CN104378170A - Near space dynamic plasma sheath channel modeling and simulating method - Google Patents

Abstract

The invention discloses a near space dynamic plasma sheath channel modeling and simulating method. The method comprises the steps that channel resources are partitioned according to large-scale space-time-frequency characteristics to construct a large-scale space-time-frequency channel resource matrix, wherein the height corresponds to large-scale space domain characteristics, the speed corresponds to large-scale time domain characteristics, and frequency points correspond to large-scale frequency domain characteristics; for all channel resource matrixes, dynamic small-scale channel parameters are obtained; small-scale channel model simulating is achieved according to given small-scale channel parameters; large-scale channel model simulating is achieved by repeating small-scale channel models at multiple states on a near space flight path. The method is suitable for channel modeling under different dynamic rules, random-amplitude phase probability density distribution which may occurs under a plasma sheath is simulated, and channel modeling feasibility is guaranteed; the method is suitable for near space aircraft plasma sheath channel modeling and spaceflight reentry-return spacecraft plasma sheath channel modeling.

Description

The method of the dynamic plasma sheath cover Channel Modeling of a kind of near space and simulation

Technical field

The invention belongs to TTC&T Technology field, particularly relate to the method for the dynamic plasma sheath cover Channel Modeling of a kind of near space and simulation.

Background technology

Hypersonic aircraft is near space high-speed flight process, by coated one deck high temperature thermic plasma (plasma sheath cover) around it, the inner charged particle based on free electron of this sheath cover will absorb, reflect and scattering electromagnetic wave, produce the effect of metalloid shielding, make electromagnetic signal generation deep fades, make that the impedance operator of antenna changes, pattern distortion simultaneously.These effects will cause communication quality to worsen, and cause signal of communication to interrupt time serious, produce black barrier phenomenon.Black barrier phenomenon by have a strong impact on ground station to the catching of aircraft, follow the tracks of and real-time telemetry transfer of data, cause unpredictable consequence.

Alleviate the impact of plasma sheath cover on communication to resist or weakening, researchers propose a lot of physico-chemical process and attempt to weaken plasma, improve the possibility of communication.These measures can reduce the degree of decay in theory to a certain extent.For communication, concern are mostly impacts that the particularity of plasma sheath cover are brought to transmission channel.This special channel is summed up as decay and phase deviation by numerous research, and this characteristic can be obtained by Computational Electromagnetic Methods usually in the non-homogeneous plasma of stable state.Along with cognitive the going deep into of article on plasma sheath cover, find that plasma sheath cover not only has steady-state characteristic, and there is dynamic characteristic, the dynamic state of parameters distribution character of plasma sheath cover and height, speed, track, attitudes vibration, turbulent flow, pressure fluctuation, ablation numerous enchancement factor such as to peel off and multifactorial close-coupled relevant.The dynamic of plasma sheath cover result in complicated random medium electromagnetic property, and then produces more complicated width phase mudulation effect to signal.Even if when signal is through plasma, the width phase mudulation effect that its dynamic characteristic causes also can severe exacerbation communication quality.Therefore for design is adapted to the communication system service under this Complex Channel, the research of dynamic plasma sheath cover Channel Modeling is most important.Almost blank is in the research of dynamic plasma channel and the research of model modeling thereof.

In fact, from the physical features angle of channel, isoionic dynamic can be divided into large scale dynamic and small scale dynamic." large scale " dynamic characteristic is introduced for physical states such as flying height (sky), speed (time), frequencies (frequently), the division of the empty time-frequency channel resource of large scale can be carried out, to the modeling of large scale behavioral characteristics, work in coordination with optimizing network resource utilization for the more channel resource window of communication system requirements and expand channel capacity service.For physics " small scale " dynamic characteristics such as ablation turbulent flows, embody the impact of Micro dynamic on signal amplitude, phase place and power spectrum disperse, carry out small scale Channel Modeling, for Communication System Design, coded modulation thus improving performance approach the service of capacity circle more targetedly.

Summary of the invention

The object of the embodiment of the present invention is the method providing the dynamic plasma sheath cover Channel Modeling of a kind of near space and simulation, because current channel detection is flying cannot realize in experiment in reality, and on dynamic plasma on signal and the cognitive not enough problem of characteristic of channel impact, be intended to solve dynamic plasma channel model modeling problem from theory calculate two aspect of theoretical modeling method and channel parameter, for design alleviation or the adaptive communication technology provide guide service.

The embodiment of the present invention is achieved in that the method for the dynamic plasma sheath cover Channel Modeling of a kind of near space and simulation, and the method for the dynamic plasma sheath cover Channel Modeling of this near space and simulation comprises the following steps:

Step one, for each channel resource matrix, obtains dynamic small scale channel parameter; Obtain the three-dimensional field intensity data of far field acceptance point by Computational Electromagnetic Methods, obtain amplitude and the phase place probability density function of small scale channel, obtain small scale channel Doppler power spectrum function;

Step 2, according to given small scale channel parameter, realizes the simulation of small scale channel model; Specifically comprise:

The first step, adopts even cap to give up method simulation and meets institute and extract the random sequence R (k) of amplitude probability distribution and phase probability distribution random sequence θ (k);

Second step, adopts Doppler's formed filter S (k) that iir digital filter Direct Design Method design normalization is discrete;

3rd step, superposition amplitude random sequence and phase place random sequence generate multiple random sequence Z (k)=R (k) e of fading channel envelope ^{j θ (k)};

4th step, the multiple random sequence of channel envelope, by Doppler's formed filter sequence, generates dynamic plasma sheath cover channel random sequence C _p( _k)=Z (k) S (k);

Step 3, for each channel resource matrix, repeats step 2, obtains the dynamic plasma sheath cover channel random sequence under different receiving polarization.

Further, needed to divide channel resource according to the empty time-frequency characteristics of large scale before step one, build the empty time-frequency channel resource matrix of large scale; Wherein highly corresponding large scale spatial feature, the corresponding large scale temporal signatures of speed, the corresponding large scale frequency domain character of frequency;

Further, in step one, obtain the three-dimensional field intensity data of far field acceptance point by Computational Electromagnetic Methods; Specifically comprise:

The first step, to distribute and dynamic rule according to N group plasma electron density corresponding under large-scale characteristics, build plasma sheath cover electromagnetic parameter model, wherein often organizing under non-homogeneous electron distributions, to non-homogeneous electron density layering Homogenization Treatments, every layer of electromagnetic medium parameter model is:

${\mathrm{\ϵ}}_r^m=[1-\frac{{\mathrm{\ω}}_{p,m}}{{\mathrm{\ω}}^2+{v_m}^2}+i\frac{{\mathrm{\ω}}_{p,m}(v_m/\mathrm{\ω})}{{\mathrm{\ω}}^2+{v_m}^2}]{\mathrm{\ϵ}}_0;$

be m layer plasma relative dielectric constant, ε ₀for free space dielectric constant, ω is incident wave frequency, υ _mbe m layer plasma collision frequency, ω _p,mbe m layer plasma characteristics frequency, m is the plasma number of plies;

Second step, three-dimensional FDTD electromagnetism computational algorithm is adopted to obtain the field intensity E often organizing acceptance point place under quasistatic _p, E _p=E _xa _x+ E _ya _y+ E _za _z, wherein E _x=(a+bi), E _y=(c+di), E _z=(e+fi), a _x, a _y, a _zfor the unit vector in x, y, z direction;

3rd step, repetition second step simulation calculation, obtain the multiple field intensity data of N group under large scale behavioral characteristics ${\left\{E_p\right\}}_{p=1}^N.$

Further, in step one, obtain amplitude and the phase place probability density function of small scale channel, specifically comprise:

The first step, according to antenna receiving polarization form, select corresponding polarization components and obtain N number of Received signal strength amplitude data and and phase data

During left-handed reception $\tilde{R}\left(t\right)=\{E_{\mathrm{Li}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Li}},i=1...N\},$

When dextrorotation receives $\tilde{R}\left(t\right)=\{E_{\mathrm{Ri}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Ri}},i=1...N\},$

Wherein $\left|E_R\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}},{\mathrm{\θ}}_R=\arctan \frac{E_y}{E_x}$

$\left|E_L\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}},{\mathrm{\θ}}_L=\arctan \frac{E_y}{E_x}$

Second step, to received signal amplitude data and and phase data carry out statistical analysis and fitting of a polynomial, obtain amplitude-phase probability density function f _r(x) and phase place probability density function f _θ(x); Obtain the amplitude probability density function under different receiving polarization; Obtain the phase place probability density function under different receiving polarization.

Further, in step one, obtain small scale channel Doppler power spectrum function, specifically comprise:

The first step, by amplitude data and and phase data obtain Received signal strength complex data namely data continuous time be similar to are obtained by the multiple field intensity data of N group;

Second step, solve Received signal strength its auto-correlation function carry out Fourier transform and obtain Doppler power spectral function obtain the Doppler power spectra under different receiving polarization.

Further, in the first step of step 2, even cap method step is as follows, produces f _rthe random sequence X of (x);

The first step, to produce at (0, a _x) upper equally distributed V _1X, wherein a _xit is the maximum of X;

Second step, to produce at (0, b _x) upper equally distributed V _2X, wherein b _xthe f be not less than _x(x) maximum;

If the 3rd step V _1X≤ f _x(V _1X), make X=V _1X; If inequality does not meet, then abandon V _1Xand V _2X, the above process of repetition from the first step;

4th step, obtain obedience amplitude probability-distribution function f _rrandom sequence R (the k)=X of (x); Amplitude simulation random sequence under different receiving polarization.

Further, in the first step of step 2, even cap method step is as follows, produces f _θthe random sequence Y of (x);

The first step, to produce at (0, a _y) upper equally distributed V _1Y, wherein a _yit is the maximum of Y;

Second step, to produce at (0, b _y) upper equally distributed V _2Y, wherein b _ythe f be not less than _x(x) maximum;

If the 3rd step V _1Y≤ f _x(V _1Y), make Y=V _1Y; If inequality does not meet, then abandon V _1Yand V _2Y, the above process of repetition from the first step;

4th step, obtain obeying phase probability distribution function f _θrandom sequence θ (the k)=Y of (x); Phase mode quasi-random sequence under different receiving polarization.

Further, Doppler's formed filter S (k) that the 3rd step in step 2 adopts iir digital filter Direct Design Method design normalization discrete, specifically comprises:

The first step, form Doppler's formed filter by K Second Order Network cascade, system function is expressed as S (z) and is:

$S\left(z\right)=A\underset{j=1}{\overset{K}{\mathrm{\Π}}}\frac{1+a_j{z}^{-1}+b_j{z}^{-2}}{1+c_j{z}^{-1}+d_j{z}^{-2}}$

In formula, A is constant, a _j, b _j, c _j, d _jbe jth a to be asked filter coefficient, K is cascade second order filter number;

Second step, employing Yule-Walker equation method solve coefficient and solve a filter coefficient 4K+1 filter coefficient, get M point numerical frequency ω in (0, π) interval _i, i=1,2.....M, M are frequency points, on these frequencies, make S _d(e ^{j ω}) and expect S (e ^{j ω}) between amplitude square error E minimum; Wherein, $E=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{\left[\right|S_d\left(e^{j{\mathrm{\ω}}_i}\right)|-|S\left(e^{j{\mathrm{\ω}}_i}\right)\left|\right]}^2,$ S _d(e ^{j ω}) be the frequency response expecting filter, $S\left(e^{\mathrm{j\ω}}\right)=S\left(z\right){|}_{z=e^{\mathrm{jw}}}$ It is the frequency response of designing filter;

3rd step, discretization S _d(e ^jw) waveform, obtain Doppler's formed filter sequence S (k), wherein number and the first step of k are identical with in second step.

Further, after step 2, repeat the small scale channel model of multiple state in step one and step 2 near space flight path, namely realize the simulation of large scale channel model.

The method of the dynamic plasma sheath cover Channel Modeling of near space provided by the invention and simulation, the method carries out statistical modeling based on the physical influence yardstick mechanism of dynamic, with existing reentry telemetry channel and near space channel only consider stable state plasma sheath overlap under decling phase ratio, considered different scale physically dynamic on the impact of characteristics of signals and the characteristic of channel; The present invention is applicable to the Channel Modeling under different plasma sheath cover dynamic law, and the channel parameter acquisition methods adopted can avoid channel parameter cannot detect a difficult problem, adopts quasistatic mode to extract channel parameter from far field data; The arbitrariness probability distributing functional simulation method proposed in the present invention, can simulate by article on plasma sheath cover lower issuable any amplitude-phase probability density distribution, ensures the feasibility of Channel Modeling; The present invention is applicable near space vehicle plasma sheath cover Channel Modeling, also be applicable to space flight reenter return aircraft plasma sheath cover Channel Modeling, the channel model set up can be used for algorithm design and the Performance Evaluation of the communication physical layer transmission technologys such as modulating/demodulating, chnnel coding, channel estimating and equilibrium.

Accompanying drawing explanation

Fig. 1 is the method flow diagram of the dynamic plasma sheath cover Channel Modeling of near space that the embodiment of the present invention provides and simulation;

Fig. 2 is the large scale channel resource matrix trace inequality schematic diagram that the embodiment of the present invention provides;

Fig. 3 is (certain large scale channel) 100 groups of plasma electron density regularity of distribution schematic diagrames under single state of providing of the embodiment of the present invention;

Fig. 4 is the CST non-homogeneous plasma sheath cover electromagnetic parameter modeling and simulating schematic diagram that the embodiment of the present invention provides;

Fig. 5 is the three-dimensional field intensity schematic diagram of the acceptance point acquisition that the embodiment of the present invention provides;

Fig. 6 is the amplitude probability density function schematic diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Fig. 7 is the phase place probability density function schematic diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Fig. 8 is the Doppler power spectra schematic diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Fig. 9 is the amplitude simulation random sequence schematic diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Figure 10 is the phase mode quasi-random sequence diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Figure 11 is the multiple random sequence schematic diagram of channel envelope under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Figure 12 is the dynamic plasma sheath cover channel random sequence schematic diagram under the typicalness that provides of the embodiment of the present invention under different receiving polarization;

Figure 13 is the method specific implementation flow chart of the dynamic plasma sheath cover Channel Modeling of near space that the embodiment of the present invention provides and simulation.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Below in conjunction with drawings and the specific embodiments, application principle of the present invention is further described.

As shown in Fig. 1 and Figure 13, the dynamic plasma sheath cover Channel Modeling of near space of the embodiment of the present invention and the method for simulation comprise the following steps:

S101: divide channel resource according to the empty time-frequency characteristics of large scale, builds the empty time-frequency channel resource matrix of large scale; Wherein highly corresponding large scale spatial feature, the corresponding large scale temporal signatures of speed, the corresponding large scale frequency domain character of frequency;

S102: for each channel resource matrix, obtains dynamic small scale channel parameter;

S103: according to given small scale channel parameter, realize the simulation of small scale channel model;

S104: the small scale channel model repeating multiple state in S102 and S103 near space flight path, namely realizes the simulation of large scale channel model.

As shown in Figure 1, the method for the dynamic plasma sheath cover Channel Modeling of the near space of the embodiment of the present invention and simulation comprises the following steps:

The concrete steps of the embodiment of the present invention are:

Reenter hypersonic aircraft flight path single typicalness small scale channel model for certain near space, the specific embodiments of the embodiment of the present invention is as follows:

Step one, divides according to the empty time-frequency characteristics (highly, speed, frequency) of large scale, as shown in Figure 2, provides 100 groups of electron density distribution under this state and shake rule thereof, as shown in Figure 3; Wherein actual conditions is set as: electron density distribution double gauss, and thickness is 10cm, and peak value is 1*10 ¹⁷/ m ³, shake all obeys (0.5,1.5), is uniformly distributed shake saltus step interval T _s=1us; Collision frequency is 1GHz, wave frequency 2.3GHz;

Step 2, for each channel resource matrix, obtains dynamic small scale channel parameter:

The first step, obtains the three-dimensional field intensity data of far field acceptance point by Computational Electromagnetic Methods; Specifically comprise:

(1), according to N group plasma electron density corresponding under large-scale characteristics distribution and dynamic rule thereof, build plasma sheath cover electromagnetic parameter model, wherein often organizing under non-homogeneous electron distributions, to non-homogeneous electron density layering Homogenization Treatments, every layer of electromagnetic medium parameter model is:

${\mathrm{\ϵ}}_r^m=[1-\frac{{\mathrm{\ω}}_{p,m}}{{\mathrm{\ω}}^2+{v_m}^2}+i\frac{{\mathrm{\ω}}_{p,m}(v_m/\mathrm{\ω})}{{\mathrm{\ω}}^2+{v_m}^2}]{\mathrm{\ϵ}}_0;$

be m layer plasma relative dielectric constant, ε ₀for free space dielectric constant, ω is incident wave frequency, υ _mbe m layer plasma collision frequency, ω _p,mbe m layer plasma characteristics frequency, m is the plasma number of plies; Calculate 10km far field data; With CST software emulation for such as shown in Fig. 4, calculate 10km far field data, aircraft and antenna storehouse size are as shown in the figure;

(2) three-dimensional FDTD Computational Electromagnetic Methods, is adopted to obtain the field intensity E often organizing acceptance point place under quasistatic _p, E _p=E _xa _x+ E _ya _y+ E _za _z, wherein E _x=(a+bi), E _y=(c+di), E _z=(e+fi), a _x, a _y, a _zfor the unit vector in x, y, z direction; Schematic diagram as shown in Figure 3;

(3), repeat (2) simulation calculation, obtain the multiple field intensity data of N group under large scale behavioral characteristics ${\left\{E_p\right\}}_{p=1}^N;$

Second step, obtains amplitude and the phase place probability density function of small scale channel:

(1), according to antenna receiving polarization form, select corresponding polarization components and obtain N number of Received signal strength amplitude data and and phase data during left-handed reception $\tilde{R}\left(t\right)=\{E_{\mathrm{Li}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Li}},i=1...N\},$ When dextrorotation receives $\tilde{R}\left(t\right)=\{E_{\mathrm{Ri}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Ri}},i=1...N\},$

Wherein $\left|E_R\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}},{\mathrm{\θ}}_R=\arctan \frac{E_y}{E_x}$

$\left|E_L\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}},{\mathrm{\θ}}_L=\arctan \frac{E_y}{E_x}$

(2), to received signal amplitude data and and phase data carry out statistical analysis and fitting of a polynomial, obtain amplitude-phase probability density function f _r(x) and phase place probability density function f _θ(x); Amplitude probability density function under different receiving polarization as shown in Figure 6; Obtain phase place probability density function under different receiving polarization as shown in Figure 7;

3rd step, obtains small scale channel Doppler power spectrum function:

(1), by amplitude data and and phase data obtain Received signal strength complex data namely data continuous time be similar to are obtained by the multiple field intensity data of N group;

(2), Received signal strength is solved its auto-correlation function fourier transform is carried out to it and obtains Doppler power spectral function obtain Doppler power spectra under different receiving polarization as shown in Figure 8;

Step 3, according to given small scale channel parameter, realizes the simulation of small scale channel model:

The first step, adopts even cap to give up method simulation and meets institute and extract the random sequence R (k) of amplitude probability distribution and phase probability distribution random sequence θ (k); Wherein evenly cap method step is as follows, supposes to produce f _rthe random sequence X of (x);

(1), produce at (0, a _x) upper equally distributed V _1X, wherein a _xit is the maximum of X;

(2), produce at (0, b _x) upper equally distributed V _2X, wherein b _xthe f be not less than _x(x) maximum;

(3) if V _1X≤ f _x(V _1X), make X=V _1X; If inequality does not meet, then abandon V _1Xand V _2X, the above process of repetition from (1);

(4) obedience amplitude probability-distribution function f, is obtained _rrandom sequence R (the k)=X of (x); Amplitude simulation random sequence under different receiving polarization as shown in Figure 9;

Second step, adopt even cap give up method simulation meet extract the random sequence θ (k) of amplitude probability distribution; Step is with (4) of step 3; Obtain phase mode quasi-random sequence under different receiving polarization as shown in Figure 10;

3rd step, adopts Doppler's formed filter S (k) that iir digital filter Direct Design Method design normalization is discrete;

(1), by K Second Order Network cascade form Doppler's formed filter, system function is expressed as S (z) and is:

in formula, A is constant, a _i, b, c _i, d _iit is coefficient to be asked;

(2), adopt Yule-Walker equation method to solve coefficient to solve a filter coefficient 4K+1 filter coefficient, in (0, π) interval, get M point numerical frequency ω _i, i=1,2.....M, in this M dot frequency, make to design S _d(e ^{j ω}) and expect S (e ^{j ω}) between amplitude square error E minimum; Wherein, $E=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{\left[\right|S_d\left(e^{j{\mathrm{\ω}}_i}\right)|-|S\left(e^{j{\mathrm{\ω}}_i}\right)\left|\right]}^2,$ S _d(e ^{j ω}) be the frequency response expecting filter, $S\left(e^{\mathrm{j\ω}}\right)=S\left(z\right){|}_{z=e^{\mathrm{jw}}}$ It is the frequency response of designing filter;

(3) discretization S _d(e ^jw) waveform, obtain Doppler's formed filter sequence S (k), wherein number and the first step of k are identical with in second step;

4th step, superposition amplitude random sequence and phase place random sequence generate multiple random sequence Z (k)=R (k) e of fading channel envelope ^{j θ (k)}; The channel envelope obtained under different receiving polarization answers random sequence as shown in figure 11;

5th step, the multiple random sequence of channel envelope, by Doppler's formed filter sequence, generates dynamic plasma sheath cover channel random sequence C _p( _k)=Z (k) S (k); The dynamic plasma sheath obtained under different receiving polarization overlaps channel random sequence as shown in figure 12;

Step 6, repeats step 2 and step 3, carries out modeling, realize structure and the simulation of large scale channel model to the small scale channel of large-scale characteristics state multiple on close to space vehicle track.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. a method for the dynamic plasma sheath cover Channel Modeling of near space and simulation, is characterized in that, the method for the dynamic plasma sheath cover Channel Modeling of this near space and simulation comprises the following steps:

Step one, for each channel resource matrix, obtains dynamic small scale channel parameter; Obtain the three-dimensional field intensity data of far field acceptance point by Computational Electromagnetic Methods, obtain amplitude and the phase place probability density function of small scale channel, obtain small scale channel Doppler power spectrum function;

Step 2, according to given small scale channel parameter, realizes the simulation of small scale channel model; Specifically comprise:

The first step, adopts even cap to give up method simulation and meets institute and extract the random sequence R (k) of amplitude probability distribution and phase probability distribution random sequence θ (k);

Second step, adopts Doppler's formed filter S (k) that iir digital filter Direct Design Method design normalization is discrete;

3rd step, superposition amplitude random sequence and phase place random sequence generate multiple random sequence Z (k)=R (k) e of fading channel envelope ^{j θ (k)};

4th step, the multiple random sequence of channel envelope, by Doppler's formed filter sequence, generates dynamic plasma sheath cover channel random sequence C _p(k)=Z (k) S (k);

Step 3, for each channel resource matrix, repeats step 2, obtains the dynamic plasma sheath cover channel random sequence under different receiving polarization.

2. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, is characterized in that, needs to divide channel resource according to the empty time-frequency characteristics of large scale before step one, builds the empty time-frequency channel resource matrix of large scale; Wherein highly corresponding large scale spatial feature, the corresponding large scale temporal signatures of speed, the corresponding large scale frequency domain character of frequency, wherein height divides with 5km interval, and speed divides with 0.5 Mach of interval, and frequency divides with 500MHz interval.

3. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, is characterized in that, in step one, obtains the three-dimensional field intensity data of far field acceptance point by Computational Electromagnetic Methods; Specifically comprise:

The first step, to distribute and dynamic rule according to N group plasma electron density corresponding under large-scale characteristics, build plasma sheath cover electromagnetic parameter model, wherein often organizing under non-homogeneous electron distributions, to non-homogeneous electron density layering Homogenization Treatments, every layer of electromagnetic medium parameter model is:

${\mathrm{\ϵ}}_r^m=[1-\frac{{\mathrm{\ω}}_{p,m}}{{\mathrm{\ω}}^2+{v_m}^2}+i\frac{{\mathrm{\ω}}_{p,m}(v_m/\mathrm{\ω})}{{\mathrm{\ω}}^2+{v_m}^2}]{\mathrm{\ϵ}}_0;$

be m layer plasma relative dielectric constant, ε ₀for free space dielectric constant, ω is incident wave frequency, υ _mbe m layer plasma collision frequency, ω _p,mbe m layer plasma characteristics frequency, m is the plasma number of plies;

Second step, three-dimensional FDTD electromagnetism computational algorithm is adopted to obtain the field intensity E often organizing acceptance point place under quasistatic _p, E _p=E _xa _x+ E _ya _y+ E _za _z, wherein E _x=(a+bi), E _y=(c+di), E _z=(e+fi), a _x, a _y, a _zfor the unit vector in x, y, z direction;

3rd step, repetition second step simulation calculation, obtain the multiple field intensity data of N group under large scale behavioral characteristics ${\left\{E_p\right\}}_{p=1}^N.$

4. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, is characterized in that, in step one, obtains amplitude and the phase place probability density function of small scale channel, specifically comprises:

The first step, according to antenna receiving polarization form, select corresponding polarization components and obtain N number of Received signal strength amplitude data and and phase data

During left-handed reception $\tilde{R}\left(t\right)=\{E_{\mathrm{Li}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Li}},i=1...N\},$

When dextrorotation receives $\tilde{R}\left(t\right)=\{E_{\mathrm{Ri}},i=1...N\},\widetilde{\mathrm{\θ}}\left(t\right)=\{{\mathrm{\θ}}_{\mathrm{Ri}},i=1...N\};$

Wherein $\begin{array}{cc}\left|E_R\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}}& {\mathrm{\θ}}_E=\arctan \frac{E_y}{E_x}\\ \left|E_L\right|=\frac{\sqrt{E_x^2+E_y^2}}{\sqrt{2}}& {\mathrm{\θ}}_L=\arctan \frac{E_x}{E_y}\end{array}$

Second step, to received signal amplitude data and and phase data carry out statistical analysis and fitting of a polynomial, obtain amplitude-phase probability density function f _r(x) and phase place probability density function f _θ(x); Obtain the amplitude probability density function under different receiving polarization; Obtain the phase place probability density function under different receiving polarization.

5. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, is characterized in that, in step one, obtains small scale channel Doppler power spectrum function, specifically comprises:

The first step, by amplitude data and and phase data obtain Received signal strength complex data namely data continuous time be similar to are obtained by the multiple field intensity data of N group;

Second step, solve Received signal strength its auto-correlation function carry out Fourier transform and obtain Doppler power spectral function obtain the Doppler power spectra under different receiving polarization.

6. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, it is characterized in that, in the first step of step 2, even cap method step is as follows, produces f _rthe random sequence X of (x);

The first step, to produce at (0, a _x) upper equally distributed V _1X, wherein a _xit is the maximum of X;

Second step, to produce at (0, b _x) upper equally distributed V _2X, wherein b _xthe f be not less than _x(x) maximum;

If the 3rd step V _1X≤ f _x(V _1X), make X=V _1X; If inequality does not meet, then abandon V _1Xand V _2X, the above process of repetition from the first step;

4th step, obtain obedience amplitude probability-distribution function f _rrandom sequence R (the k)=X of (x); Amplitude simulation random sequence under different receiving polarization.

7. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, it is characterized in that, in the first step of step 2, even cap method step is as follows, produces f _θthe random sequence Y of (x);

The first step, to produce at (0, a _y) upper equally distributed V _1Y, wherein a _yit is the maximum of Y;

Second step, to produce at (0, b _y) upper equally distributed V _2Y, wherein b _ythe f be not less than _x(x) maximum;

If the 3rd step V _1Y≤ f _x(V _1Y), make Y=V _1Y; If inequality does not meet, then abandon V _1Yand V _2Y, the above process of repetition from the first step;

4th step, obtain obeying phase probability distribution function f _θrandom sequence θ (the k)=Y of (x); Phase mode quasi-random sequence under different receiving polarization.

8. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, it is characterized in that, Doppler's formed filter S (k) that the 3rd step in step 2 adopts iir digital filter Direct Design Method design normalization discrete, specifically comprises:

The first step, form Doppler's formed filter by K Second Order Network cascade, system function is expressed as S (z) and is:

$S\left(z\right)=A\underset{j=1}{\overset{K}{\mathrm{\Π}}}\frac{1+a_j{z}^{-1}+b_j{z}^{-2}}{1+c_j{z}^{-1}+d_j{z}^{-2}}$

In formula, A is constant, a _j, b _j, c _j, d _jbe jth a to be asked filter coefficient, K is cascade second order filter number;

Second step, employing Yule-Walker equation method solve coefficient and solve a filter coefficient 4K+1 filter coefficient, get M point numerical frequency ω in (0, π) interval _i, i=1,2.....M, M are frequency points, on these frequencies, make S _d(e ^{j ω}) and expect S (e ^{j ω}) between amplitude square error E minimum; Wherein, $E=\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{\left[\right|S_d\left(e^{j{\mathrm{\ω}}_i}\right)|-|S\left(e^{j{\mathrm{\ω}}_i}\right)\left|\right]}^2,$ S _d(e ^{j ω}) be the frequency response expecting filter, $S\left(e^{\mathrm{j\ω}}\right)=S\left(z\right){|}_{z=e^{\mathrm{jw}}}$ It is the frequency response of designing filter;

3rd step, discretization S _d(e ^jw) waveform, obtain Doppler's formed filter sequence S (k), wherein number and the first step of k are identical with in second step.

9. the method for the dynamic plasma sheath cover Channel Modeling of near space as claimed in claim 1 and simulation, it is characterized in that, after step 2, repeat the small scale channel model of multiple state in step one and step 2 near space flight path, namely realize the simulation of large scale channel model.