenna and the midpoint of the antenna array is:

[0034] ;

[0035] in, ; Indicates the deflection angle of the transmitter in the horizontal azimuth; Represents the distance between any two antennas on the transmitter's linear antenna;

[0036] represents the velocity vector of the transmitter, Expressed as the transmitter's direction of motion and horizontal plane The angle between the axes; Represents the real-time motion speed of the transmitter. The distance vector from the origin to the midpoint of the linear array of transmitters is described as ;

[0037] When the signal from the transmitter reaches the receiver through the UAV IRS array, the transmitter’s The time-varying transmission distance between the root antenna and the UAV IRS array is:

[0038] ;

[0039] In the UAV IRS array assisted V2V wireless communication channel, when the signal sent by the transmitter is reflected by the UAV IRS array and reaches the receiver, the receiver’s The time-varying transmission distance between the root antenna and the midpoint of the antenna array is:

[0040] ;

[0041] in, , Indicates the deflection angle of the receiver in the horizontal azimuth; Represents the distance between any two antennas on the receiver's linear antenna;

[0042] represents the velocity vector of the receiver, Represented as the direction of motion of the receiver and the horizontal plane The angle between the axes; Represents the real-time motion speed of the receiver. The distance vector from the origin to the midpoint of the linear array of the receiver is described as ;

[0043] When the signal from the transmitter reaches the receiver through the IRS, calculate the receiver's The time-varying transmission distance between the root antenna and the UAV IRS array is:

[0044] .

[0045] Furthermore, the complex impulse response function expression of the channel of the transmission path from the signal passing through the UAV IRS array to the receiver is:

[0046] ;

[0047] in, represents a natural constant; Indicates plural; Indicates the attitude change fading coefficient; and represent the time-varying modulation amplitude and phase of the RIS array, respectively; and They represent the relative real-time motion speeds of the transmitter and receiver to the UAV IRS array respectively; and They represent the distance from the transmitter to the UAV IRS array ( ) units’ real-time departure azimuth and elevation; and They represent the distance from the transmitter to the UAV IRS array ( ) units’ real-time departure azimuth and elevation; and They represent the receiver to the UAV IRS array ( ) units’ real-time arrival azimuth and elevation angles; and Represent the velocity vectors of the transmitter and receiver respectively; and are the unit direction vectors from the antenna of the transmitter and the receiver to the reflector unit, expressed as:

[0048] .

[0049] Further, the method of calculating the transmission distance between the transmitter and the receiver and the scattering cluster includes:

[0050] Assume that there is a Scattering clusters, ;

[0051] When the signal from the transmitter reaches the receiver after being reflected by the scattering cluster, The distance vector of the scattering clusters is expressed as , Indicates The propagation distance of the ray is calculated Antenna and The transmission distance between the scattering clusters is: ; Calculate the receiver Antenna and The transmission distance between the scattering clusters is: .

[0052] Furthermore, the complex impulse response function expression of the channel of the transmission path where the signal is reflected by the scattering cluster and reaches the receiver is:

[0053] ;

[0054] in, represents random phase; and Respectively represent the transmitter to the Real-time departure azimuth and elevation of each scattering cluster; and Respectively represent the receiver to the Real-time arrival azimuth and elevation of each scattering cluster; and are the unit direction vectors from the transmitter and receiver antennas to the UAV IRS array, expressed as; .

[0055] Furthermore, the transmitter Antenna and receiver The autocorrelation function of the transmission path between the root antennas in the time domain is: ;

[0056] in, Indicates the time interval, represents the expectation operation; Indicates the transmitter Antenna and receiver Complex impulse response function of the root antenna; Indicates the transmitter Antenna and receiver Complex impulse response function of the antenna. and Represent the time domain autocorrelation functions of the IRS path and the NLoS path respectively.

[0057] Transmitter Antenna and receiver The spatial cross-correlation function of the transmission path between the root antennas is: ;

[0058] in, and represent the normalized antenna spacing respectively.

[0059] Furthermore, the transmitter Antenna and receiver The correlation function of the transmission path between the root antennas in the frequency domain is:

[0060] ;

[0061] in, represents the frequency interval; the frequency domain correlation function is also expressed as:

[0062] ;

[0063] in, and represent the propagation delays of the IRS path and the NLoS path respectively.

[0064] The beneficial effects achieved by the present invention are:

[0065] The present invention introduces the three-dimensional rotation and scattering effects of UAVs, constructs a channel for aerial IRS wireless communication based on geometric characteristics, gives expressions for the channel matrix and complex channel impulse response, and reveals the wireless signal propagation mechanism of aerial IRS-assisted communication. The proposed channel model can accurately capture the channel characteristics and dynamically adapt to changes in the channel state. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 A schematic diagram of a channel model based on wireless communication of an IRS array of a UAV constructed for the present invention;

[0067] FIG2 is a schematic diagram of the three-dimensional rotation angle of the UAV;

[0068] FIG3 is a schematic diagram of the transmission link of the transmitter and the receiver in the IRS component and the non-line-of-sight component in the present invention;

[0069] FIG4 is a schematic diagram showing the effect of the fading of the UAV attitude change on the transmission path of the UAV IRS array component signal;

[0070] Figure 5 is a schematic diagram of four motion trajectories of a UAV equipped with an IRS array;

[0071] Figure 6 is a schematic diagram showing the effect of transmitters and receivers in different motion states on the time domain autocorrelation characteristics of UAV IRS array assisted vehicle wireless communication;

[0072] FIG7 is a schematic diagram showing the effect of different Rice factors on the spatial cross-correlation characteristics of the UAV IRS array assisted vehicle wireless communication channel;

[0073] FIG8 is a schematic diagram showing the effect of different UAV altitudes on the time domain autocorrelation characteristics of UAV IRS array assisted vehicle wireless communication;

[0074] FIG9 is a schematic diagram showing the effect of different UAV altitudes on the frequency domain related characteristics of UAV IRS array assisted vehicle wireless communication;

[0075] Fig.10 Schematic diagram of the impact of different IRS array element numbers and sizes on the capacity of the UAV IRS array-assisted vehicle wireless communication channel. DETAILED DESCRIPTION

[0076] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0077] The present invention provides a channel construction method based on wireless communication of an unmanned aerial vehicle IRS array, comprising the following steps:

[0078] Step 1: Construct a channel model for UAV IRS array-assisted vehicle wireless communication and establish Rectangular coordinate system, set model parameters.

[0079] like Figure 1 As shown, the invention considers a vehicle-to-vehicle (V2V) communication scenario, deploys an IRS array on a drone, forms a drone IRS array-assisted V2V wireless communication channel, and establishes A rectangular coordinate system, where the line defining the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array is Axis; defines the axis passing through the midpoint of the transmitter antenna array and perpendicular to The axis line is Axis; defines the axis passing through the midpoint of the transmitter antenna array and perpendicular to The line of the plane is The initial distance between the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array is expressed as , the initial height of the drone is expressed as .

[0080] Step 2: In the channel of UAV IRS array assisted vehicle wireless communication, when the signal sent by the transmitter reaches the receiver through the UAV IRS array, calculate the function expression of the transmission distance between the transmitter and the receiver and the UAV IRS array. The specific steps are:

[0081] Step 201: In the UAV IRS array assisted V2V wireless communication channel, in order to describe the three degrees of freedom in the rotation of the UAV, use , and To represent the pitch angle, yaw angle and roll angle of the IRS in the air, the direction cosine matrix of the drone is calculated as:

[0082] ;

[0083] Among them, the rotation matrix can be described as:

[0084] ;

[0085] ;

[0086] ;

[0087] Assume that there are units, then from the center of the drone IRS array to the Line The distance vector of the column reflection unit can be expressed as:

[0088] ;

[0089] Assumptions represents the speed of the IRS in the air, then the distance vector from the center of the drone IRS array to the origin can be expressed as:

[0090] ;

[0091] in, and They represent the coordinates of the IRS in the air at the initial moment, and , and Respectively indicate time The coordinates of the reflecting surface at the time; the movement direction of the UAV IRS array can be determined by the azimuth and elevation To express.

[0092] Assume that there is a layout in IRS units, of which Time IRS No. )indivual( , ) The distance vector of the geometric coordinates of the unit relative to the origin is expressed as .

[0093] Step 202: In the channel of the drone IRS array assisted V2V wireless communication, when the signal sent by the transmitter is reflected by the drone IRS array and reaches the receiver, the transmitter's root The time-varying transmission distance between the antenna and the midpoint of the antenna array is:

[0094] ;

[0095] in, Indicates the deflection angle of the transmitter in the horizontal azimuth; Represents the distance between any two antennas on the transmitter's linear antenna;

[0096] represents the velocity vector of the transmitter, Expressed as the transmitter's direction of motion and horizontal plane The angle between the axes, represents the real-time motion speed of the transmitter, then the distance vector from the origin to the midpoint of the linear array of the transmitter can be described as .

[0097] When the signal from the transmitter reaches the receiver through the UAV IRS array, the transmitter’s root The time-varying transmission distance between the antenna and the UAV IRS array is:

[0098] ;

[0099] Step 203: In the channel of the drone IRS array-assisted V2V wireless communication, when the signal sent by the transmitter is reflected by the drone IRS array and reaches the receiver, the receiver first root The time-varying transmission distance between the antenna and the midpoint of the antenna array is:

[0100] ;

[0101] in, Indicates the deflection angle of the transmitter in the horizontal azimuth; Represents the distance between any two antennas on the transmitter's linear antenna; Represented as the direction of motion of the receiver and the horizontal plane The angle between the axes, Indicates the real-time movement speed of the receiver. represents the velocity vector of the receiver, then the distance vector from the origin to the midpoint of the linear array of the receiver can be described as .

[0102] When the signal from the transmitter reaches the receiver through the drone IRS array, the receiver is calculated. root The time-varying transmission distance between the antenna and the UAV IRS array is:

[0103] .

[0104] Step 3: Based on the above step 2, calculate the channel complex impulse response function expression of the transmission path where the signal reaches the receiver through the IRS:

[0105]

[0106] in, represents a natural constant; Indicates plural; Indicates the attitude change fading coefficient; and represent the time-varying modulation amplitude and phase of the RIS array, respectively; and They represent the relative real-time motion speeds of the transmitter and receiver to the UAV IRS array respectively; and They represent the distance from the transmitter to the UAV IRS array ( ) units’ real-time departure azimuth and elevation; and Respectively represent the receiver to IRS ( ) reflector units in real time. In addition, and are the unit direction vectors from the antenna of the transmitter and the receiver to the reflector unit, expressed as

[0107] ;

[0108] Step 4: When the signal from the transmitter is reflected by the scattering cluster and reaches the receiver, it is assumed that there are Scattering clusters, , calculate the function expression of the transmission distance between the transmitter and the receiver and the scattering cluster. The specific steps are:

[0109] Step 401: In the channel of the drone IRS array assisted V2V wireless communication, when the signal sent by the transmitter reaches the receiver after being reflected by the scattering cluster, the distance from the origin to the first The distance vector of the scattering clusters is expressed as ,and Indicates The propagation distance of the ray is calculated Antenna and The transmission distance between the scattering clusters is:

[0110] ;

[0111] Step 402: In the channel of the drone IRS array assisted V2V wireless communication, when the signal sent by the transmitter reaches the receiver after being reflected by the scattering cluster, the receiver first Antenna and The transmission distance between the scattering clusters is:

[0112] ;

[0113] Step 5: Based on the above step 4, the channel complex impulse response function expression of the transmission path where the signal is reflected by the scattering cluster and reaches the receiver is calculated as follows:

[0114] ;

[0115] in, represents random phase; and Respectively represent the transmitter to the Real-time departure azimuth and elevation of each scattering cluster; and Respectively represent the receiver to the The real-time arrival azimuth and elevation of each scattering cluster. In addition, and are the unit direction vectors from the antenna of the transmitter and the receiver to the reflector unit, expressed as

[0116] ;

[0117] Step 6: Based on the above steps, analyze the non-stationary characteristics of the transmission path in the time domain, spatial domain and frequency domain under different motion states, reveal the relationship between the non-stationary channel and parameter configuration, build the UAV IRS array assisted V2V wireless communication channel, and further optimize signal transmission. The specific steps are:

[0118] Step 601: In the channel of the drone IRS array assisted V2V wireless communication, when the signal sent by the transmitter reaches the receiver after being reflected by the drone IRS array and the scattering cluster, the transmitter's Antenna and receiver The autocorrelation function of the transmission path between the root antennas in the time domain is:

[0119] ;

[0120] in, Indicates the time interval, represents the expectation operation; Indicates the transmitter Antenna and receiver Complex impulse response function of the root antenna; Indicates the transmitter Antenna and receiver Complex impulse response function of the antenna. and Represent the time domain autocorrelation functions of the IRS path and the NLoS path respectively.

[0121] Step 602: In the UAV IRS array assisted V2V wireless communication channel, when the signal sent by the transmitter reaches the receiver after being reflected by the UAV IRS array and the scattering cluster, the transmitter Antenna and receiver The spatial cross-correlation function of the transmission path between the root antennas is: ;

[0122] in, and represent the normalized antenna spacing respectively.

[0123] Step 603: In the channel of the drone IRS array assisted V2V wireless communication, when the signal sent by the transmitter reaches the receiver after being reflected by the IRS and the scattering cluster, the transmitter's Antenna and receiver The correlation function of the transmission path between the root antennas in the frequency domain is:

[0124] ;

[0125] in, Represents the frequency interval. The frequency domain correlation function can also be expressed as:

[0126] ;

[0127] in and represent the propagation delays of the IRS path and the NLoS path respectively.

[0128] like Figure 5 As shown in the figure, four typical UAV motion trajectory simulations are shown, where trajectory 1 represents the UAV moving in a straight line along a certain direction, trajectory 2 represents the UAV moving in a circle on the spot, trajectory 3 represents the UAV rising with a large acceleration, and trajectory 4 represents the UAV moving in a curved line with rising and falling.

[0129] like Figure 6 As shown, = 2 s, the proposed channel model based on the time domain autocorrelation characteristics of the transmitter and receiver in different motion states roughly simulates the various parameter settings in the V2V communication scenario. It can be observed that under different motion states, the time domain correlation shows obvious non-stationarity, among which the third motion state slows down the rate of decrease of the time domain correlation. The above observations reveal that the application of aerial IRS in the channel can significantly improve the time domain correlation performance of the propagation link in the wireless communication environment. In addition, the proposed channel model accurately captures the non-stationary propagation characteristics of the IRS-assisted V2V communication system under various motion states, providing strong support for performance optimization and system design in practical applications.

[0130] like Figure 7 As shown in the figure, the spatial domain cross-correlation function values ​​of the channel model proposed in the present invention for different propagation links. As the antenna index increases, the obtained curve first fluctuates and then tends to be stable. In the non-line-of-sight path, the spatial cross-correlation characteristics will drop sharply, and after introducing the drone IRS array component, the spatial domain correlation of the channel model is enhanced. In addition, as the Rice factor As the value increases from 0.5 to 10, the spatial cross-correlation function value of the curve also increases after stabilization. This is because The value affects the proportion of non-line-of-sight components in the overall channel. When the value is 1, the channel model will have a better effect. These observations are consistent with the research results in other literature, further verifying the accuracy of the proposed channel model in the derivation of frequency-related characteristics and simulation results, and fully demonstrating that the introduction of the UAV IRS array has a significant effect on channel optimization.

[0131] like Figure 8 As shown in the figure, under the default motion state of the simulation, the influence of the drone at different altitudes on the time domain autocorrelation function, where the drone altitude is set to 20 m, 100 m, 500 m and 1000 m respectively. It can be observed that as the initial altitude of the drone increases, the rate of decrease of the time domain autocorrelation function value gradually slows down. This is because there are some local scattering clusters near the receiver, such as buildings, trees, etc., and these scattering clusters are relatively far away from the IRS in the air, resulting in smaller changes in the arrival azimuth and arrival elevation angles, so the time domain autocorrelation also slows down. Based on this finding, wireless transmission can be optimized by adjusting the drone altitude in actual drone communication scenarios.

[0132] like Fig. 9 As shown, in = 2 s, the normalized frequency correlation function of the proposed geometric channel model at different straight-line distances between the transmitter and the receiver under the simulated default motion state. The results show that the frequency correlation shows significant differences, and the frequency interval As increases, the frequency correlation gradually decreases and tends to be smooth, which indicates that the channel is non-stationary in the frequency domain. It can also be found that as the distance between the transmitter and the receiver increases, the amplitude of the change trend of the frequency correlation gradually decreases. At the same time, after the introduction of the aerial IRS link, the curve fluctuates and eventually tends to be stable. The above observations show that it is necessary to comprehensively consider the non-stationary characteristics of the channel in the space, time, and frequency domains to set the parameters of the IRS-assisted UAV communication to ensure the efficiency of the transmission performance.

[0133] like Fig.10 As shown in the figure, the channel capacity of the proposed channel model under different numbers and sizes of IRS array units is compared. The results show that the increase in the size and number of IRS array units will lead to an increase in channel capacity. The reason for this phenomenon is that the spatial correlation will decrease. However, the larger the IRS units, the better, which may lead to more frequent channel estimation. Therefore, in actual UAV communication scenarios, the number and size of IRS array units need to be selected according to specific communication requirements to achieve the best transmission performance. The above simulation results can provide an important technical reference for the research, design and performance optimization of subsequent UAV IRS array communication systems.

[0134] The present invention realizes a wireless signal transmission method for assisting low-altitude UAV cooperative communication based on the channel constructed by the wireless communication of the UAV IRS array. When the direct path between the transmitter and the receiver is blocked by obstacles, the UAV adjusts the phase and amplitude of the signal by adjusting the altitude and the IRS array. This regulation not only enables the signal to bypass the obstacle, but also enables it to be efficiently transmitted directly toward the user.

[0135] The above is only 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0136] A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform a channel construction method based on wireless communication of an unmanned aerial vehicle IRS array.

[0137] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a channel construction method based on wireless communication of an unmanned aerial vehicle IRS array.

[0138] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0139] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0140] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0141] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0142] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A channel construction method based on wireless communication of UAV IRS array, characterized in that: include: Establish an xyz rectangular coordinate system in three-dimensional space that includes the transmitter, receiver, scattering cluster, and UAV IRS array, and define the channel model parameters; When the signal from the transmitter reaches the receiver through the UAV IRS array, the three-dimensional rotation matrix of the UAV is calculated, and the transmission distance between the transmitter and the receiver and the UAV IRS array is calculated; The channel complex impulse response of the transmission path from the UAV IRS array to the receiver is calculated based on the UAV's three-dimensional rotation matrix and the transmission distance between the transmitter and the receiver and the UAV IRS array; When the signal from the transmitter is reflected by the scattering cluster and reaches the receiver, the transmission distance between the transmitter and the receiver and the scattering cluster is calculated; The channel complex impulse response of the transmission path of the signal from the scattering cluster to the receiver is calculated according to the transmission distance between the transmitter and the receiver and the scattering cluster; According to the channel complex impulse response of the transmission path of the signal reaching the receiver after the action of the UAV IRS array and the channel complex impulse response of the transmission path of the signal reaching the receiver after the reflection of the scattering cluster, the correlation of the transmission path between the transmitter and the receiver in the time domain, space and frequency domain is calculated when the signal sent by the transmitter reaches the receiver after the action of the UAV IRS array and the reflection of the scattering cluster; The channel for wireless communication based on the UAV IRS array is constructed according to the correlation of the transmission path between the transmitter and the receiver in the time domain, space and frequency domain; The method of establishing an xyz rectangular coordinate system including a transmitter, a receiver, and an IRS array of a UAV in a three-dimensional space and defining channel model parameters includes: Define the line connecting the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array as the x-axis; define the line passing through the midpoint of the transmitter antenna array and perpendicular to the x-axis as the y-axis; define the line passing through the midpoint of the transmitter antenna array and perpendicular to the xy plane as the z-axis; the initial distance between the midpoint of the transmitter antenna array and the midpoint of the receiver antenna array is denoted as D0, and the initial height of the drone IRS array is denoted as H0; Methods for calculating the three-dimensional rotation matrix of a drone include: Assume that the transmitter is provided with P uniform linear antenna arrays and the receiver is provided with Q uniform linear antenna arrays; use and To represent the pitch angle, yaw angle and roll angle of the UAV IRS array, the direction cosine matrix of the UAV is calculated as: Among them, the rotation matrices are described as: Assume that there are M arrays arranged in the IRS array. x ×M z units, then from the center of the IRS array to the mth x Row m z The distance vector of the column reflection unit is expressed as: Assume v A (t) represents the movement speed of the drone IRS array, and the distance vector from the center of the drone IRS array to the origin is expressed as: Among them, d A，x (0) and d A，y (0) represents the coordinates of the UAV IRS array at the initial time, d A，x (t), d A，y (t) and d A，z (t) represents the coordinates of the UAV IRS array at time t, and the motion direction of the UAV IRS array is determined by the azimuth angle. and elevation To express; Methods for calculating the transmission distance between the transmitter and receiver and the UAV IRS array include: When the signal sent by the transmitter reaches the receiver through the IRS, at time t, the (m x , m x ) units’ geometric coordinates relative to the origin are expressed as [d A，x (t), d A，y (t), d A，z (t)] T ;m x =1,2,...M x , m z =1,2,...M z ; When the signal sent by the transmitter is reflected by the UAV IRS array and reaches the receiver, the time-varying transmission distance between the transmitter's pth antenna and the midpoint of the antenna array is calculated as: Wherein, p=1, 2, ...P; Indicates the deflection angle of the transmitter in the horizontal azimuth; δ T Represents the distance between any two antennas on the transmitter's linear antenna; v T (t) = v T (t)[cosη T ,sinη T ,0] represents the velocity vector of the transmitter, η T Expressed as the angle between the transmitter's direction of motion and the x-axis of the horizontal plane; v T (t) represents the real-time velocity of the transmitter, and the distance vector from the origin to the midpoint of the linear array of transmitters is described as d T (t) = v T (t)t; When the signal sent by the transmitter reaches the receiver through the UAV IRS array, the time-varying transmission distance between the transmitter's pth antenna and the UAV IRS array is calculated as: In the UAV IRS array-assisted V2V wireless communication channel, when the signal sent by the transmitter is reflected by the UAV IRS array and reaches the receiver, the time-varying transmission distance between the receiver's qth antenna and the midpoint of the antenna array is calculated as: Where q = 1, 2, ... Q, Indicates the deflection angle of the receiver in the horizontal azimuth; δ R Represents the distance between any two antennas on the receiver's linear antenna; v R (t) = v R (t)[cosη R ,sinη R ,0] represents the velocity vector of the receiver, η R Expressed as the angle between the receiver's direction of motion and the x-axis of the horizontal plane; v R (t) represents the real-time motion speed of the receiver. The distance vector from the origin to the midpoint of the linear array of the receiver is described as d R (t) = v R (t)t+[0D0,0,0]; When the signal sent by the transmitter reaches the receiver through the IRS, the time-varying transmission distance between the qth antenna of the receiver and the IRS array of the drone is calculated as: The complex impulse response function expression of the channel of the transmission path from the UAV IRS array to the receiver is: Wherein, e represents a natural constant; j represents a complex number; P(t) represents the attitude change fading coefficient; and Respectively represent the time-varying control amplitude and phase of the RIS array; v T-AIRS (t) and v RAIRS (t) represents the relative real-time motion speed of the transmitter and receiver to the UAV IRS array; and They represent the distance from the transmitter to the UAV IRS array (m x , m z ) units’ real-time departure azimuth and elevation; and They represent the receiver to the UAV IRS array (m x ,m z ) units’ real-time arrival azimuth and elevation; v T (t) = v T (t)[cosη T ,sinη T ,0] and v R (t) = v R (t)[cosη R ,sinη R ,0] represent the velocity vectors of the transmitter and receiver respectively; and are the unit direction vectors from the antenna of the transmitter and the receiver to the reflector unit, expressed as: Methods for calculating the transmission distance between the transmitter and the receiver and the scattering cluster include: Assume there are L scattering clusters, l = 1, 2, ..., L; When the signal from the transmitter reaches the receiver after being reflected by the scattering cluster, the distance vector from the origin to the scattering cluster in the cluster is expressed as d l =[x l ,y l , z l ] T , represents the propagation distance of the lth ray, and the transmission distance between the pth antenna of the transmitter and the lth scattering cluster is calculated as: ξ p，l (t)=||d l -d T，p -d T (t)||; Calculate the transmission distance between the qth antenna of the receiver and the lth scattering cluster as: ξ q，l (t)=||d l -d R，q -d R (t)||; The complex impulse response function expression of the channel of the transmission path where the signal is reflected by the scattering cluster and reaches the receiver is: in, represents random phase; α T，l and β T，l They represent the real-time departure azimuth and elevation angle from the transmitter to the lth scattering cluster respectively; α R，l and β R，l denote the real-time arrival azimuth and elevation angle from the receiver to the lth scattering cluster respectively; e T，l (t) and e R，l (t) are the unit direction vectors from the transmitter and receiver antennas to the UAV IRS array, expressed as; The autocorrelation function of the transmission path between the transmitter's pth antenna and the receiver's qth antenna in the time domain is: Where Δt represents the time interval, represents the expected operation; h pq (t) represents the complex impulse response function of the transmitter's pth antenna and the receiver's qth antenna; h p′q′ (t) represents the complex impulse response function of the transmitter's p'th antenna and the receiver's q'th antenna; and represent the time domain autocorrelation functions of the IRS path and the NLoS path respectively; The spatial cross-correlation function of the transmission path between the transmitter's pth antenna and the receiver's qth antenna is: Where Δp=|p′-p|δ T / λ and Δq=|q′-q|δ R / λ represent the normalized antenna spacing; The correlation function of the transmission path between the transmitter's pth antenna and the receiver's qth antenna in the frequency domain is: Where Δf represents the frequency interval; the frequency domain correlation function is also expressed as: Among them, τ AIRS (t) and τ NLoS (t) represents the propagation delay of IRS path and NLoS path respectively.

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