Low earth orbit satellite wireless channel modeling method based on geometric random

Abstract

The invention discloses a low earth orbit satellite wireless channel modeling method based on geometric random, and relates to the technical field of wireless channel simulation, and the method comprises the steps: generating a satellite channel variation caused by satellite motion through an FPGA according to on-satellite load antenna information of a satellite, a satellite departure angle and a satellite velocity vector; generating horizontal and vertical influence components of a satellite directional diagram according to on-satellite load antenna information and a satellite departure angle; generating ground station horizontal and vertical channel variations caused by the movement of the satellite ground station through a ground station geometric channel model according to the ground load antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector; transmitting signals of the transmitter are input into the channel simulation instrument, and a simulation result is output according to the satellite channel change, the horizontal and vertical influence components of the satellite azimuth map, the horizontal and vertical channel variation of the ground station and the transmitting signals of the transmitter. Therefore, the data volume during satellite-ground wireless channel simulation is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of wireless channel simulation, and in particular to a method for modeling low-orbit satellite wireless channels based on geometric randomness. Background Art

[0002] At present, the speed of low-orbit satellites is extremely high, usually up to 7.9km / s. Such high-speed mobility places extremely high demands on the real-time and stability of satellite communications. Low-orbit satellite communications rely on large-scale phased array communication systems, which provide efficient communication support for low-orbit satellites with their multi-beam forming and fast scanning capabilities. However, due to this high efficiency, the system will generate a large amount of channel coefficient data during the satellite's overhead time.

[0003] This huge amount of data not only puts tremendous pressure on the data transmission of the channel emulator, but also poses a severe challenge to its storage and exchange capabilities.

[0004] In this context, how to reduce the amount of data during channel simulation has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the main purpose of the present application is to provide a low-orbit satellite wireless channel modeling method based on geometric randomness, with the aim of reducing the amount of data during wireless channel simulation.

[0006] The first aspect of the present application provides a method for modeling a low-orbit satellite wireless channel based on geometric randomness, the method comprising:

[0007] Through the field programmable gate array FPGA, the satellite channel change caused by satellite movement is generated according to the satellite's onboard payload antenna information, satellite departure angle and satellite velocity vector;

[0008] Generate the horizontal impact component of the satellite pattern and the vertical impact component of the satellite pattern according to the onboard payload antenna information and the satellite departure angle;

[0009] Through the ground station geometric channel model, according to the ground load antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector, the ground station horizontal channel change and the ground station vertical channel change caused by the satellite ground station movement are generated;

[0010] The transmitter's transmission signal is input into the channel simulator, and the simulation result is output according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitter's transmission signal.

[0011] In some implementations of the first aspect of the present application, the method further includes:

[0012] Generate satellite departure angle and satellite velocity vector through satellite trajectory points;

[0013] The ground station arrival angle and ground station velocity vector are generated through the satellite ground station trajectory points.

[0014] In some implementations of the first aspect of the present application, outputting simulation results according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the ground station horizontal channel change, and the ground station vertical channel change includes:

[0015] Multiplying the horizontal impact component of the satellite azimuth diagram and the horizontal channel change of the ground station to obtain a first calculation result;

[0016] Multiplying the vertical impact component of the satellite azimuth diagram and the vertical channel change of the ground station to obtain a second calculation result;

[0017] The sum of the first calculation result and the second calculation result is multiplied by the satellite channel change amount, and the transmission signal of the transmitter is used as a simulation parameter to output the simulation result.

[0018] In some implementations of the first aspect of the present application, the ground station channel model is a channel model established based on the ground 5GNR standard.

[0019] In some implementations of the first aspect of the present application, the satellite channel change amount is generated by a satellite channel change formula, and the satellite channel change formula is:

[0020]

[0021] Among them, H sa,v (t) represents the satellite channel change at different times t, j represents the imaginary unit, π represents the circumference of a circle, represents the satellite departure angle, represents the coordinate vector of the sth transmitting antenna determined according to the onboard payload antenna information, represents the satellite velocity vector, t represents time, and λ 0 Indicates wavelength.

[0022] In some implementations of the first aspect of the present application, the ground station horizontal channel change amount is generated by a ground station horizontal channel change formula, and the ground station horizontal channel change formula is:

[0023]

[0024] Among them, H ue,v1(t) represents the change of the ground station horizontal channel at different times t, F rx,u,θ represents the directional component of the elevation angle θ of the u-th receiving antenna of the satellite ground station, θ 1,ZOA represents the pitch angle θ determined by the arrival zenith angle ZOA of cluster 1, represents the arrival azimuth of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0025] In some implementations of the first aspect of the present application, the ground station vertical channel change amount is generated by a ground station vertical channel change formula, and the ground station vertical channel change formula is:

[0026]

[0027] Among them, H ue,v2 (t) represents the change of the vertical channel of the ground station at different times t, represents the azimuth of the u-th receiving antenna of the satellite ground station The directional pattern component, θ 1,ZOA represents the pitch angle θ determined according to the arrival zenith angle ZOA of cluster 1, represents the arrival azimuth of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0028] The second aspect of the present application provides a low-orbit satellite wireless channel modeling device based on geometric randomness, the device is a channel simulator, and the device includes:

[0029] A satellite channel change determination module is used to generate a satellite channel change amount caused by satellite motion according to onboard payload antenna information, a satellite departure angle of the satellite, and a satellite velocity vector through a field programmable gate array FPGA;

[0030] A satellite pattern impact determination module is used to generate a horizontal impact component of the satellite pattern and a vertical impact component of the satellite pattern according to the onboard payload antenna information and the satellite departure angle;

[0031] The ground station channel change determination module is used to generate the ground station horizontal channel change amount and the ground station vertical channel change amount caused by the satellite ground station movement through the ground station geometric channel model according to the ground load antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector;

[0032] The channel simulation result output module is used to input the transmitter's transmission signal into the channel simulator, and output the simulation result according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitter's transmission signal.

[0033] The third aspect of the present application provides a low-orbit satellite wireless channel modeling device based on geometric randomness, and the channel simulation device includes a memory and a processor, and the processor is used to execute the program stored in the memory and run any one of the low-orbit satellite wireless channel modeling methods based on geometric randomness provided in the first aspect of the present application.

[0034] The fourth aspect of the present application provides a readable storage medium on which a computer program is stored, characterized in that when the computer program is executed by a processor, it implements the various steps of any one of the geometric random-based low-orbit satellite wireless channel modeling methods provided in the first aspect of the present application.

[0035] The technical solution provided by this application has the following beneficial effects:

[0036] In the technical solution provided in the present application, first, through the field programmable gate array FPGA, the satellite channel change caused by the satellite movement is generated according to the on-board payload antenna information, the satellite departure angle of the satellite and the satellite velocity vector; then, the horizontal influence component of the satellite pattern and the vertical influence component of the satellite pattern are generated according to the on-board payload antenna information and the satellite departure angle; thereafter, through the ground station geometric channel model, according to the ground payload antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector, the ground station horizontal channel change and the ground station vertical channel change caused by the satellite ground station movement are generated; finally, the transmitter's transmission signal is input into the channel simulator, and the simulation result is output according to the satellite channel change, the horizontal influence component of the satellite azimuth map, the vertical influence component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitter's transmission signal.

[0037] In the above process, FPGA is used to generate the channel change caused by the satellite movement according to the satellite's onboard payload antenna information, satellite departure angle and satellite velocity vector, so that the influence of the relatively high-speed moving satellite on the channel during the movement is realized through the FPGA logic in the channel simulator to quickly simulate the channel change, reduce the intermediate data generated during the simulation, and save wireless channel simulation resources; through the ground station geometric channel model, according to the satellite ground station's ground load information, ground station arrival angle and ground station velocity vector, the channel change caused by the satellite ground station is generated, so that the influence of the relatively low-speed moving satellite ground station on the channel during the movement is realized through the geometric channel model. Channel modeling can relatively statically describe the influence of the low-speed movement of the ground station on the channel, without the need for real-time processing like FPGA, which can further save the generation time and storage resources of the channel impulse response. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of calculating a speed scalar provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of calculating the satellite motion distance provided in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of a flow chart of a method for modeling a low-orbit satellite wireless channel based on geometric randomness provided in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of a simulation process of a channel simulator provided in an embodiment of the present application;

[0042] Figure 5 A schematic diagram of a process flow of a low-orbit satellite wireless channel modeling method based on geometric randomness in practical application provided in an embodiment of the present application;

[0043] Figure 6 A schematic diagram of the structure of a low-orbit satellite wireless channel modeling device based on geometric randomness provided in an embodiment of the present application;

[0044] Figure 7 A schematic diagram of the structure of a low-orbit satellite wireless channel modeling device based on geometric randomness provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] The terms "first", "second", "third", "fourth", etc. in the specification and claims of the present application and the above-mentioned drawings, if present, are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] In the 3GPP-38901 protocol, the geometry-based modeling formula is as follows:

[0048]

[0049] In formula (1), Indicates non-line-of-sight NLOS, Indicates the line of sight LOS, K R is the Rice K factor, K R It represents the proportion of the direct view path in all paths. Each non-direct view path is composed of 20 sub-paths.

[0050] In the above formula (1), the non-direct line of sight The modeling method is as follows:

[0051]

[0052] In the above formula (1), the straight line diameter The modeling method is as follows:

[0053]

[0054] In equations (2) and (3), the parameters are explained as follows: u represents the antenna index of the receiving antenna; s represents the antenna index of the transmitting antenna; n represents the cluster index; m represents the subpath index; P n represents the normalized nth cluster power; M represents the number of subpaths; θ represents the elevation angle; Indicates the azimuth, F rx,u,θ represents the directional pattern component of the u-th receiving antenna elevation angle θ; represents the azimuth of the uth receiving antenna The directional pattern component of ; κ represents the cross-polarization ratio; Φ represents the uniformly distributed random phase; The spherical unit coordinates representing the angle of arrival of the receiving terminal; The spherical unit coordinates representing the departure angle of the transmitting terminal; represents the coordinate vector of the u-th receiving antenna; represents the coordinate vector of the sth transmitting antenna; 0 represents the wavelength; v represents the velocity vector of the terminal.

[0055] It is understandable that for communication between a satellite and a satellite ground station, there is a continuous relative motion between the transmitter and the receiver, so for any time t, or The terminal velocity vector v in can be expressed as:

[0056]

[0057] In equation (4), the velocity vector of the ground satellite station is It can be expressed as:

[0058]

[0059] Among them, v rx They represent the velocity scalar of the receiving end at time t, θ v,rx represents the pitch angle of the receiving end at time t, φ v,rx They represent the azimuth of the receiving end's motion at time t,

[0060] In equation (4), the satellite velocity vector It can be expressed as:

[0061]

[0062] Among them, v tx represents the velocity scalar of the transmitter at time t, θ v,tx represents the pitch angle of the transmitter at time t, φ v,tx Indicates the azimuth of the transmitter's movement at time t.

[0063] In the design of the simulation scheme of the embodiment of the present application, it is considered that the satellite-to-ground wireless channel has the characteristics of large spatial span, long time extension, and fewer channel feedback link channels. The distance from the satellite to the ground terminal is much greater than the distance from the ground base station to the user equipment, resulting in a longer delay in signal transmission. In addition, due to the influence of the atmosphere such as atmospheric scattering, absorption and refraction, the signal will experience more attenuation, propagation delay, phase distortion and multipath effect during transmission. Therefore, the modeling method of the ground 5G (5th generation mobile networks) cell is not suitable for satellite-to-ground wireless channel modeling.

[0064] Here, it is assumed that the satellite-to-ground wireless communication channel modeling adopts the implementation method of half-wavelength sampling density ρ, that is, ρ points are sampled within half a wavelength, then the distance d between the transmitter and receiver can be expressed as: d = λ / 2ρ. Further assume that the half-wavelength sampling density ρ = 8, the center frequency is 2.6GHz, the wavelength is 0.1154m, and the half-wavelength is 0.0577m, that is, 8 points are sampled at a distance of 0.0577m. Based on this, through the Doppler formula f d =v / c×f center × cosθ, we can calculate that the distance d between every two points is 0.0072m. Among them, c is the speed of light, f center is the center frequency, and c and f center are all fixed values, cosθ is the angle of the incoming wave, which is determined by the geometric relationship between the transmitting and receiving ends. Figure 1 As shown in the figure, since |v| = d / t′, |v| represents the scalar value of velocity, and t′ represents the time between two sample points. In this way, without considering the direction, the Doppler formula can be converted to f d =d / (t'c)×f center ×cosθ.

[0065] It can be understood that the direction of the velocity is the direction of motion of the terminal, which can be realized through geometric relationships. From the converted Doppler formula, it can be seen that after the half-wavelength sampling density is determined, the simulation system can control the Doppler simply by controlling t'.

[0066] Substituting d = λ / 2ρ into the converted Doppler formula, we can get formula f d =1 / (2ρt')×cosθ. Let F s =1 / t', it can be further expressed as F s =2ρf d / cosθ=2ρf d,max Among them, f d,max =(v / c)×f center represents the maximum Doppler frequency shift. When the terminal velocity v is constant, f d,max It is to determine the value.

[0067] It can be seen from the above that the baseband sampling rate is proportional to the maximum Doppler frequency deviation. Since low-orbit satellites run at extremely high speeds, usually around 7.9 km / s, and low-orbit satellite communications are based on large-scale phased array communication systems, the amount of channel coefficient data generated during the satellite's overhead time is extremely large, which brings great challenges to the data transmission, storage and exchange of the channel simulator.

[0068] In order to solve the above problems, the embodiments of the present application are based on the parameters of the non-terrestrial network (NTN) standard channel model in the 3GPP-38811 protocol, and propose a real-time and non-real-time joint simulation technology based on geometric modeling of satellite-to-ground wireless channels, so as to realize geometry-based satellite-to-ground wireless channel simulation while greatly reducing the corresponding data of channel impact during modeling.

[0069] The 3GPP-38811 protocol provides satellite-to-ground channel models for two scenarios: NLOS (NTN-CDL-A, NTN-CDL-B) and LOS (NTN-CDL-C, NTN-CDL-D), as shown in Tables 1 to 4:

[0070] Table 1 NTN-CDL-A pitch angle α mdel =50°

[0071]

[0072] Table 2 NTN-CDL-B elevation angle α mdel =50°

[0073]

[0074] Table 3 NTN-CDL-C elevation angle α mdel =50°

[0075]

[0076] Table 4 NTN-CDL-D elevation angle α mdel =50°

[0077]

[0078] From the satellite channel models shown in Tables 1 to 4, it can be seen that among the four angles of departure azimuth angle AOD, arrival azimuth angle AOA, departure zenith angle ZOD and arrival zenith angle ZOA, AOD and ZOD are fixed values, and the angle expansion C ASD and C ZSD Both are 0.

[0079] Here, formula (2) is expanded to obtain the following formula:

[0080]

[0081]

[0082] In the 3GPP-38811 protocol, the departure angle is mainly used to describe the directionality of the wireless signal when it leaves the antenna, while the cluster is used to describe the signal set formed by factors such as multipath effect during the propagation of the wireless signal. The two are independent of each other in terms of physical meaning and description object. Therefore, the departure angle AOD and ZOD have nothing to do with the cluster, and the angle expansion C ASD and C ZSD If both are 0, then:

[0083]

[0084] The above equations (8), (9), and (10) show that the directional pattern and departure angle on the satellite side are not affected by the number of clusters and the number of sub-paths. In view of this, the inventors found that if the impact of satellite motion on the channel is realized quickly using FPGA alone, wireless channel simulation resources can be saved.

[0085] Modeling formula By swapping the positions of some data, we can get:

[0086]

[0087]

[0088] Let H sa,v (t) represents the channel change caused by the movement of the satellite, then we can get:

[0089]

[0090] Let H sa,Ant,V (t) represents the influence of the horizontal component of the satellite pattern, then we can get:

[0091]

[0092] Let H sa,Ant,H (t) represents the influence of the vertical component of the satellite pattern, then we can get:

[0093]

[0094] Let H ue,v,1 Representing the channel change caused by the movement of the ground station, we can get:

[0095] Let H ue,v,2 Representing the channel change caused by the movement of the ground station, we can get:

[0096] at this time, Expressed as:

[0097]

[0098]

[0099] According to the above formula (12).

[0100]

[0101] in, The direction representing the satellite departure angle is projected onto the satellite panel;

[0102] The projection is consistent with the phase value of the number of satellite antennas. According to the 3GPP-38811 protocol, the departure angle AOD and ZOD are independent of the cluster, and the angle extension C ASD and C ZSD are all 0, then

[0103] After the above transformation, the inventors found that H sa,v The storage capacity of (t) is still large because Represents the coordinates of the satellite antenna panel. This value changes with the movement of the satellite and has the same dimension as the number of satellite antennas.

[0104] For formula (17), we can further obtain:

[0105]

[0106] Because the altitude of low-orbit satellites must be at least 500km above the ground. It is necessary to meet the modeling needs of high-speed satellite motion, so the embodiments of this application are aimed at H sa,Ant,V and H sa,Ant,H Further consideration is whether it is possible to conduct research by modeling the movement of ground stations at low speed.

[0107] Assume that the satellite moves at a speed v sat , the Earth's rotation speed is v ear , the communication center frequency is f center , half-wavelength sampling density ρ, with the Earth's rotation speed v ear The interval between two sampling points modeled is Δd ear =c / 2f center ρ; sampling time is Δt ear =Δd ear / v ear =c / 2v ear f center ρ. At the same sampling time, the satellite movement distance is Δd sat =Δtear v sat =cv sat / 2v ear f center ρ.

[0108] Assume f center =6GHz, v sat =7.9km / s,v ear =466m / s,ρ=4,c=3×10 8 m / s, we can calculate that Δd ear =0.0063m,Δd sat =0.106m, through calculation we can know Δd sat It is so small compared to 500km that it can be considered that ear The angle does not change during the time, as shown in the schematic diagram Figure 2 shown.

[0109] Based on this, the present application embodiment believes that H sa,Ant,V and H sa,Ant,H The motion of the ground station can be modeled at low speed.

[0110] Δd vat Inversely proportional to the center frequency, Δd vat The approximate condition can still be achieved by magnifying 10 times. According to the tangent calculation of the trajectory point, the angle change ΔΩ between the two adjacent trajectory points of the payload and the ground station sat , when Δd sat =6m, that is, ΔΩ sat =6.8755×10 -4 °. According to the 3GPP-38811 protocol, the departure angles AOD and ZOD are independent of the cluster, and the angle extension C ASD and C ZSD If both are 0, then:

[0111]

[0112] It can be seen that this value changes slowly and can be generated at a low speed. Since it is independent of the number of clusters, H sa,Ant,V and H sa,Ant,H They are all one-dimensional arrays, so we can get:

[0113]

[0114] in, Real-time generation through FPGA high-speed modeling,

[0115] The modeling method of the ground 5G network is used to achieve this, which can save the storage and computing resources of the wireless channel simulator.

[0116] Regarding the channel modeling of the LOS path implemented by formula (2), it can be understood that there is no generation of sub-paths in the LOS path, so the embodiment of the present application uses The number of subpaths in M ​​is set to 1; that is, but:

[0117]

[0118]

[0119] It can be seen from the above formulas that for line-of-sight LOS, the high-speed modeling on the satellite side has not changed, and the modeling of the ground station is simpler than that of non-line-of-sight NLOS.

[0120] In view of this, the embodiment of the present application provides a method for modeling a low-orbit satellite wireless channel based on geometric randomness, see Figure 3 , the method specifically comprises the following steps:

[0121] S301: Generate satellite channel changes caused by satellite movement through a field programmable gate array (FPGA) according to the satellite's onboard payload antenna information, satellite departure angle, and satellite velocity vector.

[0122] In the embodiments of the present application, the FPGA is a highly flexible integrated circuit in the channel emulator, which can be further programmed and configured according to custom logic, has high parallel processing capabilities and low latency characteristics, and is suitable for real-time channel simulation. Based on this, the present application uses FPGA to realize the impact of high-speed satellite movement on the channel.

[0123] Onboard payload antenna information refers to the operating status and parameter information of the antenna on the satellite, such as the type, quantity, directivity, power and other parameters of the antenna; satellite velocity vector refers to the speed and direction of the satellite's movement in space; satellite departure angle refers to the spherical unit coordinates of the satellite departure angle, where the satellite departure angle can be expressed by two angles, azimuth and pitch angle, in the spherical coordinate system; satellite channel change refers to the change in channel characteristics caused by the high-speed movement of the satellite, such as Doppler frequency shift, signal attenuation, etc.

[0124] In some implementations of the embodiments of the present application, the satellite departure angle and the satellite velocity vector are generated by the satellite's trajectory points, wherein the satellite's trajectory points are specifically obtained from the satellite ephemeris data. The satellite ephemeris data contains detailed data such as the position and velocity of the satellite in orbit. By sampling the satellite ephemeris data, the precise position of the satellite at different time points in the same interval, that is, the trajectory points, can be obtained. Afterwards, the satellite departure angle and velocity vector at any time can be obtained by calculating the trajectory points.

[0125] In some implementations of the embodiments of the present application, the satellite channel change amount is generated by a satellite channel change formula, and the satellite channel change formula is:

[0126]

[0127] Among them, H sa,v (t) represents the satellite channel change at different times t, j represents the imaginary unit, π represents the circumference of a circle, represents the satellite departure angle, represents the coordinate vector of the sth transmitting antenna determined according to the onboard payload antenna information, represents the satellite velocity vector, t represents time, and λ 0 Indicates wavelength.

[0128] S302: Generate a horizontal impact component of the satellite pattern and a vertical impact component of the satellite pattern according to the on-board payload antenna information and the satellite departure angle.

[0129] In the embodiments of the present application, the horizontal impact component of the satellite pattern refers to the impact of the radiation characteristics of the satellite antenna in the horizontal direction on the channel, and the vertical impact component of the satellite pattern refers to the impact of the radiation characteristics of the satellite antenna in the vertical direction on the channel. Both components can be calculated based on the onboard payload antenna information and the satellite departure angle. Specifically, by substituting the departure angle of the pitch angle and the departure angle of the azimuth angle into the azimuth diagram, which describes the radiation intensity distribution of the antenna in different directions, the impact components in the horizontal and vertical directions can be obtained.

[0130] In some implementations of the embodiments of the present application, the horizontal impact component of the satellite pattern is generated by a satellite pattern horizontal component impact formula, and the satellite pattern horizontal component impact formula is:

[0131] H sa,Ant,V (t) = F tx,s,θ (θ ZOD ,φ AOD

[0132] Among them, H sa,Ant,V (t) represents the horizontal impact component of the satellite pattern at different times t, F tx,s,θ represents the directional component of the satellite's sth transmitting antenna elevation angle θ, θ ZOD represents the pitch angle determined based on the departure from the zenith angle, φ AOD Indicates the departure azimuth.

[0133] H sa,Ant,H (t) = F tx,s,φ (θ ZOD ,φ AOD )

[0134] Among them, H sa,Ant,H (t) represents the vertical impact component of the satellite pattern at different times t, F tx,s,φ represents the azimuth pattern component of the satellite’s sth transmitting antenna, θ ZOD represents the pitch angle determined based on the departure from the zenith angle, φ AOD Indicates the departure azimuth.

[0135] S303: Generate the horizontal channel change of the ground station and the vertical channel change of the ground station caused by the movement of the satellite ground station through the ground station geometric channel model according to the ground payload antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector.

[0136] In the embodiments of the present application, the ground station channel geometry model refers to a mathematical model used to describe the channel characteristics between the ground station and the satellite, and is used to consider the influence of factors such as the relative position between the ground station and the satellite on the channel. Ground payload antenna information refers to the operating status and parameter information of the antenna of the satellite ground station, such as the type, quantity, directivity, power and other parameters of the antenna. The ground station velocity vector refers to the speed and direction of movement of the satellite ground station in space, and the ground station arrival angle refers to the spherical unit coordinates of the ground station arrival angle; the ground station horizontal channel change refers to the change in channel characteristics in the horizontal direction due to the movement of the ground station; the ground station vertical channel change refers to the change in channel characteristics in the vertical direction due to the movement of the ground station.

[0137] In some implementations of the embodiments of the present application, the ground station arrival angle and the ground station velocity vector are generated through the trajectory points of the satellite ground station. Specifically, the position of the ground station at different time points in the same interval, that is, the trajectory points of the ground station, can be obtained, and then the ground station arrival angle and velocity vector at any time can be obtained by calculating the trajectory points.

[0138] In some implementations of the embodiments of the present application, the ground station horizontal channel change amount is generated by a ground station horizontal channel change formula, and the ground station horizontal channel change formula is:

[0139]

[0140] Among them, H ue,v1 (t) represents the change of the ground station horizontal channel at different times t, F rx,u,θ represents the directional component of the elevation angle θ of the u-th receiving antenna of the satellite ground station, θ 1,ZOA represents the pitch angle θ determined by the arrival zenith angle ZOA of cluster 1, φ 1,AOA represents the arrival azimuth of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0141] In some implementations of the embodiments of the present application, the ground station vertical channel change amount is generated by a ground station vertical channel change formula, and the ground station vertical channel change formula is:

[0142]

[0143] Among them, H ue,v2 (t) represents the change of the vertical channel of the ground station at different times t, F rx,u,φ represents the directional component of the u-th receiving antenna azimuth φ of the satellite ground station, θ 1,ZOA represents the pitch angle θ, φ determined according to the arrival zenith angle ZOA of cluster 1 1,AOA represents the arrival azimuth AOA of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0144] In some implementations of the embodiments of the present application, the 5G ground modeling method is continued to be used to model the satellite ground station. At this time, the ground station channel model is a channel model established based on the ground 5GNR (5G New Radio) standard.

[0145] S304: Input the transmission signal of the transmitter to the channel simulator, and output the simulation result according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmission signal of the transmitter.

[0146] In the embodiment of the present application, the channel simulator is used to simulate the actual channel environment. By inputting the transmission signal of the transmitter and combining the channel change and directional pattern influence components of the satellite and ground station, the channel simulator outputs the simulation results, which are used to reflect the signal transmission characteristics under the actual channel environment.

[0147] In some implementations of the embodiments of the present application, the simulation results are outputted specifically through the following operation rules: The horizontal impact component of the satellite azimuth map and the change amount of the horizontal channel of the ground station are multiplied to obtain a first calculation result; the vertical impact component of the satellite azimuth map and the change amount of the vertical channel of the ground station are multiplied to obtain a second calculation result; the sum of the first calculation result and the second calculation result is multiplied by the change amount of the satellite channel, and the transmission signal of the transmitter is used as a simulation parameter to output the simulation result.

[0148] It can be expressed as:

[0149]

[0150] in, represents the channel change between the transmitting antenna s and the receiving antenna u at different times t, H sa,v (t) represents the satellite channel change, H sa,Ant,V represents the horizontal impact component of the satellite azimuth pattern, H ue,v1 Ground station horizontal channel change, H sa,Ant,H Represents the vertical impact component of the satellite azimuth pattern, H ue,v2 Vertical channel variation of the ground station.

[0151] In the technical solution provided in the present application, first, through the field programmable gate array FPGA, the satellite channel change caused by the satellite movement is generated according to the on-board payload antenna information, the satellite departure angle of the satellite and the satellite velocity vector; then, the horizontal influence component of the satellite pattern and the vertical influence component of the satellite pattern are generated according to the on-board payload antenna information and the satellite departure angle; thereafter, through the ground station geometric channel model, according to the ground payload antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector, the ground station horizontal channel change and the ground station vertical channel change caused by the satellite ground station movement are generated; finally, the transmitter's transmission signal is input into the channel simulator, and the simulation result is output according to the satellite channel change, the horizontal influence component of the satellite azimuth map, the vertical influence component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitter's transmission signal.

[0152] Combination Figure 4It can be seen from the shown content and the above process that the present application uses FPGA to generate the channel change caused by the satellite movement according to the satellite's onboard payload antenna information, satellite departure angle and satellite velocity vector, so as to realize the rapid simulation of channel changes through the FPGA logic in the channel simulator, thereby reducing the intermediate data generated during simulation and saving wireless channel simulation resources; through the ground station geometric channel model, according to the satellite ground station's ground load information, ground station arrival angle and ground station velocity vector, the channel changes caused by the satellite ground station are generated, so as to realize channel simulation through the geometric channel model, and channel modeling can relatively statically describe the impact of the low-speed movement of the ground station on the channel without the need for real-time processing like FPGA, which can further save the generation time and storage resources of the channel impulse response.

[0153] See also Figure 5 As shown, in the actual application scenario of the technical solution provided by the present application, the entire wireless channel simulation process may specifically include the following steps:

[0154] S501: Start, execute S502.

[0155] S502: Obtain satellite trajectory points according to the satellite's ephemeris information; execute S503.

[0156] S503: Calculate the satellite departure angle and the satellite velocity vector according to the trajectory points; execute S504.

[0157] S504: Write the satellite departure angle and the satellite velocity vector into the memory of the channel simulator, and execute S505.

[0158] S505: The channel simulator determines whether the current moment is the last moment of the simulation, if not, executes S506, if so, executes S511.

[0159] S506: Calculate the satellite channel change caused by the satellite movement in real time according to the onboard payload antenna information, satellite departure angle and satellite velocity vector configured by the user; and execute S507.

[0160] S507: Calculate the horizontal impact component of the satellite pattern and the vertical impact component of the satellite pattern in real time according to the onboard payload antenna information configured by the user and the satellite departure angle; execute S508.

[0161] S508: According to the satellite ground station position configured by the user, ground low-speed modeling is performed with reference to 5GNR, and the horizontal channel change amount and the vertical channel change amount of the ground station at the current moment are read; and S509 is executed.

[0162] S509: Multiply the horizontal impact component of the satellite azimuth map and the horizontal channel change of the ground station to obtain a first calculation result; multiply the vertical impact component of the satellite azimuth map and the vertical channel change of the ground station to obtain a second calculation result; multiply the sum of the first calculation result and the second calculation result by the satellite channel change; execute S510.

[0163] S510: The channel simulator outputs simulation results, and execution proceeds to 505.

[0164] S511: End.

[0165] The following is a description of the technical effects of the solutions provided in the embodiments of the present application.

[0166] First, when using the 5G ground modeling method to simulate the wireless channel, assume that the satellite movement speed is v sat , the satellite passing time is t v , the communication center frequency is f center , considering the rotation of the earth, ignoring the movement of the ground station relative to the earth, assuming that the number of satellite antennas is M, the number of ground station antennas is N, and the number of multipaths is P, then according to the baseband sampling rate in the modeling formula:

[0167] The number of data points that the host computer needs to store is N total =M×N×P×t v ×F s .

[0168] If the method provided in the embodiment of this application is adopted, and the modeling process is divided into two parts, the following formula:

[0169]

[0170] It can be written as the original formula:

[0171]

[0172] The first part is the data generated by the high-speed motion of the satellite, N total,1 =t v ×F s .

[0173] The amount of data brought by the movement of the ground station is closely considered to be affected by the rotation of the earth. Assuming that the rotation speed of the earth is v ear ,but:

[0174]

[0175] See Table 5 for the comparative data below.

[0176] Table 5 Comparison data

[0177] Parameter name Chinese explanation Numeric Remark M Number of satellite antennas 32 N Number of ground station antennas 4 ρ Half-wavelength sampling density 4 Minimum value is 4 <![CDATA[t v ]]> Satellite overhead time 180 Unit: Seconds <![CDATA[f center ]]> Center frequency 6GHz c Speed ​​of Light <![CDATA[3×10 8 ]]> Unit: m / s P Number of multipaths 4 38811 protocol up to 4 <![CDATA[v ear ]]> Earth's rotation speed 466 Unit: m / sReference value

[0178] According to the above parameters, the modeling data using the ground 5G method is N total =32×4×4×180×2×4×7.9×10 3 / 3×10 8 ×6×10 9 =1.1649024×10 11 . total This translates to 433.96Gbyte of storage space.

[0179] If the technical solution provided in this application is adopted, then N total,1 =t v ×F s =180×2×4×7.9×10 3 / 3×10 8 ×6×10 9 =227520000, which is converted into 867.9199Mbyte of storage space. total,2 =32×4×4×180×2×4×466 / 3×10 8 ×6×10 9 =6.8714×10 9 , which is equivalent to 25.59Gbyte of storage space; the total storage space is 26.4457Gbyte.

[0180] In comparison, the amount of data generated by using the scheme provided in the embodiment of the present application for satellite-to-ground channel simulation is only 6.09% of the amount of data generated by using the ground 5G modeling method for satellite-to-ground channel simulation. It can be seen that the technical solution provided by the present application can realize the simulation of satellite-to-ground wireless channels while greatly reducing the amount of data generated by geometry-based channel modeling.

[0181] See also Figure 6 The embodiment of the present application provides a low-orbit satellite wireless channel modeling device based on geometric randomness, and the channel simulation device is a channel simulator, which includes:

[0182] The satellite channel change determination module 601 is used to generate the satellite channel change amount caused by the satellite movement according to the on-board payload antenna information, the satellite departure angle of the satellite and the satellite velocity vector through the field programmable gate array FPGA;

[0183] The satellite pattern impact determination module 602 is used to generate a horizontal impact component of the satellite pattern and a vertical impact component of the satellite pattern according to the onboard payload antenna information and the satellite departure angle;

[0184] The ground station channel change determination module 603 is used to generate the ground station horizontal channel change amount and the ground station vertical channel change amount caused by the satellite ground station movement through the ground station geometric channel model according to the ground load antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector;

[0185] The channel simulation result output module 604 is used to input the transmitter's transmission signal into the channel simulator, and output the simulation result according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitter's transmission signal.

[0186] In some implementations of the embodiments of the present application, the device further includes an angle and speed calculation module, which is used to:

[0187] Generate satellite departure angle and satellite velocity vector through satellite trajectory points;

[0188] The ground station arrival angle and ground station velocity vector are generated through the satellite ground station trajectory points.

[0189] In some implementations of the embodiments of the present application, according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, and the vertical channel change of the ground station, the simulation results are output, including:

[0190] Multiplying the horizontal impact component of the satellite azimuth diagram and the horizontal channel change of the ground station to obtain a first calculation result;

[0191] Multiplying the vertical impact component of the satellite azimuth diagram and the vertical channel change of the ground station to obtain a second calculation result;

[0192] The sum of the first calculation result and the second calculation result is multiplied by the satellite channel change amount, and the transmission signal of the transmitter is used as a simulation parameter to output the simulation result.

[0193] In some implementations of the embodiments of the present application, the ground station channel model is a channel model established based on the ground 5GNR standard.

[0194] In some implementations of the embodiments of the present application, the satellite channel change amount is generated by a satellite channel change formula, and the satellite channel change formula is:

[0195]

[0196] Among them, H sa,v (t) represents the satellite channel change at different times t, j represents the imaginary unit, π represents the circumference of a circle, represents the satellite departure angle, represents the coordinate vector of the sth transmitting antenna determined according to the onboard payload antenna information, represents the satellite velocity vector, t represents time, and λ 0 Indicates wavelength.

[0197] In some implementations of the embodiments of the present application, the ground station horizontal channel change amount is generated by a ground station horizontal channel change formula, and the ground station horizontal channel change formula is:

[0198]

[0199] Among them, H ue,v1 (t) represents the change of the ground station horizontal channel at different times t, F rx,u,θ represents the directional component of the elevation angle θ of the u-th receiving antenna of the satellite ground station, θ 1,ZOA represents the pitch angle θ determined by the arrival zenith angle ZOA of cluster 1, represents the arrival azimuth AOA of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0200] In some implementations of the embodiments of the present application, the ground station vertical channel change amount is generated by a ground station vertical channel change formula, and the ground station vertical channel change formula is:

[0201]

[0202] Among them, H ue,v2 (t) represents the change of the vertical channel of the ground station at different times t, represents the azimuth of the u-th receiving antenna of the satellite ground station The directional pattern component, θ 1,ZOA represents the pitch angle θ determined according to the arrival zenith angle ZOA of cluster 1, represents the arrival azimuth of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, λ 0 Indicates wavelength.

[0203] like Figure 7As shown, the embodiment of the present application also provides a low-orbit satellite wireless channel modeling device based on geometric randomness, including: a memory 701, a processor 702;

[0204] Wherein, the memory 701 is used to store programs;

[0205] The processor 702 is used to execute the program in the memory to implement each step of the channel simulation method provided in the embodiment of the present application.

[0206] An embodiment of the present application also provides a readable storage medium on which a computer program is stored, characterized in that when the computer program is executed by a processor, each step of the low-orbit satellite wireless channel modeling method based on geometric randomness as provided in the embodiment of the present application is implemented.

[0207] Finally, it should be noted that, in the embodiments of the present application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0208] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for modeling low-orbit satellite wireless channels based on geometric randomness, characterized in that: The method comprises: Generate the satellite channel change caused by the satellite movement according to the satellite's onboard payload antenna information, the satellite departure angle and the satellite velocity vector through a field programmable gate array FPGA; Generate a horizontal impact component of a satellite pattern and a vertical impact component of a satellite pattern according to the onboard payload antenna information and the satellite departure angle; Generate a ground station horizontal channel change and a ground station vertical channel change caused by the movement of the satellite ground station through a ground station geometric channel model according to the ground payload antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector; The transmitting signal of the transmitter is input into the channel simulator, and the simulation result is output according to the channel change of the satellite channel, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmitting signal of the transmitter.

2. The method according to claim 1, characterized in that The method further comprises: Generate the satellite departure angle and the satellite velocity vector through the trajectory points of the satellite; The ground station arrival angle and the ground station velocity vector are generated through the trajectory points of the satellite ground station.

3. The method according to claim 1, characterized in that Outputting simulation results according to the satellite channel change, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the ground station horizontal channel change, and the ground station vertical channel change includes: Multiplying the horizontal impact component of the satellite azimuth map and the horizontal channel change of the ground station to obtain a first calculation result; Multiplying the vertical impact component of the satellite azimuth diagram and the vertical channel change of the ground station to obtain a second calculation result; The sum of the first calculation result and the second calculation result is multiplied by the satellite channel change amount, and the transmission signal of the transmitter is used as a simulation parameter to output the simulation result.

4. The method according to claim 1, characterized in that: The ground station channel model is a channel model established based on the ground 5GNR standard.

5. The method according to claim 1, characterized in that The satellite channel change amount is generated by a satellite channel change formula, and the satellite channel change formula is: Among them, H sa,v (t) represents the satellite channel variation at different time t, j represents an imaginary unit, π represents the circumference of a circle, represents the departure angle of the satellite, represents the coordinate vector of the sth transmitting antenna determined according to the on-board payload antenna information, represents the satellite velocity vector, t represents time, and λ0 represents wavelength.

6. The method according to claim 1, characterized in that The ground station horizontal channel change amount is generated by the ground station horizontal channel change formula, and the ground station horizontal channel change formula is: Among them, H ue,v1 (t) represents the change of the horizontal channel of the ground station at different time t, F rx,u,θ represents the directional component of the elevation angle θ of the u-th receiving antenna of the satellite ground station, θ 1,ZOA represents the pitch angle θ determined by the arrival zenith angle ZOA of cluster 1, φ 1,AOA represents the arrival azimuth AOA of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, and λ0 represents wavelength.

7. The method according to claim 1, characterized in that The ground station vertical channel change amount is generated by the ground station vertical channel change formula, and the ground station vertical channel change formula is: Among them, H ue,v2 (t) represents the vertical channel change of the ground station at different time t, F rx,u,φ represents the azimuth angle φ of the u-th receiving antenna of the satellite ground station, θ 1,ZOA represents the pitch angle θ, φ determined according to the arrival zenith angle ZOA of cluster 1 1,AOA represents the arrival azimuth AOA of the first cluster, j represents the imaginary unit, π represents the circumference of a circle, represents the ground station arrival angle, represents the coordinate vector of the uth receiving antenna determined according to the ground load antenna information, represents the satellite ground station velocity vector, t represents time, and λ0 represents wavelength.

8. A low-orbit satellite wireless channel modeling device based on geometric randomness, characterized in that: The device is a channel emulator, and the device comprises: A satellite channel change determination module is used to generate a satellite channel change amount caused by the satellite movement according to the on-board payload antenna information, the satellite departure angle of the satellite and the satellite velocity vector through a field programmable gate array FPGA; A satellite pattern impact determination module, used to generate a horizontal impact component of the satellite pattern and a vertical impact component of the satellite pattern according to the onboard payload antenna information and the satellite departure angle; A ground station channel change determination module is used to generate a ground station horizontal channel change amount and a ground station vertical channel change amount caused by the movement of the satellite ground station according to the ground load antenna information of the satellite ground station, the ground station arrival angle and the ground station velocity vector through a ground station geometric channel model; The channel simulation result output module is used to input the transmission signal of the transmitter into the channel simulator, and output the simulation result according to the channel change of the satellite channel, the horizontal impact component of the satellite azimuth map, the vertical impact component of the satellite azimuth map, the horizontal channel change of the ground station, the vertical channel change of the ground station and the transmission signal of the transmitter.

9. A low-orbit satellite wireless channel modeling device based on geometric randomness, characterized in that: The device includes a memory and a processor, and the processor is used to execute the program stored in the memory to run the low-orbit satellite wireless channel modeling method based on geometric randomness as described in any one of claims 1 to 7.

10. A readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, each step of the method for modeling low-orbit satellite wireless channels based on geometric randomness as described in any one of claims 1 to 7 is implemented.

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