CN112731273B - Low-complexity signal direction-of-arrival estimation method based on sparse Bayesian - Google Patents
Low-complexity signal direction-of-arrival estimation method based on sparse Bayesian Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
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Abstract
The invention discloses a sparse Bayesian-based low-complexity signal direction-of-arrival estimation method, and aims to solve the technical problems of high computational complexity and low computational efficiency of an MMV model in the prior art when time correlation problems are considered. It comprises the following steps: expanding an incident signal, and obtaining the prior of the expanded incident signal by using a Markov probability prior model; and (3) obtaining an input function and an output function of a GAMP algorithm according to the priori of the expanded incident signal, performing GAMP iteration, obtaining a recovered expanded incident signal, and obtaining a signal direction of arrival according to the recovered expanded incident signal. The method can reduce the calculation complexity of DOA estimation on the premise of considering time-related factors, improve the calculation efficiency and accurately estimate the signal arrival direction.
Description
Technical Field
The invention relates to a sparse Bayesian-based low-complexity signal direction-of-arrival estimation method, and belongs to the technical field of signal processing.
Background
The signal arrival direction (Direction of Arrival, DOA) is the incoming wave direction of an incident signal estimated by using the received data of an antenna array in a noisy environment, the basic principle is to estimate the space angle of the signal arrival array by using the phase difference existing between the received data of different array elements of a space array, and the method can be applied to the fields of radio communication, radar, sonar, navigation, seismic detection, biomedicine and the like and has important significance.
The SBL algorithm developed in recent years was originally proposed as a machine learning algorithm by Tipping et al before and after 2001, and then was introduced into the sparse signal recovery/compressed sensing field, and an initial SBL was applied to a model of a single measurement vector (Signal Measurement Vector, SMV) and then gradually expanded to a multi-measurement vector (Multiple Measurement Vectors, MMV), which has the advantages of higher resolution and a small reduction in calculation amount, but the DOA model used in MMV is more ideal and does not consider more practical factors. Zhang Zhilin et al in 2011 applied SBL to a time-dependent direction finding scene, proposed a time-dependent sparse bayesian learning (Temporally Sparse Bayesian Learning, TSBL) algorithm, introduced a super parameter to control the time correlation between snapshots, which can solve the time-dependent problem, but the introduced super parameter can cause an increase in the calculated amount, and the efficiency becomes very low, if on a large scale of problems such as a large number of array elements, accurate direction finding cannot be realized, and further algorithm optimization is necessary.
Disclosure of Invention
In order to solve the problems of high computational complexity and low computational efficiency of an MMV model in the prior art when time correlation problems are considered, the invention provides a sparse Bayesian-based low-complexity signal direction-of-arrival estimation method, which optimizes a derivation process of posterior probability by using Markov prior probability distribution on the basis of considering time correlation factors, decouples by using a GAMP algorithm, replaces matrix inversion steps in the prior art, reduces the calculated amount and improves the computational efficiency.
In order to solve the technical problems, the invention adopts the following technical means:
the invention provides a sparse Bayesian-based low-complexity signal direction-of-arrival estimation method, which comprises the following steps:
expanding an incident signal based on spatial domain meshing;
obtaining the priori of the expanded incident signal by using a Markov probability priori model;
obtaining an input function and an output function of a GAMP algorithm according to the priori of the expanded incident signal;
performing GAMP iteration on the snapshot of the expanded incident signal by using an input function and an output function of a GAMP algorithm to obtain a restored expanded incident signal;
and obtaining the signal arrival direction according to the recovered expanded incident signal.
Further, the specific steps of the incident signal expansion are as follows:
let the incident signal be x, the receiving array is made up of M homogeneous linear array antennas, when the receiving array receives T snapshots of the incident signal, obtain the output model of the array:
y=A(θ)x+e (1)
wherein y is a receiving signal of a receiving array, A (theta) is an array flow pattern matrix, and e is Gaussian white noise received by the receiving array;
grid dividing the space domain of the receiving array by using an exhaustion method to obtain an ultra-complete angle setWherein (1)>Indicating the nth overcomplete angle, H is the overcomplete angle set +.>N=1, 2, …, H;
wherein A (θ) _spark represents the expanded array flow pattern matrix;
obtaining an ultra-complete array output model according to the expanded array flow pattern matrix:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the expandedReceive signal,/->Representing the spread incident signal.
Further, the spatial domain of the receiving array is [ -90 °,90 ° ].
Further, the prior acquisition of the expanded incident signal includes the following steps:
modeling the expanded incident signal by using a Markov probability prior model to obtain the relation between the nth snapshot and the (t-1) th snapshot of the nth expanded incident signal:
wherein, the liquid crystal display device comprises a liquid crystal display device,an nth expanded incident signal representing a nth snapshot, +.>An n-th expanded incident signal representing the t-1 th snapshot, +.>Representation->And->The relation between beta and beta is the time correlation coefficient, beta epsilon (-1, 1), gamma n Is the a priori error of the nth spread incident signal, t=1, 2, …, T;
obtaining the influence of the previous snapshot according to the relation between the front snapshot and the rear snapshot of the expanded incident signalAnd the latterInfluence of snapshot->Wherein (1)>Representing the incident signal +.>Is>Represents the mean value of forward transmission of the t-1 snapshot in the nth expanded incident signal t snapshot,/->Representing the variance of the forward transmission of the t-1 snapshot in the nth expanded incident signal t snapshot,/for>Representing the incident signal +.>Is>Represents the mean value of backward transmission of t+1 snapshot in the time of t snapshot of the n-th expanded incident signal,/and>representing the variance of backward transfer of the t+1 snapshot in the snapshot of the nth expanded incident signal t;
further, the expression of the input function of the GAMP algorithm is as follows:
wherein g s Represents the input function, q (t) An approximation of the received signal representing the t-th snapshot without noise effects,represents q (t) Noise variance of y (t) Received signal, sigma, representing the t-th snapshot receiving matrix 2 Representing y (t) Is a noise variance of (1);
the expression of the output function of the GAMP algorithm is as follows:
wherein g x The output function is represented as a function of the output,representing an approximation of the nth expanded incident signal of the nth snapshot,representation->Is a noise variance of (a).
Further, the specific operation of obtaining the recovered expanded incident signal is as follows:
Input function and output function pairs using GAMP algorithmPerforming GAMP iteration, and updating the mean value and variance of the expanded incident signal;
updating iteration parameters by using an EM algorithm in each iteration process, and carrying out iteration convergence judgment by using iteration convergence conditions;
obtaining a recovered expanded incident signal according to the mean value and the variance of the expanded incident signal meeting the iterative convergence judgment;
wherein the iteration convergence condition comprises a GAMP iteration convergence condition and an EM iteration convergence condition.
Further, if the maximum iteration number of the GAMP algorithm is G, the iteration process of each iteration is specifically as follows:
according to the output of the ith-1 th iteration, obtaining the expanded incident signal of the t snapshot in the ith iterationVariance of->Mean value X i(t) Priori error gamma i And the noise variance (sigma) of the received signal 2 ) i Wherein i is [1, G ]];
Let s= |a (θ) _spark| 2 By usingAnd X i(t) Calculating the approximation q of the received signal of the t snapshot without noise effect in the i-th iteration i(t) :
Wherein g s (i-1)(t) An input function representing a t-snapshot of the i-1 th iteration;
using gamma i 、(σ 2 ) i And q i(t) Updating the input function g of the t snapshot of the ith iteration s i(t) ;
Using updated input function g s i(t) Respectively calculating approximate values r of the expanded incident signals of the t-th snapshot i(t) Noise variance of
Wherein A (θ) _spark T Represents a transpose of a (θ) _space, for inputting damping coefficient,/>s (i-1)(t) Representing the value of the i-1 th iteration, S T The transition of S is represented (g) s i(t) ) ' represents the input function g s i(t) Is a derivative of (2);
using gamma i 、r i(t) Andupdating the output function g of the t snapshot of the ith iteration x i(t) ;
According to the updated output function g x i(t) Updating the variance and the mean value of the expanded incident signal:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the variance of the expanded incident signal output from the ith iteration, (g) x i(t) ) ' represents the output function g x i(t) Derivative of X (i+1)(t) Representing the mean value of the expanded incident signal output from the ith iteration, < >>For outputting damping coefficient->
Pair X using GAMP iteration convergence conditions (i+1)(t) Andperforming GAMP iteration convergence judgment, ending iteration when GAMP iteration convergence conditions are met, outputting the mean value and the variance of the incident signal after the expansion of the ith iteration, and entering the next step when GAMP iteration convergence conditions are not met;
x output by ith iteration based on EM algorithm (i+1)(t) Andcalculating a priori error gamma in the (i+1) th iteration i+1 And noise variance (sigma) 2 ) i+1 The calculation formula is as follows:
(σ 2 ) i+1 =||y (t) -A(θ)_sparse·X (i+1)(t) || 2 (15)
pair X using EM iteration convergence conditions (i+1)(t) Andand (3) carrying out EM iteration convergence judgment, outputting the mean value and the variance of the incident signal after the expansion of the (i+1) th iteration when the EM iteration convergence condition is met, ending the iteration, and continuing the iteration when the EM iteration convergence condition is not met.
Further, the GAMP iteration convergence condition is:
or the iteration number i reaches the maximum iteration number G of the GAMP algorithm, wherein epsilon gamp Representing normalized tolerance parameters for the GAMP algorithm iterations.
Further, the EM iteration convergence condition is:
or the iteration number i reaches the maximum iteration number of the EM algorithmNumber K, where ε em Representing normalized tolerance parameters for EM algorithm iterations.
The following advantages can be obtained by adopting the technical means:
the invention provides a low-complexity signal direction-of-arrival estimation method based on sparse Bayes, which utilizes a Markov probability prior model to carry out modeling, considers factors related to the time when a plurality of beats are estimated by the direction-of-arrival estimation, improves the accuracy of a DOA model under a large-scale beat and time-related MMV model, is suitable for DOA model estimation in a non-ideal environment, and improves the robustness of the DOA estimation under the condition of low signal-to-noise ratio. After the priori of the incident signal is obtained, the invention combines with the GAMP idea, carries out GAMP iteration by introducing intermediate parameters, replaces the step of matrix inversion when solving the posterior probability density under the traditional Bayesian framework by iterative operation, greatly reduces the calculation complexity, improves the calculation efficiency and improves the resolution of signal arrival direction estimation.
In the signal direction of arrival estimation process, the method considers non-ideal environments such as time correlation and the like, balances good performances such as high resolution, low complexity and the like, breaks through the limitation of the existing SBL algorithm in the aspects of precision, complexity, robustness and the like, and has very important significance for the research of modern application scenes.
Drawings
Fig. 1 is a flowchart of steps of a sparse bayesian-based low-complexity signal direction-of-arrival estimation method according to the present invention.
FIG. 2 is a diagram illustrating messaging between multiple snapshot time frames in an embodiment of the present invention.
Fig. 3 is a normalized power spectrum diagram of the method and TMSBL algorithm under the condition of low signal to noise ratio in the embodiment of the present invention.
Fig. 4 is a normalized power spectrum diagram of the method and TMSBL algorithm under the condition of high signal to noise ratio in the embodiment of the present invention.
Fig. 5 is a graph comparing the RMSE of the method of the present invention and the TMSBL algorithm in an embodiment of the present invention.
FIG. 6 is a graph showing the comparison between the method of the present invention and TMSBL algorithm at CUP-time in the embodiment of the present invention.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings:
the invention provides a sparse Bayesian-based low-complexity signal direction-of-arrival estimation method, which is shown in fig. 1 and specifically comprises the following steps:
step 4, performing GAMP iteration on the snapshot of the expanded incident signal by utilizing an input function and an output function of a GAMP algorithm to obtain a restored expanded incident signal;
and step 5, obtaining the signal arrival direction according to the restored expanded incident signal.
In the embodiment of the invention, W narrow-band far-field signal sources with wavelength lambda are arranged, and theta is used for w Is injected into the receiving end, W is {1,2, and W, the incident signal is x, the receiving array of the receiving end consists of M uniform linear array antennas.
When the receiving array receives T snapshots of the incident signal, an array output model is obtained:
y=A(θ)x+e (16)
wherein y is a receiving signal of a receiving array, A (theta) is an array flow pattern matrix, e is Gaussian white noise received by the receiving array, e meets normal distribution, and e-N (0, sigma) 2 I),σ 2 Representing the noise variance of the received signal.
The expression of the array flow pattern matrix is as follows:
based on thinSparse representation theory, the incoming direction of the incident signal is sparse in the whole spatial domain, the resolvable spatial domain of the receiving array is [ -90 °,90 °]Grid division is carried out on the space domain of the receiving array by using an exhaustion method to obtain an ultra-complete angle setExpanding the incident signal, wherein +_>Represents the nth overcomplete angle, H is the overcomplete angle set +.>N=1, 2, …, H.
because the incident signal falls onto the grid, an overcomplete array output model is obtained from the expanded array flow pattern matrix:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the spread received signal, < >>Representing the expanded incident signal, < >>
The invention recovers the expanded incident signal by using the received signal and A (theta) _sparkThen use the expanded incident signal +.>The DOA direction of the incident signal x is obtained.
In step 2, the prior acquisition of the expanded incident signal is as follows:
step 201, under the bayesian framework, taking time-related factors, namely that an incident signal is affected by front and rear snapshots at the current moment, modeling a signal source by using a markov probability prior model, and combining the products of the front and rear snapshots into one message.
The invention introduces a time correlation coefficient beta, beta epsilon (-1, 1), beta can represent the relation between the previous snapshot and the next snapshot of a signal. Nth expanded incident signal of the nth snapshotCan be expressed as:
wherein, the liquid crystal display device comprises a liquid crystal display device,an n-th expanded incident signal representing the t-1 th snapshot, +.>γ n T=1, 2, …, T, a priori error of the nth spread incident signal.
Obtaining the relation between the nth snapshot and the (t-1) th snapshot of the nth expanded incident signal according to formula (19):
wherein, the liquid crystal display device comprises a liquid crystal display device,representation->And->Relationship between them.
Under MMV model, letThe message passing between the multiple snapshots is shown in fig. 2 for the first pass of the nth expanded incident signal of the nth snapshot.
Assuming that the prior of forward message transmission is a Gaussian distribution, introducing parameters eta and psi as the mean value and variance of the parameters eta and psi, the influence of the previous snapshot isLet the first pass of backward message be a gaussian distribution, introduce parameters v and phi as their mean and variance, then the effect of the latter snapshot is +.>Wherein (1)>Representing the incident signal +.>Is>Represents the mean value of forward transmission of the t-1 snapshot in the nth expanded incident signal t snapshot,/->Representing the variance of the forward transmission of the t-1 snapshot in the nth expanded incident signal t snapshot,representing the incident signal +.>Is>Represents the mean value of backward transmission of t+1 snapshot in the time of t snapshot of the n-th expanded incident signal,/and>representing the variance of the backward transmission of the t+1 snapshot of the nth expanded incident signal t snapshot.
after the priori of the incident signal is obtained, the invention combines with the GAMP idea, and performs subsequent calculation through intermediate parameters to replace the related step of matrix inversion, thereby reducing the calculation complexity. The invention introduces an intermediate parameter r as an approximation of the spread incident signal, giving the noise variance τ of r r Introducing an intermediate parameter q as an approximation of A (θ) x, i.e. joint without noise effectsApproximation of the received signal, given the noise variance τ of q q 。
According to Gaussian probability density function and convolution operation, substituting the formula (20) to obtain the average value of forward extinction transfer priorSum of variances->Is represented by the expression:
so that:
wherein, the liquid crystal display device comprises a liquid crystal display device,approximation of the n expanded incident signal representing the t-1 th snapshot,/>Representation->Is a noise variance of (a).
Similarly, a mean value of the prior of the backward message transmission can be obtainedSum of variances->Is represented by the expression:
the expression of the input function can be derived from the definition of the input function in the GAMP algorithm:
wherein g s Represents the input function, q (t) An approximation of the received signal representing the t-th snapshot without noise effects,represents q (t) Is z=a (θ) x, y (t) Received signal, sigma, representing the t-th snapshot receiving matrix 2 Representing y (t) Is a noise variance of (a).
From the definition and prior of output functions in the GAMP algorithmThe expression of the output function can be deduced:
wherein g x The output function is represented as a function of the output,representing an approximation of the nth expanded incident signal of the nth snapshot,representation->Is a noise variance of (a).
In the embodiment of the present invention, the specific operation of step 4 is as follows:
Input function and output function pairs using GAMP algorithmPerforming GAMP iteration, and updating the mean value and variance of the expanded incident signal;
updating iteration parameters by using an EM algorithm in each iteration process, and carrying out iteration convergence judgment by using iteration convergence conditions;
obtaining a recovered expanded incident signal according to the mean value and the variance of the expanded incident signal meeting the iterative convergence judgment;
the iteration convergence conditions comprise a GAMP iteration convergence condition and an EM iteration convergence condition, two convergence judgments are carried out according to 2 iteration convergence conditions in each iteration process, any one convergence judgments pass, and the iteration is terminated.
Setting the maximum iteration number of the GAMP algorithm as G, when the first iteration is carried out, initializing the values of the iteration number, the mean value, the variance, the priori error, the noise variance of the received signal and the like of the expanded incident signal, and outputting the recovered expanded incident signal when the iteration number is increased and the values are changed along with the increase of the iteration number until the iteration convergence condition is met.
Taking the ith iteration as an example, the iterative process is specifically as follows:
(1) According to the output of the ith-1 th iteration, obtaining the expanded incident signal of the t snapshot in the ith iterationVariance of->Mean value X i(t) Priori error gamma i And the noise variance (sigma) of the received signal 2 ) i Wherein i is [1, G ]]。
(2) Let s= |a (θ) _spark| 2 A calculation formula of variance of approximation of the received signal is obtained:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the variance of the approximation of the received signal for the t snapshot without noise effects in the i-th iteration.
(3) By means ofAnd X i(t) Calculating the approximation q of the received signal of the t snapshot without noise effect in the i-th iteration i(t) :
Wherein g s (i-1)(t) An input function representing a t-snapshot of the i-1 th iteration.
(4) Will gamma i 、(σ 2 ) i And q i(t) Equal substitution formula (28), updating the input function g of t snapshot of the ith iteration s i (t) 。
(5) For convergence of GAMP iterations, an input damping coefficient is introducedAnd output damping coefficient +.>Furthermore, an intermediate parameter s is introduced, the expression of s is:
wherein s is i(t) The value representing the ith iteration, which has no actual physical meaning, is simply a mathematical equation, s (i -1)(t) Representing the value of the i-1 th iteration.
(6) Using updated input function g s i(t) Respectively calculating approximate values r of the expanded incident signals of the t-th snapshot i(t) Noise variance of
Wherein A (θ) _spark T Represents the transpose of A (θ) _space, S T The transpose of S is represented (g) s i(t) ) ' represents the input function g s i(t) Is a derivative of (a).
(7) Will gamma i 、r i(t) And τ r i(t) Equal substitution formula (29), updating output function g of t snapshot of the ith iteration x i (t) 。
(8) According to the updated output function g x i(t) Updating the variance and the mean value of the expanded incident signal:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the variance of the expanded incident signal output from the ith iteration, (g) x i(t) ) ' represents the output function g x i(t) Derivative of X (i+1)(t) Representing the mean value of the expanded incident signal output by the ith iteration.
(9) Pair X using GAMP iteration convergence conditions (i+1)(t) Andand (3) performing GAMP iteration convergence judgment, wherein the GAMP iteration convergence condition is as follows: />
Or the iteration number i reaches the maximum iteration number G of the GAMP algorithm, wherein epsilon gamp Representing normalized tolerance parameters for the GAMP algorithm iterations.
Ending iteration and outputting when GAMP iteration convergence condition is satisfiedAnd X (i+1)(t) And when the GAMP iteration convergence condition is not satisfied, entering the next step.
(10) Iteration parameters are updated based on the EM algorithm (expectation maximization algorithm), and the ith iteration output X is utilized (i+1)(t) Andcalculating a priori error gamma in the (i+1) th iteration i+1 And noise variance (sigma) 2 ) i+1 The calculation formula is as follows:
(σ 2 ) i+1 =||y (t) -A(θ)_sparse·X (i+1)(t) || 2 (37)
(11) Pair X using EM iteration convergence conditions (i+1)(t) Andand (3) carrying out EM iteration convergence judgment, wherein the EM iteration convergence condition is as follows:
or the iteration number i reaches the maximum iteration number K of the EM algorithm, wherein ε em Representing normalized tolerance parameters for EM algorithm iterations.
When the EM iteration convergence condition is met, the (i+1) th iteration is carried out, only steps (1) - (8) are carried out in the (i+1) th iteration, the iteration is ended, and the average value X of the expanded incident signal of the (i+1) th iteration is output (i+2)(t) Sum of variancesAnd when the EM iteration convergence condition is not met, continuing iteration.
In step 5, each row of the recovered expanded incident signal contains only W non-zero values, the positions of which correspond to the DOA direction of the incident signal x.
Several groups of simulation experiments are provided for verifying the effect of the method:
simulation experiment 1:
the uniform linear array is adopted to receive the incident signals, the number M=12 of array elements of the receiving array is set, 4 signal sources are set, and the incoming wave angles are respectively as follows: -30.15, -10.23, 40.74, 28.39. In the MMV model, the sampling snapshot number T is 100, the signal direction of arrival estimation is carried out by using the method and the existing TMSBL algorithm respectively, normalized power spectrograms of the method and the existing TMSBL algorithm under different noise environments are shown in figures 3 and 4, and as can be seen from the figures, under the condition that the SNR=10dB of the low signal-to-noise ratio, the TMSBL algorithm taking time correlation factors into consideration can not be estimated, and the method can still accurately carry out the signal direction of arrival estimation; under the condition of high signal-to-noise ratio, namely SNR=40 dB, the peak of the power spectrum of the TMSBL algorithm is still inaccurate, and a false peak exists, so that the method is applicable to DOA model estimation of a non-ideal environment.
Simulation experiment 2:
let the number of array elements m=10 of the receiving array, there are 2 signal sources, the incoming wave direction is-11.21 and 0.74 respectively, the snapshot number T is 40. The predetermined grid point range is [ -90 °,90 ° ], and the resolution is 1 °. The performance comparison condition of the RMSE under the variation of signal-to-noise ratio (SNR) is researched by using the method and the existing TMSBL algorithm, and the root mean square error is obtained by averaging 500 Monte Carlo experiments aiming at each group of simulation parameter setting.
Fig. 5 is a graph comparing the RMES with the TMSBL algorithm, and it can be seen that, in consideration of the time correlation factor, the error of the method is far smaller than that of the TMSBL algorithm at the time of low signal to noise ratio, so that the accuracy of the method in a non-ideal environment is higher.
Simulation experiment 3:
under the condition that other simulation conditions are identical to the simulation experiment 2, the SNR=30dB is set, the performance comparison condition of CUP time along with the change of the snapshot number is researched by using the method and TMSBL algorithm, and the result is shown in figure 6, compared with TMSBL, the time required by the method is far smaller than TMSBL under the condition of large snapshot, the calculation complexity of the method under the condition of large snapshot number is lower, and the calculation efficiency is higher.
In summary, the method solves the problem of time correlation of the signal source in MMV direction of arrival estimation under a Bayesian framework, utilizes GAMP to replace a matrix inversion part in the traditional SBL algorithm, reduces the calculation complexity, and can estimate DOA more rapidly and with high precision. Under the non-ideal environment considering time correlation and the like, the method has the advantages of high resolution, low complexity, high accuracy, good robustness and the like.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (8)
1. A low-complexity signal direction-of-arrival estimation method based on sparse Bayes is characterized by comprising the following steps:
expanding an incident signal based on spatial domain meshing;
obtaining the priori of the expanded incident signal by using a Markov probability priori model;
obtaining an input function and an output function of a GAMP algorithm according to the priori of the expanded incident signal;
performing GAMP iteration on the snapshot of the expanded incident signal by using an input function and an output function of a GAMP algorithm to obtain a restored expanded incident signal;
obtaining a signal direction of arrival according to the recovered expanded incident signal;
the specific steps of the incident signal expansion are as follows:
let the incident signal be x, the receiving array is made up of M homogeneous linear array antennas, when the receiving array receives T snapshots of the incident signal, obtain the output model of the array:
y=A(θ)x+e
wherein y is a receiving signal of a receiving array, A (theta) is an array flow pattern matrix, and e is Gaussian white noise received by the receiving array;
grid dividing the space domain of the receiving array by using an exhaustion method to obtain an ultra-complete angle setWherein (1)>Represents the nth overcomplete angle, H is the overcomplete angle set +.>N=1, 2, …, H;
wherein A (θ) _spark represents the expanded array flow pattern matrix;
obtaining an ultra-complete array output model according to the expanded array flow pattern matrix:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the spread received signal, < >>Representing the expanded incident signal;
the a priori acquisition of the expanded incident signal is as follows:
modeling the expanded incident signal by using a Markov probability prior model to obtain the relation between the nth snapshot and the (t-1) th snapshot of the nth expanded incident signal:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the t-th speedN-th expanded incident signal of beat, < >>An n-th expanded incident signal representing the t-1 th snapshot, +.>Representation->And->The relation between beta and beta is the time correlation coefficient, beta epsilon (-1, 1), gamma n Is the a priori error of the nth spread incident signal, t=1, 2, …, T;
obtaining the influence of the previous snapshot according to the relation between the front snapshot and the rear snapshot of the expanded incident signalAnd the influence of the latter snapshot +.>Wherein (1)>Representing the incident signal +.>Is>Represents the mean value of forward transmission of the t-1 snapshot in the nth expanded incident signal t snapshot,/->Representing the nth expanded incident signalVariance of forward transmission of t-1 snapshot at t-th snapshot, +.>Representing the incident signal +.>Is used to determine the prior probability of (c) for a given channel,represents the mean value of backward transmission of t+1 snapshot in the time of t snapshot of the n-th expanded incident signal,/and>representing the variance of backward transmission of the t+1 snapshot in the snapshot of the nth expanded incident signal t;
2. a sparse bayesian-based low complexity signal direction of arrival estimation method according to claim 1, wherein the spatial domain of the receive array is [ -90 °,90 ° ].
4. the sparse bayesian-based low-complexity signal direction of arrival estimation method according to claim 1, wherein the expression of the input function of the GAMP algorithm is as follows:
wherein g s Represents the input function, q (t) An approximation of the received signal representing the t-th snapshot without noise effects,represents q (t) Noise variance of y (t) Received signal, sigma, representing the t-th snapshot receiving matrix 2 Representing y (t) Is a noise variance of (1);
the expression of the output function of the GAMP algorithm is as follows:
5. The sparse bayesian-based low-complexity signal direction of arrival estimation method of claim 4, wherein the specific operation of obtaining the recovered expanded incident signal is as follows:
Input function and output function pairs using GAMP algorithmPerforming GAMP iteration, and updating the mean value and variance of the expanded incident signal;
updating iteration parameters by using an EM algorithm in each iteration process, and carrying out iteration convergence judgment by using iteration convergence conditions;
obtaining a recovered expanded incident signal according to the mean value and the variance of the expanded incident signal meeting the iterative convergence judgment;
wherein the iteration convergence condition comprises a GAMP iteration convergence condition and an EM iteration convergence condition.
6. The sparse bayesian-based low-complexity signal direction of arrival estimation method according to claim 5, wherein if the maximum iteration number of the GAMP algorithm is G, the iteration process of each iteration is specifically as follows:
according to the output of the ith-1 th iteration, obtaining the expanded incident signal of the t snapshot in the ith iterationVariance of (2)Mean value X i(t) Priori error gamma i And the noise variance (sigma) of the received signal 2 ) i Wherein i is [1, G ]];
Let s= |a (θ) _spark| 2 By usingAnd X i(t) Calculating the approximation q of the received signal of the t snapshot without noise effect in the i-th iteration i(t) :
Wherein g s (i-1)(t) An input function representing a t-snapshot of the i-1 th iteration;
using gamma i 、(σ 2 ) i And q i(t) Updating the input function g of the t snapshot of the ith iteration s i(t) ;
Using updated input function g s i(t) Respectively calculating approximate values r of the expanded incident signals of the t-th snapshot i(t) Noise variance of
Wherein A (θ) _sparse T Represents a transpose of a (θ) _space, for inputting damping coefficient->s (i-1)(t) Representing the value of the i-1 th iteration, S T The transpose of S is represented (g) s i(t) ) ' represents the input function g s i(t) Is a derivative of (2);
using gamma i 、r i(t) Andupdating the output function g of the t snapshot of the ith iteration x i(t) ;
According to the updated output function g x i(t) Updating the variance and the mean value of the expanded incident signal:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the variance of the expanded incident signal output from the ith iteration, (g) x i(t) ) ' represents the output function g x i(t) Derivative of X (i+1)(t) Representing the mean value of the expanded incident signal output from the ith iteration, < >>In order to output the damping coefficient,
pair X using GAMP iteration convergence conditions (i+1)(t) Andperforming GAMP iteration convergence judgment, ending iteration when GAMP iteration convergence conditions are met, outputting the mean value and the variance of the incident signal after the expansion of the ith iteration, and entering the next step when GAMP iteration convergence conditions are not met;
x output by ith iteration based on EM algorithm (i+1)(t) Andcalculating a priori error gamma in the (i+1) th iteration i+1 And noise variance (sigma) 2 ) i+1 The calculation formula is as follows:
(σ 2 ) i+1 =||y (t) -A(θ)_sparse·X (i+1)(t) || 2
pair X using EM iteration convergence conditions (i+1)(t) Andand (3) carrying out EM iteration convergence judgment, outputting the mean value and the variance of the incident signal after the expansion of the (i+1) th iteration when the EM iteration convergence condition is met, ending the iteration, and continuing the iteration when the EM iteration convergence condition is not met.
7. The sparse bayesian-based low-complexity signal direction of arrival estimation method of claim 6, wherein the GAMP iterative convergence condition is:
8. The sparse bayesian-based low-complexity signal direction of arrival estimation method of claim 6, wherein said EM iteration convergence condition is:
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