A UAV air-to-air channel modeling and simulation method for urban low-altitude scenes

Abstract

The present invention discloses a UAV air-to-air channel modeling and simulation method for urban low-altitude scenarios, comprising: calculating the delay, total phase, and power of the UAV's line-of-sight path in the channel model based on input transceiver position parameters; calculating the channel impulse response of the line-of-sight path in combination with the attitude-related line-of-sight path antenna pattern function; calculating the delay, total phase, and power of the rooftop reflection path in the channel model in combination with communication scenario parameters; calculating the channel impulse response of the rooftop reflection path in combination with the attitude-related non-line-of-sight path antenna pattern function; calculating the delay, total phase, and power of the non-line-of-sight path in the channel model in combination with the geometric relationship parameters that limit the distribution of scatterers; calculating the channel impulse response of the non-line-of-sight path in combination with the attitude-related antenna pattern function; establishing a UAV air-to-air channel model and outputting channel coefficients. The present invention achieves efficient and accurate reproduction of UAV air-to-air channels.

Description

Technical Field

[0001] The present invention relates to the field of wireless information transmission, and in particular to a method for modeling and simulating air-to-air channels of unmanned aerial vehicles (UAVs) for urban low-altitude scenarios. Background Art

[0002] With the development of 5G / 6G and the Internet of Things (IoT), low-altitude digital infrastructure has become crucial for intelligent development. Combined with technological breakthroughs in artificial intelligence (AI) and edge computing, the application of drones is accelerating, particularly with the increasing demand for communication in low-altitude environments. In low-altitude urban environments, drones can not only perform tasks such as urban surveillance and logistics distribution, but also play a vital role in emergency communications and disaster relief. The complexity of low-altitude urban environments presents significant challenges for inter-UAV communication, particularly due to factors such as densely populated buildings and multipath signal propagation, which significantly impact signal transmission. Therefore, accurate air-to-air channel modeling in low-altitude scenarios is crucial for improving UAV communication performance.

[0003] Traditional channel models, such as those for ground-to-ground or air-to-ground communication, have been extensively studied. However, air-to-air channels present unique challenges and require new modeling approaches. Unlike ground-to-ground or air-to-ground scenarios, air-to-air communication in low-altitude urban environments requires both the transmitter and receiver to be in mid-air, a characteristic that alters signal propagation characteristics and the distribution of scatterers in the environment. Furthermore, most air-to-ground channel models for drones treat drones as point masses, ignoring the impact of their structure and posture variations on the channel. Summary of the Invention

[0004] The purpose of this invention is to provide a UAV air-to-air channel modeling and simulation method for urban low-altitude scenarios, which can comprehensively consider factors such as the attitude and position changes of the UAV, the actual distribution characteristics of the scatterers, etc., which can effectively improve the authenticity and accuracy of the channel model, thereby improving the quality of UAV communication.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A method for modeling and simulating an air-to-air channel of a UAV for low-altitude urban scenarios, comprising the following steps:

[0007] S1, based on the input transceiver position parameters, calculates the delay, total phase and power of the UAV transceiver line-of-sight path in the channel model; combined with the attitude-related line-of-sight path antenna pattern function, calculates the channel impulse response of the line-of-sight path;

[0008] S2, combined with the communication scenario parameters, calculates the delay, total phase, and power of the rooftop reflection path in the channel model; combined with the attitude-related non-line-of-sight path antenna pattern function, calculates the channel impulse response of the rooftop reflection path;

[0009] S3, combining the height and horizontal geometric relationship parameters of the restricted scatterer distribution, calculates the delay, total phase, and power of the non-line-of-sight path in the channel model; combining the attitude-related non-line-of-sight path antenna pattern function, calculates the channel impulse response of the non-line-of-sight path;

[0010] S4, establish a UAV air-to-air channel model, substitute the calculation results of steps S1 to S3, and output the channel coefficient; the UAV air-to-air channel model is:

[0011] ;

[0012] Where, Indicates the The transmitting antenna and The channel impulse response between the root receiving antennas, t represents time, Indicates delay, represents the time-varying Rice factor, and Represents the power coefficient of the roof reflection path and the non-line-of-sight path, satisfying ; 、 and Represents the channel impulse response of the line-of-sight path, rooftop reflection path, and non-line-of-sight path.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] First, the UAV air-to-air channel modeling and simulation method for urban low-altitude scenarios of the present invention combines factors such as the real scattering environment and the UAV fuselage structure. Under the conditions of three-dimensional motion of the air-to-air communication transceiver, rotation and occlusion of the fuselage, the generation and calculation methods of channel parameters are given at the simulation level, thereby realizing efficient and accurate reproduction of the UAV air-to-air channel.

[0015] Second, the present invention proposes a method for modeling and simulating UAV air-to-air channels in low-altitude urban environments. This method incorporates rooftop reflections and incorporates the occlusion effect of the UAV fuselage for power correction. Compared to traditional standardized models, this method more accurately characterizes non-line-of-sight propagation paths in low-altitude urban environments, addressing the limitations of current models and improving the accuracy of channel modeling.

[0016] Third, the present invention's air-to-air channel modeling and simulation method for UAVs in urban low-altitude scenarios uses terrain statistics to calculate parameters related to rooftop reflection paths. This method provides a method for calculating parameters related to non-line-of-sight paths, improving the inaccuracy of traditional methods in calculating line-of-sight path power when the aircraft is obstructed. This method enables efficient and accurate simulation and reproduction of air-to-air channels in urban scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of the UAV air-to-air channel modeling and simulation method for urban low-altitude scenarios of the present invention;

[0018] Figure 2 Schematic diagram of the air-to-air communication scenario of the UAV in the present invention;

[0019] Figure 3 The power delay diagram of the rooftop reflection path and the non-line-of-sight path in the present invention;

[0020] Figure 4 This is a schematic diagram of the channel coefficients for the first 3 seconds generated by the present invention;

[0021] Figure 5 Schematic diagram of user-defined parameters entered in the example;

[0022] Figure 6 Schematic diagram of the UAV motion parameters in the example. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0024] The present invention discloses a UAV air-to-air channel modeling and simulation method for low-altitude urban scenes, comprising the following steps:

[0025] 1) Input user configuration parameters, including: communication scenario type, carrier frequency, antenna type, initial position vector and velocity vector of the UAV transceiver, and motion trajectory of the transceiver;

[0026] 2) Calculate the delay, total phase, and power of the UAV’s line-of-sight path between the transmitter and receiver in the channel model based on the transmitter and receiver locations;

[0027] 3) Based on the communication scenario, calculate the delay, total phase, and power of the rooftop reflection path in the channel model;

[0028] 4) Calculate the delay, total phase, and power of the non-line-of-sight path in the channel model based on geometric relationships;

[0029] 5) Establish the UAV air-to-air channel model, substitute the parameters calculated in steps 1) to 4), and output the channel coefficients.

[0030] Step 2) specifically includes:

[0031] 21) Calculate the position vector of the transmitting and receiving antennas as follows:

[0032] calculate The location of the drone's transmitter and receiver at all times :

[0033] ;

[0034] in and Represent the velocity vectors of the UAV transmitter and receiver respectively, and the calculation method is:

[0035] ;

[0036] in, represents the modulo operation, Indicates the azimuth angle of the transmitting and receiving ends, The pitch angle that represents the movement speed of the transmitter and receiver.

[0037] Then the position vector of the transmitting and receiving antennas It can be expressed as:

[0038] ;

[0039] in, and The center of the transmitting and receiving end points to the transmitting end and the receiving end respectively. Root and Vector of root antenna element units.

[0040] 22) Calculate the time delay of the line-of-sight path based on the position vector of the transmitting and receiving antennas calculated in step 21) :

[0041] ;

[0042] in represents the line-of-sight path length, is the propagation speed of electromagnetic waves.

[0043] 23) Calculate the total phase of the line-of-sight path using the following steps:

[0044] 231) Calculate the initial phase of the line-of-sight path based on the line-of-sight path length calculated in step 22) :

[0045] ;

[0046] in, represents the wave number, Indicates the carrier frequency in MHz.

[0047] 232) Calculate the Doppler phase of the line-of-sight path :

[0048] ;

[0049] Where, The angular unit vector representing the line-of-sight path of the transmitter can be obtained by converting the azimuth and elevation angles of the line-of-sight path into a Cartesian coordinate system. The azimuth of the transmitter is , receiving end azimuth , Transmitter pitch angle and the receiving end pitch angle The calculation method is:

[0050] ;

[0051] ;

[0052] ;

[0053] ;

[0054] 233) Calculate antenna correction phase for line-of-sight paths :

[0055] ;

[0056] in The attitude matrix representing the transmitting or receiving end of the drone is provided in real time by the drone's own inertial measurement unit and can be modeled as:

[0057] ;

[0058] , and They represent the roll angle, pitch angle and yaw angle in the attitude angle respectively.

[0059] 234) Calculate the total phase of the line-of-sight path based on the initial phase, Doppler phase and antenna correction phase of the line-of-sight path in steps 231), 232) and 233) :

[0060] ;

[0061] 24) Calculate the power of the line-of-sight path. The steps are as follows:

[0062] 241) Define the fuselage structure parameter set :

[0063] ;

[0064] in, represents the leading edge sweep angle, represents the trailing edge sweep angle, represents the dihedral angle, Indicates the width of the fuselage. represents the wing span, Indicates the fuselage length, represents the vertical distance between the antenna and the xy plane, Indicates the chord length of the wing.

[0065] 242) Calculate the position vector of the diffraction point on the fuselage :

[0066] ;

[0067] in Indicates the diffraction paths; Indicates the Root launch or The vector from the root receiving antenna element to the edge of the fuselage is determined by the fuselage structure parameter set and coordinate system.

[0068] 243) To describe the attenuation of the signal, define the dimensionless parameter :

[0069] ;

[0070] in It represents the vertical distance from the diffraction point on the fuselage to the straight line connecting the transmitter and the receiver. It represents the angle (in radians) formed by the transmitting end, the diffraction point and the receiving end, and the calculation methods are:

[0071] ;

[0072] ;

[0073] 244) Calculate the power factor of the line-of-sight path considering the obstruction effect of the fuselage :

[0074] ;

[0075] in and Indicates the threshold value determined according to the diffraction attenuation degree, is a correction constant.

[0076] Step 3) specifically includes:

[0077] 31) Calculate the time delay of the roof reflection path. The steps are as follows:

[0078] 311) Calculate the path length of the roof reflection path :

[0079] ;

[0080] in To represent the coordinates of the roof reflection point, establish a coordinate system along the projection of the line between the transmitter and receiver on the horizontal plane as the x-axis, determine the y-axis component to be 0, and calculate the remaining components using the triangle similarity property as follows:

[0081] ;

[0082] ;

[0083] in represents the height of the roof reflection point from the ground, and its probability density function is:

[0084] ;

[0085] in represents the proportion of land covered by buildings, Indicates the average building height.

[0086] 312) Calculate the delay based on the path length of the roof reflection path :

[0087] ;

[0088] 32) Calculate the total phase of the roof reflection path as follows:

[0089] 321) Calculate the initial phase of the roof reflection path :

[0090] ;

[0091] 322) Calculate the Doppler phase of the roof reflection path :

[0092] ;

[0093] Unit direction vector and The azimuth and elevation angles of the roof reflection path can be converted into Cartesian coordinates. and pitch angle The calculation method is:

[0094] ;

[0095] ;

[0096] 323) Calculate antenna correction phase for rooftop reflection path :

[0097] ;

[0098] 324) Calculate the total phase of the roof reflection path based on the initial phase, Doppler phase and antenna correction phase in steps 321), 322) and 323) :

[0099] ;

[0100] 33) Calculate the power factor of the roof reflection path :

[0101] ;

[0102] in represents the complex reflection coefficient, which is calculated as:

[0103] ;

[0104] in is the polarization correlation coefficient and obeys , Indicates the relative dielectric constant of the reflective material.

[0105] Step 4) specifically includes:

[0106] 41) Calculate the delay of non-line-of-sight paths as follows:

[0107] 411) Calculate the path length of the mth subpath of the nth non-line-of-sight path :

[0108] ;

[0109] in Represents the coordinate vector of the scattering point, which can be written as , the calculation method is:

[0110] ;

[0111] Where R represents the horizontal distance parameter that limits the distribution of scatterers, and H represents the vertical distance parameter that limits the distribution of scatterers.

[0112] 412) Calculate the delay of the mth subpath of the nth non-line-of-sight path :

[0113] ;

[0114] 42) Calculate the total phase of the mth subpath in the nth non-line-of-sight path as follows:

[0115] 421) Calculate the initial phase of the mth subpath in the nth non-line-of-sight path :

[0116] ;

[0117] 422) Calculate the Doppler phase of the mth subpath in the nth non-line-of-sight path :

[0118] ;

[0119] in The angular unit vector representing the mth subpath in the nth non-line-of-sight path at the transmitter or receiver can be obtained by converting the azimuth and elevation angles into a Cartesian coordinate system. and pitch angle The calculation method is:

[0120] ;

[0121] ;

[0122] 423) Calculate the antenna correction phase of the mth subpath in the nth non-line-of-sight path :

[0123] ;

[0124] 424) Calculate the total phase of the mth subpath in the nth non-line-of-sight path based on the initial phase, Doppler phase and antenna correction phase in steps 421), 422) and 423). :

[0125] ;

[0126] 43) Calculate the raw power factor of non-line-of-sight paths :

[0127] ;

[0128] in, represents the delay scalar, represents the delay spread, Represents cluster shadow fading following a Gaussian distribution and calculates the power factor of the non-line-of-sight path :

[0129] .

[0130] Step 5) specifically includes:

[0131] The constructed low-altitude drone air-to-air channel model is as follows:

[0132] ;

[0133] Where, Indicates the The transmitting antenna and The channel impulse response between the root receiving antennas, t represents time, Indicates delay, represents the time-varying Rice factor, and Represents the power coefficient of the roof reflection path and other non-line-of-sight paths, satisfying . 、 and They represent the channel impulse responses of the line-of-sight path, rooftop reflection path, and other non-line-of-sight paths, respectively. They are specifically expressed as follows:

[0134] ;

[0135] ;

[0136] ;

[0137] in, represents the number of non-line-of-sight paths, Indicates the number of subpaths. 、 and represents the power factor, 、 and represents the phase component of the propagation path, 、 and Represents the corresponding delay, and represents the antenna pattern function related to attitude, which is calculated as:

[0138] ;

[0139] ;

[0140] in and Represents the antenna pattern components of the transmitter or receiver in the vertical plane and the horizontal plane. 、 、 and Indicates the initial phase of different polarization combinations, used to describe the polarization phase changes in line-of-sight and non-line-of-sight paths. shows the cross-polarization power ratio. Represents the attitude matrix of the UAV transmitter or receiver.

[0141] Examples

[0142] refer to Figure 1 and Figure 2 As shown, one example of the UAV air-to-air channel modeling and simulation method for urban low-altitude scenes of the present invention is as follows:

[0143] 1) Input user-defined parameters, including: communication scenario type, initial position vector of the UAV transceiver, speed, three-dimensional motion trajectory, azimuth and pitch angle of motion direction, carrier frequency, antenna type, roof material, simulation time, channel state update interval, etc. Specific parameters are shown in Figure 5 and Figure 6 .

[0144] 2) Calculate the delay, total phase, and power of the line-of-sight path using the following steps:

[0145] 21) Calculate the position vector of the transmitting and receiving antennas as follows:

[0146] According to the input of the initial position and speed information of the UAV, calculate The location of the drone's transmitter and receiver at all times :

[0147] ;

[0148] in and are the velocity vectors of the transmitting and receiving ends of the UAV, respectively, which can be expressed as:

[0149] ;

[0150] in, represents the modulo operation, and Respectively represent the azimuth and pitch angles of the motion speed. For example, the velocity vector at the initial moment can be expressed as:

[0151] , ;

[0152] Then the position vector of the transmitting and receiving antennas It can be calculated as:

[0153] ;

[0154] in Indicates the direction from the center of the transmitter to the The vector of root antenna element units, Indicates the direction from the center of the receiving end to the Vector of root antenna element units.

[0155] 22) Calculate the time delay of the line-of-sight path based on the position vector of the transmitting and receiving antennas calculated in step 21) :

[0156] ;

[0157] in represents the length of the line-of-sight path, Represents the propagation speed of electromagnetic waves, and its value is .

[0158] 23) Calculate the total phase of the line-of-sight path using the following steps:

[0159] 231) Based on the line-of-sight path length obtained in step 22), calculate the initial phase of the line-of-sight path :

[0160] ;

[0161] 232) Calculate the Doppler phase of the line-of-sight path :

[0162] ;

[0163] Unit direction vector It can be obtained by converting the azimuth and elevation angles of the line-of-sight path into Cartesian coordinates.

[0164] 233) Calculate the antenna correction phase for line-of-sight paths :

[0165] ;

[0166] If the simulation is for 2.5s, the attitude matrix of the transmitter and receiver can be calculated as:

[0167] , ;

[0168] 234) Calculate the total phase of the line-of-sight path based on the initial phase, Doppler phase and antenna correction phase of the line-of-sight path in steps 231), 232) and 233). :

[0169] ;

[0170] 24) Calculate the power of the line-of-sight path. The steps are as follows:

[0171] 241) Define the fuselage structure parameter set :

[0172] ;

[0173] in, represents the leading edge sweep angle, represents the trailing edge sweep angle, represents the dihedral angle, Indicates the width of the fuselage. represents the wing span, Indicates the fuselage length, represents the vertical distance between the antenna and the xy plane, Indicates the chord length of the wing. Its value is .

[0174] 242) Determine the position vector of the fuselage diffraction point using the fuselage structure parameter set and the position vector of the drone antenna in step 21) :

[0175] ;

[0176] in Indicates the diffraction paths, Represents the vector from the transmitting or receiving antenna unit to the edge of the fuselage.

[0177] 243) Define dimensionless parameters To quantify the degree of signal attenuation:

[0178] ;

[0179] in It represents the vertical distance from the diffraction point of the fuselage to the straight line connecting the transmitter and the receiver. It represents the angle (in radians) formed by the transmitting end, the diffraction point and the receiving end, and the calculation methods are:

[0180] ;

[0181] ;

[0182] 244) Calculate the power factor of the line-of-sight path considering the obstruction effect of the fuselage :

[0183] .

[0184] Step 3) specifically includes:

[0185] 31) Calculate the time delay of the roof reflection path. The steps are as follows:

[0186] 311) Calculate the path length of the roof reflection path :

[0187] ;

[0188] in To represent the coordinates of the roof reflection point, establish a coordinate system along the projection of the line between the transmitter and receiver on the horizontal plane as the x-axis, determine the y-axis component to be 0, and calculate the remaining components using the triangle similarity property as follows:

[0189] ;

[0190] ;

[0191] in Indicates the height of the roof reflection point from the ground, generated using statistical methods , its probability density function is:

[0192] ;

[0193] 312) Calculate the time delay based on the path length of the roof reflection path calculated in step 311) :

[0194] ;

[0195] 32) Calculate the total phase of the roof reflection path as follows:

[0196] 321) Calculate the initial phase of the roof reflection path based on the path length obtained in step 311) :

[0197] ;

[0198] 322) Calculate the Doppler phase of the roof reflection path :

[0199] ;

[0200] 323) Calculate the antenna correction phase in the roof reflection path :

[0201] ;

[0202] 324) Calculate the total phase of the roof reflection path based on the initial phase, Doppler phase and antenna correction phase in steps 321), 322) and 323) :

[0203] ;

[0204] 33) Calculate the power factor of the roof reflection path :

[0205] .

[0206] Step 4) specifically includes:

[0207] 41) Calculate the delay of the mth sub-path of the nth non-line-of-sight path as follows:

[0208] 411) Calculate the path length of the mth subpath in the nth non-line-of-sight path :

[0209] ;

[0210] in Represents the coordinate vector of the scattering point, which can be written as , the calculation method is: ;

[0211] 412) Calculate the delay of the mth sub-path in the nth non-line-of-sight path:

[0212] ;

[0213] 42) Calculate the total phase of the mth subpath in the nth non-line-of-sight path as follows:

[0214] 421) Calculate the initial phase of the mth sub-path in the nth non-line-of-sight path based on the path length obtained in step 411) :

[0215] ;

[0216] 422) Calculate the Doppler phase of the mth subpath in the nth non-line-of-sight path :

[0217] ;

[0218] 423) Calculate the antenna correction phase of the mth subpath in the nth non-line-of-sight path :

[0219] ;

[0220] 424) Calculate the total phase of the mth subpath in the nth non-line-of-sight path based on the initial phase, Doppler phase and antenna correction phase of the subpath in steps 421), 422) and 423). :

[0221] ;

[0222] 43) Calculate the raw power factor of non-line-of-sight paths :

[0223] ;

[0224] in, represents the delay scalar, represents the delay spread, Represents cluster shadow fading following a Gaussian distribution and calculates the power factor of the non-line-of-sight path :

[0225] .

[0226] The delay and power of the rooftop reflection path and non-line-of-sight path calculated in this example are as follows: Figure 3 shown.

[0227] Step 5) specifically includes:

[0228] The constructed low-altitude drone air-to-air channel model is as follows:

[0229] ;

[0230] Where, Indicates the The transmitting antenna and The channel impulse response between the root receiving antennas, t represents time, Indicates delay, represents the time-varying Rice factor, and Represents the power coefficient of the roof reflection path and other non-line-of-sight paths, satisfying . 、 and The channel impulse response for line-of-sight paths, rooftop reflection paths, and other non-line-of-sight paths is expressed as follows:

[0231] ;

[0232] ;

[0233] ;

[0234] in, represents the number of non-line-of-sight paths, Indicates the number of subpaths, using an omnidirectional antenna, and represents the antenna pattern function related to attitude and Take the value 1, substitute the parameters such as delay, phase, power factor calculated in steps 1) to 4), input them into the low-altitude UAV air-to-air channel model, and output the channel coefficient. The channel coefficient obtained in this example is as follows Figure 4 shown.

[0235] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0236] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A UAV air-to-air channel modeling and simulation method for urban low-altitude scenes, characterized by: The method comprises the following steps: S1, based on the input transceiver position parameters, calculates the delay, total phase and power of the UAV transceiver line-of-sight path in the channel model; combined with the attitude-related line-of-sight path antenna pattern function, calculates the channel impulse response of the line-of-sight path; S2, combined with the communication scenario parameters, calculates the delay, total phase, and power of the rooftop reflection path in the channel model; combined with the attitude-related non-line-of-sight path antenna pattern function, calculates the channel impulse response of the rooftop reflection path; S3, combining the height and horizontal geometric relationship parameters of the restricted scatterer distribution, calculates the delay, total phase, and power of the non-line-of-sight path in the channel model; combining the attitude-related non-line-of-sight path antenna pattern function, calculates the channel impulse response of the non-line-of-sight path; S4, establish a UAV air-to-air channel model, substitute the calculation results of steps S1 to S3, and output the channel coefficient; the UAV air-to-air channel model is: Where h pq (t, τ) represents the channel impulse response between the pth transmitting antenna and the qth receiving antenna, t represents time, τ represents delay, K(t) represents the time-varying Ricean factor, η RSR (t) and η NL (t) represents the power coefficient of the roof reflection path and the non-line-of-sight path, satisfying η RSR (t)+η NL (t) = 1; and Represents the channel impulse response of the line-of-sight path, rooftop reflection path, and non-line-of-sight path.

2. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S1, the process of calculating the delay, total phase, and power of the UAV transceiver line-of-sight path in the channel model includes the following steps: S11, calculate the position L of the drone's transceiver at time t+Δt Tx / Rx (t+Δt): where v Tx (t) and v Rx (t) represents the velocity vectors of the transmitting and receiving ends of the UAV at time t, respectively. The superscripts Tx and Rx represent the transmitting and receiving ends, respectively. The position vector of the transmitting and receiving antennas Expressed as: Among them, e p (t) represents the vector from the center of the transmitter to the pth antenna element, e q (t) represents the vector pointing from the center of the receiving end to the qth antenna element; S12, calculate the time delay of the line-of-sight path based on the position vector of the transmitting and receiving antennas calculated in step S11 in represents the length of the line-of-sight path, and c is the propagation speed of electromagnetic waves; S13, calculate the initial phase of the line-of-sight path Where k = 2πf c / c represents the wave number, f c Indicates the carrier frequency; Calculate the Doppler phase of a line-of-sight path in, The angular unit vector representing the line-of-sight path of the transmitter; Calculate antenna correction phase for line-of-sight paths where R P，Tx / Rx (t) represents the attitude matrix of the UAV transmitter or receiver, s L，Rx (t) represents the angular unit vector of the receiving end’s line-of-sight path; Calculate the total phase for a line-of-sight path S14, define the fuselage structure parameter set U: U={Θ l ,I b ,I d ,d a ,d w ,l a ,l xy ,l c }; Among them, Θ 1 represents the leading edge sweep angle, Θ b represents the trailing edge sweep angle, Θ d represents the dihedral angle, d a Indicates the width of the fuselage, d w represents the wing span, l a Indicates the fuselage length, l xy represents the vertical distance between the antenna and the xy plane, l c represents the wing chord length; Calculate the position vector L of the diffraction point on the fuselage i (t): Where i represents the i-th diffraction path, e p / q，i Represents the vector from the pth transmitting or qth receiving antenna unit to the edge of the fuselage; Define the dimensionless parameter ε i (t): where d i (t) represents the vertical distance from the diffraction point on the fuselage to the straight line connecting the transmitter and the receiver, Θ i (t) represents the angle formed by the transmitting end, the diffraction point and the receiving end; Calculate the power factor of the line-of-sight path considering the shadowing effect of the fuselage Where ε1 represents the threshold for distinguishing between no obstruction and partial obstruction based on the degree of diffraction attenuation, ε2 represents the threshold for distinguishing between partial obstruction and complete obstruction based on the degree of diffraction attenuation, and J0 is the correction constant.

3. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S1, the channel impulse response of the line-of-sight path is: Where δ(·) represents the Dirac function, represents the power factor for the line-of-sight path, represents the total phase of the line-of-sight path, represents the delay of the line-of-sight path, The attitude-dependent line-of-sight path antenna pattern function: in Represents the antenna pattern component of the transmitter in the vertical plane, represents the antenna pattern component of the receiving end in the vertical plane, Represents the antenna pattern component of the transmitter in the horizontal plane, Represents the antenna pattern component of the receiving end in the horizontal plane; Indicates vertical transmission and vertical reception polarization mode, Indicates the horizontal transmission and horizontal reception polarization modes, both used to describe the polarization phase change of the line of sight; R P，Tx / Rx (t) represents the attitude matrix of the UAV transmitter or receiver.

4. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S2, the process of calculating the delay, total phase, and power of the rooftop reflection path in the channel model in combination with the communication scenario parameters includes the following steps: S21, calculate the path length of the roof reflection path in Represents the coordinate components of the position vector of the receiving antenna, Represents the coordinate components of the position vector of the transmitting antenna, represents the coordinates of the roof reflection point, Represent the coordinate components of the roof reflection point. Establish a coordinate system along the projection of the line between the transmitter and receiver on the horizontal plane as the x-axis. Determine the y-axis component to be 0. The remaining components are calculated using the triangle similarity property as follows: Among them, e x represents the unit vector of the x-axis, e z represents the unit vector of the z-axis, h RSR represents the height of the roof reflection point from the ground, and its probability density function is: where p α represents the proportion of land covered by buildings, γ A represents the average building height; Calculate the time delay based on the path length of the roof reflection path Where c is the propagation speed of electromagnetic waves; represents the path length of the roof reflection path; S22, calculate the initial phase of the roof reflection path Where k = 2πf c / c represents the wave number, f c Indicates the carrier frequency; Calculate the Doppler phase of the roof reflection path Among them, s RSR，Tx (t) represents the unit direction vector of the reflection path of the roof of the transmitter, S RSR，Rx (t) represents the unit direction vector of the reflection path of the receiving end roof, and Respectively Velocity vectors of the transmitting and receiving ends of the UAV at the moment; Calculate antenna correction phase for rooftop reflection path Among them, L Tx / Rx (t) represents the position of the transmitting end or receiving end of the UAV at time t, S P，Tx / Rx (t) represents the attitude matrix of the transmitting or receiving end of the UAV; Calculate the total phase of the roof reflection path S23, calculate the power factor of the roof reflection path where Γ RSR (t) represents the complex reflection coefficient.

5. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S2, the channel impulse response of the roof reflection path is: Where N represents the number of non-line-of-sight paths; Represents the power factor of the roof reflection path, represents the total phase of the roof reflection path, represents the time delay of the roof reflection path, represents the attitude-dependent NLOS path antenna pattern function; in Represents the antenna pattern component of the transmitter in the vertical plane, represents the antenna pattern component of the receiving end in the vertical plane, Represents the antenna pattern component of the transmitter in the horizontal plane, Represents the antenna pattern component of the receiving end in the horizontal plane; Indicates the initial phase of vertical transmission and vertical reception polarization in non-line-of-sight path. Indicates the initial phase of horizontal transmission and horizontal reception polarization in non-line-of-sight path. Indicates the initial phase of vertical transmission and horizontal reception polarization in non-line-of-sight path. Indicates the initial phase of horizontal transmission and vertical reception polarization in non-line-of-sight path; represents the cross-polarization power ratio; R P，Tx / Rx (t) represents the attitude matrix of the UAV transmitter or receiver.

6. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S3, the process of calculating the delay, total phase, and power of the non-line-of-sight path in the channel model in combination with the geometric relationship parameters that limit the distribution of scatterers includes the following steps: S31, calculate the path length of the mth sub-path of the nth non-line-of-sight path in, represents the position vector of the pth transmitting antenna unit at time t, Represents the position vector of the qth receiving antenna unit at time t; Represents the coordinate vector of the scattering point, denoted as The calculation method is: Among them, R represents the horizontal distance parameter that limits the distribution of scatterers, H represents the vertical distance parameter that limits the distribution of scatterers, and L Tx / Rx (t) represents the position of the transmitting or receiving end of the UAV at time t; Calculate the delay of the mth sub-path of the nth non-line-of-sight path S32, calculate the initial phase of the mth sub-path in the nth non-line-of-sight path Where k = 2πf c / c represents the wave number, f c Indicates the carrier frequency; Calculate the Doppler phase of the mth subpath in the nth non-line-of-sight path in Represents the angular unit vector of the mth subpath in the nth non-line-of-sight path at the transmitter or receiver, and Respectively Velocity vectors of the transmitting and receiving ends of the UAV at the moment; Calculate the antenna correction phase of the mth subpath in the nth non-line-of-sight path Where R P，Tx / Rx (t) represents the attitude matrix of the transmitting or receiving end of the UAV; Calculate the total phase of the mth subpath in the nth non-line-of-sight path S33, calculate the raw power factor of the non-line-of-sight path Among them, r τ represents the delay scalar, σ τ represents delay spread, SF c Represents cluster shadow fading following a Gaussian distribution and calculates the power factor of the non-line-of-sight path Where N is the number of non-line-of-sight paths and M is the number of sub-paths.

7. The UAV air-to-air channel modeling and simulation method for urban low-altitude scenes according to claim 1 is characterized in that: In step S3, the channel impulse response of the non-line-of-sight path is: Where N represents the number of non-line-of-sight paths and M represents the number of sub-paths; represents the power factor of the non-line-of-sight path, represents the phase component of the non-line-of-sight path, represents the delay of the non-line-of-sight path, represents the antenna pattern function related to attitude.

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