阅读说明：本技术 遥测信道非相干大规模simo处理方法、系统及应用 (Remote measuring channel incoherent large-scale SIMO processing method, system and application ) 是由 石磊 刘彦明 姚博 魏海亮 李小平 袁淑容 于 2020-12-03 设计创作，主要内容包括：本发明属于航天测控通信技术领域,公开了一种遥测信道非相干大规模SIMO处理方法、系统及应用,高超声速飞行器等离子体鞘套信道的建模：建立时变等离子体鞘套的分层电子密度模型；并计算等离子体鞘套透射系数；构建高超声速飞行器大规模下行SIMO系统模型：由高超声速飞行器端单天线和一个多天线接收站组成；优化的功率调制：依据等离子体鞘套信道的平均功率衰减和下行信道的渐进特性设计优化；非相干检测：采用简化的可变逆跳蒙特卡洛算法估计概率密度函数,基于最大似然准则(ML)的非相干检测。本发明针对高超声速飞行器下行SIMO信道,使得在等离子体鞘套信道下实现高可靠性和高效率的信号检测,提升通信质量,有效缓解黑障。(The invention belongs to the technical field of aerospace measurement and control communication, and discloses a remote measurement channel incoherent large-scale SIMO processing method, a system and application, wherein a hypersonic aircraft plasma sheath channel is modeled by the following steps: establishing a layered electron density model of a time-varying plasma sheath; and calculating a plasma sheath transmission coefficient; constructing a large-scale downlink SIMO system model of the hypersonic aircraft: the system consists of a hypersonic aircraft end single antenna and a multi-antenna receiving station; optimized power modulation: designing optimization according to the average power attenuation of the plasma sheath channel and the progressive characteristic of a downlink channel; non-coherent detection: probability density functions are estimated using a simplified variable-inverse-hopping monte-carlo algorithm, non-coherent detection based on maximum likelihood criterion (ML). Aiming at the downlink SIMO channel of the hypersonic aircraft, the invention realizes high-reliability and high-efficiency signal detection under the plasma sheath channel, improves the communication quality and effectively relieves the black fault.)

1. A telemetry channel non-coherent large-scale SIMO processing method, comprising:

modeling of hypersonic aircraft plasma sheath channel: establishing a layered electron density model of a time-varying plasma sheath; and calculating a plasma sheath transmission coefficient;

constructing a large-scale downlink SIMO system model of the hypersonic aircraft: the system consists of a hypersonic aircraft end single antenna and a multi-antenna receiving station;

optimized power modulation: designing optimization according to the average power attenuation of the plasma sheath channel and the progressive characteristic of a downlink channel;

non-coherent detection: and estimating a probability density function by adopting a simplified variable reverse-jump Monte Carlo algorithm, and carrying out ML-based fast incoherent detection.

2. The telemetry channel incoherent large-scale SIMO processing method of claim 1, wherein the establishing a layered electron density model Ne of a time-varying plasma sheath_dyn(z, t); and calculating the transmission coefficient T of the plasma sheath_dyn(t,f₀)。

3. The telemetry channel non-coherent large-scale SIMO processing method of claim 1, wherein the method of modeling the plasma sheath channel specifically comprises:

(1) establishing a layered electron density model of a time-varying plasma sheath: non-uniform plasma sheath thickness Z near the antenna window of the input hypersonic aerocraft, total number of plasma sheath layers N and each plasma sheath layer thickness d_mM is plasma sheath layering serial number m-1, 2, …, N, plasma sheath time varying time T, and according to the electron density of the plasma sheath, the plasma sheath electron density follows double-Gaussian distribution along the direction vertical to the antenna window of the aircraft, and a first Gaussian function influence parameter c₁And a second Gaussian function influence parameter c₂Peak electron density Ne_peakThe peak electron density is z in z-axis_peak，Ne_peakDetermining the electron density distribution function of the time-varying plasma sheath according to the distribution rule of sinusoidal distribution along the time direction, and establishing a time-varying plasma sheath electron density model Ne_dyn(z,t)；

(2) Calculating the transmission coefficient T of the plasma sheath_dyn(t,f₀): carrier frequency f of input communication signal₀Electron mass m_eFrequency of electron impact v of time-varying plasma sheath_enIntrinsic wave impedance z of the layers of the plasma sheath_m(m-1, 2, …, N), intrinsic wave impedance z of vacuum₀Using a time-varying plasma sheath electron density model Ne_dyn(z, T) calculating the time-varying transmission coefficient T of the plasma sheath by an equivalent transmission line method_dyn(t,f₀) (ii) a The magnitude of the transmission coefficient will be calculated and the result assigned to the plasma sheath channel T.

4. The telemetry channel non-coherent large-scale SIMO processing method of claim 1, wherein the constructing of the hypersonic aircraft large-scale downlink SIMO system model comprises: the system consists of a single antenna at the end of the hypersonic aircraft and a multi-antenna receiving station, wherein the receiving station is provided with n (n → ∞) antennas, and an equivalent baseband signal receiving model at the end of the receiving station in one time slot of the system is as follows:

y＝hx+v；

where y is the M x 1 dimensional received signal vector, x is the transmitted signal, h is the n x 1 dimensional channel matrix, and h is defined by the matrix element h_iV is complex Gaussian white noise of an n multiplied by 1 receiving end, each element of v is distributed according to circularly symmetric complex Gaussian CSCG, the mean value is zero, and the variance is sigma²I.e. v_i～CN(0，σ²)，i＝1，2，…，n；

For the downlink plasma sheath-Rice channel of a hypersonic aircraft, where T denotes the plasma sheath channel, denoted by T_dyn(t,f₀) Obtaining;indicating spatial rice channel fading, i.e.The envelope of (i) follows a rice distribution, i 1, …, n; variance of noise σ²T andthe mean power attenuation q of the plasma sheath channel is known as unknown information.

5. The telemetry channel non-coherent large-scale SIMO processing method of claim 1, wherein the optimized power modulation: transmitting symbolsWhereinIs the power of the k-th symbol,is a code book, L isBase of p_k(k is 1, 2, …, L) and satisfies the average power constraintMean power attenuation q in terms of plasma sheath channel²And progressive characteristic design optimization of downlink channel

6. The telemetry channel non-coherent large-scale SIMO processing method of claim 5, wherein the transmit constellationThe adaptive design method specifically comprises the following steps:

(1) for theLet p be_kDemodulation interval ofr(p_k) +d_r，k]Wherein d is_l，k>0，d_r，k>0，a_kIndicates the demodulation boundary r (p)_k)+d_r，kLet us order Independent random variable U from 0 mean_kImplementation, U_kHas a moment mother function ofOrder toFor optimizing constellation P^optIs provided withOrder to

(2) Searching for the highest t satisfying the power constraint using Algorithm 1 and Algorithm 2^optAnd corresponding optimal constellation P^optThe algorithm 1 is used for initializing and updating a t value, and the t value obtained by the algorithm 1 is substituted into the algorithm 2; searching a sending constellation under the current t value by using an algorithm 2; the algorithm 1 updates the value t according to whether the constellation obtained by the algorithm 2 meets the power constraint condition; algorithms 1 and 2 are cycled until the value of t meets the set precision 10^-3To obtain the highest t of which the output meets the power constraint^optAnd corresponding optimal constellation P^opt(ii) a Algorithms 1 and 2 are specifically as follows:

algorithm 1: initialization t_l＝0，t_u＝∞，Substituting t into algorithm 2; if the algorithm 2 constellation meets the power constraint condition, let t_lT; if the algorithm 2 constellation does not satisfy the power constraint condition, let t_uT; continuously substituting the obtained t value into the algorithm 2 to obtain the t value again, and circulating the algorithm 1 until the t value meets the set precision 10^-3；

And 2, algorithm: let p be₁＝0，Selection of p₂So that J (p) is₂) Is t, and this process is performed in order until p is found_L(ii) a Checking whether a power constraint condition is satisfied; if yes, the constellation is retained, t is increased by using an algorithm 1, and the process is repeated; if not, the constellation should be discarded, t is reduced using Algorithm 1 and the process repeated.

7. The telemetry channel non-coherent large-scale SIMO processing method of claim 1, wherein the ML-based fast non-coherent detection: calculate the average power of the received vector y:because of the high dynamic and deep fading characteristics of the plasma sheath channel, | | y | | non-conducting phosphor²The conditional probability density function of/n is unknown, and a simplified variable reverse-jump Monte Carlo algorithm estimation is designed at a receiving station endConditional probability density function of(CPDF)The Maximum Likelihood (ML) demodulator output is then:

whereinIs a likelihood function/conditional probability density function.

8. The telemetry channel non-coherent large-scale SIMO processing method of claim 7, wherein the simplified variable back-hopping monte carlo algorithm specifically comprises: the probability density function of the entire model is described by a mixed gaussian process c:

wherein ω is_kThe state probability of the state k in the Gaussian mixture process, namely the ratio of the k-th Gaussian process in the Gaussian mixture process,mean and variance are represented;

consider a two-dimensional time-varying sequence (c)_t，z_t) Describing a non-stationary random process of receiving statistic c, wherein (c)_t) Represents the statistical sequence of the receiving end, (z)_t) Sequence representing hidden states, z_tE {1, …, L }, L denotes the number of states in the markov model, and the parameters to be estimated are λ ═ { μ, σ, z, ω }, where μ ═ μ { (μ }_k)，σ＝(σ_k)，ω＝(ω_k). Prior distribution of parameters: omega-D (delta)₁，δ₂，...，δ_L)，δ₁，δ₂，...，δ_LInitialized to 1, mu_k～N(ξ，κ^-1)，Wherein β to G (G, h), α ═ 2, and κ ═ R^-2，ξ＝y_min＝R/2，g＝0.2，h＝10/R²，R＝c_max-c_min(ii) a G (G, h) denotes the gamma distribution with parameters G and h, D (delta)₁，δ₂，...，δ_L) Representing a Dirichlet distribution;

at the initial moment, the number of states is set to L, and the remaining variables are initialized based on their prior distributions; the maximum number of iterations is set to N_iterationThe state space x ═ (η, ω, z, μ, σ, c) of all relevant parameters at time instant N of the iteration is updated to a new state space at time instant N +1 of the iteration, i.e. x ' ═ η ', ω ', z ', μ ', σ ', c '); each iteration is summarized as:

1) updating omega;

whereinFor hidden state z at time N_tK is the number of k;

2) update (μ, σ):

3) and updating z:

4) updating the beta:

9. a telemetry channel non-coherent large-scale SIMO processing system for implementing the telemetry channel non-coherent large-scale SIMO processing method according to any one of claims 1 to 8, comprising:

the modeling module is used for realizing modeling of a hypersonic aircraft plasma sheath channel;

the system model construction module is used for constructing a downlink large-scale SIMO system model of the hypersonic aircraft;

the power modulation module is used for self-adaptive power modulation;

and the incoherent detection module is used for incoherent detection based on the RRJ-MCMC algorithm.

10. A high-speed aircraft, wherein the high-speed aircraft operates the method of incoherent large-scale SIMO processing of a telemetry channel according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of aerospace measurement and control communication, and particularly relates to a remote measurement channel incoherent large-scale SIMO processing method, system and application.

Background

At present: when a high-speed aircraft flies at a high supersonic speed or reenters the earth atmosphere, a plasma sheath coated on the surface of the aircraft can absorb, reflect and scatter electromagnetic waves, so that signals are obviously attenuated, and even the measurement and control communication of the aircraft is interrupted (black barrier). The adaptive communication method in the existing technical scheme for relieving the black barrier draws wide attention. The communication method for relieving the black fault mainly comprises the steps of increasing the transmitting power, improving the communication frequency, self-adaptive communication strategies/methods and the like, wherein the self-adaptive communication strategies are self-adaptively adjusted according to the state of a plasma sheath channel, and further the black fault is relieved, for example, the methods of self-adaptively adjusting the code rate and the coding parameters and the like by utilizing channel estimation and channel condition prediction are adopted. However, existing communication methods are directed only to plasma sheath channel communication. The downlink telemetry channel (the comprehensive channel of the plasma sheath channel and the Rice channel) of the hypersonic aerocraft is a channel which is more in line with the actual telemetry scene, and the design of the modulation method suitable for the downlink telemetry channel of the hypersonic aerocraft and the corresponding detection receiving technology are lack of breakthrough. The plasmonic-sheath channel is not known because it has high dynamic, non-stationary and fast time-varying characteristics, making it difficult to get the real-time state of the channel at the receiving end, and causes constellation rotation (parasitic modulation effect) of the PSK signal, resulting in demodulation failure. Therefore, the modulation method should avoid phase modulation and the receiver should employ non-coherent demodulation. Aiming at the problems of unknown channel information and constellation rotation, if a multi-antenna technology can be introduced and a corresponding novel modulation scheme and a signal detection method are designed, a plasma sheath channel can be adapted to improve the communication quality.

The multi-antenna technology can effectively improve the channel capacity and the communication performance of a deep fading channel. Aiming at a downlink SIMO channel (called as a hypersonic aircraft downlink SIMO channel for short) of a cascading plasma sheath channel and a Rice channel, the power modulation scheme and a corresponding signal detection method are designed by utilizing progressive correlation of the downlink SIMO channel, and the method has great challenge.

Through the above analysis, the problems and defects of the prior art are as follows: the hypersonic aircraft plasma sheath channel has high dynamic and deep fading characteristics, and channel information is unknown at a receiving end. The common communication scheme based on the known channel information is not suitable any more, and the design of a modulation scheme adaptive to the downlink SIMO channel of the hypersonic aerocraft and a corresponding adaptive incoherent signal detection method are urgently needed.

The difficulty and significance for solving the problems and defects are as follows: the prior art does not fully utilize airspace resources, and the multi-antenna receiving technology can effectively improve the channel capacity of a deep fading channel, so that a telemetering channel incoherent large-scale SIMO system is designed. The sending end of the downlink SIMO system adopts a power modulation method, can avoid phase modulation and overcome constellation rotation problem, and designs self-adaptive power modulation according to the state change of a channel in order to obtain the maximum system performance; the receiving end of the SIMO system calculates the average power of the receiving vector according to the progressive correlation characteristic of the channel, designs the correct demodulation information of the corresponding self-adaptive non-coherent ML signal detection method, and can solve the problems of unknown prior information and channel estimation of the high dynamic deep fading channel of the plasma sheath channel. The adaptive power modulation scheme and the corresponding incoherent signal detection scheme are designed for the downlink SIMO system of the hypersonic aircraft, high-reliability and high-efficiency wireless communication can be realized under a plasma sheath channel, and the black barrier is effectively relieved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a telemetry channel incoherent large-scale SIMO processing method, a telemetry channel incoherent large-scale SIMO processing system and application.

The invention is realized in such a way that a telemetry channel incoherent large-scale SIMO processing method comprises the following steps:

modeling of hypersonic aircraft plasma sheath channel: establishing a layered electron density model of a time-varying plasma sheath; and calculating a plasma sheath transmission coefficient;

constructing a large-scale downlink SIMO system model of the hypersonic aircraft: the system consists of a hypersonic aircraft end single antenna and a multi-antenna receiving station;

optimized power modulation: designing optimization according to the average power attenuation of the plasma sheath channel and the progressive characteristic of a downlink channel;

non-coherent detection: and estimating a probability density function by adopting a simplified variable reverse-jump Monte Carlo algorithm, and performing quick incoherent detection based on ML.

Further, the establishing a layered electron density model Ne of the time-varying plasma sheath_dyn(z, t); and calculating the transmission coefficient T of the plasma sheath_dyn(t,f₀)。

Further, the modeling method of the plasma sheath channel specifically includes:

(1) establishing a layered electron density model of a time-varying plasma sheath: non-uniform plasma sheath thickness Z near the antenna window of the input hypersonic aerocraft, total number of plasma sheath layers N and each plasma sheath layer thickness d_mM is plasma sheath layering serial number m-1, 2, …, N, plasma sheath time varying time T, and according to the electron density of the plasma sheath, the plasma sheath electron density follows double-Gaussian distribution along the direction vertical to the antenna window of the aircraft, and a first Gaussian function influence parameter c₁And a second Gaussian function influence parameter c₂Peak electron density Ne_peakThe peak electron density is z in z-axis_peak。Ne_peakDetermining the electron density distribution function of the time-varying plasma sheath according to the distribution rule of sinusoidal distribution along the time direction, and establishing a time-varying plasma sheath electron density model Ne_dyn(z,t)；

(2) Calculating the transmission coefficient of the plasma sheathT_dyn(t,f₀): carrier frequency f of input communication signal₀Electron mass m_eFrequency of electron impact v of time-varying plasma sheath_enIntrinsic wave impedance z of the layers of the plasma sheath_m(m-1, 2, …, N), intrinsic wave impedance z of vacuum₀Using a time-varying plasma sheath electron density model Ne_dyn(z, T) calculating the time-varying transmission coefficient T of the plasma sheath by an equivalent transmission line method_dyn(t,f₀) (ii) a The magnitude of the transmission coefficient will be calculated and the result assigned to the plasma sheath channel T.

Further, the method for constructing the large-scale downlink SIMO system model of the hypersonic aircraft comprises the following steps: the system consists of a single antenna at the end of the hypersonic aircraft and a multi-antenna receiving station, wherein the receiving station is provided with n (n → ∞) antennas, and an equivalent baseband signal receiving model at the end of the receiving station in one time slot of the system is as follows:

y＝hx+v；

wherein y is an M × 1-dimensional received signal vector, x is a transmitted signal, the specific design is given in the next section, h is an n × 1 channel matrix, v is complex gaussian white noise at an n × 1 receiving end, each element of v obeys CSCG distribution, the mean is zero, and the variance is σ²I.e. v_i～CN(0，σ²)，i＝1，2，…，n；

For the downlink plasma sheath-Rice channel of a hypersonic aircraft, where T denotes the plasma sheath channel, denoted by T_dyn(t,f₀) Obtaining;indicating spatial rice channel fading, i.e.The envelope of (i) follows a rice distribution, i 1, …, n. Assume noise variance σ²T andis unknown information and the mean power attenuation q of the plasma sheath channel is known²。

Further, the optimized power modulation: transmitting symbolsWherein The power of the k-th symbol is,is a code book, L isBase of p_k(k ═ 1, 2, ·, L) with equal probability of transmission and satisfying the average power constraintDesigned optimized according to the mean power attenuation q of the plasma sheath channel and the progressive nature of the downstream channel

Further, the transmission constellationThe adaptive design method specifically comprises the following steps:

(1) for p_kLet us orderLet p be_kDemodulation interval of r(p_k)+d_r，k]Wherein d is_l，k>0，d_r，k>0，a_kIndicates the demodulation boundary r (p)_k)+d_r，k. Order toIndependent random variable U from 0 mean_kImplementation, U_kHas a moment mother function ofOrder toFor optimizing constellation P^optIs provided withOrder to

(2) Searching for the highest t satisfying the power constraint using Algorithm 1 and Algorithm 2^optAnd corresponding optimal constellation P^opt. The algorithm 1 is used for initializing and updating a t value, and the t value obtained by the algorithm 1 is substituted into the algorithm 2; searching a sending constellation under the current t value by using an algorithm 2; the algorithm 1 updates the value t according to whether the constellation obtained by the algorithm 2 meets the power constraint condition; algorithms 1 and 2 are cycled until the value of t meets the set precision 10^-3To obtain the highest t of which the output meets the power constraint^optAnd corresponding optimal constellation P^opt. Algorithms 1 and 2 are specifically as follows:

algorithm 1: initialization t_l＝0，t_u＝∞，Substituting t into algorithm 2; if the algorithm 2 constellation satisfies the workRate constraint condition, let t_lT; if the algorithm 2 constellation does not satisfy the power constraint condition, let t_uT; continuously substituting the obtained t value into the algorithm 2 to obtain the t value again, and circulating the algorithm 1 until the t value meets the set precision 10^-3。

And 2, algorithm: let p be₁＝0，d_r，Selection of p₂So that J (p) is₂) Is t, and d_l， This process is performed in order until p is found_L(ii) a Checking whether a power constraint condition is satisfied; if yes, the constellation is retained, t is increased by using an algorithm 1, and the process is repeated; if not, the constellation should be discarded, t is reduced using Algorithm 1 and the process repeated.

Further, the ML-based fast incoherent detection: calculate the average power of the received vector y:because of the high dynamic and deep fading characteristics of the plasma sheath channel, | | y | | non-conducting phosphor²The conditional probability density function of/n is unknown. For this purpose, a simplified variable reverse-hopping Monte Carlo algorithm estimation is designed at the receiving station endConditional Probability Density Function (CPDF)The Maximum Likelihood (ML) demodulator output is then:

whereinIs a likelihood function/conditional probability density function.

Further, the simplified variable back-hopping monte carlo algorithm specifically includes: the probability density function of the entire model is described by a mixed gaussian process c:

wherein ω is_kThe state probability of the state k in the Gaussian mixture process, namely the ratio of the k-th Gaussian process in the Gaussian mixture process,mean and variance are represented;

consider a two-dimensional time-varying sequence (c)_t，z_t) Describing a non-stationary random process of receiving statistic c, wherein (c)_t) Represents the statistical sequence of the receiving end, (z)_t) Sequence representing hidden states, z_tE {1, …, L }, L representing the number of states in the Markov model. The parameters to be estimated are λ ═ { μ, σ, z, ω }, where μ ═ μ (μ ═ o }_k)，σ＝(σ_k)，ω＝(ω_k). Prior distribution of parameters: omega-D (delta)₁，δ₂，...，δ_L)，δ₁，δ₂，...，δ_LThe initialization is 1. Mu.s_k～N(ξ，κ^-1)，Wherein β to G (G, h), α ═ 2, and κ ═ R^-2，ξ＝y_minR/2，g＝ 0.2，h＝10/R²，R＝c_max-c_min(ii) a G (G, h) denotes the gamma distribution with parameters G and h, D (delta)₁，δ2，...，δ_L) Representing a Dirichlet distribution.

Number of states at initial timeSet to L, the remaining variables are initialized based on their prior distributions; the maximum number of iterations is set to N_iteration. The state space x ═ (η, ω, z, μ, σ, c) of all relevant parameters at the time of iteration N is updated to a new state space at the time of iteration N +1, i.e., x ' ═ η ', ω ', z ', μ ', σ ', c '); each iteration is summarized as:

1) updating omega;

whereinFor hidden state z at time N_tK is the number of k;

2) update (μ, σ):

3) and updating z:

4) updating the beta:

another object of the present invention is to provide a telemetry channel non-coherent large-scale SIMO processing system for implementing the telemetry channel non-coherent large-scale SIMO processing method, the telemetry channel non-coherent large-scale SIMO processing system comprising:

the modeling module is used for realizing modeling of a hypersonic aircraft plasma sheath channel;

the system model construction module is used for constructing a downlink large-scale SIMO system model of the hypersonic aircraft;

the power modulation module is used for self-adaptive power modulation;

and the incoherent detection module is used for incoherent detection based on the RRJ-MCMC algorithm.

It is another object of the present invention to provide a high speed aircraft that operates the telemetry channel non-coherent large scale SIMO processing method.

By combining all the technical schemes, the invention has the advantages and positive effects that: the invention provides a self-adaptive power modulation scheme and an incoherent signal detection scheme aiming at a downlink SIMO channel of a hypersonic aircraft, so that high-reliability and high-efficiency signal detection is realized under a plasma sheath channel, the communication quality is improved, and the black barrier is effectively relieved.

Aiming at the problems that the downlink SIMO channel receiving end of the hypersonic aircraft is unknown in channel information and the PSK signal constellation rotates, the invention adopts the multi-antenna receiving technology to effectively improve the channel capacity and the communication performance. Designing an adaptive power modulation scheme to combat or circumvent the above problems; meanwhile, the signal detection method adopts a ML-based fast incoherent detection scheme. The self-adaptive power modulation scheme and the incoherent signal detection method can realize the high-reliability and high-efficiency signal detection of the SIMO channel of the hypersonic aerocraft, improve the communication quality and effectively relieve the black barrier. The adaptive power modulation scheme and the incoherent signal detection scheme under the downlink SIMO channel of the hypersonic aircraft are provided, and high-reliability and high-efficiency information transmission under the plasma sheath channel is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.

FIG. 1 is a flow chart of a telemetry channel non-coherent large-scale SIMO processing method provided by an embodiment of the invention.

FIG. 2 is a schematic block diagram of a telemetry channel non-coherent large-scale SIMO processing system provided by an embodiment of the present invention;

in fig. 2: 1. a modeling module; 2. a system model construction module; 3. a power modulation module; 4. and a noncoherent detection module.

FIG. 3 is a schematic diagram of a telemetry channel non-coherent large-scale SIMO processing system provided by an embodiment of the invention.

FIG. 4 is a schematic diagram of a large-scale downlink SIMO system model of a hypersonic aerocraft according to an embodiment of the invention.

Fig. 5 is a schematic demodulation area diagram of a large-scale downlink SIMO system of a hypersonic aircraft provided by an embodiment of the invention when L is 6.

Fig. 6 is a time varying graph of electron density of a plasma sheath provided by an embodiment of the present invention.

Fig. 7(a) and 7(b) are amplitude and phase time diagrams of a plasma sheath channel provided by an embodiment of the present invention.

FIG. 8(a) shows the peak electron density Ne of the optimized power modulation and ASK modulation method provided by the present invention when the incoherent detection method provided by the present invention is used in the down-going telemetry SIMO channel of the hypersonic aircraft according to the embodiment of the present invention_peak＝2×10¹⁸m^-3When the rice factor K is {0, 1, ∞ }, and the signal-to-noise ratio γ is 10dB, the variation of the bit error rate with the number n of the receiving antennas is shown schematically.

FIG. 8(b) is a diagram of the optimized power modulation and ASK modulation method provided by the embodiment of the present invention when the incoherent detection method provided by the present invention is adopted in the downlink telemetry SIMO channel of the hypersonic aircraft, the Ne is_peak＝6×10¹⁸m^-3When K is {0, 1, ∞ }, and γ is 10dB, the variation of the bit error rate with n is shown schematically.

FIG. 8(c) shows that the optimized power modulation and ASK provided by the embodiment of the invention are performed in the lower telemetry SIMO channel of the hypersonic aerocraftModulation method Using the incoherent detection method of the present invention, at Ne_peak＝6×10¹⁸m^-3When K is {0, 1, ∞ }, and n is 100, the variation of the bit error rate with γ is shown schematically.

FIG. 9(a) shows the Ne and Ne of the optimized power modulation and ASK modulation method of the present invention when the incoherent detection method of the present invention is used in the down-going telemetry SIMO channel of the hypersonic aircraft according to the embodiment of the present invention_peak＝2×10¹⁸m^-3When K is {0, 1, ∞ }, and γ is 10dB, the variation of the channel capacity loss with n is shown schematically.

FIG. 9(b) shows the Ne and Ne of the optimized power modulation and ASK modulation method of the present invention when the incoherent detection method of the present invention is used in the down-going telemetry SIMO channel of the hypersonic aircraft according to the embodiment of the present invention_peak＝6×10¹⁸m^-3When K is {0, 1, ∞ }, and γ is 10dB, the variation of the channel capacity loss with n is shown schematically.

FIG. 9(c) shows the Ne and Ne of the optimized power modulation and ASK modulation method of the present invention when the incoherent detection method of the present invention is used in the down-going telemetry SIMO channel of the hypersonic aircraft according to the embodiment of the present invention_peak＝6×10¹⁸m^-3When K is {0, 1, ∞ }, and n is 100, the variation of the channel capacity loss with γ is shown schematically.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Aiming at the problems in the prior art, the invention provides a telemetry channel incoherent large-scale SIMO processing method, a telemetry channel incoherent large-scale SIMO processing system and application thereof, and the invention is described in detail below with reference to the accompanying drawings.

As shown in fig. 1, the present invention provides a telemetry channel non-coherent large-scale SIMO processing method, which comprises the following steps:

s101: modeling a hypersonic aircraft plasma sheath channel;

s102: constructing a downlink large-scale SIMO system model of the hypersonic aircraft;

s103: adaptive power modulation;

s104: and (3) incoherent detection based on an RRJ-MCMC algorithm.

Those skilled in the art can also implement the telemetry channel non-coherent large-scale SIMO processing method provided by the present invention by using other steps, and the telemetry channel non-coherent large-scale SIMO processing method provided by the present invention of fig. 1 is only one specific example.

As shown in fig. 2, the present invention provides a telemetry channel non-coherent large-scale SIMO processing system comprising:

the modeling module 1 is used for modeling a plasma sheath channel of the hypersonic aircraft;

the system model construction module 2 is used for constructing a downlink large-scale SIMO system model of the hypersonic aircraft;

the power modulation module 3 is used for self-adaptive power modulation;

and the incoherent detection module 4 is used for incoherent detection based on the RRJ-MCMC algorithm.

The technical solution of the present invention is further described below with reference to the accompanying drawings.

The invention can realize high-reliability and high-efficiency information transmission under a plasma sheath channel, and is an effective means for relieving black barrier.

As shown in fig. 3, the scheme includes the following steps:

the method comprises the following steps: modeling of hypersonic aircraft plasma sheath channel:

1) establishing a layered electron density model of a time-varying plasma sheath: non-uniform plasma sheath thickness Z near the antenna window of the input hypersonic aerocraft, total number of plasma sheath layers N and each plasma sheath layer thickness d_mM is plasma sheath layer number m-1, 2, …, N, plasma sheath time-varying time T, according to plasma sheath electron density along the vertical aircraft antenna windowThe direction (set as z-axis) follows a double Gaussian distribution, the first Gaussian function influences the parameter c₁And a second Gaussian function influence parameter c₂Peak electron density Ne_peakThe peak electron density is z in z-axis_peak。Ne_peakDetermining the electron density distribution function of the time-varying plasma sheath according to the distribution rule of sinusoidal distribution along the time direction, and establishing a time-varying plasma sheath electron density model Ne_dyn(z,t)；

2) Calculating the transmission coefficient T of the plasma sheath_dyn(t,f₀): carrier frequency f of input communication signal₀Electron mass m_eFrequency of electron impact v of time-varying plasma sheath_enIntrinsic wave impedance z of the layers of the plasma sheath_m(m-1, 2, …, N), intrinsic wave impedance z of vacuum₀Using a time-varying plasma sheath electron density model Ne_dyn(z, T) calculating the time-varying transmission coefficient T of the plasma sheath by an equivalent transmission line method_dyn(t,f₀) (ii) a The magnitude of the transmission coefficient will be calculated and the result assigned to the plasma sheath channel

Step two: constructing a large-scale downlink SIMO system model of the hypersonic aircraft:

as shown in fig. 4, it is composed of a hypersonic aircraft terminal single antenna and a multi-antenna receiving station, wherein the receiving station is equipped with n (n → ∞) antennas. The system has the receiving model of the equivalent baseband signal at the receiving station end in a time slot as follows:

y＝hx+v；

where y is the M × 1-dimensional received signal vector, x is the transmitted signal, the specific design will be given in the next section, h is the n × 1-dimensional channel matrix, and v is the complex gaussian white noise at the n × 1 receiving end. Each element of v follows a CSCG distribution with a mean of zero and a variance of σ²I.e. v_i～CN(0，σ²)，i＝1，2，…，n。

For the downlink plasma sheath-Rice channel of a hypersonic aircraft, where T denotes the plasma sheath channel, denoted by T_dyn(t,f₀) Obtaining;indicating spatial rice channel fading, i.e. matrix elementsThe envelope of (i) follows a rice distribution, i 1, …, n. Assume noise variance σ²T andis unknown information and the mean power attenuation q of the plasma sheath channel is known²。

Step three: optimized power modulation:

transmitting symbolsWhereinThe power of the k-th symbol is,is a code book, L isThe cardinality of (c). Let p be_k(k ═ 1, 2, ·, L) with equal probability of transmission and satisfying the average power constraintMean power attenuation q in terms of plasma sheath channel²And progressive characteristic design optimization of downlink channel

1) For p_k，Let p be_kDemodulation interval ofWherein d is_l，k>0，d_r，k>0，a_kIndicates the demodulation boundary r (p)_k)+d_r，k. The constellation to be designed is shown in fig. 5, for example, with L ═ 6, whereFor decision boundary, have d_r,k+d_l,k+1＝p_k+1-p_k，k∈[L-1]. Order toIndependent random variable U from 0 mean_kImplementation, U_kHas a moment mother function ofOrder toFor optimizing constellation P^optIs provided withHow to obtain the optimized t is explained below^optAnd optimizing the constellation P^opt。

(3.2) search for the highest t that satisfies the power constraint using Algorithm 1 and Algorithm 2^optAnd corresponding optimal constellation P^opt. The algorithm 1 is used for initializing and updating a t value, and the t value obtained by the algorithm 1 is substituted into the algorithm 2; searching a sending constellation under the current t value by using an algorithm 2; the algorithm 1 updates the value t according to whether the constellation obtained by the algorithm 2 meets the power constraint condition; algorithms 1 and 2 are cycled until the value of t meets the set precision 10^-3To obtain the highest t of which the output meets the power constraint^optAnd corresponding optimal constellation P^opt. Algorithms 1 and 2 are specifically as follows:

algorithm 1: initialization t_l＝0，t_u＝∞，Substituting t into algorithm 2; if the algorithm 2 constellation meets the power constraint condition, let t_lT; if the algorithm 2 constellation does not satisfy the power constraint condition, let t_uT; continuously substituting the obtained t value into the algorithm 2 to obtain the t value again, and circulating the algorithm 1 until the t value meets the set precision 10^-3。

And 2, algorithm: let p be₁＝0，Selection of p₂So that J (p) is₂) Is t, and d_l， This process is performed in order until p is found_L(ii) a Checking whether a power constraint condition is satisfied; if yes, the constellation is retained, t is increased by using an algorithm 1, and the process is repeated; if not, the constellation should be discarded, t is reduced using Algorithm 1 and the process repeated.

Step four: fast incoherent detection based on RRJ-MCMC algorithm:

to facilitate the following signal detection and performance analysis, the average power of the received vector y is first calculated:designing a simplified variable reverse-jump Monte Carlo (RRJ-MCMC) algorithm to estimateConditional Probability Density Function (CPDF)The Maximum Likelihood (ML) demodulator (or estimate of k) is then:

whereinIs a likelihood function/conditional probability density function.

In order to ensure that the Markov model can adapt to the dynamic property of the plasma sheath in various environments, the Markov model can be modeled into a Gaussian process, so that the probability density function of the whole model can be described by a Gaussian mixture process c, and the Markov model has the advantages that the Gaussian mixture process can be used for fitting any probability density function to realize unity in mathematical form, namely omega_kThe state probability of the state k in the Gaussian mixture process, namely the ratio of the k-th Gaussian process in the Gaussian mixture process,mean and variance are expressed:

the invention considers a two-dimensional time-varying sequence (c)_t，z_t) Describing reception statisticsc non-stationary random process, wherein (c)_t) Represents the statistical sequence of the receiving end, (z)_t) Sequence representing hidden states, z_tE { 1., L }, L representing the number of states in the markov model. The parameters to be estimated are λ ═ { μ, σ, z, ω } where μ ═ μ (μ ═ g)_k)，σ＝(σ_k)，ω＝(ω_k). Prior distribution of parameters: omega-D (delta)₁，δ₂，...，δ_L)，δ₁，δ₂，...，δ_LThe initialization is 1. Mu.s_k～N(ξ，κ^-1)，Wherein β to G (G, h), α ═ 2, and κ ═ R^-2，ξ＝y_min＝R/2，g＝0.2， h＝10/R²，R＝c_max-c_min(ii) a G (G, h) denotes the gamma distribution with parameters G and h, D (delta)₁，δ2，...，δ_L) Representing a Dirichlet distribution).

At the initial moment, the number of states may be set to L, with the remaining variables initialized based on their prior distributions; . The maximum number of iterations is set to N_iteration. At the time of iteration N, the state space x ═ (η, ω, z, μ, σ, c) of all relevant parameters is updated to a new state space at the time of iteration N +1, i.e., x ' ═ η ', ω ', z ', μ ', σ ', c '). Each iteration can be summarized in the following four steps:

1) update ω:

whereinFor hidden state z at time N_tK is the number of k;

2) update (μ, σ):

3) and updating z:

4) updating the beta:

the technical effects of the present invention will be described in detail with reference to simulations.

1. Simulation 1, simulation analysis of amplitude-phase characteristics of plasma sheath channel

Simulation conditions are as follows:

layered electron density model of time-varying plasma sheath: the thickness Z of the non-uniform plasma sheath near the antenna window of the hypersonic aerocraft is 0.06m, the total number N of the plasma sheath layers is 100, and the thickness d of each layer of the plasma sheath_m0.06cm, m is a plasma sheath layering sequence number m of 1, 2, …, N, the plasma sheath time-varying time T of 0.1s, and a first Gaussian function influence parameter c follows a double-Gaussian distribution along a direction vertical to an aircraft antenna window (set as a z-axis) according to the plasma sheath electron density₁＝2.56×10³And a second Gaussian function influence parameter c₂＝3.55×10³Peak electron density Ne_peak＝1×10¹⁸m^-3～1×10¹⁹m^-3The peak electron density is z in z-axis_peak0.036 m. Determining the electron density distribution function of the time-varying plasma sheath, and establishing a time-varying plasma sheath electron density model Ne_dyn(z,t)。

Calculating the transmission coefficient T of the plasma sheath_dyn(t,f₀): carrier frequency f of input communication signal₀28GHz, carrier angular frequency ω 2 pi f₀Electronic qualitym_e＝9.10953^-31kg, electron impact frequency v of time varying plasma sheath_enCalculating plasma frequency at 1GHzAnd complex dielectric constantGiving the intrinsic wave impedance of each layer of the plasma sheath Intrinsic wave impedance of vacuumElectron density model Ne using time-varying plasma sheath_dyn(z, T) calculating the time-varying transmission coefficient T of the plasma sheath by an equivalent transmission line method_dyn(t,f₀)。

2. Simulation results and analysis:

in fig. 6, a time-varying plot of plasma sheath electron density is depicted. It is seen that small scale jitter occurs in the plasma sheath electron density affected by the flow perturbation.

In fig. 7, the result of the magnitude of the transmission coefficient of the electric wave through the plasma at 28GHz is depicted, and the high dynamic disturbance occurs in the magnitude of the transmission coefficient of the electric wave through the plasma, which is affected by the disturbance of the electron density or the like. The amplitude of the transmission coefficient will consequently be assigned to the plasma sheath channel T.

3. And 2, simulating and analyzing the change conditions of the bit error rate and the channel capacity of the power modulation and incoherent detection scheme optimized by the downlink SIMO channel of the hypersonic aircraft along with the change of the signal-to-noise ratio or the number of the receiving antennas.

Simulation conditions are as follows:

the plasma sheath parameters and the electromagnetic wave time-varying transmission coefficients were the parameters and results of simulation 1. The rice factor K is {0, 1, ∞ }.

4. Simulation results and analysis:

fig. 8(a) and 8(b) show the peak electron density Ne at a signal-to-noise ratio γ of 10dB, a rice factor K of {0, 1, ∞ }, and_peakare respectively 2X 10¹⁸m^-3And 6X 10¹⁸m^-3The error rate is along with the change of the number of the receiving station antennas; fig. 8(c) shows the number of antennas 100 at the receiving station, K ═ 0, 1, ∞ Ne_peakIs 6 x 10¹⁸m^-3The error rate varies with the signal to noise ratio. It can be seen that the system error rate is exponentially reduced with the increase of the number of the receiving station antennas; with the increase of the signal-to-noise ratio, the system bit error rate is rapidly reduced; the larger the Rice factor K is, the better the system detection performance is.

Fig. 9(a) -9 (c) depict the corresponding channel capacity performance under the simulation conditions of fig. 8(a) -8 (c). The simulation finds that the channel capacity loss and the bit error rate of the system have the same variation trend along with the variation of the signal-to-noise ratio or the number of the receiving antennas. The system error rate is exponentially reduced along with the increase of the number of the receiving station antennas in the channel capacity; as the signal-to-noise ratio increases, the channel capacity decreases rapidly; the larger the rice factor K, the better the system channel capacity performance.

The invention discloses an incoherent large-scale SIMO system under a downlink telemetry channel of a hypersonic aerocraft. The scheme comprises two parts, namely a power modulation scheme of a downlink SIMO channel of the supersonic aircraft, and a corresponding self-adaptive incoherent signal detection method designed according to the modulation scheme. Firstly, establishing a hypersonic aircraft plasma sheath channel model, and establishing a hypersonic aircraft large-scale downlink SIMO system model; providing an optimized power modulation scheme on the basis of a system model; aiming at the power modulation scheme, an RRJ-MCMC algorithm is provided, and adaptive incoherent detection is provided on the basis of the algorithm. Simulations show that the method can improve the communication quality by increasing the number of receiving station antennas and improving the Rice factor and the signal-to-noise ratio. The adaptive power modulation scheme and the incoherent signal detection scheme under the downlink SIMO channel of the hypersonic aircraft disclosed by the invention can obviously improve the error rate performance of communication under a plasma channel, improve the communication quality and relieve the communication blackout.

It should be noted that the embodiments of the present invention can be realized by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or specially designed hardware. Those skilled in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such code being provided on a carrier medium such as a disk, CD-or DVD-ROM, programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier, for example. The apparatus and its modules of the present invention may be implemented by hardware circuits such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of hardware circuits and software, e.g., firmware.

The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.